Add 'backend/' from commit '51bf07d5e16469036a8363e6b9d53616cbed643f'

git-subtree-dir: backend
git-subtree-mainline: 6dc2b48035ed90480e499efdb4513dff7b566616
git-subtree-split: 51bf07d5e1

backend/src/main/java/com/petshop/backend/BackendApplication.java

@@ -0,0 +1,17 @@
+package com.petshop.backend;
+
+import com.petshop.backend.config.FlywayContextInitializer;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.data.web.config.EnableSpringDataWebSupport;
+
+@SpringBootApplication
+@EnableSpringDataWebSupport(pageSerializationMode = EnableSpringDataWebSupport.PageSerializationMode.VIA_DTO)
+public class BackendApplication {
+    public static void main(String[] args) {
+        RuntimeClasspathValidator.validate();
+        new SpringApplicationBuilder(BackendApplication.class)
+                .initializers(new FlywayContextInitializer())
+                .run(args);
+    }
+}

backend/src/main/java/com/petshop/backend/DevStackApplication.java

@@ -0,0 +1,177 @@
+package com.petshop.backend;
+
+import com.petshop.backend.config.FlywayContextInitializer;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.web.server.PortInUseException;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.event.ContextClosedEvent;
+
+import java.net.BindException;
+import java.time.Duration;
+import java.util.Locale;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public class DevStackApplication {
+
+    private static final Duration WATCH_INTERVAL = Duration.ofSeconds(2);
+
+    public static void main(String[] args) {
+        DockerComposeSupport docker = new DockerComposeSupport();
+        ConfigurableApplicationContext context = null;
+        CountDownLatch shutdownLatch = new CountDownLatch(1);
+        ScheduledExecutorService scheduler = null;
+        AtomicBoolean shuttingDown = new AtomicBoolean(false);
+        RuntimeException startupFailure = null;
+
+        try {
+            validateJavaVersion();
+            RuntimeClasspathValidator.validate();
+            docker.ensureDockerAvailable();
+            docker.startDatabase();
+            context = new SpringApplicationBuilder(BackendApplication.class)
+                    .initializers(new FlywayContextInitializer())
+                    .run(args);
+            context.addApplicationListener(event -> {
+                if (event instanceof ContextClosedEvent) {
+                    shutdownLatch.countDown();
+                }
+            });
+            scheduler = startDatabaseWatch(docker, context, shuttingDown);
+            shutdownLatch.await();
+        } catch (RuntimeException ex) {
+            startupFailure = ex;
+            throw new IllegalStateException(describeStartupFailure(ex), ex);
+        } catch (InterruptedException ex) {
+            Thread.currentThread().interrupt();
+            throw new IllegalStateException("Dev stack interrupted", ex);
+        } finally {
+            if (scheduler != null) {
+                scheduler.shutdownNow();
+            }
+            if (context != null && context.isActive()) {
+                context.close();
+            }
+            if (!shuttingDown.get()) {
+                try {
+                    docker.stopDatabase();
+                } catch (RuntimeException stopFailure) {
+                    if (startupFailure != null) {
+                        System.err.println(stopFailure.getMessage());
+                    } else {
+                        throw stopFailure;
+                    }
+                }
+            }
+        }
+    }
+
+    private static void validateJavaVersion() {
+        int feature = Runtime.version().feature();
+        if (feature < 25) {
+            throw new IllegalStateException("JDK 25 or newer is required. IntelliJ is currently using Java " + Runtime.version() + ".");
+        }
+    }
+
+    private static ScheduledExecutorService startDatabaseWatch(DockerComposeSupport docker, ConfigurableApplicationContext context, AtomicBoolean shuttingDown) {
+        ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor();
+        scheduler.scheduleWithFixedDelay(() -> {
+            if (shuttingDown.get()) {
+                return;
+            }
+            if (!docker.isDatabaseRunning()) {
+                shuttingDown.set(true);
+                if (context.isActive()) {
+                    context.close();
+                }
+            }
+        }, WATCH_INTERVAL.toSeconds(), WATCH_INTERVAL.toSeconds(), TimeUnit.SECONDS);
+        return scheduler;
+    }
+
+    private static String describeStartupFailure(RuntimeException ex) {
+        Throwable cause = deepestCause(ex);
+        String message = cause.getMessage();
+        String lowerMessage = "";
+        if (message != null) {
+            lowerMessage = message.toLowerCase(Locale.ROOT);
+        }
+
+        switch (classifyStartupFailure(cause, lowerMessage)) {
+            case SERVER_PORT_IN_USE:
+                return "Backend startup failed because port 8080 is already in use. Stop the other process or set SERVER_PORT to a different value.";
+            case DOCKER_NOT_RUNNING:
+                return "Backend startup failed because Docker is not available. Start Docker Desktop and try again.";
+            case DOCKER_NOT_INSTALLED:
+                return "Backend startup failed because Docker is not installed or not on PATH. Install Docker Desktop and reopen IntelliJ.";
+            case DATABASE_PORT_IN_USE:
+                return "Backend startup failed because port 3306 is already in use. Stop the conflicting MySQL service or container, then run Reset Database and try again.";
+            case STALE_SCHEMA:
+                return "Backend startup failed because the database schema is stale or incomplete. Run Reset Database and then start Pet Shop Application again.";
+            case FLYWAY_MIGRATION_FAILED:
+                return "Backend startup failed during Flyway migration. Run Reset Database and check the database logs if the problem persists.";
+            case DATASOURCE_CONFIG_MISSING:
+                return "Backend startup failed because datasource configuration was not loaded. Reload the Maven project and rerun Pet Shop Application.";
+            case DATABASE_UNREACHABLE:
+                return "Backend startup failed because it could not connect to MySQL. Make sure Docker Desktop is running, the database container is healthy, and port 3306 is reachable.";
+            case UNKNOWN:
+                if (message == null || message.isBlank()) {
+                    return "Backend startup failed: " + ex.getClass().getSimpleName();
+                }
+                return "Backend startup failed: " + message;
+            default:
+                throw new IllegalStateException("Unhandled startup failure classification");
+        }
+    }
+
+    private static StartupFailure classifyStartupFailure(Throwable cause, String lowerMessage) {
+        if (cause instanceof PortInUseException || cause instanceof BindException || lowerMessage.contains("port 8080") && lowerMessage.contains("already in use")) {
+            return StartupFailure.SERVER_PORT_IN_USE;
+        }
+        if (lowerMessage.contains("docker desktop") || lowerMessage.contains("docker daemon") || lowerMessage.contains("docker engine") || lowerMessage.contains("cannot connect to the docker daemon")) {
+            return StartupFailure.DOCKER_NOT_RUNNING;
+        }
+        if (lowerMessage.contains("docker executable") || lowerMessage.contains("no such file or directory") && lowerMessage.contains("docker")) {
+            return StartupFailure.DOCKER_NOT_INSTALLED;
+        }
+        if (lowerMessage.contains("port is already allocated") || lowerMessage.contains("address already in use") && lowerMessage.contains("3306")) {
+            return StartupFailure.DATABASE_PORT_IN_USE;
+        }
+        if (lowerMessage.contains("schema validation: missing table")) {
+            return StartupFailure.STALE_SCHEMA;
+        }
+        if (lowerMessage.contains("flyway") || lowerMessage.contains("migration")) {
+            return StartupFailure.FLYWAY_MIGRATION_FAILED;
+        }
+        if (lowerMessage.contains("datasource properties are required")) {
+            return StartupFailure.DATASOURCE_CONFIG_MISSING;
+        }
+        if (lowerMessage.contains("access denied for user") || lowerMessage.contains("communications link failure") || lowerMessage.contains("connection refused") || lowerMessage.contains("unable to determine dialect without jdbc metadata")) {
+            return StartupFailure.DATABASE_UNREACHABLE;
+        }
+        return StartupFailure.UNKNOWN;
+    }
+
+    private static Throwable deepestCause(Throwable throwable) {
+        Throwable current = throwable;
+        while (current.getCause() != null && current.getCause() != current) {
+            current = current.getCause();
+        }
+        return current;
+    }
+
+    private enum StartupFailure {
+        SERVER_PORT_IN_USE,
+        DOCKER_NOT_RUNNING,
+        DOCKER_NOT_INSTALLED,
+        DATABASE_PORT_IN_USE,
+        STALE_SCHEMA,
+        FLYWAY_MIGRATION_FAILED,
+        DATASOURCE_CONFIG_MISSING,
+        DATABASE_UNREACHABLE,
+        UNKNOWN
+    }
+}

backend/src/main/java/com/petshop/backend/DockerComposeSupport.java

@@ -0,0 +1,173 @@
+package com.petshop.backend;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+
+final class DockerComposeSupport {
+
+    private final Path projectDir = Paths.get("").toAbsolutePath();
+
+    void ensureDockerAvailable() {
+        CommandResult versionResult = runCommand(List.of(resolveDockerExecutable(), "version"), false);
+        if (versionResult.exitCode != 0) {
+            throw new IllegalStateException(describeDockerFailure(versionResult.output));
+        }
+    }
+
+    void startDatabase() {
+        runCommand(composeCommand("up", "-d", "--wait", "db"));
+    }
+
+    void stopDatabase() {
+        runCommand(composeCommand("stop", "db"));
+    }
+
+    void resetDatabase() {
+        runCommand(composeCommand("down", "-v", "--remove-orphans"));
+        String volumeName = getDatabaseVolumeName();
+        if (volumeExists(volumeName)) {
+            runCommand(List.of(resolveDockerExecutable(), "volume", "rm", "-f", volumeName));
+        }
+    }
+
+    boolean isDatabaseRunning() {
+        CommandResult result = runCommand(composeCommand("ps", "--status", "running", "--services", "db"), false);
+        if (result.exitCode != 0) {
+            return false;
+        }
+        return result.output.lines()
+                .map(String::trim)
+                .anyMatch("db"::equals);
+    }
+
+    private boolean volumeExists(String volumeName) {
+        CommandResult result = runCommand(List.of(resolveDockerExecutable(), "volume", "ls", "--format", "{{.Name}}"), false);
+        if (result.exitCode != 0) {
+            return false;
+        }
+        return result.output.lines()
+                .map(String::trim)
+                .anyMatch(volumeName::equals);
+    }
+
+    private String getDatabaseVolumeName() {
+        return projectDir.getFileName().toString() + "_db_data";
+    }
+
+    private List<String> composeCommand(String... args) {
+        List<String> command = new ArrayList<>();
+        command.add(resolveDockerExecutable());
+        command.add("compose");
+        command.add("-f");
+        command.add("docker-compose.dev.yml");
+        for (String arg : args) {
+            command.add(arg);
+        }
+        return command;
+    }
+
+    private String resolveDockerExecutable() {
+        String os = System.getProperty("os.name", "").toLowerCase(Locale.ROOT);
+        if (os.contains("win")) {
+            Path dockerPath = Paths.get("C:", "Program Files", "Docker", "Docker", "resources", "bin", "docker.exe");
+            if (Files.isRegularFile(dockerPath)) {
+                return dockerPath.toString();
+            }
+            Path dockerPathAlt = Paths.get("C:", "Program Files", "Docker", "Docker", "resources", "docker.exe");
+            if (Files.isRegularFile(dockerPathAlt)) {
+                return dockerPathAlt.toString();
+            }
+            return "docker.exe";
+        }
+        return "docker";
+    }
+
+    private void runCommand(List<String> command) {
+        CommandResult result = runCommand(command, true);
+        if (result.exitCode != 0) {
+            throw new IllegalStateException(describeCommandFailure(command, result.output));
+        }
+    }
+
+    private CommandResult runCommand(List<String> command, boolean printOutput) {
+        ProcessBuilder builder = new ProcessBuilder(command);
+        builder.directory(projectDir.toFile());
+        builder.redirectErrorStream(true);
+
+        try {
+            Process process = builder.start();
+            StringBuilder output = new StringBuilder();
+            try (BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()))) {
+                String line;
+                while ((line = reader.readLine()) != null) {
+                    output.append(line).append(System.lineSeparator());
+                    if (printOutput) {
+                        System.out.println(line);
+                    }
+                }
+            }
+            int exitCode = process.waitFor();
+            return new CommandResult(exitCode, output.toString().trim());
+        } catch (IOException ex) {
+            String executable = command.isEmpty() ? "docker" : command.getFirst();
+            throw new IllegalStateException("Unable to run " + executable + ". Install Docker Desktop and make sure it is available on PATH.", ex);
+        } catch (InterruptedException ex) {
+            Thread.currentThread().interrupt();
+            throw new IllegalStateException("Docker command interrupted", ex);
+        }
+    }
+
+    private String describeDockerFailure(String output) {
+        String lowerOutput = "";
+        if (output != null) {
+            lowerOutput = output.toLowerCase(Locale.ROOT);
+        }
+        if (lowerOutput.contains("docker desktop") || lowerOutput.contains("docker daemon") || lowerOutput.contains("docker engine") || lowerOutput.contains("cannot connect") || lowerOutput.contains("failed to connect") || lowerOutput.contains("docker_api") || lowerOutput.contains("docker api") || lowerOutput.contains("docker_engine") || lowerOutput.contains("pipe/docker_engine") || lowerOutput.contains("npipe")) {
+            return "Docker Desktop is not running. Start Docker Desktop and rerun the command.";
+        }
+        if (output == null || output.isBlank()) {
+            return "Docker is unavailable. Start Docker Desktop and rerun the command.";
+        }
+        return output;
+    }
+
+    private String describeCommandFailure(List<String> command, String output) {
+        String renderedCommand = String.join(" ", command);
+        String lowerOutput = "";
+        if (output != null) {
+            lowerOutput = output.toLowerCase(Locale.ROOT);
+        }
+        if (renderedCommand.contains(" up ") || renderedCommand.endsWith(" up -d --wait db")) {
+            if (lowerOutput.contains("port is already allocated") || lowerOutput.contains("address already in use")) {
+                return "Database startup failed because port 3306 is already in use. Stop the conflicting MySQL service or container, then run Reset Database.";
+            }
+            if (lowerOutput.contains("docker desktop") || lowerOutput.contains("docker daemon") || lowerOutput.contains("docker engine")) {
+                return "Database startup failed because Docker Desktop is not running.";
+            }
+            if (output == null || output.isBlank()) {
+                return "Database startup failed while bringing up the Docker MySQL container.";
+            }
+            return output;
+        }
+        if (renderedCommand.contains(" volume rm ")) {
+            if (output == null || output.isBlank()) {
+                return "Database reset failed while removing the Docker volume.";
+            }
+            return output;
+        }
+        if (output == null || output.isBlank()) {
+            return "Command failed: " + renderedCommand;
+        }
+        return output;
+    }
+
+    private record CommandResult(int exitCode, String output) {
+    }
+}

backend/src/main/java/com/petshop/backend/ResetDatabaseApplication.java

@@ -0,0 +1,10 @@
+package com.petshop.backend;
+
+public class ResetDatabaseApplication {
+
+    public static void main(String[] args) {
+        DockerComposeSupport docker = new DockerComposeSupport();
+        docker.ensureDockerAvailable();
+        docker.resetDatabase();
+    }
+}

backend/src/main/java/com/petshop/backend/RuntimeClasspathValidator.java

@@ -0,0 +1,24 @@
+package com.petshop.backend;
+
+import java.net.URL;
+
+final class RuntimeClasspathValidator {
+
+    private RuntimeClasspathValidator() {
+    }
+
+    static void validate() {
+        if (!resourceExists("application.yml")) {
+            throw new IllegalStateException("Backend resources are missing from the runtime classpath. Reimport the Maven project in IntelliJ and run the shared Maven run configuration.");
+        }
+        if (!resourceExists("db/migration/V1__baseline_schema.sql")) {
+            throw new IllegalStateException("Flyway migration files are missing from the runtime classpath. Reimport the Maven project in IntelliJ and run the shared Maven run configuration.");
+        }
+    }
+
+    private static boolean resourceExists(String path) {
+        ClassLoader classLoader = RuntimeClasspathValidator.class.getClassLoader();
+        URL resource = classLoader.getResource(path);
+        return resource != null;
+    }
+}

backend/src/main/java/com/petshop/backend/config/DataInitializer.java

@@ -0,0 +1,167 @@
+package com.petshop.backend.config;
+
+import com.petshop.backend.entity.User;
+import com.petshop.backend.repository.UserRepository;
+import com.petshop.backend.service.StoreAssignmentService;
+import com.petshop.backend.service.UserBusinessLinkageService;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.stereotype.Component;
+
+@Component
+public class DataInitializer implements CommandLineRunner {
+
+    private final UserRepository userRepository;
+    private final PasswordEncoder passwordEncoder;
+    private final UserBusinessLinkageService userBusinessLinkageService;
+    private final StoreAssignmentService storeAssignmentService;
+
+    public DataInitializer(UserRepository userRepository, PasswordEncoder passwordEncoder, UserBusinessLinkageService userBusinessLinkageService, StoreAssignmentService storeAssignmentService) {
+        this.userRepository = userRepository;
+        this.passwordEncoder = passwordEncoder;
+        this.userBusinessLinkageService = userBusinessLinkageService;
+        this.storeAssignmentService = storeAssignmentService;
+    }
+
+    @Override
+    public void run(String... args) {
+        System.out.println("==== DataInitializer: Starting user creation ====");
+
+        User admin = userRepository.findByUsername("admin").orElse(null);
+        if (admin == null) {
+            System.out.println("Creating admin user...");
+            admin = new User();
+            admin.setUsername("admin");
+            admin.setPassword(passwordEncoder.encode("admin123"));
+            admin.setEmail("admin@petshop.com");
+            admin.setFullName("Admin User");
+            admin.setPhone("000-000-1000");
+            admin.setRole(User.Role.ADMIN);
+            admin.setActive(true);
+            admin = userRepository.save(admin);
+            System.out.println("Admin user created successfully");
+        } else {
+            System.out.println("Admin user already exists");
+            // Normalize missing fields if needed
+            boolean updated = false;
+            if (admin.getFullName() == null || admin.getFullName().isEmpty()) {
+                admin.setFullName("Admin User");
+                updated = true;
+            }
+            if (admin.getEmail() == null || admin.getEmail().isEmpty()) {
+                admin.setEmail("admin@petshop.com");
+                updated = true;
+            }
+            if (admin.getPhone() == null || admin.getPhone().isEmpty()) {
+                admin.setPhone("000-000-1000");
+                updated = true;
+            }
+            if (admin.getActive() == null) {
+                admin.setActive(true);
+                updated = true;
+            }
+            if (admin.getRole() == null) {
+                admin.setRole(User.Role.ADMIN);
+                updated = true;
+            }
+            if (updated) {
+                admin = userRepository.save(admin);
+                System.out.println("Admin user normalized");
+            }
+        }
+        // Ensure linked employee
+        storeAssignmentService.assignStoreIfMissing(userBusinessLinkageService.ensureLinkedEmployee(admin), 1L);
+
+        User staff = userRepository.findByUsername("staff").orElse(null);
+        if (staff == null) {
+            System.out.println("Creating staff user...");
+            staff = new User();
+            staff.setUsername("staff");
+            staff.setPassword(passwordEncoder.encode("staff123"));
+            staff.setEmail("staff@petshop.com");
+            staff.setFullName("Staff User");
+            staff.setPhone("000-000-1001");
+            staff.setRole(User.Role.STAFF);
+            staff.setActive(true);
+            staff = userRepository.save(staff);
+            System.out.println("Staff user created successfully");
+        } else {
+            System.out.println("Staff user already exists");
+            // Normalize missing fields if needed
+            boolean updated = false;
+            if (staff.getFullName() == null || staff.getFullName().isEmpty()) {
+                staff.setFullName("Staff User");
+                updated = true;
+            }
+            if (staff.getEmail() == null || staff.getEmail().isEmpty()) {
+                staff.setEmail("staff@petshop.com");
+                updated = true;
+            }
+            if (staff.getPhone() == null || staff.getPhone().isEmpty()) {
+                staff.setPhone("000-000-1001");
+                updated = true;
+            }
+            if (staff.getActive() == null) {
+                staff.setActive(true);
+                updated = true;
+            }
+            if (staff.getRole() == null) {
+                staff.setRole(User.Role.STAFF);
+                updated = true;
+            }
+            if (updated) {
+                staff = userRepository.save(staff);
+                System.out.println("Staff user normalized");
+            }
+        }
+        // Ensure linked employee
+        storeAssignmentService.assignStoreIfMissing(userBusinessLinkageService.ensureLinkedEmployee(staff), 1L);
+
+        User customer = userRepository.findByUsername("customer").orElse(null);
+        if (customer == null) {
+            System.out.println("Creating customer user...");
+            customer = new User();
+            customer.setUsername("customer");
+            customer.setPassword(passwordEncoder.encode("customer123"));
+            customer.setEmail("customer@petshop.com");
+            customer.setFullName("Test Customer");
+            customer.setPhone("000-000-1002");
+            customer.setRole(User.Role.CUSTOMER);
+            customer.setActive(true);
+            customer = userRepository.save(customer);
+            System.out.println("Customer user created successfully");
+        } else {
+            System.out.println("Customer user already exists");
+            // Normalize missing fields if needed
+            boolean updated = false;
+            if (customer.getFullName() == null || customer.getFullName().isEmpty()) {
+                customer.setFullName("Test Customer");
+                updated = true;
+            }
+            if (customer.getEmail() == null || customer.getEmail().isEmpty()) {
+                customer.setEmail("customer@petshop.com");
+                updated = true;
+            }
+            if (customer.getPhone() == null || customer.getPhone().isEmpty()) {
+                customer.setPhone("000-000-1002");
+                updated = true;
+            }
+            if (customer.getActive() == null) {
+                customer.setActive(true);
+                updated = true;
+            }
+            if (customer.getRole() == null) {
+                customer.setRole(User.Role.CUSTOMER);
+                updated = true;
+            }
+            if (updated) {
+                customer = userRepository.save(customer);
+                System.out.println("Customer user normalized");
+            }
+        }
+        // Ensure linked customer
+        userBusinessLinkageService.ensureLinkedCustomer(customer);
+
+        System.out.println("==== DataInitializer: Completed ====");
+    }
+}

backend/src/main/java/com/petshop/backend/config/FlywayContextInitializer.java

@@ -0,0 +1,40 @@
+package com.petshop.backend.config;
+
+import org.flywaydb.core.Flyway;
+import org.flywaydb.core.api.MigrationVersion;
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.core.env.ConfigurableEnvironment;
+
+import java.util.Arrays;
+
+public class FlywayContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
+
+    @Override
+    public void initialize(ConfigurableApplicationContext applicationContext) {
+        ConfigurableEnvironment environment = applicationContext.getEnvironment();
+
+        String url = environment.getProperty("spring.datasource.url");
+        String username = environment.getProperty("spring.datasource.username");
+        String password = environment.getProperty("spring.datasource.password");
+
+        if (url == null || username == null || password == null) {
+            throw new IllegalStateException("Datasource properties are required before startup");
+        }
+
+        String[] locations = Arrays.stream(environment
+                        .getProperty("spring.flyway.locations", "classpath:db/migration")
+                        .split(","))
+                .map(String::trim)
+                .filter(location -> !location.isEmpty())
+                .toArray(String[]::new);
+
+        Flyway.configure()
+                .dataSource(url, username, password)
+                .locations(locations)
+                .baselineOnMigrate(environment.getProperty("spring.flyway.baseline-on-migrate", Boolean.class, false))
+                .baselineVersion(MigrationVersion.fromVersion(environment.getProperty("spring.flyway.baseline-version", "1")))
+                .load()
+                .migrate();
+    }
+}

backend/src/main/java/com/petshop/backend/config/TomcatPathToleranceConfig.java

@@ -0,0 +1,19 @@
+package com.petshop.backend.config;
+
+import org.springframework.boot.tomcat.servlet.TomcatServletWebServerFactory;
+import org.springframework.boot.web.server.WebServerFactoryCustomizer;
+import org.springframework.stereotype.Component;
+
+@Component
+public class TomcatPathToleranceConfig implements WebServerFactoryCustomizer<TomcatServletWebServerFactory> {
+
+    @Override
+    public void customize(TomcatServletWebServerFactory factory) {
+        factory.addConnectorCustomizers(connector -> {
+            connector.setAllowBackslash(true);
+            connector.setEncodedReverseSolidusHandling("decode");
+            connector.setProperty("relaxedPathChars", "\\");
+            connector.setProperty("relaxedQueryChars", "\\");
+        });
+    }
+}

backend/src/main/java/com/petshop/backend/config/TrailingSlashNormalizationFilter.java

@@ -0,0 +1,91 @@
+package com.petshop.backend.config;
+
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletRequestWrapper;
+import jakarta.servlet.http.HttpServletResponse;
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.Order;
+import org.springframework.stereotype.Component;
+import org.springframework.web.filter.OncePerRequestFilter;
+
+import java.io.IOException;
+
+@Component
+@Order(Ordered.HIGHEST_PRECEDENCE)
+public class TrailingSlashNormalizationFilter extends OncePerRequestFilter {
+
+    @Override
+    protected boolean shouldNotFilter(HttpServletRequest request) {
+        String requestUri = request.getRequestURI();
+        if (requestUri == null || requestUri.isBlank()) {
+            return true;
+        }
+        return requestUri.equals(normalizePath(requestUri));
+    }
+
+    @Override
+    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
+        String normalizedUri = normalizePath(request.getRequestURI());
+        String normalizedServletPath = normalizePath(request.getServletPath());
+        String normalizedPathInfo = normalizePath(request.getPathInfo());
+
+        HttpServletRequestWrapper wrapper = new HttpServletRequestWrapper(request) {
+            @Override
+            public String getRequestURI() {
+                return normalizedUri;
+            }
+
+            @Override
+            public StringBuffer getRequestURL() {
+                String original = super.getRequestURL().toString();
+                int schemeSeparator = original.indexOf("://");
+                int pathStart = schemeSeparator >= 0 ? original.indexOf('/', schemeSeparator + 3) : original.indexOf('/');
+                if (pathStart < 0) {
+                    return new StringBuffer(original);
+                }
+                String prefix = original.substring(0, pathStart);
+                return new StringBuffer(prefix + normalizedUri);
+            }
+
+            @Override
+            public String getServletPath() {
+                return normalizedServletPath;
+            }
+
+            @Override
+            public String getPathInfo() {
+                return normalizedPathInfo;
+            }
+        };
+
+        filterChain.doFilter(wrapper, response);
+    }
+
+    private String normalizePath(String value) {
+        if (value == null) {
+            return null;
+        }
+        String normalized = value.replace('\\', '/');
+        while (normalized.contains("//")) {
+            normalized = normalized.replace("//", "/");
+        }
+        if (shouldLowercase(normalized)) {
+            normalized = normalized.toLowerCase(java.util.Locale.ROOT);
+        }
+        int end = normalized.length();
+        while (end > 1 && normalized.charAt(end - 1) == '/') {
+            end--;
+        }
+        return normalized.substring(0, end);
+    }
+
+    private boolean shouldLowercase(String path) {
+        String lower = path.toLowerCase(java.util.Locale.ROOT);
+        return lower.startsWith("/api/")
+                || lower.equals("/api")
+                || lower.startsWith("/ws/")
+                || lower.equals("/ws");
+    }
+}

backend/src/main/java/com/petshop/backend/config/WebSocketAuthChannelInterceptor.java

@@ -0,0 +1,237 @@
+package com.petshop.backend.config;
+
+import com.petshop.backend.entity.User;
+import com.petshop.backend.repository.UserRepository;
+import com.petshop.backend.security.AppPrincipal;
+import com.petshop.backend.security.JwtUtil;
+import com.petshop.backend.service.ChatService;
+import io.jsonwebtoken.JwtException;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.MessageChannel;
+import org.springframework.messaging.simp.stomp.StompCommand;
+import org.springframework.messaging.simp.stomp.StompHeaderAccessor;
+import org.springframework.messaging.support.ChannelInterceptor;
+import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
+import org.springframework.stereotype.Component;
+
+import java.security.Principal;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+
+@Component
+public class WebSocketAuthChannelInterceptor implements ChannelInterceptor {
+
+    private final JwtUtil jwtUtil;
+    private final UserRepository userRepository;
+    private final ChatService chatService;
+
+    public WebSocketAuthChannelInterceptor(JwtUtil jwtUtil, UserRepository userRepository, ChatService chatService) {
+        this.jwtUtil = jwtUtil;
+        this.userRepository = userRepository;
+        this.chatService = chatService;
+    }
+
+    @Override
+    public Message<?> preSend(Message<?> message, MessageChannel channel) {
+        StompHeaderAccessor accessor = StompHeaderAccessor.wrap(message);
+        StompCommand command = accessor.getCommand();
+
+        if (command == null) {
+            return message;
+        }
+
+        if (StompCommand.CONNECT.equals(command)) {
+            String tokenHeader = firstHeader(accessor, "Authorization");
+            String token = extractToken(tokenHeader != null ? tokenHeader : firstHeader(accessor, "token"));
+            if (token == null || token.isBlank()) {
+                throw new IllegalArgumentException("Missing websocket token");
+            }
+
+            Long userId = extractUserId(token);
+            User user = userId == null ? null : userRepository.findById(userId).orElse(null);
+            if (user == null) {
+                throw new IllegalArgumentException("User not found");
+            }
+            if (user.getActive() == null || !user.getActive()) {
+                throw new IllegalArgumentException("User account is inactive");
+            }
+            if (!jwtUtil.validateToken(token, user)) {
+                throw new IllegalArgumentException("Invalid websocket token");
+            }
+
+            AppPrincipal principal = new AppPrincipal(
+                    user.getId(),
+                    user.getUsername(),
+                    user.getRole(),
+                    user.getTokenVersion()
+            );
+            UsernamePasswordAuthenticationToken authentication = new UsernamePasswordAuthenticationToken(
+                    principal,
+                    null,
+                    principal.getAuthorities()
+            );
+            accessor.setUser(authentication);
+            accessor.getSessionAttributes().put("user", authentication);
+            return message;
+        }
+
+        if (StompCommand.DISCONNECT.equals(command) || StompCommand.UNSUBSCRIBE.equals(command)) {
+            return message;
+        }
+
+        User user = resolveUser(accessor.getUser(), accessor);
+        if (user == null) {
+            throw new IllegalArgumentException("Unauthenticated websocket session");
+        }
+
+        if (StompCommand.SUBSCRIBE.equals(command)) {
+            authorizeSubscription(accessor.getDestination(), user);
+        } else if (StompCommand.SEND.equals(command)) {
+            authorizeSend(accessor.getDestination(), user);
+        }
+
+        return message;
+    }
+
+    private User resolveUser(Principal principal, StompHeaderAccessor accessor) {
+        Principal currentPrincipal = principal;
+        if (currentPrincipal == null && accessor.getSessionAttributes() != null) {
+            Object sessionUser = accessor.getSessionAttributes().get("user");
+            if (sessionUser instanceof Principal storedPrincipal) {
+                accessor.setUser(storedPrincipal);
+                currentPrincipal = storedPrincipal;
+            }
+        }
+
+        if (currentPrincipal instanceof UsernamePasswordAuthenticationToken authenticationToken
+                && authenticationToken.getPrincipal() instanceof AppPrincipal appPrincipal) {
+            return userRepository.findById(appPrincipal.getUserId())
+                    .orElseThrow(() -> new IllegalArgumentException("User not found"));
+        }
+
+        if (currentPrincipal instanceof AppPrincipal appPrincipal) {
+            return userRepository.findById(appPrincipal.getUserId())
+                    .orElseThrow(() -> new IllegalArgumentException("User not found"));
+        }
+
+        String tokenHeader = firstHeader(accessor, "Authorization");
+        String token = extractToken(tokenHeader != null ? tokenHeader : firstHeader(accessor, "token"));
+        if (token == null || token.isBlank()) {
+            return null;
+        }
+
+        Long userId = extractUserId(token);
+        User user = userId == null ? null : userRepository.findById(userId).orElse(null);
+        if (user == null) {
+            throw new IllegalArgumentException("User not found");
+        }
+        if (user.getActive() == null || !user.getActive()) {
+            throw new IllegalArgumentException("User account is inactive");
+        }
+        if (!jwtUtil.validateToken(token, user)) {
+            throw new IllegalArgumentException("Invalid websocket token");
+        }
+        return user;
+    }
+
+    private void authorizeSubscription(String destination, User user) {
+        destination = normalizeDestination(destination);
+        if (destination == null || destination.startsWith("/user/queue/")) {
+            return;
+        }
+
+        if ("/topic/chat/conversations".equals(destination)) {
+            if (user.getRole() == User.Role.CUSTOMER) {
+                throw new IllegalArgumentException("Customers cannot subscribe to staff conversation feed");
+            }
+            return;
+        }
+
+        Long conversationId = extractConversationId(destination, "/topic/chat/conversations/");
+        if (conversationId != null && chatService.hasConversationAccess(conversationId, user.getId(), user.getRole())) {
+            return;
+        }
+
+        throw new IllegalArgumentException("Not authorized to subscribe to destination");
+    }
+
+    private void authorizeSend(String destination, User user) {
+        destination = normalizeDestination(destination);
+        Long conversationId = extractConversationId(destination, "/app/chat/conversations/");
+        if (conversationId != null && destination.endsWith("/messages") && chatService.hasConversationAccess(conversationId, user.getId(), user.getRole())) {
+            return;
+        }
+
+        throw new IllegalArgumentException("Not authorized to send to destination");
+    }
+
+    private Long extractConversationId(String destination, String prefix) {
+        if (destination == null || !destination.startsWith(prefix)) {
+            return null;
+        }
+
+        String suffix = destination.substring(prefix.length());
+        String[] parts = suffix.split("/");
+        if (parts.length == 0 || parts[0].isBlank()) {
+            return null;
+        }
+
+        try {
+            return Long.parseLong(parts[0]);
+        } catch (NumberFormatException ex) {
+            return null;
+        }
+    }
+
+    private String firstHeader(StompHeaderAccessor accessor, String name) {
+        List<String> values = accessor.getNativeHeader(name);
+        if (values != null && !values.isEmpty()) {
+            return values.get(0);
+        }
+        for (String headerName : accessor.toNativeHeaderMap().keySet()) {
+            if (headerName.equalsIgnoreCase(name)) {
+                List<String> alternateValues = accessor.getNativeHeader(headerName);
+                return alternateValues == null || alternateValues.isEmpty() ? null : alternateValues.get(0);
+            }
+        }
+        return null;
+    }
+
+    private String extractToken(String rawValue) {
+        if (rawValue == null || rawValue.isBlank()) {
+            return null;
+        }
+        String normalized = rawValue.trim();
+        return normalized.regionMatches(true, 0, "Bearer ", 0, 7) ? normalized.substring(7) : normalized;
+    }
+
+    private String normalizeDestination(String destination) {
+        if (destination == null || destination.isBlank()) {
+            return destination;
+        }
+        String normalized = destination.replace('\\', '/');
+        while (normalized.contains("//")) {
+            normalized = normalized.replace("//", "/");
+        }
+        return normalized.toLowerCase(Locale.ROOT);
+    }
+
+    private Long extractUserId(String token) {
+        try {
+            return jwtUtil.extractUserId(token);
+        } catch (JwtException | IllegalArgumentException ex) {
+            throw new IllegalArgumentException("Invalid websocket token: " + ex.getMessage(), ex);
+        }
+    }
+
+    public Map<String, Object> buildErrorPayload(Exception ex, String destination, Principal principal) {
+        Map<String, Object> response = new LinkedHashMap<>();
+        response.put("message", ex.getMessage() == null || ex.getMessage().isBlank() ? "WebSocket request failed" : ex.getMessage());
+        response.put("details", ex.getClass().getSimpleName());
+        response.put("destination", normalizeDestination(destination));
+        response.put("authenticated", principal != null);
+        return response;
+    }
+}

backend/src/main/java/com/petshop/backend/config/WebSocketConfig.java

@@ -0,0 +1,45 @@
+package com.petshop.backend.config;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.messaging.simp.config.ChannelRegistration;
+import org.springframework.messaging.simp.config.MessageBrokerRegistry;
+import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
+import org.springframework.web.socket.config.annotation.StompEndpointRegistry;
+import org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurer;
+
+@Configuration
+@EnableWebSocketMessageBroker
+public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {
+
+    private final WebSocketAuthChannelInterceptor webSocketAuthChannelInterceptor;
+
+    public WebSocketConfig(WebSocketAuthChannelInterceptor webSocketAuthChannelInterceptor) {
+        this.webSocketAuthChannelInterceptor = webSocketAuthChannelInterceptor;
+    }
+
+    @Override
+    public void configureMessageBroker(MessageBrokerRegistry config) {
+        config.enableSimpleBroker("/topic", "/queue");
+        config.setApplicationDestinationPrefixes("/app");
+        config.setUserDestinationPrefix("/user");
+    }
+
+    @Override
+    public void configureClientInboundChannel(ChannelRegistration registration) {
+        registration.interceptors(webSocketAuthChannelInterceptor);
+    }
+
+    @Override
+    public void registerStompEndpoints(StompEndpointRegistry registry) {
+        registry.addEndpoint("/ws/chat")
+                .setAllowedOriginPatterns("*");
+        registry.addEndpoint("/ws/chat/")
+                .setAllowedOriginPatterns("*");
+        registry.addEndpoint("/ws/chat-sockjs")
+                .setAllowedOriginPatterns("*")
+                .withSockJS();
+        registry.addEndpoint("/ws/chat-sockjs/")
+                .setAllowedOriginPatterns("*")
+                .withSockJS();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/AdoptionController.java

@@ -0,0 +1,113 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.adoption.AdoptionRequest;
+import com.petshop.backend.dto.adoption.AdoptionResponse;
+import com.petshop.backend.dto.common.BulkDeleteRequest;
+import com.petshop.backend.entity.Customer;
+import com.petshop.backend.repository.CustomerRepository;
+import com.petshop.backend.repository.UserRepository;
+import com.petshop.backend.service.AdoptionService;
+import com.petshop.backend.util.AuthenticationHelper;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/adoptions")
+public class AdoptionController {
+
+    private final AdoptionService adoptionService;
+    private final UserRepository userRepository;
+    private final CustomerRepository customerRepository;
+
+    public AdoptionController(AdoptionService adoptionService, UserRepository userRepository, CustomerRepository customerRepository) {
+        this.adoptionService = adoptionService;
+        this.userRepository = userRepository;
+        this.customerRepository = customerRepository;
+    }
+
+    @GetMapping
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<Page<AdoptionResponse>> getAllAdoptions(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        String role = authentication.getAuthorities().stream()
+                .findFirst()
+                .map(authority -> authority.getAuthority().replace("ROLE_", ""))
+                .orElse(null);
+
+        Long customerId = null;
+        if (role != null && role.equals("CUSTOMER")) {
+            Customer customer = AuthenticationHelper.getAuthenticatedCustomer(userRepository, customerRepository);
+            customerId = customer.getCustomerId();
+        }
+
+        return ResponseEntity.ok(adoptionService.getAllAdoptions(q, pageable, customerId));
+    }
+
+    @GetMapping("/{id}")
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<AdoptionResponse> getAdoptionById(@PathVariable Long id) {
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        String role = authentication.getAuthorities().stream()
+                .findFirst()
+                .map(authority -> authority.getAuthority().replace("ROLE_", ""))
+                .orElse(null);
+
+        Long customerId = null;
+        if (role != null && role.equals("CUSTOMER")) {
+            Customer customer = AuthenticationHelper.getAuthenticatedCustomer(userRepository, customerRepository);
+            customerId = customer.getCustomerId();
+        }
+
+        return ResponseEntity.ok(adoptionService.getAdoptionById(id, customerId));
+    }
+
+    @PostMapping
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<AdoptionResponse> createAdoption(@Valid @RequestBody AdoptionRequest request) {
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        String role = authentication.getAuthorities().stream()
+                .findFirst()
+                .map(authority -> authority.getAuthority().replace("ROLE_", ""))
+                .orElse(null);
+
+        if (role != null && role.equals("CUSTOMER")) {
+            Customer customer = AuthenticationHelper.getAuthenticatedCustomer(userRepository, customerRepository);
+            if (!request.getCustomerId().equals(customer.getCustomerId())) {
+                throw new org.springframework.security.access.AccessDeniedException("You can only create adoptions for yourself");
+            }
+        }
+
+        return ResponseEntity.status(HttpStatus.CREATED).body(adoptionService.createAdoption(request));
+    }
+
+    @PutMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<AdoptionResponse> updateAdoption(
+            @PathVariable Long id,
+            @Valid @RequestBody AdoptionRequest request) {
+        return ResponseEntity.ok(adoptionService.updateAdoption(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<Void> deleteAdoption(@PathVariable Long id) {
+        adoptionService.deleteAdoption(id);
+        return ResponseEntity.noContent().build();
+    }
+
+    @DeleteMapping
+    @PreAuthorize("hasRole('ADMIN')")
+    public ResponseEntity<Void> bulkDeleteAdoptions(@Valid @RequestBody BulkDeleteRequest request) {
+        adoptionService.bulkDeleteAdoptions(request);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/AnalyticsController.java

@@ -0,0 +1,26 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.analytics.DashboardResponse;
+import com.petshop.backend.service.AnalyticsService;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/analytics")
+@PreAuthorize("hasRole('ADMIN')")
+public class AnalyticsController {
+
+    private final AnalyticsService analyticsService;
+
+    public AnalyticsController(AnalyticsService analyticsService) {
+        this.analyticsService = analyticsService;
+    }
+
+    @GetMapping("/dashboard")
+    public ResponseEntity<DashboardResponse> getDashboard(
+            @RequestParam(defaultValue = "30") int days,
+            @RequestParam(defaultValue = "10") int top) {
+        return ResponseEntity.ok(analyticsService.getDashboardData(days, top));
+    }
+}

backend/src/main/java/com/petshop/backend/controller/AppointmentController.java

@@ -0,0 +1,125 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.appointment.AppointmentRequest;
+import com.petshop.backend.dto.appointment.AppointmentResponse;
+import com.petshop.backend.dto.common.BulkDeleteRequest;
+import com.petshop.backend.entity.Customer;
+import com.petshop.backend.repository.CustomerRepository;
+import com.petshop.backend.repository.UserRepository;
+import com.petshop.backend.service.AppointmentService;
+import com.petshop.backend.util.AuthenticationHelper;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.web.bind.annotation.*;
+
+import java.time.LocalDate;
+import java.util.List;
+
+@RestController
+@RequestMapping("/api/v1/appointments")
+public class AppointmentController {
+
+    private final AppointmentService appointmentService;
+    private final UserRepository userRepository;
+    private final CustomerRepository customerRepository;
+
+    public AppointmentController(AppointmentService appointmentService, UserRepository userRepository, CustomerRepository customerRepository) {
+        this.appointmentService = appointmentService;
+        this.userRepository = userRepository;
+        this.customerRepository = customerRepository;
+    }
+
+    @GetMapping
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<Page<AppointmentResponse>> getAllAppointments(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        String role = authentication.getAuthorities().stream()
+                .findFirst()
+                .map(authority -> authority.getAuthority().replace("ROLE_", ""))
+                .orElse(null);
+
+        Long customerId = null;
+        if (role != null && role.equals("CUSTOMER")) {
+            Customer customer = AuthenticationHelper.getAuthenticatedCustomer(userRepository, customerRepository);
+            customerId = customer.getCustomerId();
+        }
+
+        return ResponseEntity.ok(appointmentService.getAllAppointments(q, pageable, customerId));
+    }
+
+    @GetMapping("/{id}")
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<AppointmentResponse> getAppointmentById(@PathVariable Long id) {
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        String role = authentication.getAuthorities().stream()
+                .findFirst()
+                .map(authority -> authority.getAuthority().replace("ROLE_", ""))
+                .orElse(null);
+
+        Long customerId = null;
+        if (role != null && role.equals("CUSTOMER")) {
+            Customer customer = AuthenticationHelper.getAuthenticatedCustomer(userRepository, customerRepository);
+            customerId = customer.getCustomerId();
+        }
+
+        return ResponseEntity.ok(appointmentService.getAppointmentById(id, customerId));
+    }
+
+    @PostMapping
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<AppointmentResponse> createAppointment(@Valid @RequestBody AppointmentRequest request) {
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        String role = authentication.getAuthorities().stream()
+                .findFirst()
+                .map(authority -> authority.getAuthority().replace("ROLE_", ""))
+                .orElse(null);
+
+        if (role != null && role.equals("CUSTOMER")) {
+            Customer customer = AuthenticationHelper.getAuthenticatedCustomer(userRepository, customerRepository);
+            if (!request.getCustomerId().equals(customer.getCustomerId())) {
+                throw new org.springframework.security.access.AccessDeniedException("You can only create appointments for yourself");
+            }
+        }
+
+        return ResponseEntity.status(HttpStatus.CREATED).body(appointmentService.createAppointment(request));
+    }
+
+    @PutMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<AppointmentResponse> updateAppointment(
+            @PathVariable Long id,
+            @Valid @RequestBody AppointmentRequest request) {
+        return ResponseEntity.ok(appointmentService.updateAppointment(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<Void> deleteAppointment(@PathVariable Long id) {
+        appointmentService.deleteAppointment(id);
+        return ResponseEntity.noContent().build();
+    }
+
+    @DeleteMapping
+    @PreAuthorize("hasRole('ADMIN')")
+    public ResponseEntity<Void> bulkDeleteAppointments(@Valid @RequestBody BulkDeleteRequest request) {
+        appointmentService.bulkDeleteAppointments(request);
+        return ResponseEntity.noContent().build();
+    }
+
+    @GetMapping("/availability")
+    public ResponseEntity<List<String>> checkAvailability(
+            @RequestParam Long storeId,
+            @RequestParam Long serviceId,
+            @RequestParam String date) {
+        LocalDate appointmentDate = LocalDate.parse(date);
+        return ResponseEntity.ok(appointmentService.checkAvailability(storeId, serviceId, appointmentDate));
+    }
+}

backend/src/main/java/com/petshop/backend/controller/AuthController.java

@@ -0,0 +1,353 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.auth.AvatarUploadResponse;
+import com.petshop.backend.dto.auth.LoginRequest;
+import com.petshop.backend.dto.auth.LoginResponse;
+import com.petshop.backend.dto.auth.ProfileUpdateRequest;
+import com.petshop.backend.dto.auth.RegisterRequest;
+import com.petshop.backend.dto.auth.RegisterResponse;
+import com.petshop.backend.dto.auth.UserInfoResponse;
+import com.petshop.backend.entity.EmployeeStore;
+import com.petshop.backend.entity.User;
+import com.petshop.backend.repository.EmployeeRepository;
+import com.petshop.backend.repository.EmployeeStoreRepository;
+import com.petshop.backend.repository.UserRepository;
+import com.petshop.backend.security.JwtUtil;
+import com.petshop.backend.service.UserBusinessLinkageService;
+import com.petshop.backend.util.AuthenticationHelper;
+import jakarta.validation.Valid;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.authentication.AuthenticationManager;
+import org.springframework.security.authentication.BadCredentialsException;
+import org.springframework.security.authentication.DisabledException;
+import org.springframework.security.authentication.InternalAuthenticationServiceException;
+import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
+import org.springframework.security.core.userdetails.UsernameNotFoundException;
+import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.web.bind.annotation.*;
+import org.springframework.web.multipart.MultipartFile;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardCopyOption;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+
+@RestController
+@RequestMapping("/api/v1/auth")
+public class AuthController {
+
+    private final AuthenticationManager authenticationManager;
+    private final UserRepository userRepository;
+    private final JwtUtil jwtUtil;
+    private final PasswordEncoder passwordEncoder;
+    private final UserBusinessLinkageService userBusinessLinkageService;
+    private final EmployeeRepository employeeRepository;
+    private final EmployeeStoreRepository employeeStoreRepository;
+
+    public AuthController(AuthenticationManager authenticationManager, UserRepository userRepository, JwtUtil jwtUtil, PasswordEncoder passwordEncoder, UserBusinessLinkageService userBusinessLinkageService, EmployeeRepository employeeRepository, EmployeeStoreRepository employeeStoreRepository) {
+        this.authenticationManager = authenticationManager;
+        this.userRepository = userRepository;
+        this.jwtUtil = jwtUtil;
+        this.passwordEncoder = passwordEncoder;
+        this.userBusinessLinkageService = userBusinessLinkageService;
+        this.employeeRepository = employeeRepository;
+        this.employeeStoreRepository = employeeStoreRepository;
+    }
+
+    @PostMapping("/register")
+    public ResponseEntity<?> register(@Valid @RequestBody RegisterRequest request) {
+        if (userRepository.findByUsername(request.getUsername()).isPresent()) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", "Username already exists");
+            return ResponseEntity.status(HttpStatus.CONFLICT).body(error);
+        }
+
+        if (userRepository.findByEmail(request.getEmail()).isPresent()) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", "Email already exists");
+            return ResponseEntity.status(HttpStatus.CONFLICT).body(error);
+        }
+
+        String phone = trimToNull(request.getPhone());
+        if (phone != null && userRepository.findByPhone(phone).isPresent()) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", "Phone already exists");
+            return ResponseEntity.status(HttpStatus.CONFLICT).body(error);
+        }
+
+        User user = new User();
+        user.setUsername(request.getUsername());
+        user.setPassword(passwordEncoder.encode(request.getPassword()));
+        user.setEmail(request.getEmail());
+        user.setFullName(request.getFullName());
+        user.setPhone(phone);
+        user.setRole(User.Role.CUSTOMER);
+        user.setActive(true);
+
+        User savedUser = userRepository.save(user);
+
+        // Create or link customer record
+        userBusinessLinkageService.ensureLinkedCustomer(savedUser);
+
+        String token = jwtUtil.generateToken(savedUser);
+
+        return ResponseEntity.status(HttpStatus.CREATED).body(new RegisterResponse(
+                savedUser.getId(),
+                savedUser.getUsername(),
+                savedUser.getEmail(),
+                savedUser.getPhone(),
+                savedUser.getRole().name(),
+                token
+        ));
+    }
+
+    @PostMapping("/login")
+    public ResponseEntity<?> login(@Valid @RequestBody LoginRequest request) {
+        try {
+            authenticationManager.authenticate(
+                    new UsernamePasswordAuthenticationToken(request.getUsername(), request.getPassword())
+            );
+
+            User user = userRepository.findByUsername(request.getUsername())
+                    .orElseThrow(() -> new UsernameNotFoundException("User not found"));
+
+            String token = jwtUtil.generateToken(user);
+
+            return ResponseEntity.ok(new LoginResponse(
+                    token,
+                    user.getUsername(),
+                    user.getRole().name()
+            ));
+
+        } catch (BadCredentialsException e) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", "Invalid username or password");
+            return ResponseEntity.status(HttpStatus.UNAUTHORIZED).body(error);
+        } catch (InternalAuthenticationServiceException e) {
+            if (e.getCause() instanceof DisabledException disabledException) {
+                Map<String, String> error = new HashMap<>();
+                error.put("message", disabledException.getMessage());
+                return ResponseEntity.status(HttpStatus.FORBIDDEN).body(error);
+            }
+            throw e;
+        } catch (DisabledException e) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", e.getMessage());
+            return ResponseEntity.status(HttpStatus.FORBIDDEN).body(error);
+        }
+    }
+
+    @GetMapping("/me")
+    public ResponseEntity<UserInfoResponse> getCurrentUser() {
+        User user = getAuthenticatedUser();
+
+        EmployeeStore employeeStore = resolveEmployeeStore(user);
+
+        return ResponseEntity.ok(new UserInfoResponse(
+                user.getId(),
+                user.getUsername(),
+                user.getEmail(),
+                user.getFullName(),
+                user.getPhone(),
+                user.getAvatarUrl(),
+                user.getRole().name(),
+                employeeStore != null ? employeeStore.getStore().getStoreId() : null,
+                employeeStore != null ? employeeStore.getStore().getStoreName() : null
+        ));
+    }
+
+    @PutMapping("/me")
+    public ResponseEntity<?> updateProfile(@Valid @RequestBody ProfileUpdateRequest request) {
+        User user = getAuthenticatedUser();
+        boolean invalidateToken = false;
+
+        if (request.getUsername() != null && !request.getUsername().equals(user.getUsername())) {
+            if (userRepository.findByUsername(request.getUsername()).isPresent()) {
+                Map<String, String> error = new HashMap<>();
+                error.put("message", "Username already exists");
+                return ResponseEntity.status(HttpStatus.CONFLICT).body(error);
+            }
+            user.setUsername(request.getUsername());
+            invalidateToken = true;
+        }
+
+        if (request.getEmail() != null && !request.getEmail().equals(user.getEmail())) {
+            if (userRepository.findByEmail(request.getEmail()).isPresent()) {
+                Map<String, String> error = new HashMap<>();
+                error.put("message", "Email already exists");
+                return ResponseEntity.status(HttpStatus.CONFLICT).body(error);
+            }
+            user.setEmail(request.getEmail());
+        }
+
+        if (request.getFullName() != null) {
+            user.setFullName(request.getFullName());
+        }
+
+        if (request.getPhone() != null) {
+            String phone = trimToNull(request.getPhone());
+            if (!java.util.Objects.equals(phone, user.getPhone())) {
+                if (phone != null && userRepository.findByPhone(phone)
+                        .filter(existing -> !existing.getId().equals(user.getId()))
+                        .isPresent()) {
+                    Map<String, String> error = new HashMap<>();
+                    error.put("message", "Phone already exists");
+                    return ResponseEntity.status(HttpStatus.CONFLICT).body(error);
+                }
+                user.setPhone(phone);
+            }
+        }
+
+        if (request.getPassword() != null && !request.getPassword().isEmpty()) {
+            user.setPassword(passwordEncoder.encode(request.getPassword()));
+            invalidateToken = true;
+        }
+
+        if (invalidateToken) {
+            user.setTokenVersion(user.getTokenVersion() + 1);
+        }
+
+        User updatedUser = userRepository.save(user);
+        userBusinessLinkageService.syncLinkedRecords(updatedUser);
+
+        EmployeeStore employeeStore = resolveEmployeeStore(updatedUser);
+
+        return ResponseEntity.ok(new UserInfoResponse(
+                updatedUser.getId(),
+                updatedUser.getUsername(),
+                updatedUser.getEmail(),
+                updatedUser.getFullName(),
+                updatedUser.getPhone(),
+                updatedUser.getAvatarUrl(),
+                updatedUser.getRole().name(),
+                employeeStore != null ? employeeStore.getStore().getStoreId() : null,
+                employeeStore != null ? employeeStore.getStore().getStoreName() : null
+        ));
+    }
+
+    private EmployeeStore resolveEmployeeStore(User user) {
+        if (user.getRole() == User.Role.CUSTOMER) {
+            return null;
+        }
+
+        return employeeRepository.findByUserId(user.getId())
+                .flatMap(employee -> employeeStoreRepository.findByEmployeeEmployeeId(employee.getEmployeeId()))
+                .orElse(null);
+    }
+
+    private String trimToNull(String value) {
+        if (value == null) {
+            return null;
+        }
+        String trimmed = value.trim();
+        return trimmed.isEmpty() ? null : trimmed;
+    }
+
+    @PostMapping("/me/avatar")
+    public ResponseEntity<?> uploadAvatar(@RequestParam("avatar") MultipartFile file) {
+        User user = getAuthenticatedUser();
+
+        if (file.isEmpty()) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", "Please select a file to upload");
+            return ResponseEntity.badRequest().body(error);
+        }
+
+        if (file.getSize() > 5 * 1024 * 1024) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", "File size must not exceed 5MB");
+            return ResponseEntity.badRequest().body(error);
+        }
+
+        String contentType = file.getContentType();
+        if (contentType == null || (!contentType.equals("image/jpeg") && !contentType.equals("image/png") && !contentType.equals("image/gif"))) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", "Only JPG, PNG, and GIF images are allowed");
+            return ResponseEntity.badRequest().body(error);
+        }
+
+        try {
+            String uploadDir = "uploads/avatars";
+            File directory = new File(uploadDir);
+            if (!directory.exists()) {
+                directory.mkdirs();
+            }
+
+            String originalFilename = file.getOriginalFilename();
+            String extension = originalFilename != null && originalFilename.contains(".")
+                    ? originalFilename.substring(originalFilename.lastIndexOf("."))
+                    : ".jpg";
+            String filename = UUID.randomUUID().toString() + extension;
+            Path filePath = Paths.get(uploadDir, filename);
+
+            Files.copy(file.getInputStream(), filePath, StandardCopyOption.REPLACE_EXISTING);
+
+            String avatarUrl = "/uploads/avatars/" + filename;
+            user.setAvatarUrl(avatarUrl);
+            userRepository.save(user);
+
+            return ResponseEntity.ok(new AvatarUploadResponse(avatarUrl, "Avatar uploaded successfully"));
+
+        } catch (IOException e) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", "Failed to upload avatar: " + e.getMessage());
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(error);
+        }
+    }
+
+    @GetMapping("/me/avatar")
+    public ResponseEntity<?> getAvatar() {
+        User user = getAuthenticatedUser();
+
+        if (user.getAvatarUrl() == null || user.getAvatarUrl().isEmpty()) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", "No avatar uploaded");
+            return ResponseEntity.status(HttpStatus.NOT_FOUND).body(error);
+        }
+
+        Map<String, String> response = new HashMap<>();
+        response.put("avatarUrl", user.getAvatarUrl());
+        return ResponseEntity.ok(response);
+    }
+
+    @DeleteMapping("/me/avatar")
+    public ResponseEntity<?> deleteAvatar() {
+        User user = getAuthenticatedUser();
+
+        if (user.getAvatarUrl() != null && !user.getAvatarUrl().isEmpty()) {
+            try {
+                Path filePath = Paths.get("." + user.getAvatarUrl());
+                Files.deleteIfExists(filePath);
+            } catch (IOException e) {
+            }
+            user.setAvatarUrl(null);
+            userRepository.save(user);
+        }
+
+        Map<String, String> response = new HashMap<>();
+        response.put("message", "Avatar deleted successfully");
+        return ResponseEntity.ok(response);
+    }
+
+    @PostMapping("/logout")
+    public ResponseEntity<?> logout() {
+        Map<String, String> response = new HashMap<>();
+        response.put("message", "Logged out successfully");
+        response.put("note", "Token remains valid until expiration. Clear token from client storage.");
+        return ResponseEntity.ok(response);
+    }
+
+    private User getAuthenticatedUser() {
+        try {
+            return AuthenticationHelper.getAuthenticatedUser(userRepository);
+        } catch (RuntimeException ex) {
+            throw new UsernameNotFoundException(ex.getMessage(), ex);
+        }
+    }
+}

backend/src/main/java/com/petshop/backend/controller/CategoryController.java

@@ -0,0 +1,64 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.category.CategoryRequest;
+import com.petshop.backend.dto.category.CategoryResponse;
+import com.petshop.backend.dto.common.BulkDeleteRequest;
+import com.petshop.backend.service.CategoryService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/categories")
+public class CategoryController {
+
+    private final CategoryService categoryService;
+
+    public CategoryController(CategoryService categoryService) {
+        this.categoryService = categoryService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<CategoryResponse>> getAllCategories(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        return ResponseEntity.ok(categoryService.getAllCategories(q, pageable));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<CategoryResponse> getCategoryById(@PathVariable Long id) {
+        return ResponseEntity.ok(categoryService.getCategoryById(id));
+    }
+
+    @PostMapping
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<CategoryResponse> createCategory(@Valid @RequestBody CategoryRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(categoryService.createCategory(request));
+    }
+
+    @PutMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<CategoryResponse> updateCategory(
+            @PathVariable Long id,
+            @Valid @RequestBody CategoryRequest request) {
+        return ResponseEntity.ok(categoryService.updateCategory(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<Void> deleteCategory(@PathVariable Long id) {
+        categoryService.deleteCategory(id);
+        return ResponseEntity.noContent().build();
+    }
+
+    @DeleteMapping
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<Void> bulkDeleteCategories(@Valid @RequestBody BulkDeleteRequest request) {
+        categoryService.bulkDeleteCategories(request);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/ChatController.java

@@ -0,0 +1,99 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.chat.ConversationRequest;
+import com.petshop.backend.dto.chat.ConversationResponse;
+import com.petshop.backend.dto.chat.MessageRequest;
+import com.petshop.backend.dto.chat.MessageResponse;
+import com.petshop.backend.entity.User;
+import com.petshop.backend.repository.CustomerRepository;
+import com.petshop.backend.repository.UserRepository;
+import com.petshop.backend.service.ChatRealtimeService;
+import com.petshop.backend.service.ChatService;
+import com.petshop.backend.util.AuthenticationHelper;
+import jakarta.validation.Valid;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.security.core.userdetails.UsernameNotFoundException;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@RestController
+@RequestMapping("/api/v1/chat")
+public class ChatController {
+
+    private final ChatService chatService;
+    private final ChatRealtimeService chatRealtimeService;
+    private final UserRepository userRepository;
+    private final CustomerRepository customerRepository;
+
+    public ChatController(ChatService chatService, ChatRealtimeService chatRealtimeService, UserRepository userRepository, CustomerRepository customerRepository) {
+        this.chatService = chatService;
+        this.chatRealtimeService = chatRealtimeService;
+        this.userRepository = userRepository;
+        this.customerRepository = customerRepository;
+    }
+
+    private User getCurrentUser() {
+        try {
+            return AuthenticationHelper.getAuthenticatedUser(userRepository);
+        } catch (RuntimeException ex) {
+            throw new UsernameNotFoundException(ex.getMessage(), ex);
+        }
+    }
+
+    @PostMapping("/conversations")
+    @PreAuthorize("hasRole('CUSTOMER')")
+    public ResponseEntity<ConversationResponse> createConversation(@Valid @RequestBody ConversationRequest request) {
+        User user = getCurrentUser();
+        ConversationResponse response = chatService.createConversation(user.getId(), request);
+        chatRealtimeService.publishNewConversation(response);
+        return ResponseEntity.status(HttpStatus.CREATED).body(response);
+    }
+
+    @GetMapping("/conversations")
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<List<ConversationResponse>> getConversations() {
+        User user = getCurrentUser();
+        List<ConversationResponse> conversations = chatService.getConversations(user.getId(), user.getRole());
+        return ResponseEntity.ok(conversations);
+    }
+
+    @GetMapping("/conversations/{id}")
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<ConversationResponse> getConversation(@PathVariable Long id) {
+        User user = getCurrentUser();
+        ConversationResponse conversation = chatService.getConversation(id, user.getId(), user.getRole());
+        return ResponseEntity.ok(conversation);
+    }
+
+    @PostMapping("/conversations/{id}/messages")
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<MessageResponse> sendMessage(
+            @PathVariable Long id,
+            @Valid @RequestBody MessageRequest request) {
+        User user = getCurrentUser();
+        MessageResponse message = chatService.sendMessage(id, user.getId(), user.getRole(), request);
+        chatRealtimeService.publishMessage(id, message);
+        chatRealtimeService.publishConversationUpdate(id);
+        return ResponseEntity.status(HttpStatus.CREATED).body(message);
+    }
+
+    @GetMapping("/conversations/{id}/messages")
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<List<MessageResponse>> getMessages(@PathVariable Long id) {
+        User user = getCurrentUser();
+        List<MessageResponse> messages = chatService.getMessages(id, user.getId(), user.getRole());
+        return ResponseEntity.ok(messages);
+    }
+
+    @PostMapping("/conversations/{id}/request-human")
+    @PreAuthorize("hasRole('CUSTOMER')")
+    public ResponseEntity<ConversationResponse> requestHumanTakeover(@PathVariable Long id) {
+        User user = getCurrentUser();
+        ConversationResponse conversation = chatService.requestHumanTakeover(id, user.getId(), user.getRole());
+        chatRealtimeService.publishConversationUpdate(id);
+        return ResponseEntity.ok(conversation);
+    }
+}

backend/src/main/java/com/petshop/backend/controller/ChatWebSocketController.java

@@ -0,0 +1,123 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.config.WebSocketAuthChannelInterceptor;
+import com.petshop.backend.dto.chat.MessageRequest;
+import com.petshop.backend.dto.chat.MessageResponse;
+import com.petshop.backend.entity.User;
+import com.petshop.backend.repository.UserRepository;
+import com.petshop.backend.security.AppPrincipal;
+import com.petshop.backend.security.JwtUtil;
+import com.petshop.backend.service.ChatRealtimeService;
+import com.petshop.backend.service.ChatService;
+import jakarta.validation.Valid;
+import org.springframework.messaging.handler.annotation.DestinationVariable;
+import org.springframework.messaging.handler.annotation.MessageExceptionHandler;
+import org.springframework.messaging.handler.annotation.MessageMapping;
+import org.springframework.messaging.handler.annotation.Payload;
+import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
+import org.springframework.messaging.simp.annotation.SendToUser;
+import org.springframework.stereotype.Controller;
+
+import java.security.Principal;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+@Controller
+public class ChatWebSocketController {
+
+    private final ChatService chatService;
+    private final ChatRealtimeService chatRealtimeService;
+    private final UserRepository userRepository;
+    private final JwtUtil jwtUtil;
+    private final WebSocketAuthChannelInterceptor webSocketAuthChannelInterceptor;
+
+    public ChatWebSocketController(
+            ChatService chatService,
+            ChatRealtimeService chatRealtimeService,
+            UserRepository userRepository,
+            JwtUtil jwtUtil,
+            WebSocketAuthChannelInterceptor webSocketAuthChannelInterceptor
+    ) {
+        this.chatService = chatService;
+        this.chatRealtimeService = chatRealtimeService;
+        this.userRepository = userRepository;
+        this.jwtUtil = jwtUtil;
+        this.webSocketAuthChannelInterceptor = webSocketAuthChannelInterceptor;
+    }
+
+    @MessageMapping("/chat/conversations/{id}/messages")
+    @SendToUser("/queue/chat/errors")
+    public void sendMessage(@DestinationVariable Long id, @Valid @Payload MessageRequest request, SimpMessageHeaderAccessor headerAccessor) {
+        User user = resolveUser(headerAccessor);
+        MessageResponse message = chatService.sendMessage(id, user.getId(), user.getRole(), request);
+        chatRealtimeService.publishMessage(id, message);
+        chatRealtimeService.publishConversationUpdate(id);
+    }
+
+    @MessageExceptionHandler({IllegalArgumentException.class, RuntimeException.class})
+    @SendToUser("/queue/chat/errors")
+    public Map<String, Object> handleMessageException(Exception ex, SimpMessageHeaderAccessor headerAccessor) {
+        return webSocketAuthChannelInterceptor.buildErrorPayload(ex, headerAccessor.getDestination(), headerAccessor.getUser());
+    }
+
+    private User resolveUser(SimpMessageHeaderAccessor headerAccessor) {
+        Principal principal = headerAccessor.getUser();
+        if (principal instanceof org.springframework.security.authentication.UsernamePasswordAuthenticationToken authenticationToken
+                && authenticationToken.getPrincipal() instanceof AppPrincipal appPrincipal) {
+            return userRepository.findById(appPrincipal.getUserId())
+                    .orElseThrow(() -> new IllegalArgumentException("User not found"));
+        }
+
+        if (principal instanceof AppPrincipal appPrincipal) {
+            return userRepository.findById(appPrincipal.getUserId())
+                    .orElseThrow(() -> new IllegalArgumentException("User not found"));
+        }
+
+        String tokenHeader = firstHeader(headerAccessor, "Authorization");
+        if (tokenHeader == null || tokenHeader.isBlank()) {
+            tokenHeader = firstHeader(headerAccessor, "token");
+        }
+        if (tokenHeader == null || tokenHeader.isBlank()) {
+            throw new IllegalArgumentException("User not authenticated");
+        }
+
+        String token = extractToken(tokenHeader);
+        Long userId;
+        try {
+            userId = jwtUtil.extractUserId(token);
+        } catch (RuntimeException ex) {
+            throw new IllegalArgumentException("Invalid websocket token", ex);
+        }
+        User user = userId == null ? null : userRepository.findById(userId).orElse(null);
+        if (user == null) {
+            throw new IllegalArgumentException("User not found");
+        }
+        if (user.getActive() == null || !user.getActive()) {
+            throw new IllegalArgumentException("User account is inactive");
+        }
+        if (!jwtUtil.validateToken(token, user)) {
+            throw new IllegalArgumentException("Invalid websocket token");
+        }
+        return user;
+    }
+
+    private String firstHeader(SimpMessageHeaderAccessor headerAccessor, String name) {
+        List<String> values = headerAccessor.getNativeHeader(name);
+        if (values != null && !values.isEmpty()) {
+            return values.get(0);
+        }
+        Map<String, List<String>> headers = headerAccessor.toNativeHeaderMap();
+        for (Map.Entry<String, List<String>> entry : headers.entrySet()) {
+            if (entry.getKey().equalsIgnoreCase(name)) {
+                return entry.getValue() == null || entry.getValue().isEmpty() ? null : entry.getValue().get(0);
+            }
+        }
+        return null;
+    }
+
+    private String extractToken(String rawValue) {
+        String normalized = rawValue.trim();
+        return normalized.regionMatches(true, 0, "Bearer ", 0, 7) ? normalized.substring(7) : normalized;
+    }
+}

backend/src/main/java/com/petshop/backend/controller/CustomerController.java

@@ -0,0 +1,61 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.common.BulkDeleteRequest;
+import com.petshop.backend.dto.customer.CustomerRequest;
+import com.petshop.backend.dto.customer.CustomerResponse;
+import com.petshop.backend.service.CustomerService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/customers")
+@PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+public class CustomerController {
+
+    private final CustomerService customerService;
+
+    public CustomerController(CustomerService customerService) {
+        this.customerService = customerService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<CustomerResponse>> getAllCustomers(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        return ResponseEntity.ok(customerService.getAllCustomers(q, pageable));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<CustomerResponse> getCustomerById(@PathVariable Long id) {
+        return ResponseEntity.ok(customerService.getCustomerById(id));
+    }
+
+    @PostMapping
+    public ResponseEntity<CustomerResponse> createCustomer(@Valid @RequestBody CustomerRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(customerService.createCustomer(request));
+    }
+
+    @PutMapping("/{id}")
+    public ResponseEntity<CustomerResponse> updateCustomer(
+            @PathVariable Long id,
+            @Valid @RequestBody CustomerRequest request) {
+        return ResponseEntity.ok(customerService.updateCustomer(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Void> deleteCustomer(@PathVariable Long id) {
+        customerService.deleteCustomer(id);
+        return ResponseEntity.noContent().build();
+    }
+
+    @PostMapping("/bulk-delete")
+    public ResponseEntity<Void> bulkDeleteCustomers(@Valid @RequestBody BulkDeleteRequest request) {
+        customerService.bulkDeleteCustomers(request);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/DropdownController.java

@@ -0,0 +1,103 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.common.DropdownOption;
+import com.petshop.backend.repository.*;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+@RestController
+@RequestMapping("/api/v1/dropdowns")
+public class DropdownController {
+
+    private final PetRepository petRepository;
+    private final CustomerRepository customerRepository;
+    private final ServiceRepository serviceRepository;
+    private final ProductRepository productRepository;
+    private final CategoryRepository categoryRepository;
+    private final StoreRepository storeRepository;
+    private final SupplierRepository supplierRepository;
+
+    public DropdownController(PetRepository petRepository, CustomerRepository customerRepository,
+                             ServiceRepository serviceRepository, ProductRepository productRepository,
+                             CategoryRepository categoryRepository, StoreRepository storeRepository,
+                             SupplierRepository supplierRepository) {
+        this.petRepository = petRepository;
+        this.customerRepository = customerRepository;
+        this.serviceRepository = serviceRepository;
+        this.productRepository = productRepository;
+        this.categoryRepository = categoryRepository;
+        this.storeRepository = storeRepository;
+        this.supplierRepository = supplierRepository;
+    }
+
+    @GetMapping("/pets")
+    public ResponseEntity<List<DropdownOption>> getPets() {
+        return ResponseEntity.ok(
+            petRepository.findAll().stream()
+                .map(p -> new DropdownOption(p.getPetId(), p.getPetName()))
+                .collect(Collectors.toList())
+        );
+    }
+
+    @GetMapping("/customers")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<List<DropdownOption>> getCustomers() {
+        return ResponseEntity.ok(
+            customerRepository.findAll().stream()
+                .map(c -> new DropdownOption(c.getCustomerId(), c.getFirstName() + " " + c.getLastName()))
+                .collect(Collectors.toList())
+        );
+    }
+
+    @GetMapping("/services")
+    public ResponseEntity<List<DropdownOption>> getServices() {
+        return ResponseEntity.ok(
+            serviceRepository.findAll().stream()
+                .map(s -> new DropdownOption(s.getServiceId(), s.getServiceName()))
+                .collect(Collectors.toList())
+        );
+    }
+
+    @GetMapping("/products")
+    public ResponseEntity<List<DropdownOption>> getProducts() {
+        return ResponseEntity.ok(
+            productRepository.findAll().stream()
+                .map(p -> new DropdownOption(p.getProdId(), p.getProdName()))
+                .collect(Collectors.toList())
+        );
+    }
+
+    @GetMapping("/categories")
+    public ResponseEntity<List<DropdownOption>> getCategories() {
+        return ResponseEntity.ok(
+            categoryRepository.findAll().stream()
+                .map(c -> new DropdownOption(c.getCategoryId(), c.getCategoryName()))
+                .collect(Collectors.toList())
+        );
+    }
+
+    @GetMapping("/stores")
+    public ResponseEntity<List<DropdownOption>> getStores() {
+        return ResponseEntity.ok(
+            storeRepository.findAll().stream()
+                .map(s -> new DropdownOption(s.getStoreId(), s.getStoreName()))
+                .collect(Collectors.toList())
+        );
+    }
+
+    @GetMapping("/suppliers")
+    @PreAuthorize("hasRole('ADMIN')")
+    public ResponseEntity<List<DropdownOption>> getSuppliers() {
+        return ResponseEntity.ok(
+            supplierRepository.findAll().stream()
+                .map(s -> new DropdownOption(s.getSupId(), s.getSupCompany()))
+                .collect(Collectors.toList())
+        );
+    }
+}

backend/src/main/java/com/petshop/backend/controller/EmployeeController.java

@@ -0,0 +1,49 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.employee.EmployeeRequest;
+import com.petshop.backend.dto.employee.EmployeeResponse;
+import com.petshop.backend.service.EmployeeService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/employees")
+@PreAuthorize("hasRole('ADMIN')")
+public class EmployeeController {
+    private final EmployeeService employeeService;
+
+    public EmployeeController(EmployeeService employeeService) {
+        this.employeeService = employeeService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<EmployeeResponse>> getAllEmployees(@RequestParam(required = false) String q, Pageable pageable) {
+        return ResponseEntity.ok(employeeService.getAllEmployees(q, pageable));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<EmployeeResponse> getEmployeeById(@PathVariable Long id) {
+        return ResponseEntity.ok(employeeService.getEmployeeById(id));
+    }
+
+    @PostMapping
+    public ResponseEntity<EmployeeResponse> createEmployee(@Valid @RequestBody EmployeeRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(employeeService.createEmployee(request));
+    }
+
+    @PutMapping("/{id}")
+    public ResponseEntity<EmployeeResponse> updateEmployee(@PathVariable Long id, @Valid @RequestBody EmployeeRequest request) {
+        return ResponseEntity.ok(employeeService.updateEmployee(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Void> deleteEmployee(@PathVariable Long id) {
+        employeeService.deleteEmployee(id);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/HealthController.java

@@ -0,0 +1,18 @@
+package com.petshop.backend.controller;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.Map;
+
+@RestController
+@RequestMapping("/api/v1/health")
+public class HealthController {
+
+    @GetMapping
+    public ResponseEntity<Map<String, String>> healthCheck() {
+        return ResponseEntity.ok(Map.of("status", "UP"));
+    }
+}

backend/src/main/java/com/petshop/backend/controller/InventoryController.java

@@ -0,0 +1,61 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.common.BulkDeleteRequest;
+import com.petshop.backend.dto.inventory.InventoryRequest;
+import com.petshop.backend.dto.inventory.InventoryResponse;
+import com.petshop.backend.service.InventoryService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/inventory")
+@PreAuthorize("hasRole('ADMIN')")
+public class InventoryController {
+
+    private final InventoryService inventoryService;
+
+    public InventoryController(InventoryService inventoryService) {
+        this.inventoryService = inventoryService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<InventoryResponse>> getAllInventory(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        return ResponseEntity.ok(inventoryService.getAllInventory(q, pageable));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<InventoryResponse> getInventoryById(@PathVariable Long id) {
+        return ResponseEntity.ok(inventoryService.getInventoryById(id));
+    }
+
+    @PostMapping
+    public ResponseEntity<InventoryResponse> createInventory(@Valid @RequestBody InventoryRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(inventoryService.createInventory(request));
+    }
+
+    @PutMapping("/{id}")
+    public ResponseEntity<InventoryResponse> updateInventory(
+            @PathVariable Long id,
+            @Valid @RequestBody InventoryRequest request) {
+        return ResponseEntity.ok(inventoryService.updateInventory(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Void> deleteInventory(@PathVariable Long id) {
+        inventoryService.deleteInventory(id);
+        return ResponseEntity.noContent().build();
+    }
+
+    @DeleteMapping
+    public ResponseEntity<Void> bulkDeleteInventory(@Valid @RequestBody BulkDeleteRequest request) {
+        inventoryService.bulkDeleteInventory(request);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/PetController.java

@@ -0,0 +1,64 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.common.BulkDeleteRequest;
+import com.petshop.backend.dto.pet.PetRequest;
+import com.petshop.backend.dto.pet.PetResponse;
+import com.petshop.backend.service.PetService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/pets")
+public class PetController {
+
+    private final PetService petService;
+
+    public PetController(PetService petService) {
+        this.petService = petService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<PetResponse>> getAllPets(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        return ResponseEntity.ok(petService.getAllPets(q, pageable));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<PetResponse> getPetById(@PathVariable Long id) {
+        return ResponseEntity.ok(petService.getPetById(id));
+    }
+
+    @PostMapping
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<PetResponse> createPet(@Valid @RequestBody PetRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(petService.createPet(request));
+    }
+
+    @PutMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<PetResponse> updatePet(
+            @PathVariable Long id,
+            @Valid @RequestBody PetRequest request) {
+        return ResponseEntity.ok(petService.updatePet(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<Void> deletePet(@PathVariable Long id) {
+        petService.deletePet(id);
+        return ResponseEntity.noContent().build();
+    }
+
+    @DeleteMapping
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<Void> bulkDeletePets(@Valid @RequestBody BulkDeleteRequest request) {
+        petService.bulkDeletePets(request);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/ProductController.java

@@ -0,0 +1,64 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.common.BulkDeleteRequest;
+import com.petshop.backend.dto.product.ProductRequest;
+import com.petshop.backend.dto.product.ProductResponse;
+import com.petshop.backend.service.ProductService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/products")
+public class ProductController {
+
+    private final ProductService productService;
+
+    public ProductController(ProductService productService) {
+        this.productService = productService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<ProductResponse>> getAllProducts(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        return ResponseEntity.ok(productService.getAllProducts(q, pageable));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<ProductResponse> getProductById(@PathVariable Long id) {
+        return ResponseEntity.ok(productService.getProductById(id));
+    }
+
+    @PostMapping
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<ProductResponse> createProduct(@Valid @RequestBody ProductRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(productService.createProduct(request));
+    }
+
+    @PutMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<ProductResponse> updateProduct(
+            @PathVariable Long id,
+            @Valid @RequestBody ProductRequest request) {
+        return ResponseEntity.ok(productService.updateProduct(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    @PreAuthorize("hasRole('ADMIN')")
+    public ResponseEntity<Void> deleteProduct(@PathVariable Long id) {
+        productService.deleteProduct(id);
+        return ResponseEntity.noContent().build();
+    }
+
+    @DeleteMapping
+    @PreAuthorize("hasRole('ADMIN')")
+    public ResponseEntity<Void> bulkDeleteProducts(@Valid @RequestBody BulkDeleteRequest request) {
+        productService.bulkDeleteProducts(request);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/ProductSupplierController.java

@@ -0,0 +1,66 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.productsupplier.BulkDeleteProductSupplierRequest;
+import com.petshop.backend.dto.productsupplier.ProductSupplierRequest;
+import com.petshop.backend.dto.productsupplier.ProductSupplierResponse;
+import com.petshop.backend.service.ProductSupplierService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/product-suppliers")
+@PreAuthorize("hasRole('ADMIN')")
+public class ProductSupplierController {
+
+    private final ProductSupplierService productSupplierService;
+
+    public ProductSupplierController(ProductSupplierService productSupplierService) {
+        this.productSupplierService = productSupplierService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<ProductSupplierResponse>> getAllProductSuppliers(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        return ResponseEntity.ok(productSupplierService.getAllProductSuppliers(q, pageable));
+    }
+
+    @GetMapping("/{productId}/{supplierId}")
+    public ResponseEntity<ProductSupplierResponse> getProductSupplierById(
+            @PathVariable Long productId,
+            @PathVariable Long supplierId) {
+        return ResponseEntity.ok(productSupplierService.getProductSupplierById(productId, supplierId));
+    }
+
+    @PostMapping
+    public ResponseEntity<ProductSupplierResponse> createProductSupplier(@Valid @RequestBody ProductSupplierRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(productSupplierService.createProductSupplier(request));
+    }
+
+    @PutMapping("/{productId}/{supplierId}")
+    public ResponseEntity<ProductSupplierResponse> updateProductSupplier(
+            @PathVariable Long productId,
+            @PathVariable Long supplierId,
+            @Valid @RequestBody ProductSupplierRequest request) {
+        return ResponseEntity.ok(productSupplierService.updateProductSupplier(productId, supplierId, request));
+    }
+
+    @DeleteMapping("/{productId}/{supplierId}")
+    public ResponseEntity<Void> deleteProductSupplier(
+            @PathVariable Long productId,
+            @PathVariable Long supplierId) {
+        productSupplierService.deleteProductSupplier(productId, supplierId);
+        return ResponseEntity.noContent().build();
+    }
+
+    @DeleteMapping
+    public ResponseEntity<Void> bulkDeleteProductSuppliers(@Valid @RequestBody BulkDeleteProductSupplierRequest request) {
+        productSupplierService.bulkDeleteProductSuppliers(request);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/PurchaseOrderController.java

@@ -0,0 +1,33 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.purchaseorder.PurchaseOrderResponse;
+import com.petshop.backend.service.PurchaseOrderService;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/purchase-orders")
+@PreAuthorize("hasRole('ADMIN')")
+public class PurchaseOrderController {
+
+    private final PurchaseOrderService purchaseOrderService;
+
+    public PurchaseOrderController(PurchaseOrderService purchaseOrderService) {
+        this.purchaseOrderService = purchaseOrderService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<PurchaseOrderResponse>> getAllPurchaseOrders(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        return ResponseEntity.ok(purchaseOrderService.getAllPurchaseOrders(q, pageable));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<PurchaseOrderResponse> getPurchaseOrderById(@PathVariable Long id) {
+        return ResponseEntity.ok(purchaseOrderService.getPurchaseOrderById(id));
+    }
+}

backend/src/main/java/com/petshop/backend/controller/RefundController.java

@@ -0,0 +1,133 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.refund.RefundRequest;
+import com.petshop.backend.dto.refund.RefundResponse;
+import com.petshop.backend.dto.refund.RefundUpdateRequest;
+import com.petshop.backend.entity.Customer;
+import com.petshop.backend.repository.CustomerRepository;
+import com.petshop.backend.repository.UserRepository;
+import com.petshop.backend.service.RefundService;
+import com.petshop.backend.util.AuthenticationHelper;
+import jakarta.validation.Valid;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+@RestController
+@RequestMapping("/api/v1/refunds")
+public class RefundController {
+
+    private final RefundService refundService;
+    private final UserRepository userRepository;
+    private final CustomerRepository customerRepository;
+
+    public RefundController(RefundService refundService, UserRepository userRepository, CustomerRepository customerRepository) {
+        this.refundService = refundService;
+        this.userRepository = userRepository;
+        this.customerRepository = customerRepository;
+    }
+
+    @PostMapping
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<?> createRefund(@Valid @RequestBody RefundRequest request) {
+        try {
+            Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+            String role = authentication.getAuthorities().stream()
+                    .findFirst()
+                    .map(authority -> authority.getAuthority().replace("ROLE_", ""))
+                    .orElse(null);
+
+            Long customerId = null;
+            if (role != null && role.equals("CUSTOMER")) {
+                Customer customer = AuthenticationHelper.getAuthenticatedCustomer(userRepository, customerRepository);
+                customerId = customer.getCustomerId();
+            }
+
+            RefundResponse refund = refundService.createRefund(request, customerId);
+            return ResponseEntity.status(HttpStatus.CREATED).body(refund);
+        } catch (RuntimeException e) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", e.getMessage());
+            return ResponseEntity.badRequest().body(error);
+        }
+    }
+
+    @GetMapping
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<List<RefundResponse>> getAllRefunds() {
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        String role = authentication.getAuthorities().stream()
+                .findFirst()
+                .map(authority -> authority.getAuthority().replace("ROLE_", ""))
+                .orElse(null);
+
+        Long customerId = null;
+        if (role != null && role.equals("CUSTOMER")) {
+            Customer customer = AuthenticationHelper.getAuthenticatedCustomer(userRepository, customerRepository);
+            customerId = customer.getCustomerId();
+        }
+
+        List<RefundResponse> refunds = refundService.getAllRefunds(customerId);
+        return ResponseEntity.ok(refunds);
+    }
+
+    @GetMapping("/{id}")
+    @PreAuthorize("hasAnyRole('CUSTOMER', 'STAFF', 'ADMIN')")
+    public ResponseEntity<?> getRefundById(@PathVariable Long id) {
+        try {
+            Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+            String role = authentication.getAuthorities().stream()
+                    .findFirst()
+                    .map(authority -> authority.getAuthority().replace("ROLE_", ""))
+                    .orElse(null);
+
+            Long customerId = null;
+            if (role != null && role.equals("CUSTOMER")) {
+                Customer customer = AuthenticationHelper.getAuthenticatedCustomer(userRepository, customerRepository);
+                customerId = customer.getCustomerId();
+            }
+
+            RefundResponse refund = refundService.getRefundById(id, customerId);
+            return ResponseEntity.ok(refund);
+        } catch (RuntimeException e) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", e.getMessage());
+            return ResponseEntity.status(HttpStatus.NOT_FOUND).body(error);
+        }
+    }
+
+    @PutMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<?> updateRefund(@PathVariable Long id, @Valid @RequestBody RefundUpdateRequest request) {
+        try {
+            RefundResponse refund = refundService.updateRefundStatus(id, request.getStatus());
+            return ResponseEntity.ok(refund);
+        } catch (RuntimeException e) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", e.getMessage());
+            return ResponseEntity.badRequest().body(error);
+        }
+    }
+
+    @DeleteMapping("/{id}")
+    @PreAuthorize("hasRole('ADMIN')")
+    public ResponseEntity<?> deleteRefund(@PathVariable Long id) {
+        try {
+            refundService.deleteRefund(id);
+            Map<String, String> response = new HashMap<>();
+            response.put("message", "Refund deleted successfully");
+            return ResponseEntity.ok(response);
+        } catch (RuntimeException e) {
+            Map<String, String> error = new HashMap<>();
+            error.put("message", e.getMessage());
+            return ResponseEntity.status(HttpStatus.NOT_FOUND).body(error);
+        }
+    }
+}

backend/src/main/java/com/petshop/backend/controller/SaleController.java

@@ -0,0 +1,43 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.sale.SaleRequest;
+import com.petshop.backend.dto.sale.SaleResponse;
+import com.petshop.backend.service.SaleService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/sales")
+public class SaleController {
+
+    private final SaleService saleService;
+
+    public SaleController(SaleService saleService) {
+        this.saleService = saleService;
+    }
+
+    @GetMapping
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<Page<SaleResponse>> getAllSales(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        return ResponseEntity.ok(saleService.getAllSales(q, pageable));
+    }
+
+    @GetMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<SaleResponse> getSaleById(@PathVariable Long id) {
+        return ResponseEntity.ok(saleService.getSaleById(id));
+    }
+
+    @PostMapping
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<SaleResponse> createSale(@Valid @RequestBody SaleRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(saleService.createSale(request));
+    }
+}

backend/src/main/java/com/petshop/backend/controller/ServiceController.java

@@ -0,0 +1,64 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.common.BulkDeleteRequest;
+import com.petshop.backend.dto.service.ServiceRequest;
+import com.petshop.backend.dto.service.ServiceResponse;
+import com.petshop.backend.service.ServiceService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/services")
+public class ServiceController {
+
+    private final ServiceService serviceService;
+
+    public ServiceController(ServiceService serviceService) {
+        this.serviceService = serviceService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<ServiceResponse>> getAllServices(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        return ResponseEntity.ok(serviceService.getAllServices(q, pageable));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<ServiceResponse> getServiceById(@PathVariable Long id) {
+        return ResponseEntity.ok(serviceService.getServiceById(id));
+    }
+
+    @PostMapping
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<ServiceResponse> createService(@Valid @RequestBody ServiceRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(serviceService.createService(request));
+    }
+
+    @PutMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<ServiceResponse> updateService(
+            @PathVariable Long id,
+            @Valid @RequestBody ServiceRequest request) {
+        return ResponseEntity.ok(serviceService.updateService(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<Void> deleteService(@PathVariable Long id) {
+        serviceService.deleteService(id);
+        return ResponseEntity.noContent().build();
+    }
+
+    @DeleteMapping
+    @PreAuthorize("hasAnyRole('STAFF', 'ADMIN')")
+    public ResponseEntity<Void> bulkDeleteServices(@Valid @RequestBody BulkDeleteRequest request) {
+        serviceService.bulkDeleteServices(request);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/StoreController.java

@@ -0,0 +1,61 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.common.BulkDeleteRequest;
+import com.petshop.backend.dto.store.StoreRequest;
+import com.petshop.backend.dto.store.StoreResponse;
+import com.petshop.backend.service.StoreService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/stores")
+@PreAuthorize("hasRole('ADMIN')")
+public class StoreController {
+
+    private final StoreService storeService;
+
+    public StoreController(StoreService storeService) {
+        this.storeService = storeService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<StoreResponse>> getAllStores(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        return ResponseEntity.ok(storeService.getAllStores(q, pageable));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<StoreResponse> getStoreById(@PathVariable Long id) {
+        return ResponseEntity.ok(storeService.getStoreById(id));
+    }
+
+    @PostMapping
+    public ResponseEntity<StoreResponse> createStore(@Valid @RequestBody StoreRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(storeService.createStore(request));
+    }
+
+    @PutMapping("/{id}")
+    public ResponseEntity<StoreResponse> updateStore(
+            @PathVariable Long id,
+            @Valid @RequestBody StoreRequest request) {
+        return ResponseEntity.ok(storeService.updateStore(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Void> deleteStore(@PathVariable Long id) {
+        storeService.deleteStore(id);
+        return ResponseEntity.noContent().build();
+    }
+
+    @DeleteMapping
+    public ResponseEntity<Void> bulkDeleteStores(@Valid @RequestBody BulkDeleteRequest request) {
+        storeService.bulkDeleteStores(request);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/SupplierController.java

@@ -0,0 +1,61 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.common.BulkDeleteRequest;
+import com.petshop.backend.dto.supplier.SupplierRequest;
+import com.petshop.backend.dto.supplier.SupplierResponse;
+import com.petshop.backend.service.SupplierService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/suppliers")
+@PreAuthorize("hasRole('ADMIN')")
+public class SupplierController {
+
+    private final SupplierService supplierService;
+
+    public SupplierController(SupplierService supplierService) {
+        this.supplierService = supplierService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<SupplierResponse>> getAllSuppliers(
+            @RequestParam(required = false) String q,
+            Pageable pageable) {
+        return ResponseEntity.ok(supplierService.getAllSuppliers(q, pageable));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<SupplierResponse> getSupplierById(@PathVariable Long id) {
+        return ResponseEntity.ok(supplierService.getSupplierById(id));
+    }
+
+    @PostMapping
+    public ResponseEntity<SupplierResponse> createSupplier(@Valid @RequestBody SupplierRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(supplierService.createSupplier(request));
+    }
+
+    @PutMapping("/{id}")
+    public ResponseEntity<SupplierResponse> updateSupplier(
+            @PathVariable Long id,
+            @Valid @RequestBody SupplierRequest request) {
+        return ResponseEntity.ok(supplierService.updateSupplier(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Void> deleteSupplier(@PathVariable Long id) {
+        supplierService.deleteSupplier(id);
+        return ResponseEntity.noContent().build();
+    }
+
+    @DeleteMapping
+    public ResponseEntity<Void> bulkDeleteSuppliers(@Valid @RequestBody BulkDeleteRequest request) {
+        supplierService.bulkDeleteSuppliers(request);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/controller/UserController.java

@@ -0,0 +1,63 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.common.BulkDeleteRequest;
+import com.petshop.backend.dto.user.UserRequest;
+import com.petshop.backend.dto.user.UserResponse;
+import com.petshop.backend.entity.User;
+import com.petshop.backend.service.UserService;
+import jakarta.validation.Valid;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/users")
+@PreAuthorize("hasRole('ADMIN')")
+public class UserController {
+
+    private final UserService userService;
+
+    public UserController(UserService userService) {
+        this.userService = userService;
+    }
+
+    @GetMapping
+    public ResponseEntity<Page<UserResponse>> getAllUsers(
+            @RequestParam(required = false) String q,
+            @RequestParam(required = false) String role,
+            Pageable pageable) {
+        return ResponseEntity.ok(userService.getAllUsers(q, role, pageable));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<UserResponse> getUserById(@PathVariable Long id) {
+        return ResponseEntity.ok(userService.getUserById(id));
+    }
+
+    @PostMapping
+    public ResponseEntity<UserResponse> createUser(@Valid @RequestBody UserRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(userService.createUser(request));
+    }
+
+    @PutMapping("/{id}")
+    public ResponseEntity<UserResponse> updateUser(
+            @PathVariable Long id,
+            @Valid @RequestBody UserRequest request) {
+        return ResponseEntity.ok(userService.updateUser(id, request));
+    }
+
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Void> deleteUser(@PathVariable Long id) {
+        userService.deleteUser(id);
+        return ResponseEntity.noContent().build();
+    }
+
+    @DeleteMapping
+    public ResponseEntity<Void> bulkDeleteUsers(@Valid @RequestBody BulkDeleteRequest request) {
+        userService.bulkDeleteUsers(request);
+        return ResponseEntity.noContent().build();
+    }
+}

backend/src/main/java/com/petshop/backend/dto/adoption/AdoptionRequest.java

@@ -0,0 +1,78 @@
+package com.petshop.backend.dto.adoption;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import java.time.LocalDate;
+import java.util.Objects;
+
+public class AdoptionRequest {
+    @NotNull(message = "Pet ID is required")
+    private Long petId;
+
+    @NotNull(message = "Customer ID is required")
+    private Long customerId;
+
+    @NotNull(message = "Adoption date is required")
+    private LocalDate adoptionDate;
+
+    @NotBlank(message = "Adoption status is required")
+    private String adoptionStatus;
+
+    public Long getPetId() {
+        return petId;
+    }
+
+    public void setPetId(Long petId) {
+        this.petId = petId;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public LocalDate getAdoptionDate() {
+        return adoptionDate;
+    }
+
+    public void setAdoptionDate(LocalDate adoptionDate) {
+        this.adoptionDate = adoptionDate;
+    }
+
+    public String getAdoptionStatus() {
+        return adoptionStatus;
+    }
+
+    public void setAdoptionStatus(String adoptionStatus) {
+        this.adoptionStatus = adoptionStatus;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        AdoptionRequest that = (AdoptionRequest) o;
+        return Objects.equals(petId, that.petId) &&
+                Objects.equals(customerId, that.customerId) &&
+                Objects.equals(adoptionDate, that.adoptionDate) &&
+                Objects.equals(adoptionStatus, that.adoptionStatus);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(petId, customerId, adoptionDate, adoptionStatus);
+    }
+
+    @Override
+    public String toString() {
+        return "AdoptionRequest{" +
+                "petId=" + petId +
+                ", customerId=" + customerId +
+                ", adoptionDate=" + adoptionDate +
+                ", adoptionStatus='" + adoptionStatus + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/adoption/AdoptionResponse.java

@@ -0,0 +1,144 @@
+package com.petshop.backend.dto.adoption;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class AdoptionResponse {
+    private Long adoptionId;
+    private Long petId;
+    private String petName;
+    private Long customerId;
+    private String customerName;
+    private LocalDate adoptionDate;
+    private String adoptionStatus;
+    private BigDecimal adoptionFee;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public AdoptionResponse() {
+    }
+
+    public AdoptionResponse(Long adoptionId, Long petId, String petName, Long customerId, String customerName, LocalDate adoptionDate, String adoptionStatus, BigDecimal adoptionFee, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.adoptionId = adoptionId;
+        this.petId = petId;
+        this.petName = petName;
+        this.customerId = customerId;
+        this.customerName = customerName;
+        this.adoptionDate = adoptionDate;
+        this.adoptionStatus = adoptionStatus;
+        this.adoptionFee = adoptionFee;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getAdoptionId() {
+        return adoptionId;
+    }
+
+    public void setAdoptionId(Long adoptionId) {
+        this.adoptionId = adoptionId;
+    }
+
+    public Long getPetId() {
+        return petId;
+    }
+
+    public void setPetId(Long petId) {
+        this.petId = petId;
+    }
+
+    public String getPetName() {
+        return petName;
+    }
+
+    public void setPetName(String petName) {
+        this.petName = petName;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public String getCustomerName() {
+        return customerName;
+    }
+
+    public void setCustomerName(String customerName) {
+        this.customerName = customerName;
+    }
+
+    public LocalDate getAdoptionDate() {
+        return adoptionDate;
+    }
+
+    public void setAdoptionDate(LocalDate adoptionDate) {
+        this.adoptionDate = adoptionDate;
+    }
+
+    public String getAdoptionStatus() {
+        return adoptionStatus;
+    }
+
+    public void setAdoptionStatus(String adoptionStatus) {
+        this.adoptionStatus = adoptionStatus;
+    }
+
+    public BigDecimal getAdoptionFee() {
+        return adoptionFee;
+    }
+
+    public void setAdoptionFee(BigDecimal adoptionFee) {
+        this.adoptionFee = adoptionFee;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        AdoptionResponse that = (AdoptionResponse) o;
+        return Objects.equals(adoptionId, that.adoptionId) && Objects.equals(petId, that.petId) && Objects.equals(petName, that.petName) && Objects.equals(customerId, that.customerId) && Objects.equals(customerName, that.customerName) && Objects.equals(adoptionDate, that.adoptionDate) && Objects.equals(adoptionStatus, that.adoptionStatus) && Objects.equals(adoptionFee, that.adoptionFee) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(adoptionId, petId, petName, customerId, customerName, adoptionDate, adoptionStatus, adoptionFee, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "AdoptionResponse{" +
+                "adoptionId=" + adoptionId +
+                ", petId=" + petId +
+                ", petName='" + petName + '\'' +
+                ", customerId=" + customerId +
+                ", customerName='" + customerName + '\'' +
+                ", adoptionDate=" + adoptionDate +
+                ", adoptionStatus='" + adoptionStatus + '\'' +
+                ", adoptionFee=" + adoptionFee +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/analytics/DashboardResponse.java

@@ -0,0 +1,343 @@
+package com.petshop.backend.dto.analytics;
+
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Objects;
+
+public class DashboardResponse {
+    private SalesSummary salesSummary;
+    private InventorySummary inventorySummary;
+    private List<TopProduct> topProducts;
+    private List<DailySales> dailySales;
+
+    public DashboardResponse() {
+    }
+
+    public DashboardResponse(SalesSummary salesSummary, InventorySummary inventorySummary, List<TopProduct> topProducts, List<DailySales> dailySales) {
+        this.salesSummary = salesSummary;
+        this.inventorySummary = inventorySummary;
+        this.topProducts = topProducts;
+        this.dailySales = dailySales;
+    }
+
+    public SalesSummary getSalesSummary() {
+        return salesSummary;
+    }
+
+    public void setSalesSummary(SalesSummary salesSummary) {
+        this.salesSummary = salesSummary;
+    }
+
+    public InventorySummary getInventorySummary() {
+        return inventorySummary;
+    }
+
+    public void setInventorySummary(InventorySummary inventorySummary) {
+        this.inventorySummary = inventorySummary;
+    }
+
+    public List<TopProduct> getTopProducts() {
+        return topProducts;
+    }
+
+    public void setTopProducts(List<TopProduct> topProducts) {
+        this.topProducts = topProducts;
+    }
+
+    public List<DailySales> getDailySales() {
+        return dailySales;
+    }
+
+    public void setDailySales(List<DailySales> dailySales) {
+        this.dailySales = dailySales;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        DashboardResponse that = (DashboardResponse) o;
+        return Objects.equals(salesSummary, that.salesSummary) && Objects.equals(inventorySummary, that.inventorySummary) && Objects.equals(topProducts, that.topProducts) && Objects.equals(dailySales, that.dailySales);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(salesSummary, inventorySummary, topProducts, dailySales);
+    }
+
+    @Override
+    public String toString() {
+        return "DashboardResponse{" +
+                "salesSummary=" + salesSummary +
+                ", inventorySummary=" + inventorySummary +
+                ", topProducts=" + topProducts +
+                ", dailySales=" + dailySales +
+                '}';
+    }
+
+    public static class SalesSummary {
+    private BigDecimal totalRevenue;
+    private Long totalSales;
+    private BigDecimal totalRefunds;
+    private Long totalRefundCount;
+
+    public SalesSummary() {
+    }
+
+    public SalesSummary(BigDecimal totalRevenue, Long totalSales, BigDecimal totalRefunds, Long totalRefundCount) {
+        this.totalRevenue = totalRevenue;
+        this.totalSales = totalSales;
+        this.totalRefunds = totalRefunds;
+        this.totalRefundCount = totalRefundCount;
+    }
+
+    public BigDecimal getTotalRevenue() {
+        return totalRevenue;
+    }
+
+    public void setTotalRevenue(BigDecimal totalRevenue) {
+        this.totalRevenue = totalRevenue;
+    }
+
+    public Long getTotalSales() {
+        return totalSales;
+    }
+
+    public void setTotalSales(Long totalSales) {
+        this.totalSales = totalSales;
+    }
+
+    public BigDecimal getTotalRefunds() {
+        return totalRefunds;
+    }
+
+    public void setTotalRefunds(BigDecimal totalRefunds) {
+        this.totalRefunds = totalRefunds;
+    }
+
+    public Long getTotalRefundCount() {
+        return totalRefundCount;
+    }
+
+    public void setTotalRefundCount(Long totalRefundCount) {
+        this.totalRefundCount = totalRefundCount;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        SalesSummary that = (SalesSummary) o;
+        return Objects.equals(totalRevenue, that.totalRevenue) && Objects.equals(totalSales, that.totalSales) && Objects.equals(totalRefunds, that.totalRefunds) && Objects.equals(totalRefundCount, that.totalRefundCount);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(totalRevenue, totalSales, totalRefunds, totalRefundCount);
+    }
+
+    @Override
+    public String toString() {
+        return "SalesSummary{" +
+                "totalRevenue=" + totalRevenue +
+                ", totalSales=" + totalSales +
+                ", totalRefunds=" + totalRefunds +
+                ", totalRefundCount=" + totalRefundCount +
+                '}';
+    }
+}
+
+    public static class InventorySummary {
+    private Long totalProducts;
+    private Long lowStockProducts;
+    private Long outOfStockProducts;
+
+    public InventorySummary() {
+    }
+
+    public InventorySummary(Long totalProducts, Long lowStockProducts, Long outOfStockProducts) {
+        this.totalProducts = totalProducts;
+        this.lowStockProducts = lowStockProducts;
+        this.outOfStockProducts = outOfStockProducts;
+    }
+
+    public Long getTotalProducts() {
+        return totalProducts;
+    }
+
+    public void setTotalProducts(Long totalProducts) {
+        this.totalProducts = totalProducts;
+    }
+
+    public Long getLowStockProducts() {
+        return lowStockProducts;
+    }
+
+    public void setLowStockProducts(Long lowStockProducts) {
+        this.lowStockProducts = lowStockProducts;
+    }
+
+    public Long getOutOfStockProducts() {
+        return outOfStockProducts;
+    }
+
+    public void setOutOfStockProducts(Long outOfStockProducts) {
+        this.outOfStockProducts = outOfStockProducts;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        InventorySummary that = (InventorySummary) o;
+        return Objects.equals(totalProducts, that.totalProducts) && Objects.equals(lowStockProducts, that.lowStockProducts) && Objects.equals(outOfStockProducts, that.outOfStockProducts);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(totalProducts, lowStockProducts, outOfStockProducts);
+    }
+
+    @Override
+    public String toString() {
+        return "InventorySummary{" +
+                "totalProducts=" + totalProducts +
+                ", lowStockProducts=" + lowStockProducts +
+                ", outOfStockProducts=" + outOfStockProducts +
+                '}';
+    }
+}
+
+    public static class TopProduct {
+    private Long productId;
+    private String productName;
+    private Long quantitySold;
+    private BigDecimal revenue;
+
+    public TopProduct() {
+    }
+
+    public TopProduct(Long productId, String productName, Long quantitySold, BigDecimal revenue) {
+        this.productId = productId;
+        this.productName = productName;
+        this.quantitySold = quantitySold;
+        this.revenue = revenue;
+    }
+
+    public Long getProductId() {
+        return productId;
+    }
+
+    public void setProductId(Long productId) {
+        this.productId = productId;
+    }
+
+    public String getProductName() {
+        return productName;
+    }
+
+    public void setProductName(String productName) {
+        this.productName = productName;
+    }
+
+    public Long getQuantitySold() {
+        return quantitySold;
+    }
+
+    public void setQuantitySold(Long quantitySold) {
+        this.quantitySold = quantitySold;
+    }
+
+    public BigDecimal getRevenue() {
+        return revenue;
+    }
+
+    public void setRevenue(BigDecimal revenue) {
+        this.revenue = revenue;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        TopProduct that = (TopProduct) o;
+        return Objects.equals(productId, that.productId) && Objects.equals(productName, that.productName) && Objects.equals(quantitySold, that.quantitySold) && Objects.equals(revenue, that.revenue);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(productId, productName, quantitySold, revenue);
+    }
+
+    @Override
+    public String toString() {
+        return "TopProduct{" +
+                "productId=" + productId +
+                ", productName='" + productName + '\'' +
+                ", quantitySold=" + quantitySold +
+                ", revenue=" + revenue +
+                '}';
+    }
+}
+
+    public static class DailySales {
+    private String date;
+    private BigDecimal revenue;
+    private Long salesCount;
+
+    public DailySales() {
+    }
+
+    public DailySales(String date, BigDecimal revenue, Long salesCount) {
+        this.date = date;
+        this.revenue = revenue;
+        this.salesCount = salesCount;
+    }
+
+    public String getDate() {
+        return date;
+    }
+
+    public void setDate(String date) {
+        this.date = date;
+    }
+
+    public BigDecimal getRevenue() {
+        return revenue;
+    }
+
+    public void setRevenue(BigDecimal revenue) {
+        this.revenue = revenue;
+    }
+
+    public Long getSalesCount() {
+        return salesCount;
+    }
+
+    public void setSalesCount(Long salesCount) {
+        this.salesCount = salesCount;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        DailySales that = (DailySales) o;
+        return Objects.equals(date, that.date) && Objects.equals(revenue, that.revenue) && Objects.equals(salesCount, that.salesCount);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(date, revenue, salesCount);
+    }
+
+    @Override
+    public String toString() {
+        return "DailySales{" +
+                "date='" + date + '\'' +
+                ", revenue=" + revenue +
+                ", salesCount=" + salesCount +
+                '}';
+    }
+}
+}

backend/src/main/java/com/petshop/backend/dto/appointment/AppointmentRequest.java

@@ -0,0 +1,119 @@
+package com.petshop.backend.dto.appointment;
+
+import jakarta.validation.constraints.NotEmpty;
+import jakarta.validation.constraints.NotNull;
+import java.time.LocalDate;
+import java.time.LocalTime;
+import java.util.List;
+import java.util.Objects;
+
+public class AppointmentRequest {
+    @NotNull(message = "Customer ID is required")
+    private Long customerId;
+
+    @NotNull(message = "Store ID is required")
+    private Long storeId;
+
+    @NotNull(message = "Service ID is required")
+    private Long serviceId;
+
+    @NotNull(message = "Appointment date is required")
+    private LocalDate appointmentDate;
+
+    @NotNull(message = "Appointment time is required")
+    private LocalTime appointmentTime;
+
+    @NotNull(message = "Appointment status is required")
+    private String appointmentStatus;
+
+    @NotEmpty(message = "At least one pet must be specified")
+    private List<Long> petIds;
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public Long getStoreId() {
+        return storeId;
+    }
+
+    public void setStoreId(Long storeId) {
+        this.storeId = storeId;
+    }
+
+    public Long getServiceId() {
+        return serviceId;
+    }
+
+    public void setServiceId(Long serviceId) {
+        this.serviceId = serviceId;
+    }
+
+    public LocalDate getAppointmentDate() {
+        return appointmentDate;
+    }
+
+    public void setAppointmentDate(LocalDate appointmentDate) {
+        this.appointmentDate = appointmentDate;
+    }
+
+    public LocalTime getAppointmentTime() {
+        return appointmentTime;
+    }
+
+    public void setAppointmentTime(LocalTime appointmentTime) {
+        this.appointmentTime = appointmentTime;
+    }
+
+    public String getAppointmentStatus() {
+        return appointmentStatus;
+    }
+
+    public void setAppointmentStatus(String appointmentStatus) {
+        this.appointmentStatus = appointmentStatus;
+    }
+
+    public List<Long> getPetIds() {
+        return petIds;
+    }
+
+    public void setPetIds(List<Long> petIds) {
+        this.petIds = petIds;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        AppointmentRequest that = (AppointmentRequest) o;
+        return Objects.equals(customerId, that.customerId) &&
+                Objects.equals(storeId, that.storeId) &&
+                Objects.equals(serviceId, that.serviceId) &&
+                Objects.equals(appointmentDate, that.appointmentDate) &&
+                Objects.equals(appointmentTime, that.appointmentTime) &&
+                Objects.equals(appointmentStatus, that.appointmentStatus) &&
+                Objects.equals(petIds, that.petIds);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(customerId, storeId, serviceId, appointmentDate, appointmentTime, appointmentStatus, petIds);
+    }
+
+    @Override
+    public String toString() {
+        return "AppointmentRequest{" +
+                "customerId=" + customerId +
+                ", storeId=" + storeId +
+                ", serviceId=" + serviceId +
+                ", appointmentDate=" + appointmentDate +
+                ", appointmentTime=" + appointmentTime +
+                ", appointmentStatus='" + appointmentStatus + '\'' +
+                ", petIds=" + petIds +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/appointment/AppointmentResponse.java

@@ -0,0 +1,189 @@
+package com.petshop.backend.dto.appointment;
+
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.util.List;
+import java.util.Objects;
+
+public class AppointmentResponse {
+    private Long appointmentId;
+    private Long customerId;
+    private String customerName;
+    private Long storeId;
+    private String storeName;
+    private Long serviceId;
+    private String serviceName;
+    private LocalDate appointmentDate;
+    private LocalTime appointmentTime;
+    private String appointmentStatus;
+    private List<String> petNames;
+    private List<Long> petIds;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public AppointmentResponse() {
+    }
+
+    public AppointmentResponse(Long appointmentId, Long customerId, String customerName, Long storeId, String storeName, Long serviceId, String serviceName, LocalDate appointmentDate, LocalTime appointmentTime, String appointmentStatus, List<String> petNames, List<Long> petIds, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.appointmentId = appointmentId;
+        this.customerId = customerId;
+        this.customerName = customerName;
+        this.storeId = storeId;
+        this.storeName = storeName;
+        this.serviceId = serviceId;
+        this.serviceName = serviceName;
+        this.appointmentDate = appointmentDate;
+        this.appointmentTime = appointmentTime;
+        this.appointmentStatus = appointmentStatus;
+        this.petNames = petNames;
+        this.petIds = petIds;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getAppointmentId() {
+        return appointmentId;
+    }
+
+    public void setAppointmentId(Long appointmentId) {
+        this.appointmentId = appointmentId;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public String getCustomerName() {
+        return customerName;
+    }
+
+    public void setCustomerName(String customerName) {
+        this.customerName = customerName;
+    }
+
+    public Long getStoreId() {
+        return storeId;
+    }
+
+    public void setStoreId(Long storeId) {
+        this.storeId = storeId;
+    }
+
+    public String getStoreName() {
+        return storeName;
+    }
+
+    public void setStoreName(String storeName) {
+        this.storeName = storeName;
+    }
+
+    public Long getServiceId() {
+        return serviceId;
+    }
+
+    public void setServiceId(Long serviceId) {
+        this.serviceId = serviceId;
+    }
+
+    public String getServiceName() {
+        return serviceName;
+    }
+
+    public void setServiceName(String serviceName) {
+        this.serviceName = serviceName;
+    }
+
+    public LocalDate getAppointmentDate() {
+        return appointmentDate;
+    }
+
+    public void setAppointmentDate(LocalDate appointmentDate) {
+        this.appointmentDate = appointmentDate;
+    }
+
+    public LocalTime getAppointmentTime() {
+        return appointmentTime;
+    }
+
+    public void setAppointmentTime(LocalTime appointmentTime) {
+        this.appointmentTime = appointmentTime;
+    }
+
+    public String getAppointmentStatus() {
+        return appointmentStatus;
+    }
+
+    public void setAppointmentStatus(String appointmentStatus) {
+        this.appointmentStatus = appointmentStatus;
+    }
+
+    public List<String> getPetNames() {
+        return petNames;
+    }
+
+    public void setPetNames(List<String> petNames) {
+        this.petNames = petNames;
+    }
+
+    public List<Long> getPetIds() {
+        return petIds;
+    }
+
+    public void setPetIds(List<Long> petIds) {
+        this.petIds = petIds;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        AppointmentResponse that = (AppointmentResponse) o;
+        return Objects.equals(appointmentId, that.appointmentId) && Objects.equals(customerId, that.customerId) && Objects.equals(customerName, that.customerName) && Objects.equals(storeId, that.storeId) && Objects.equals(storeName, that.storeName) && Objects.equals(serviceId, that.serviceId) && Objects.equals(serviceName, that.serviceName) && Objects.equals(appointmentDate, that.appointmentDate) && Objects.equals(appointmentTime, that.appointmentTime) && Objects.equals(appointmentStatus, that.appointmentStatus) && Objects.equals(petNames, that.petNames) && Objects.equals(petIds, that.petIds) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(appointmentId, customerId, customerName, storeId, storeName, serviceId, serviceName, appointmentDate, appointmentTime, appointmentStatus, petNames, petIds, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "AppointmentResponse{" +
+                "appointmentId=" + appointmentId +
+                ", customerId=" + customerId +
+                ", customerName='" + customerName + '\'' +
+                ", storeId=" + storeId +
+                ", storeName='" + storeName + '\'' +
+                ", serviceId=" + serviceId +
+                ", serviceName='" + serviceName + '\'' +
+                ", appointmentDate=" + appointmentDate +
+                ", appointmentTime=" + appointmentTime +
+                ", appointmentStatus='" + appointmentStatus + '\'' +
+                ", petNames=" + petNames +
+                ", petIds=" + petIds +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/auth/AvatarUploadResponse.java

@@ -0,0 +1,54 @@
+package com.petshop.backend.dto.auth;
+
+import java.util.Objects;
+
+public class AvatarUploadResponse {
+    private String avatarUrl;
+    private String message;
+
+    public AvatarUploadResponse() {
+    }
+
+    public AvatarUploadResponse(String avatarUrl, String message) {
+        this.avatarUrl = avatarUrl;
+        this.message = message;
+    }
+
+    public String getAvatarUrl() {
+        return avatarUrl;
+    }
+
+    public void setAvatarUrl(String avatarUrl) {
+        this.avatarUrl = avatarUrl;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        AvatarUploadResponse that = (AvatarUploadResponse) o;
+        return Objects.equals(avatarUrl, that.avatarUrl) &&
+                Objects.equals(message, that.message);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(avatarUrl, message);
+    }
+
+    @Override
+    public String toString() {
+        return "AvatarUploadResponse{" +
+                "avatarUrl='" + avatarUrl + '\'' +
+                ", message='" + message + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/auth/LoginRequest.java

@@ -0,0 +1,50 @@
+package com.petshop.backend.dto.auth;
+
+import jakarta.validation.constraints.NotBlank;
+import java.util.Objects;
+
+public class LoginRequest {
+    @NotBlank(message = "Username is required")
+    private String username;
+
+    @NotBlank(message = "Password is required")
+    private String password;
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        LoginRequest that = (LoginRequest) o;
+        return Objects.equals(username, that.username) &&
+                Objects.equals(password, that.password);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(username, password);
+    }
+
+    @Override
+    public String toString() {
+        return "LoginRequest{" +
+                "username='" + username + '\'' +
+                ", password='" + password + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/auth/LoginResponse.java

@@ -0,0 +1,64 @@
+package com.petshop.backend.dto.auth;
+
+import java.util.Objects;
+
+public class LoginResponse {
+    private String token;
+    private String username;
+    private String role;
+
+    public LoginResponse() {
+    }
+
+    public LoginResponse(String token, String username, String role) {
+        this.token = token;
+        this.username = username;
+        this.role = role;
+    }
+
+    public String getToken() {
+        return token;
+    }
+
+    public void setToken(String token) {
+        this.token = token;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getRole() {
+        return role;
+    }
+
+    public void setRole(String role) {
+        this.role = role;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        LoginResponse that = (LoginResponse) o;
+        return Objects.equals(token, that.token) && Objects.equals(username, that.username) && Objects.equals(role, that.role);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(token, username, role);
+    }
+
+    @Override
+    public String toString() {
+        return "LoginResponse{" +
+                "token='" + token + '\'' +
+                ", username='" + username + '\'' +
+                ", role='" + role + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/auth/ProfileUpdateRequest.java

@@ -0,0 +1,90 @@
+package com.petshop.backend.dto.auth;
+
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.Size;
+import java.util.Objects;
+
+public class ProfileUpdateRequest {
+    @Size(min = 3, max = 50, message = "Username must be between 3 and 50 characters")
+    private String username;
+
+    @Email(message = "Email must be valid")
+    private String email;
+
+    @Size(max = 100, message = "Full name must not exceed 100 characters")
+    private String fullName;
+
+    @Size(max = 20, message = "Phone must not exceed 20 characters")
+    private String phone;
+
+    @Size(min = 6, message = "Password must be at least 6 characters")
+    private String password;
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getFullName() {
+        return fullName;
+    }
+
+    public void setFullName(String fullName) {
+        this.fullName = fullName;
+    }
+
+    public String getPhone() {
+        return phone;
+    }
+
+    public void setPhone(String phone) {
+        this.phone = phone;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ProfileUpdateRequest that = (ProfileUpdateRequest) o;
+        return Objects.equals(username, that.username) &&
+                Objects.equals(email, that.email) &&
+                Objects.equals(fullName, that.fullName) &&
+                Objects.equals(phone, that.phone) &&
+                Objects.equals(password, that.password);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(username, email, fullName, phone, password);
+    }
+
+    @Override
+    public String toString() {
+        return "ProfileUpdateRequest{" +
+                "username='" + username + '\'' +
+                ", email='" + email + '\'' +
+                ", fullName='" + fullName + '\'' +
+                ", phone='" + phone + '\'' +
+                ", password='" + password + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/auth/RegisterRequest.java

@@ -0,0 +1,96 @@
+package com.petshop.backend.dto.auth;
+
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
+import java.util.Objects;
+
+public class RegisterRequest {
+    @NotBlank(message = "Username is required")
+    @Size(min = 3, max = 50, message = "Username must be between 3 and 50 characters")
+    private String username;
+
+    @NotBlank(message = "Password is required")
+    @Size(min = 6, message = "Password must be at least 6 characters")
+    private String password;
+
+    @NotBlank(message = "Email is required")
+    @Email(message = "Email must be valid")
+    private String email;
+
+    @NotBlank(message = "Full name is required")
+    @Size(max = 100, message = "Full name must not exceed 100 characters")
+    private String fullName;
+
+    @NotBlank(message = "Phone is required")
+    @Size(max = 20, message = "Phone must not exceed 20 characters")
+    private String phone;
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getFullName() {
+        return fullName;
+    }
+
+    public void setFullName(String fullName) {
+        this.fullName = fullName;
+    }
+
+    public String getPhone() {
+        return phone;
+    }
+
+    public void setPhone(String phone) {
+        this.phone = phone;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        RegisterRequest that = (RegisterRequest) o;
+        return Objects.equals(username, that.username) &&
+                Objects.equals(password, that.password) &&
+                Objects.equals(email, that.email) &&
+                Objects.equals(fullName, that.fullName) &&
+                Objects.equals(phone, that.phone);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(username, password, email, fullName, phone);
+    }
+
+    @Override
+    public String toString() {
+        return "RegisterRequest{" +
+                "username='" + username + '\'' +
+                ", password='" + password + '\'' +
+                ", email='" + email + '\'' +
+                ", fullName='" + fullName + '\'' +
+                ", phone='" + phone + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/auth/RegisterResponse.java

@@ -0,0 +1,102 @@
+package com.petshop.backend.dto.auth;
+
+import java.util.Objects;
+
+public class RegisterResponse {
+    private Long id;
+    private String username;
+    private String email;
+    private String phone;
+    private String role;
+    private String token;
+
+    public RegisterResponse() {
+    }
+
+    public RegisterResponse(Long id, String username, String email, String phone, String role, String token) {
+        this.id = id;
+        this.username = username;
+        this.email = email;
+        this.phone = phone;
+        this.role = role;
+        this.token = token;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getPhone() {
+        return phone;
+    }
+
+    public void setPhone(String phone) {
+        this.phone = phone;
+    }
+
+    public String getRole() {
+        return role;
+    }
+
+    public void setRole(String role) {
+        this.role = role;
+    }
+
+    public String getToken() {
+        return token;
+    }
+
+    public void setToken(String token) {
+        this.token = token;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        RegisterResponse that = (RegisterResponse) o;
+        return Objects.equals(id, that.id) &&
+                Objects.equals(username, that.username) &&
+                Objects.equals(email, that.email) &&
+                Objects.equals(phone, that.phone) &&
+                Objects.equals(role, that.role) &&
+                Objects.equals(token, that.token);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, username, email, phone, role, token);
+    }
+
+    @Override
+    public String toString() {
+        return "RegisterResponse{" +
+                "id=" + id +
+                ", username='" + username + '\'' +
+                ", email='" + email + '\'' +
+                ", phone='" + phone + '\'' +
+                ", role='" + role + '\'' +
+                ", token='" + token + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/auth/UserInfoResponse.java

@@ -0,0 +1,138 @@
+package com.petshop.backend.dto.auth;
+
+import java.util.Objects;
+
+public class UserInfoResponse {
+    private Long id;
+    private String username;
+    private String email;
+    private String fullName;
+    private String phone;
+    private String avatarUrl;
+    private String role;
+    private Long storeId;
+    private String storeName;
+
+    public UserInfoResponse() {
+    }
+
+    public UserInfoResponse(Long id, String username, String email, String fullName, String phone, String avatarUrl, String role, Long storeId, String storeName) {
+        this.id = id;
+        this.username = username;
+        this.email = email;
+        this.fullName = fullName;
+        this.phone = phone;
+        this.avatarUrl = avatarUrl;
+        this.role = role;
+        this.storeId = storeId;
+        this.storeName = storeName;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getFullName() {
+        return fullName;
+    }
+
+    public void setFullName(String fullName) {
+        this.fullName = fullName;
+    }
+
+    public String getPhone() {
+        return phone;
+    }
+
+    public void setPhone(String phone) {
+        this.phone = phone;
+    }
+
+    public String getAvatarUrl() {
+        return avatarUrl;
+    }
+
+    public void setAvatarUrl(String avatarUrl) {
+        this.avatarUrl = avatarUrl;
+    }
+
+    public String getRole() {
+        return role;
+    }
+
+    public void setRole(String role) {
+        this.role = role;
+    }
+
+    public Long getStoreId() {
+        return storeId;
+    }
+
+    public void setStoreId(Long storeId) {
+        this.storeId = storeId;
+    }
+
+    public String getStoreName() {
+        return storeName;
+    }
+
+    public void setStoreName(String storeName) {
+        this.storeName = storeName;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        UserInfoResponse that = (UserInfoResponse) o;
+        return Objects.equals(id, that.id) &&
+                Objects.equals(username, that.username) &&
+                Objects.equals(email, that.email) &&
+                Objects.equals(fullName, that.fullName) &&
+                Objects.equals(phone, that.phone) &&
+                Objects.equals(avatarUrl, that.avatarUrl) &&
+                Objects.equals(role, that.role) &&
+                Objects.equals(storeId, that.storeId) &&
+                Objects.equals(storeName, that.storeName);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, username, email, fullName, phone, avatarUrl, role, storeId, storeName);
+    }
+
+    @Override
+    public String toString() {
+        return "UserInfoResponse{" +
+                "id=" + id +
+                ", username='" + username + '\'' +
+                ", email='" + email + '\'' +
+                ", fullName='" + fullName + '\'' +
+                ", phone='" + phone + '\'' +
+                ", avatarUrl='" + avatarUrl + '\'' +
+                ", role='" + role + '\'' +
+                ", storeId=" + storeId +
+                ", storeName='" + storeName + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/category/CategoryRequest.java

@@ -0,0 +1,49 @@
+package com.petshop.backend.dto.category;
+
+import jakarta.validation.constraints.NotBlank;
+import java.util.Objects;
+
+public class CategoryRequest {
+    @NotBlank(message = "Category name is required")
+    private String categoryName;
+
+    private String categoryType;
+
+    public String getCategoryName() {
+        return categoryName;
+    }
+
+    public void setCategoryName(String categoryName) {
+        this.categoryName = categoryName;
+    }
+
+    public String getCategoryType() {
+        return categoryType;
+    }
+
+    public void setCategoryType(String categoryType) {
+        this.categoryType = categoryType;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        CategoryRequest that = (CategoryRequest) o;
+        return Objects.equals(categoryName, that.categoryName) &&
+                Objects.equals(categoryType, that.categoryType);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(categoryName, categoryType);
+    }
+
+    @Override
+    public String toString() {
+        return "CategoryRequest{" +
+                "categoryName='" + categoryName + '\'' +
+                ", categoryType='" + categoryType + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/category/CategoryResponse.java

@@ -0,0 +1,87 @@
+package com.petshop.backend.dto.category;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class CategoryResponse {
+    private Long categoryId;
+    private String categoryName;
+    private String categoryType;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public CategoryResponse() {
+    }
+
+    public CategoryResponse(Long categoryId, String categoryName, String categoryType, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.categoryId = categoryId;
+        this.categoryName = categoryName;
+        this.categoryType = categoryType;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getCategoryId() {
+        return categoryId;
+    }
+
+    public void setCategoryId(Long categoryId) {
+        this.categoryId = categoryId;
+    }
+
+    public String getCategoryName() {
+        return categoryName;
+    }
+
+    public void setCategoryName(String categoryName) {
+        this.categoryName = categoryName;
+    }
+
+    public String getCategoryType() {
+        return categoryType;
+    }
+
+    public void setCategoryType(String categoryType) {
+        this.categoryType = categoryType;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        CategoryResponse that = (CategoryResponse) o;
+        return Objects.equals(categoryId, that.categoryId) && Objects.equals(categoryName, that.categoryName) && Objects.equals(categoryType, that.categoryType) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(categoryId, categoryName, categoryType, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "CategoryResponse{" +
+                "categoryId=" + categoryId +
+                ", categoryName='" + categoryName + '\'' +
+                ", categoryType='" + categoryType + '\'' +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/chat/ConversationRequest.java

@@ -0,0 +1,23 @@
+package com.petshop.backend.dto.chat;
+
+import jakarta.validation.constraints.NotBlank;
+
+public class ConversationRequest {
+    @NotBlank(message = "Initial message is required")
+    private String message;
+
+    public ConversationRequest() {
+    }
+
+    public ConversationRequest(String message) {
+        this.message = message;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+}

backend/src/main/java/com/petshop/backend/dto/chat/ConversationResponse.java

@@ -0,0 +1,118 @@
+package com.petshop.backend.dto.chat;
+
+import com.petshop.backend.entity.Conversation;
+
+import java.time.LocalDateTime;
+
+public class ConversationResponse {
+    private Long id;
+    private Long customerId;
+    private Long staffId;
+    private String status;
+    private String mode;
+    private String lastMessage;
+    private LocalDateTime humanRequestedAt;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public ConversationResponse() {
+    }
+
+    public ConversationResponse(Long id, Long customerId, Long staffId, String status, String mode, String lastMessage, LocalDateTime humanRequestedAt, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.id = id;
+        this.customerId = customerId;
+        this.staffId = staffId;
+        this.status = status;
+        this.mode = mode;
+        this.lastMessage = lastMessage;
+        this.humanRequestedAt = humanRequestedAt;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public static ConversationResponse fromEntity(Conversation conversation, String lastMessage) {
+        ConversationResponse response = new ConversationResponse();
+        response.setId(conversation.getId());
+        response.setCustomerId(conversation.getCustomerId());
+        response.setStaffId(conversation.getStaffId());
+        response.setStatus(conversation.getStatus().name());
+        response.setMode(conversation.getMode().name());
+        response.setLastMessage(lastMessage);
+        response.setHumanRequestedAt(conversation.getHumanRequestedAt());
+        response.setCreatedAt(conversation.getCreatedAt());
+        response.setUpdatedAt(conversation.getUpdatedAt());
+        return response;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public Long getStaffId() {
+        return staffId;
+    }
+
+    public void setStaffId(Long staffId) {
+        this.staffId = staffId;
+    }
+
+    public String getStatus() {
+        return status;
+    }
+
+    public void setStatus(String status) {
+        this.status = status;
+    }
+
+    public String getMode() {
+        return mode;
+    }
+
+    public void setMode(String mode) {
+        this.mode = mode;
+    }
+
+    public String getLastMessage() {
+        return lastMessage;
+    }
+
+    public void setLastMessage(String lastMessage) {
+        this.lastMessage = lastMessage;
+    }
+
+    public LocalDateTime getHumanRequestedAt() {
+        return humanRequestedAt;
+    }
+
+    public void setHumanRequestedAt(LocalDateTime humanRequestedAt) {
+        this.humanRequestedAt = humanRequestedAt;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+}

backend/src/main/java/com/petshop/backend/dto/chat/MessageRequest.java

@@ -0,0 +1,23 @@
+package com.petshop.backend.dto.chat;
+
+import jakarta.validation.constraints.NotBlank;
+
+public class MessageRequest {
+    @NotBlank(message = "Message content is required")
+    private String content;
+
+    public MessageRequest() {
+    }
+
+    public MessageRequest(String content) {
+        this.content = content;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+}

backend/src/main/java/com/petshop/backend/dto/chat/MessageResponse.java

@@ -0,0 +1,85 @@
+package com.petshop.backend.dto.chat;
+
+import com.petshop.backend.entity.Message;
+
+import java.time.LocalDateTime;
+
+public class MessageResponse {
+    private Long id;
+    private Long conversationId;
+    private Long senderId;
+    private String content;
+    private LocalDateTime timestamp;
+    private Boolean isRead;
+
+    public MessageResponse() {
+    }
+
+    public MessageResponse(Long id, Long conversationId, Long senderId, String content, LocalDateTime timestamp, Boolean isRead) {
+        this.id = id;
+        this.conversationId = conversationId;
+        this.senderId = senderId;
+        this.content = content;
+        this.timestamp = timestamp;
+        this.isRead = isRead;
+    }
+
+    public static MessageResponse fromEntity(Message message) {
+        MessageResponse response = new MessageResponse();
+        response.setId(message.getId());
+        response.setConversationId(message.getConversationId());
+        response.setSenderId(message.getSenderId());
+        response.setContent(message.getContent());
+        response.setTimestamp(message.getTimestamp());
+        response.setIsRead(message.getIsRead());
+        return response;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getConversationId() {
+        return conversationId;
+    }
+
+    public void setConversationId(Long conversationId) {
+        this.conversationId = conversationId;
+    }
+
+    public Long getSenderId() {
+        return senderId;
+    }
+
+    public void setSenderId(Long senderId) {
+        this.senderId = senderId;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+
+    public LocalDateTime getTimestamp() {
+        return timestamp;
+    }
+
+    public void setTimestamp(LocalDateTime timestamp) {
+        this.timestamp = timestamp;
+    }
+
+    public Boolean getIsRead() {
+        return isRead;
+    }
+
+    public void setIsRead(Boolean isRead) {
+        this.isRead = isRead;
+    }
+}

backend/src/main/java/com/petshop/backend/dto/common/BulkDeleteRequest.java

@@ -0,0 +1,38 @@
+package com.petshop.backend.dto.common;
+
+import jakarta.validation.constraints.NotEmpty;
+import java.util.List;
+import java.util.Objects;
+
+public class BulkDeleteRequest {
+    @NotEmpty(message = "IDs list cannot be empty")
+    private List<Long> ids;
+
+    public List<Long> getIds() {
+        return ids;
+    }
+
+    public void setIds(List<Long> ids) {
+        this.ids = ids;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        BulkDeleteRequest that = (BulkDeleteRequest) o;
+        return Objects.equals(ids, that.ids);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(ids);
+    }
+
+    @Override
+    public String toString() {
+        return "BulkDeleteRequest{" +
+                "ids=" + ids +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/common/DropdownOption.java

@@ -0,0 +1,53 @@
+package com.petshop.backend.dto.common;
+
+import java.util.Objects;
+
+public class DropdownOption {
+    private Long id;
+    private String label;
+
+    public DropdownOption() {
+    }
+
+    public DropdownOption(Long id, String label) {
+        this.id = id;
+        this.label = label;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getLabel() {
+        return label;
+    }
+
+    public void setLabel(String label) {
+        this.label = label;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        DropdownOption that = (DropdownOption) o;
+        return Objects.equals(id, that.id) && Objects.equals(label, that.label);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, label);
+    }
+
+    @Override
+    public String toString() {
+        return "DropdownOption{" +
+                "id=" + id +
+                ", label='" + label + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/customer/CustomerRequest.java

@@ -0,0 +1,64 @@
+package com.petshop.backend.dto.customer;
+
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.NotBlank;
+import java.util.Objects;
+
+public class CustomerRequest {
+    @NotBlank(message = "First name is required")
+    private String firstName;
+
+    @NotBlank(message = "Last name is required")
+    private String lastName;
+
+    @Email(message = "Invalid email format")
+    private String email;
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        CustomerRequest that = (CustomerRequest) o;
+        return Objects.equals(firstName, that.firstName) &&
+                Objects.equals(lastName, that.lastName) &&
+                Objects.equals(email, that.email);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(firstName, lastName, email);
+    }
+
+    @Override
+    public String toString() {
+        return "CustomerRequest{" +
+                "firstName='" + firstName + '\'' +
+                ", lastName='" + lastName + '\'' +
+                ", email='" + email + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/customer/CustomerResponse.java

@@ -0,0 +1,98 @@
+package com.petshop.backend.dto.customer;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class CustomerResponse {
+    private Long customerId;
+    private String firstName;
+    private String lastName;
+    private String email;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public CustomerResponse() {
+    }
+
+    public CustomerResponse(Long customerId, String firstName, String lastName, String email, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.customerId = customerId;
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.email = email;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        CustomerResponse that = (CustomerResponse) o;
+        return Objects.equals(customerId, that.customerId) && Objects.equals(firstName, that.firstName) && Objects.equals(lastName, that.lastName) && Objects.equals(email, that.email) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(customerId, firstName, lastName, email, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "CustomerResponse{" +
+                "customerId=" + customerId +
+                ", firstName='" + firstName + '\'' +
+                ", lastName='" + lastName + '\'' +
+                ", email='" + email + '\'' +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/employee/EmployeeRequest.java

@@ -0,0 +1,51 @@
+package com.petshop.backend.dto.employee;
+
+import com.petshop.backend.entity.User;
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Size;
+
+public class EmployeeRequest {
+    @NotBlank(message = "Username is required")
+    @Size(min = 3, max = 50, message = "Username must be between 3 and 50 characters")
+    private String username;
+
+    @Size(min = 6, message = "Password must be at least 6 characters")
+    private String password;
+
+    @NotBlank(message = "First name is required")
+    private String firstName;
+
+    @NotBlank(message = "Last name is required")
+    private String lastName;
+
+    @Email(message = "Invalid email format")
+    private String email;
+
+    @NotBlank(message = "Phone is required")
+    @Size(max = 20, message = "Phone must not exceed 20 characters")
+    private String phone;
+
+    @NotNull(message = "Role is required")
+    private User.Role role;
+
+    private Boolean active = true;
+
+    public String getUsername() { return username; }
+    public void setUsername(String username) { this.username = username; }
+    public String getPassword() { return password; }
+    public void setPassword(String password) { this.password = password; }
+    public String getFirstName() { return firstName; }
+    public void setFirstName(String firstName) { this.firstName = firstName; }
+    public String getLastName() { return lastName; }
+    public void setLastName(String lastName) { this.lastName = lastName; }
+    public String getEmail() { return email; }
+    public void setEmail(String email) { this.email = email; }
+    public String getPhone() { return phone; }
+    public void setPhone(String phone) { this.phone = phone; }
+    public User.Role getRole() { return role; }
+    public void setRole(User.Role role) { this.role = role; }
+    public Boolean getActive() { return active; }
+    public void setActive(Boolean active) { this.active = active; }
+}

backend/src/main/java/com/petshop/backend/dto/employee/EmployeeResponse.java

@@ -0,0 +1,43 @@
+package com.petshop.backend.dto.employee;
+
+import java.time.LocalDateTime;
+
+public class EmployeeResponse {
+    private Long employeeId;
+    private Long userId;
+    private String username;
+    private String firstName;
+    private String lastName;
+    private String fullName;
+    private String email;
+    private String phone;
+    private String role;
+    private Boolean active;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public Long getEmployeeId() { return employeeId; }
+    public void setEmployeeId(Long employeeId) { this.employeeId = employeeId; }
+    public Long getUserId() { return userId; }
+    public void setUserId(Long userId) { this.userId = userId; }
+    public String getUsername() { return username; }
+    public void setUsername(String username) { this.username = username; }
+    public String getFirstName() { return firstName; }
+    public void setFirstName(String firstName) { this.firstName = firstName; }
+    public String getLastName() { return lastName; }
+    public void setLastName(String lastName) { this.lastName = lastName; }
+    public String getFullName() { return fullName; }
+    public void setFullName(String fullName) { this.fullName = fullName; }
+    public String getEmail() { return email; }
+    public void setEmail(String email) { this.email = email; }
+    public String getPhone() { return phone; }
+    public void setPhone(String phone) { this.phone = phone; }
+    public String getRole() { return role; }
+    public void setRole(String role) { this.role = role; }
+    public Boolean getActive() { return active; }
+    public void setActive(Boolean active) { this.active = active; }
+    public LocalDateTime getCreatedAt() { return createdAt; }
+    public void setCreatedAt(LocalDateTime createdAt) { this.createdAt = createdAt; }
+    public LocalDateTime getUpdatedAt() { return updatedAt; }
+    public void setUpdatedAt(LocalDateTime updatedAt) { this.updatedAt = updatedAt; }
+}

backend/src/main/java/com/petshop/backend/dto/inventory/InventoryRequest.java

@@ -0,0 +1,52 @@
+package com.petshop.backend.dto.inventory;
+
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.PositiveOrZero;
+import java.util.Objects;
+
+public class InventoryRequest {
+    @NotNull(message = "Product ID is required")
+    private Long prodId;
+
+    @NotNull(message = "Quantity is required")
+    @PositiveOrZero(message = "Quantity must be zero or positive")
+    private Integer quantity;
+
+    public Long getProdId() {
+        return prodId;
+    }
+
+    public void setProdId(Long prodId) {
+        this.prodId = prodId;
+    }
+
+    public Integer getQuantity() {
+        return quantity;
+    }
+
+    public void setQuantity(Integer quantity) {
+        this.quantity = quantity;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        InventoryRequest that = (InventoryRequest) o;
+        return Objects.equals(prodId, that.prodId) &&
+                Objects.equals(quantity, that.quantity);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(prodId, quantity);
+    }
+
+    @Override
+    public String toString() {
+        return "InventoryRequest{" +
+                "prodId=" + prodId +
+                ", quantity=" + quantity +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/inventory/InventoryResponse.java

@@ -0,0 +1,109 @@
+package com.petshop.backend.dto.inventory;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class InventoryResponse {
+    private Long inventoryId;
+    private Long prodId;
+    private String productName;
+    private String categoryName;
+    private Integer quantity;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public InventoryResponse() {
+    }
+
+    public InventoryResponse(Long inventoryId, Long prodId, String productName, String categoryName, Integer quantity, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.inventoryId = inventoryId;
+        this.prodId = prodId;
+        this.productName = productName;
+        this.categoryName = categoryName;
+        this.quantity = quantity;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getInventoryId() {
+        return inventoryId;
+    }
+
+    public void setInventoryId(Long inventoryId) {
+        this.inventoryId = inventoryId;
+    }
+
+    public Long getProdId() {
+        return prodId;
+    }
+
+    public void setProdId(Long prodId) {
+        this.prodId = prodId;
+    }
+
+    public String getProductName() {
+        return productName;
+    }
+
+    public void setProductName(String productName) {
+        this.productName = productName;
+    }
+
+    public String getCategoryName() {
+        return categoryName;
+    }
+
+    public void setCategoryName(String categoryName) {
+        this.categoryName = categoryName;
+    }
+
+    public Integer getQuantity() {
+        return quantity;
+    }
+
+    public void setQuantity(Integer quantity) {
+        this.quantity = quantity;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        InventoryResponse that = (InventoryResponse) o;
+        return Objects.equals(inventoryId, that.inventoryId) && Objects.equals(prodId, that.prodId) && Objects.equals(productName, that.productName) && Objects.equals(categoryName, that.categoryName) && Objects.equals(quantity, that.quantity) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(inventoryId, prodId, productName, categoryName, quantity, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "InventoryResponse{" +
+                "inventoryId=" + inventoryId +
+                ", prodId=" + prodId +
+                ", productName='" + productName + '\'' +
+                ", categoryName='" + categoryName + '\'' +
+                ", quantity=" + quantity +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/pet/PetRequest.java

@@ -0,0 +1,103 @@
+package com.petshop.backend.dto.pet;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Positive;
+import java.math.BigDecimal;
+import java.util.Objects;
+
+public class PetRequest {
+    @NotBlank(message = "Pet name is required")
+    private String petName;
+
+    @NotBlank(message = "Species is required")
+    private String petSpecies;
+
+    private String petBreed;
+
+    @Positive(message = "Age must be positive")
+    private Integer petAge;
+
+    @NotNull(message = "Status is required")
+    private String petStatus;
+
+    private BigDecimal petPrice;
+
+    public String getPetName() {
+        return petName;
+    }
+
+    public void setPetName(String petName) {
+        this.petName = petName;
+    }
+
+    public String getPetSpecies() {
+        return petSpecies;
+    }
+
+    public void setPetSpecies(String petSpecies) {
+        this.petSpecies = petSpecies;
+    }
+
+    public String getPetBreed() {
+        return petBreed;
+    }
+
+    public void setPetBreed(String petBreed) {
+        this.petBreed = petBreed;
+    }
+
+    public Integer getPetAge() {
+        return petAge;
+    }
+
+    public void setPetAge(Integer petAge) {
+        this.petAge = petAge;
+    }
+
+    public String getPetStatus() {
+        return petStatus;
+    }
+
+    public void setPetStatus(String petStatus) {
+        this.petStatus = petStatus;
+    }
+
+    public BigDecimal getPetPrice() {
+        return petPrice;
+    }
+
+    public void setPetPrice(BigDecimal petPrice) {
+        this.petPrice = petPrice;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        PetRequest that = (PetRequest) o;
+        return Objects.equals(petName, that.petName) &&
+                Objects.equals(petSpecies, that.petSpecies) &&
+                Objects.equals(petBreed, that.petBreed) &&
+                Objects.equals(petAge, that.petAge) &&
+                petStatus == that.petStatus &&
+                Objects.equals(petPrice, that.petPrice);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(petName, petSpecies, petBreed, petAge, petStatus, petPrice);
+    }
+
+    @Override
+    public String toString() {
+        return "PetRequest{" +
+                "petName='" + petName + '\'' +
+                ", petSpecies='" + petSpecies + '\'' +
+                ", petBreed='" + petBreed + '\'' +
+                ", petAge=" + petAge +
+                ", petStatus=" + petStatus +
+                ", petPrice=" + petPrice +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/pet/PetResponse.java

@@ -0,0 +1,132 @@
+package com.petshop.backend.dto.pet;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class PetResponse {
+    private Long petId;
+    private String petName;
+    private String petSpecies;
+    private String petBreed;
+    private Integer petAge;
+    private String petStatus;
+    private BigDecimal petPrice;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public PetResponse() {
+    }
+
+    public PetResponse(Long petId, String petName, String petSpecies, String petBreed, Integer petAge, String petStatus, BigDecimal petPrice, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.petId = petId;
+        this.petName = petName;
+        this.petSpecies = petSpecies;
+        this.petBreed = petBreed;
+        this.petAge = petAge;
+        this.petStatus = petStatus;
+        this.petPrice = petPrice;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getPetId() {
+        return petId;
+    }
+
+    public void setPetId(Long petId) {
+        this.petId = petId;
+    }
+
+    public String getPetName() {
+        return petName;
+    }
+
+    public void setPetName(String petName) {
+        this.petName = petName;
+    }
+
+    public String getPetSpecies() {
+        return petSpecies;
+    }
+
+    public void setPetSpecies(String petSpecies) {
+        this.petSpecies = petSpecies;
+    }
+
+    public String getPetBreed() {
+        return petBreed;
+    }
+
+    public void setPetBreed(String petBreed) {
+        this.petBreed = petBreed;
+    }
+
+    public Integer getPetAge() {
+        return petAge;
+    }
+
+    public void setPetAge(Integer petAge) {
+        this.petAge = petAge;
+    }
+
+    public String getPetStatus() {
+        return petStatus;
+    }
+
+    public void setPetStatus(String petStatus) {
+        this.petStatus = petStatus;
+    }
+
+    public BigDecimal getPetPrice() {
+        return petPrice;
+    }
+
+    public void setPetPrice(BigDecimal petPrice) {
+        this.petPrice = petPrice;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        PetResponse that = (PetResponse) o;
+        return Objects.equals(petId, that.petId) && Objects.equals(petName, that.petName) && Objects.equals(petSpecies, that.petSpecies) && Objects.equals(petBreed, that.petBreed) && Objects.equals(petAge, that.petAge) && Objects.equals(petStatus, that.petStatus) && Objects.equals(petPrice, that.petPrice) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(petId, petName, petSpecies, petBreed, petAge, petStatus, petPrice, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "PetResponse{" +
+                "petId=" + petId +
+                ", petName='" + petName + '\'' +
+                ", petSpecies='" + petSpecies + '\'' +
+                ", petBreed='" + petBreed + '\'' +
+                ", petAge=" + petAge +
+                ", petStatus='" + petStatus + '\'' +
+                ", petPrice=" + petPrice +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/product/ProductRequest.java

@@ -0,0 +1,79 @@
+package com.petshop.backend.dto.product;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Positive;
+import java.math.BigDecimal;
+import java.util.Objects;
+
+public class ProductRequest {
+    @NotBlank(message = "Product name is required")
+    private String prodName;
+
+    @NotNull(message = "Category ID is required")
+    private Long categoryId;
+
+    private String prodDesc;
+
+    @NotNull(message = "Product price is required")
+    @Positive(message = "Price must be positive")
+    private BigDecimal prodPrice;
+
+    public String getProdName() {
+        return prodName;
+    }
+
+    public void setProdName(String prodName) {
+        this.prodName = prodName;
+    }
+
+    public Long getCategoryId() {
+        return categoryId;
+    }
+
+    public void setCategoryId(Long categoryId) {
+        this.categoryId = categoryId;
+    }
+
+    public String getProdDesc() {
+        return prodDesc;
+    }
+
+    public void setProdDesc(String prodDesc) {
+        this.prodDesc = prodDesc;
+    }
+
+    public BigDecimal getProdPrice() {
+        return prodPrice;
+    }
+
+    public void setProdPrice(BigDecimal prodPrice) {
+        this.prodPrice = prodPrice;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ProductRequest that = (ProductRequest) o;
+        return Objects.equals(prodName, that.prodName) &&
+                Objects.equals(categoryId, that.categoryId) &&
+                Objects.equals(prodDesc, that.prodDesc) &&
+                Objects.equals(prodPrice, that.prodPrice);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(prodName, categoryId, prodDesc, prodPrice);
+    }
+
+    @Override
+    public String toString() {
+        return "ProductRequest{" +
+                "prodName='" + prodName + '\'' +
+                ", categoryId=" + categoryId +
+                ", prodDesc='" + prodDesc + '\'' +
+                ", prodPrice=" + prodPrice +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/product/ProductResponse.java

@@ -0,0 +1,121 @@
+package com.petshop.backend.dto.product;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class ProductResponse {
+    private Long prodId;
+    private String prodName;
+    private Long categoryId;
+    private String categoryName;
+    private String prodDesc;
+    private BigDecimal prodPrice;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public ProductResponse() {
+    }
+
+    public ProductResponse(Long prodId, String prodName, Long categoryId, String categoryName, String prodDesc, BigDecimal prodPrice, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.prodId = prodId;
+        this.prodName = prodName;
+        this.categoryId = categoryId;
+        this.categoryName = categoryName;
+        this.prodDesc = prodDesc;
+        this.prodPrice = prodPrice;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getProdId() {
+        return prodId;
+    }
+
+    public void setProdId(Long prodId) {
+        this.prodId = prodId;
+    }
+
+    public String getProdName() {
+        return prodName;
+    }
+
+    public void setProdName(String prodName) {
+        this.prodName = prodName;
+    }
+
+    public Long getCategoryId() {
+        return categoryId;
+    }
+
+    public void setCategoryId(Long categoryId) {
+        this.categoryId = categoryId;
+    }
+
+    public String getCategoryName() {
+        return categoryName;
+    }
+
+    public void setCategoryName(String categoryName) {
+        this.categoryName = categoryName;
+    }
+
+    public String getProdDesc() {
+        return prodDesc;
+    }
+
+    public void setProdDesc(String prodDesc) {
+        this.prodDesc = prodDesc;
+    }
+
+    public BigDecimal getProdPrice() {
+        return prodPrice;
+    }
+
+    public void setProdPrice(BigDecimal prodPrice) {
+        this.prodPrice = prodPrice;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ProductResponse that = (ProductResponse) o;
+        return Objects.equals(prodId, that.prodId) && Objects.equals(prodName, that.prodName) && Objects.equals(categoryId, that.categoryId) && Objects.equals(categoryName, that.categoryName) && Objects.equals(prodDesc, that.prodDesc) && Objects.equals(prodPrice, that.prodPrice) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(prodId, prodName, categoryId, categoryName, prodDesc, prodPrice, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "ProductResponse{" +
+                "prodId=" + prodId +
+                ", prodName='" + prodName + '\'' +
+                ", categoryId=" + categoryId +
+                ", categoryName='" + categoryName + '\'' +
+                ", prodDesc='" + prodDesc + '\'' +
+                ", prodPrice=" + prodPrice +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/productsupplier/BulkDeleteProductSupplierRequest.java

@@ -0,0 +1,38 @@
+package com.petshop.backend.dto.productsupplier;
+
+import jakarta.validation.constraints.NotEmpty;
+import java.util.List;
+import java.util.Objects;
+
+public class BulkDeleteProductSupplierRequest {
+    @NotEmpty(message = "Keys list cannot be empty")
+    private List<ProductSupplierKey> keys;
+
+    public List<ProductSupplierKey> getKeys() {
+        return keys;
+    }
+
+    public void setKeys(List<ProductSupplierKey> keys) {
+        this.keys = keys;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        BulkDeleteProductSupplierRequest that = (BulkDeleteProductSupplierRequest) o;
+        return Objects.equals(keys, that.keys);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(keys);
+    }
+
+    @Override
+    public String toString() {
+        return "BulkDeleteProductSupplierRequest{" +
+                "keys=" + keys +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/productsupplier/ProductSupplierKey.java

@@ -0,0 +1,54 @@
+package com.petshop.backend.dto.productsupplier;
+
+import java.util.Objects;
+
+public class ProductSupplierKey {
+    private Long productId;
+    private Long supplierId;
+
+    public ProductSupplierKey() {
+    }
+
+    public ProductSupplierKey(Long productId, Long supplierId) {
+        this.productId = productId;
+        this.supplierId = supplierId;
+    }
+
+    public Long getProductId() {
+        return productId;
+    }
+
+    public void setProductId(Long productId) {
+        this.productId = productId;
+    }
+
+    public Long getSupplierId() {
+        return supplierId;
+    }
+
+    public void setSupplierId(Long supplierId) {
+        this.supplierId = supplierId;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ProductSupplierKey that = (ProductSupplierKey) o;
+        return Objects.equals(productId, that.productId) && Objects.equals(supplierId, that.supplierId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(productId, supplierId);
+    }
+
+    @Override
+    public String toString() {
+        return "ProductSupplierKey{" +
+                "productId=" + productId +
+                ", supplierId=" + supplierId +
+                '}';
+    }
+}
+

backend/src/main/java/com/petshop/backend/dto/productsupplier/ProductSupplierRequest.java

@@ -0,0 +1,66 @@
+package com.petshop.backend.dto.productsupplier;
+
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Positive;
+import java.math.BigDecimal;
+import java.util.Objects;
+
+public class ProductSupplierRequest {
+    @NotNull(message = "Product ID is required")
+    private Long productId;
+
+    @NotNull(message = "Supplier ID is required")
+    private Long supplierId;
+
+    @NotNull(message = "Cost is required")
+    @Positive(message = "Cost must be positive")
+    private BigDecimal cost;
+
+    public Long getProductId() {
+        return productId;
+    }
+
+    public void setProductId(Long productId) {
+        this.productId = productId;
+    }
+
+    public Long getSupplierId() {
+        return supplierId;
+    }
+
+    public void setSupplierId(Long supplierId) {
+        this.supplierId = supplierId;
+    }
+
+    public BigDecimal getCost() {
+        return cost;
+    }
+
+    public void setCost(BigDecimal cost) {
+        this.cost = cost;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ProductSupplierRequest that = (ProductSupplierRequest) o;
+        return Objects.equals(productId, that.productId) &&
+                Objects.equals(supplierId, that.supplierId) &&
+                Objects.equals(cost, that.cost);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(productId, supplierId, cost);
+    }
+
+    @Override
+    public String toString() {
+        return "ProductSupplierRequest{" +
+                "productId=" + productId +
+                ", supplierId=" + supplierId +
+                ", cost=" + cost +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/productsupplier/ProductSupplierResponse.java

@@ -0,0 +1,110 @@
+package com.petshop.backend.dto.productsupplier;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class ProductSupplierResponse {
+    private Long productId;
+    private String productName;
+    private Long supplierId;
+    private String supplierName;
+    private BigDecimal cost;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public ProductSupplierResponse() {
+    }
+
+    public ProductSupplierResponse(Long productId, String productName, Long supplierId, String supplierName, BigDecimal cost, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.productId = productId;
+        this.productName = productName;
+        this.supplierId = supplierId;
+        this.supplierName = supplierName;
+        this.cost = cost;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getProductId() {
+        return productId;
+    }
+
+    public void setProductId(Long productId) {
+        this.productId = productId;
+    }
+
+    public String getProductName() {
+        return productName;
+    }
+
+    public void setProductName(String productName) {
+        this.productName = productName;
+    }
+
+    public Long getSupplierId() {
+        return supplierId;
+    }
+
+    public void setSupplierId(Long supplierId) {
+        this.supplierId = supplierId;
+    }
+
+    public String getSupplierName() {
+        return supplierName;
+    }
+
+    public void setSupplierName(String supplierName) {
+        this.supplierName = supplierName;
+    }
+
+    public BigDecimal getCost() {
+        return cost;
+    }
+
+    public void setCost(BigDecimal cost) {
+        this.cost = cost;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ProductSupplierResponse that = (ProductSupplierResponse) o;
+        return Objects.equals(productId, that.productId) && Objects.equals(productName, that.productName) && Objects.equals(supplierId, that.supplierId) && Objects.equals(supplierName, that.supplierName) && Objects.equals(cost, that.cost) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(productId, productName, supplierId, supplierName, cost, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "ProductSupplierResponse{" +
+                "productId=" + productId +
+                ", productName='" + productName + '\'' +
+                ", supplierId=" + supplierId +
+                ", supplierName='" + supplierName + '\'' +
+                ", cost=" + cost +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/purchaseorder/PurchaseOrderResponse.java

@@ -0,0 +1,110 @@
+package com.petshop.backend.dto.purchaseorder;
+
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class PurchaseOrderResponse {
+    private Long purchaseOrderId;
+    private Long supId;
+    private String supplierName;
+    private LocalDate orderDate;
+    private String status;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public PurchaseOrderResponse() {
+    }
+
+    public PurchaseOrderResponse(Long purchaseOrderId, Long supId, String supplierName, LocalDate orderDate, String status, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.purchaseOrderId = purchaseOrderId;
+        this.supId = supId;
+        this.supplierName = supplierName;
+        this.orderDate = orderDate;
+        this.status = status;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getPurchaseOrderId() {
+        return purchaseOrderId;
+    }
+
+    public void setPurchaseOrderId(Long purchaseOrderId) {
+        this.purchaseOrderId = purchaseOrderId;
+    }
+
+    public Long getSupId() {
+        return supId;
+    }
+
+    public void setSupId(Long supId) {
+        this.supId = supId;
+    }
+
+    public String getSupplierName() {
+        return supplierName;
+    }
+
+    public void setSupplierName(String supplierName) {
+        this.supplierName = supplierName;
+    }
+
+    public LocalDate getOrderDate() {
+        return orderDate;
+    }
+
+    public void setOrderDate(LocalDate orderDate) {
+        this.orderDate = orderDate;
+    }
+
+    public String getStatus() {
+        return status;
+    }
+
+    public void setStatus(String status) {
+        this.status = status;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        PurchaseOrderResponse that = (PurchaseOrderResponse) o;
+        return Objects.equals(purchaseOrderId, that.purchaseOrderId) && Objects.equals(supId, that.supId) && Objects.equals(supplierName, that.supplierName) && Objects.equals(orderDate, that.orderDate) && Objects.equals(status, that.status) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(purchaseOrderId, supId, supplierName, orderDate, status, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "PurchaseOrderResponse{" +
+                "purchaseOrderId=" + purchaseOrderId +
+                ", supId=" + supId +
+                ", supplierName='" + supplierName + '\'' +
+                ", orderDate=" + orderDate +
+                ", status='" + status + '\'' +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/refund/RefundRequest.java

@@ -0,0 +1,51 @@
+package com.petshop.backend.dto.refund;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import java.util.Objects;
+
+public class RefundRequest {
+    @NotNull(message = "Sale ID is required")
+    private Long saleId;
+
+    @NotBlank(message = "Reason is required")
+    private String reason;
+
+    public Long getSaleId() {
+        return saleId;
+    }
+
+    public void setSaleId(Long saleId) {
+        this.saleId = saleId;
+    }
+
+    public String getReason() {
+        return reason;
+    }
+
+    public void setReason(String reason) {
+        this.reason = reason;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        RefundRequest that = (RefundRequest) o;
+        return Objects.equals(saleId, that.saleId) &&
+                Objects.equals(reason, that.reason);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(saleId, reason);
+    }
+
+    @Override
+    public String toString() {
+        return "RefundRequest{" +
+                "saleId=" + saleId +
+                ", reason='" + reason + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/refund/RefundResponse.java

@@ -0,0 +1,128 @@
+package com.petshop.backend.dto.refund;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class RefundResponse {
+    private Long id;
+    private Long saleId;
+    private Long customerId;
+    private BigDecimal amount;
+    private String reason;
+    private String status;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public RefundResponse() {
+    }
+
+    public RefundResponse(Long id, Long saleId, Long customerId, BigDecimal amount, String reason, String status, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.id = id;
+        this.saleId = saleId;
+        this.customerId = customerId;
+        this.amount = amount;
+        this.reason = reason;
+        this.status = status;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getSaleId() {
+        return saleId;
+    }
+
+    public void setSaleId(Long saleId) {
+        this.saleId = saleId;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public BigDecimal getAmount() {
+        return amount;
+    }
+
+    public void setAmount(BigDecimal amount) {
+        this.amount = amount;
+    }
+
+    public String getReason() {
+        return reason;
+    }
+
+    public void setReason(String reason) {
+        this.reason = reason;
+    }
+
+    public String getStatus() {
+        return status;
+    }
+
+    public void setStatus(String status) {
+        this.status = status;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        RefundResponse that = (RefundResponse) o;
+        return Objects.equals(id, that.id) &&
+                Objects.equals(saleId, that.saleId) &&
+                Objects.equals(customerId, that.customerId) &&
+                Objects.equals(amount, that.amount) &&
+                Objects.equals(reason, that.reason) &&
+                Objects.equals(status, that.status) &&
+                Objects.equals(createdAt, that.createdAt) &&
+                Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, saleId, customerId, amount, reason, status, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "RefundResponse{" +
+                "id=" + id +
+                ", saleId=" + saleId +
+                ", customerId=" + customerId +
+                ", amount=" + amount +
+                ", reason='" + reason + '\'' +
+                ", status='" + status + '\'' +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/refund/RefundUpdateRequest.java

@@ -0,0 +1,37 @@
+package com.petshop.backend.dto.refund;
+
+import jakarta.validation.constraints.NotBlank;
+import java.util.Objects;
+
+public class RefundUpdateRequest {
+    @NotBlank(message = "Status is required")
+    private String status;
+
+    public String getStatus() {
+        return status;
+    }
+
+    public void setStatus(String status) {
+        this.status = status;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        RefundUpdateRequest that = (RefundUpdateRequest) o;
+        return Objects.equals(status, that.status);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(status);
+    }
+
+    @Override
+    public String toString() {
+        return "RefundUpdateRequest{" +
+                "status='" + status + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/sale/SaleItemRequest.java

@@ -0,0 +1,51 @@
+package com.petshop.backend.dto.sale;
+
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Positive;
+import java.util.Objects;
+
+public class SaleItemRequest {
+    @NotNull(message = "Product ID is required")
+    private Long prodId;
+
+    @NotNull(message = "Quantity is required")
+    private Integer quantity;
+
+    public Long getProdId() {
+        return prodId;
+    }
+
+    public void setProdId(Long prodId) {
+        this.prodId = prodId;
+    }
+
+    public Integer getQuantity() {
+        return quantity;
+    }
+
+    public void setQuantity(Integer quantity) {
+        this.quantity = quantity;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        SaleItemRequest that = (SaleItemRequest) o;
+        return Objects.equals(prodId, that.prodId) &&
+                Objects.equals(quantity, that.quantity);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(prodId, quantity);
+    }
+
+    @Override
+    public String toString() {
+        return "SaleItemRequest{" +
+                "prodId=" + prodId +
+                ", quantity=" + quantity +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/sale/SaleRequest.java

@@ -0,0 +1,102 @@
+package com.petshop.backend.dto.sale;
+
+import jakarta.validation.Valid;
+import jakarta.validation.constraints.NotEmpty;
+import jakarta.validation.constraints.NotNull;
+import java.util.List;
+import java.util.Objects;
+
+public class SaleRequest {
+    @NotNull(message = "Store ID is required")
+    private Long storeId;
+
+    private String paymentMethod;
+
+    @NotEmpty(message = "At least one item is required")
+    @Valid
+    private List<SaleItemRequest> items;
+
+    private Boolean isRefund = false;
+
+    private Long originalSaleId;
+
+    private Long customerId;
+
+    public Long getStoreId() {
+        return storeId;
+    }
+
+    public void setStoreId(Long storeId) {
+        this.storeId = storeId;
+    }
+
+    public String getPaymentMethod() {
+        return paymentMethod;
+    }
+
+    public void setPaymentMethod(String paymentMethod) {
+        this.paymentMethod = paymentMethod;
+    }
+
+    public List<SaleItemRequest> getItems() {
+        return items;
+    }
+
+    public void setItems(List<SaleItemRequest> items) {
+        this.items = items;
+    }
+
+    public Boolean getIsRefund() {
+        return isRefund;
+    }
+
+    public void setIsRefund(Boolean isRefund) {
+        this.isRefund = isRefund;
+    }
+
+    public Long getOriginalSaleId() {
+        return originalSaleId;
+    }
+
+    public void setOriginalSaleId(Long originalSaleId) {
+        this.originalSaleId = originalSaleId;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        SaleRequest that = (SaleRequest) o;
+        return Objects.equals(storeId, that.storeId) &&
+                Objects.equals(paymentMethod, that.paymentMethod) &&
+                Objects.equals(items, that.items) &&
+                Objects.equals(isRefund, that.isRefund) &&
+                Objects.equals(originalSaleId, that.originalSaleId) &&
+                Objects.equals(customerId, that.customerId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(storeId, paymentMethod, items, isRefund, originalSaleId, customerId);
+    }
+
+    @Override
+    public String toString() {
+        return "SaleRequest{" +
+                "storeId=" + storeId +
+                ", paymentMethod='" + paymentMethod + '\'' +
+                ", items=" + items +
+                ", isRefund=" + isRefund +
+                ", originalSaleId=" + originalSaleId +
+                ", customerId=" + customerId +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/sale/SaleResponse.java

@@ -0,0 +1,249 @@
+package com.petshop.backend.dto.sale;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.List;
+import java.util.Objects;
+
+public class SaleResponse {
+    private Long saleId;
+    private LocalDateTime saleDate;
+    private Long employeeId;
+    private String employeeName;
+    private Long storeId;
+    private String storeName;
+    private BigDecimal totalAmount;
+    private String paymentMethod;
+    private Boolean isRefund;
+    private Long originalSaleId;
+    private List<SaleItemResponse> items;
+    private LocalDateTime createdAt;
+
+    public SaleResponse() {
+    }
+
+    public SaleResponse(Long saleId, LocalDateTime saleDate, Long employeeId, String employeeName, Long storeId, String storeName, BigDecimal totalAmount, String paymentMethod, Boolean isRefund, Long originalSaleId, List<SaleItemResponse> items, LocalDateTime createdAt) {
+        this.saleId = saleId;
+        this.saleDate = saleDate;
+        this.employeeId = employeeId;
+        this.employeeName = employeeName;
+        this.storeId = storeId;
+        this.storeName = storeName;
+        this.totalAmount = totalAmount;
+        this.paymentMethod = paymentMethod;
+        this.isRefund = isRefund;
+        this.originalSaleId = originalSaleId;
+        this.items = items;
+        this.createdAt = createdAt;
+    }
+
+    public Long getSaleId() {
+        return saleId;
+    }
+
+    public void setSaleId(Long saleId) {
+        this.saleId = saleId;
+    }
+
+    public LocalDateTime getSaleDate() {
+        return saleDate;
+    }
+
+    public void setSaleDate(LocalDateTime saleDate) {
+        this.saleDate = saleDate;
+    }
+
+    public Long getEmployeeId() {
+        return employeeId;
+    }
+
+    public void setEmployeeId(Long employeeId) {
+        this.employeeId = employeeId;
+    }
+
+    public String getEmployeeName() {
+        return employeeName;
+    }
+
+    public void setEmployeeName(String employeeName) {
+        this.employeeName = employeeName;
+    }
+
+    public Long getStoreId() {
+        return storeId;
+    }
+
+    public void setStoreId(Long storeId) {
+        this.storeId = storeId;
+    }
+
+    public String getStoreName() {
+        return storeName;
+    }
+
+    public void setStoreName(String storeName) {
+        this.storeName = storeName;
+    }
+
+    public BigDecimal getTotalAmount() {
+        return totalAmount;
+    }
+
+    public void setTotalAmount(BigDecimal totalAmount) {
+        this.totalAmount = totalAmount;
+    }
+
+    public String getPaymentMethod() {
+        return paymentMethod;
+    }
+
+    public void setPaymentMethod(String paymentMethod) {
+        this.paymentMethod = paymentMethod;
+    }
+
+    public Boolean getIsRefund() {
+        return isRefund;
+    }
+
+    public void setIsRefund(Boolean isRefund) {
+        this.isRefund = isRefund;
+    }
+
+    public Long getOriginalSaleId() {
+        return originalSaleId;
+    }
+
+    public void setOriginalSaleId(Long originalSaleId) {
+        this.originalSaleId = originalSaleId;
+    }
+
+    public List<SaleItemResponse> getItems() {
+        return items;
+    }
+
+    public void setItems(List<SaleItemResponse> items) {
+        this.items = items;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        SaleResponse that = (SaleResponse) o;
+        return Objects.equals(saleId, that.saleId) && Objects.equals(saleDate, that.saleDate) && Objects.equals(employeeId, that.employeeId) && Objects.equals(employeeName, that.employeeName) && Objects.equals(storeId, that.storeId) && Objects.equals(storeName, that.storeName) && Objects.equals(totalAmount, that.totalAmount) && Objects.equals(paymentMethod, that.paymentMethod) && Objects.equals(isRefund, that.isRefund) && Objects.equals(originalSaleId, that.originalSaleId) && Objects.equals(items, that.items) && Objects.equals(createdAt, that.createdAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(saleId, saleDate, employeeId, employeeName, storeId, storeName, totalAmount, paymentMethod, isRefund, originalSaleId, items, createdAt);
+    }
+
+    @Override
+    public String toString() {
+        return "SaleResponse{" +
+                "saleId=" + saleId +
+                ", saleDate=" + saleDate +
+                ", employeeId=" + employeeId +
+                ", employeeName='" + employeeName + '\'' +
+                ", storeId=" + storeId +
+                ", storeName='" + storeName + '\'' +
+                ", totalAmount=" + totalAmount +
+                ", paymentMethod='" + paymentMethod + '\'' +
+                ", isRefund=" + isRefund +
+                ", originalSaleId=" + originalSaleId +
+                ", items=" + items +
+                ", createdAt=" + createdAt +
+                '}';
+    }
+
+    public static class SaleItemResponse {
+        private Long saleItemId;
+        private Long prodId;
+        private String productName;
+        private Integer quantity;
+        private BigDecimal unitPrice;
+
+        public SaleItemResponse() {
+        }
+
+        public SaleItemResponse(Long saleItemId, Long prodId, String productName, Integer quantity, BigDecimal unitPrice) {
+            this.saleItemId = saleItemId;
+            this.prodId = prodId;
+            this.productName = productName;
+            this.quantity = quantity;
+            this.unitPrice = unitPrice;
+        }
+
+        public Long getSaleItemId() {
+            return saleItemId;
+        }
+
+        public void setSaleItemId(Long saleItemId) {
+            this.saleItemId = saleItemId;
+        }
+
+        public Long getProdId() {
+            return prodId;
+        }
+
+        public void setProdId(Long prodId) {
+            this.prodId = prodId;
+        }
+
+        public String getProductName() {
+            return productName;
+        }
+
+        public void setProductName(String productName) {
+            this.productName = productName;
+        }
+
+        public Integer getQuantity() {
+            return quantity;
+        }
+
+        public void setQuantity(Integer quantity) {
+            this.quantity = quantity;
+        }
+
+        public BigDecimal getUnitPrice() {
+            return unitPrice;
+        }
+
+        public void setUnitPrice(BigDecimal unitPrice) {
+            this.unitPrice = unitPrice;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            SaleItemResponse that = (SaleItemResponse) o;
+            return Objects.equals(saleItemId, that.saleItemId) && Objects.equals(prodId, that.prodId) && Objects.equals(productName, that.productName) && Objects.equals(quantity, that.quantity) && Objects.equals(unitPrice, that.unitPrice);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(saleItemId, prodId, productName, quantity, unitPrice);
+        }
+
+        @Override
+        public String toString() {
+            return "SaleItemResponse{" +
+                    "saleItemId=" + saleItemId +
+                    ", prodId=" + prodId +
+                    ", productName='" + productName + '\'' +
+                    ", quantity=" + quantity +
+                    ", unitPrice=" + unitPrice +
+                    '}';
+        }
+    }
+}

backend/src/main/java/com/petshop/backend/dto/service/ServiceRequest.java

@@ -0,0 +1,79 @@
+package com.petshop.backend.dto.service;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Positive;
+import java.math.BigDecimal;
+import java.util.Objects;
+
+public class ServiceRequest {
+    @NotBlank(message = "Service name is required")
+    private String serviceName;
+
+    private String serviceDesc;
+
+    @NotNull(message = "Service price is required")
+    @Positive(message = "Price must be positive")
+    private BigDecimal servicePrice;
+
+    @Positive(message = "Duration must be positive")
+    private Integer serviceDuration;
+
+    public String getServiceName() {
+        return serviceName;
+    }
+
+    public void setServiceName(String serviceName) {
+        this.serviceName = serviceName;
+    }
+
+    public String getServiceDesc() {
+        return serviceDesc;
+    }
+
+    public void setServiceDesc(String serviceDesc) {
+        this.serviceDesc = serviceDesc;
+    }
+
+    public BigDecimal getServicePrice() {
+        return servicePrice;
+    }
+
+    public void setServicePrice(BigDecimal servicePrice) {
+        this.servicePrice = servicePrice;
+    }
+
+    public Integer getServiceDuration() {
+        return serviceDuration;
+    }
+
+    public void setServiceDuration(Integer serviceDuration) {
+        this.serviceDuration = serviceDuration;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ServiceRequest that = (ServiceRequest) o;
+        return Objects.equals(serviceName, that.serviceName) &&
+                Objects.equals(serviceDesc, that.serviceDesc) &&
+                Objects.equals(servicePrice, that.servicePrice) &&
+                Objects.equals(serviceDuration, that.serviceDuration);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(serviceName, serviceDesc, servicePrice, serviceDuration);
+    }
+
+    @Override
+    public String toString() {
+        return "ServiceRequest{" +
+                "serviceName='" + serviceName + '\'' +
+                ", serviceDesc='" + serviceDesc + '\'' +
+                ", servicePrice=" + servicePrice +
+                ", serviceDuration=" + serviceDuration +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/service/ServiceResponse.java

@@ -0,0 +1,110 @@
+package com.petshop.backend.dto.service;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class ServiceResponse {
+    private Long serviceId;
+    private String serviceName;
+    private String serviceDesc;
+    private BigDecimal servicePrice;
+    private Integer serviceDuration;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public ServiceResponse() {
+    }
+
+    public ServiceResponse(Long serviceId, String serviceName, String serviceDesc, BigDecimal servicePrice, Integer serviceDuration, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.serviceId = serviceId;
+        this.serviceName = serviceName;
+        this.serviceDesc = serviceDesc;
+        this.servicePrice = servicePrice;
+        this.serviceDuration = serviceDuration;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getServiceId() {
+        return serviceId;
+    }
+
+    public void setServiceId(Long serviceId) {
+        this.serviceId = serviceId;
+    }
+
+    public String getServiceName() {
+        return serviceName;
+    }
+
+    public void setServiceName(String serviceName) {
+        this.serviceName = serviceName;
+    }
+
+    public String getServiceDesc() {
+        return serviceDesc;
+    }
+
+    public void setServiceDesc(String serviceDesc) {
+        this.serviceDesc = serviceDesc;
+    }
+
+    public BigDecimal getServicePrice() {
+        return servicePrice;
+    }
+
+    public void setServicePrice(BigDecimal servicePrice) {
+        this.servicePrice = servicePrice;
+    }
+
+    public Integer getServiceDuration() {
+        return serviceDuration;
+    }
+
+    public void setServiceDuration(Integer serviceDuration) {
+        this.serviceDuration = serviceDuration;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ServiceResponse that = (ServiceResponse) o;
+        return Objects.equals(serviceId, that.serviceId) && Objects.equals(serviceName, that.serviceName) && Objects.equals(serviceDesc, that.serviceDesc) && Objects.equals(servicePrice, that.servicePrice) && Objects.equals(serviceDuration, that.serviceDuration) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(serviceId, serviceName, serviceDesc, servicePrice, serviceDuration, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "ServiceResponse{" +
+                "serviceId=" + serviceId +
+                ", serviceName='" + serviceName + '\'' +
+                ", serviceDesc='" + serviceDesc + '\'' +
+                ", servicePrice=" + servicePrice +
+                ", serviceDuration=" + serviceDuration +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/store/StoreRequest.java

@@ -0,0 +1,78 @@
+package com.petshop.backend.dto.store;
+
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.NotBlank;
+import java.util.Objects;
+
+public class StoreRequest {
+    @NotBlank(message = "Store name is required")
+    private String storeName;
+
+    @NotBlank(message = "Address is required")
+    private String address;
+
+    @NotBlank(message = "Phone is required")
+    private String phone;
+
+    @NotBlank(message = "Email is required")
+    @Email(message = "Email must be valid")
+    private String email;
+
+    public String getStoreName() {
+        return storeName;
+    }
+
+    public void setStoreName(String storeName) {
+        this.storeName = storeName;
+    }
+
+    public String getAddress() {
+        return address;
+    }
+
+    public void setAddress(String address) {
+        this.address = address;
+    }
+
+    public String getPhone() {
+        return phone;
+    }
+
+    public void setPhone(String phone) {
+        this.phone = phone;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        StoreRequest that = (StoreRequest) o;
+        return Objects.equals(storeName, that.storeName) &&
+                Objects.equals(address, that.address) &&
+                Objects.equals(phone, that.phone) &&
+                Objects.equals(email, that.email);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(storeName, address, phone, email);
+    }
+
+    @Override
+    public String toString() {
+        return "StoreRequest{" +
+                "storeName='" + storeName + '\'' +
+                ", address='" + address + '\'' +
+                ", phone='" + phone + '\'' +
+                ", email='" + email + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/store/StoreResponse.java

@@ -0,0 +1,98 @@
+package com.petshop.backend.dto.store;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class StoreResponse {
+    private Long storeId;
+    private String storeName;
+    private String address;
+    private String phone;
+    private String email;
+    private LocalDateTime createdAt;
+
+    public StoreResponse() {
+    }
+
+    public StoreResponse(Long storeId, String storeName, String address, String phone, String email, LocalDateTime createdAt) {
+        this.storeId = storeId;
+        this.storeName = storeName;
+        this.address = address;
+        this.phone = phone;
+        this.email = email;
+        this.createdAt = createdAt;
+    }
+
+    public Long getStoreId() {
+        return storeId;
+    }
+
+    public void setStoreId(Long storeId) {
+        this.storeId = storeId;
+    }
+
+    public String getStoreName() {
+        return storeName;
+    }
+
+    public void setStoreName(String storeName) {
+        this.storeName = storeName;
+    }
+
+    public String getAddress() {
+        return address;
+    }
+
+    public void setAddress(String address) {
+        this.address = address;
+    }
+
+    public String getPhone() {
+        return phone;
+    }
+
+    public void setPhone(String phone) {
+        this.phone = phone;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        StoreResponse that = (StoreResponse) o;
+        return Objects.equals(storeId, that.storeId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(storeId);
+    }
+
+    @Override
+    public String toString() {
+        return "StoreResponse{" +
+                "storeId=" + storeId +
+                ", storeName='" + storeName + '\'' +
+                ", address='" + address + '\'' +
+                ", phone='" + phone + '\'' +
+                ", email='" + email + '\'' +
+                ", createdAt=" + createdAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/supplier/SupplierRequest.java

@@ -0,0 +1,87 @@
+package com.petshop.backend.dto.supplier;
+
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.NotBlank;
+import java.util.Objects;
+
+public class SupplierRequest {
+    @NotBlank(message = "Supplier company is required")
+    private String supCompany;
+
+    private String supContactFirstName;
+
+    private String supContactLastName;
+
+    @Email(message = "Invalid email format")
+    private String supEmail;
+
+    private String supPhone;
+
+    public String getSupCompany() {
+        return supCompany;
+    }
+
+    public void setSupCompany(String supCompany) {
+        this.supCompany = supCompany;
+    }
+
+    public String getSupContactFirstName() {
+        return supContactFirstName;
+    }
+
+    public void setSupContactFirstName(String supContactFirstName) {
+        this.supContactFirstName = supContactFirstName;
+    }
+
+    public String getSupContactLastName() {
+        return supContactLastName;
+    }
+
+    public void setSupContactLastName(String supContactLastName) {
+        this.supContactLastName = supContactLastName;
+    }
+
+    public String getSupEmail() {
+        return supEmail;
+    }
+
+    public void setSupEmail(String supEmail) {
+        this.supEmail = supEmail;
+    }
+
+    public String getSupPhone() {
+        return supPhone;
+    }
+
+    public void setSupPhone(String supPhone) {
+        this.supPhone = supPhone;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        SupplierRequest that = (SupplierRequest) o;
+        return Objects.equals(supCompany, that.supCompany) &&
+                Objects.equals(supContactFirstName, that.supContactFirstName) &&
+                Objects.equals(supContactLastName, that.supContactLastName) &&
+                Objects.equals(supEmail, that.supEmail) &&
+                Objects.equals(supPhone, that.supPhone);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(supCompany, supContactFirstName, supContactLastName, supEmail, supPhone);
+    }
+
+    @Override
+    public String toString() {
+        return "SupplierRequest{" +
+                "supCompany='" + supCompany + '\'' +
+                ", supContactFirstName='" + supContactFirstName + '\'' +
+                ", supContactLastName='" + supContactLastName + '\'' +
+                ", supEmail='" + supEmail + '\'' +
+                ", supPhone='" + supPhone + '\'' +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/supplier/SupplierResponse.java

@@ -0,0 +1,120 @@
+package com.petshop.backend.dto.supplier;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class SupplierResponse {
+    private Long supId;
+    private String supCompany;
+    private String supContactFirstName;
+    private String supContactLastName;
+    private String supEmail;
+    private String supPhone;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public SupplierResponse() {
+    }
+
+    public SupplierResponse(Long supId, String supCompany, String supContactFirstName, String supContactLastName, String supEmail, String supPhone, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.supId = supId;
+        this.supCompany = supCompany;
+        this.supContactFirstName = supContactFirstName;
+        this.supContactLastName = supContactLastName;
+        this.supEmail = supEmail;
+        this.supPhone = supPhone;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getSupId() {
+        return supId;
+    }
+
+    public void setSupId(Long supId) {
+        this.supId = supId;
+    }
+
+    public String getSupCompany() {
+        return supCompany;
+    }
+
+    public void setSupCompany(String supCompany) {
+        this.supCompany = supCompany;
+    }
+
+    public String getSupContactFirstName() {
+        return supContactFirstName;
+    }
+
+    public void setSupContactFirstName(String supContactFirstName) {
+        this.supContactFirstName = supContactFirstName;
+    }
+
+    public String getSupContactLastName() {
+        return supContactLastName;
+    }
+
+    public void setSupContactLastName(String supContactLastName) {
+        this.supContactLastName = supContactLastName;
+    }
+
+    public String getSupEmail() {
+        return supEmail;
+    }
+
+    public void setSupEmail(String supEmail) {
+        this.supEmail = supEmail;
+    }
+
+    public String getSupPhone() {
+        return supPhone;
+    }
+
+    public void setSupPhone(String supPhone) {
+        this.supPhone = supPhone;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        SupplierResponse that = (SupplierResponse) o;
+        return Objects.equals(supId, that.supId) && Objects.equals(supCompany, that.supCompany) && Objects.equals(supContactFirstName, that.supContactFirstName) && Objects.equals(supContactLastName, that.supContactLastName) && Objects.equals(supEmail, that.supEmail) && Objects.equals(supPhone, that.supPhone) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(supId, supCompany, supContactFirstName, supContactLastName, supEmail, supPhone, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "SupplierResponse{" +
+                "supId=" + supId +
+                ", supCompany='" + supCompany + '\'' +
+                ", supContactFirstName='" + supContactFirstName + '\'' +
+                ", supContactLastName='" + supContactLastName + '\'' +
+                ", supEmail='" + supEmail + '\'' +
+                ", supPhone='" + supPhone + '\'' +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/user/UserRequest.java

@@ -0,0 +1,119 @@
+package com.petshop.backend.dto.user;
+
+import com.petshop.backend.entity.User;
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Size;
+import java.util.Objects;
+
+public class UserRequest {
+    @NotBlank(message = "Username is required")
+    @Size(min = 3, max = 50, message = "Username must be between 3 and 50 characters")
+    private String username;
+
+    @Size(min = 6, message = "Password must be at least 6 characters")
+    private String password;
+
+    @NotBlank(message = "Full name is required")
+    private String fullName;
+
+    @Email(message = "Invalid email format")
+    private String email;
+
+    @Size(max = 20, message = "Phone must not exceed 20 characters")
+    private String phone;
+
+    @NotNull(message = "Role is required")
+    private User.Role role;
+
+    private Boolean active = true;
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public String getFullName() {
+        return fullName;
+    }
+
+    public void setFullName(String fullName) {
+        this.fullName = fullName;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getPhone() {
+        return phone;
+    }
+
+    public void setPhone(String phone) {
+        this.phone = phone;
+    }
+
+    public User.Role getRole() {
+        return role;
+    }
+
+    public void setRole(User.Role role) {
+        this.role = role;
+    }
+
+    public Boolean getActive() {
+        return active;
+    }
+
+    public void setActive(Boolean active) {
+        this.active = active;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        UserRequest that = (UserRequest) o;
+        return Objects.equals(username, that.username) &&
+                Objects.equals(password, that.password) &&
+                Objects.equals(fullName, that.fullName) &&
+                Objects.equals(email, that.email) &&
+                Objects.equals(phone, that.phone) &&
+                role == that.role &&
+                Objects.equals(active, that.active);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(username, password, fullName, email, phone, role, active);
+    }
+
+    @Override
+    public String toString() {
+        return "UserRequest{" +
+                "username='" + username + '\'' +
+                ", password='" + password + '\'' +
+                ", fullName='" + fullName + '\'' +
+                ", email='" + email + '\'' +
+                ", phone='" + phone + '\'' +
+                ", role=" + role +
+                ", active=" + active +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/dto/user/UserResponse.java

@@ -0,0 +1,131 @@
+package com.petshop.backend.dto.user;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class UserResponse {
+    private Long id;
+    private String username;
+    private String fullName;
+    private String email;
+    private String phone;
+    private String role;
+    private Boolean active;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public UserResponse() {
+    }
+
+    public UserResponse(Long id, String username, String fullName, String email, String phone, String role, Boolean active, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.id = id;
+        this.username = username;
+        this.fullName = fullName;
+        this.email = email;
+        this.phone = phone;
+        this.role = role;
+        this.active = active;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getFullName() {
+        return fullName;
+    }
+
+    public void setFullName(String fullName) {
+        this.fullName = fullName;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getPhone() {
+        return phone;
+    }
+
+    public void setPhone(String phone) {
+        this.phone = phone;
+    }
+
+    public String getRole() {
+        return role;
+    }
+
+    public void setRole(String role) {
+        this.role = role;
+    }
+
+    public Boolean getActive() {
+        return active;
+    }
+
+    public void setActive(Boolean active) {
+        this.active = active;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        UserResponse that = (UserResponse) o;
+        return Objects.equals(id, that.id) && Objects.equals(username, that.username) && Objects.equals(fullName, that.fullName) && Objects.equals(email, that.email) && Objects.equals(phone, that.phone) && Objects.equals(role, that.role) && Objects.equals(active, that.active) && Objects.equals(createdAt, that.createdAt) && Objects.equals(updatedAt, that.updatedAt);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, username, fullName, email, phone, role, active, createdAt, updatedAt);
+    }
+
+    @Override
+    public String toString() {
+        return "UserResponse{" +
+                "id=" + id +
+                ", username='" + username + '\'' +
+                ", fullName='" + fullName + '\'' +
+                ", email='" + email + '\'' +
+                ", phone='" + phone + '\'' +
+                ", role='" + role + '\'' +
+                ", active=" + active +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/ActivityLog.java

@@ -0,0 +1,90 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "activityLog")
+public class ActivityLog {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long logId;
+
+    @ManyToOne
+    @JoinColumn(name = "employeeId", nullable = false)
+    private Employee employee;
+
+    @Column(nullable = false, columnDefinition = "TEXT")
+    private String activity;
+
+    @Column(nullable = false)
+    private LocalDateTime logTimestamp = LocalDateTime.now();
+
+    public ActivityLog() {
+    }
+
+    public ActivityLog(Long logId, Employee employee, String activity, LocalDateTime logTimestamp) {
+        this.logId = logId;
+        this.employee = employee;
+        this.activity = activity;
+        this.logTimestamp = logTimestamp;
+    }
+
+    public Long getLogId() {
+        return logId;
+    }
+
+    public void setLogId(Long logId) {
+        this.logId = logId;
+    }
+
+    public Employee getEmployee() {
+        return employee;
+    }
+
+    public void setEmployee(Employee employee) {
+        this.employee = employee;
+    }
+
+    public String getActivity() {
+        return activity;
+    }
+
+    public void setActivity(String activity) {
+        this.activity = activity;
+    }
+
+    public LocalDateTime getLogTimestamp() {
+        return logTimestamp;
+    }
+
+    public void setLogTimestamp(LocalDateTime logTimestamp) {
+        this.logTimestamp = logTimestamp;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ActivityLog that = (ActivityLog) o;
+        return Objects.equals(logId, that.logId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(logId);
+    }
+
+    @Override
+    public String toString() {
+        return "ActivityLog{" +
+                "logId=" + logId +
+                ", employee=" + employee +
+                ", activity='" + activity + '\'' +
+                ", logTimestamp=" + logTimestamp +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Adoption.java

@@ -0,0 +1,136 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "adoption")
+public class Adoption {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long adoptionId;
+
+    @ManyToOne
+    @JoinColumn(name = "petId", nullable = false)
+    private Pet pet;
+
+    @ManyToOne
+    @JoinColumn(name = "customerId", nullable = false)
+    private Customer customer;
+
+    @Column(nullable = false)
+    private LocalDate adoptionDate;
+
+    @Column(nullable = false, length = 20)
+    private String adoptionStatus;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public Adoption() {
+    }
+
+    public Adoption(Long adoptionId, Pet pet, Customer customer, LocalDate adoptionDate, String adoptionStatus, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.adoptionId = adoptionId;
+        this.pet = pet;
+        this.customer = customer;
+        this.adoptionDate = adoptionDate;
+        this.adoptionStatus = adoptionStatus;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getAdoptionId() {
+        return adoptionId;
+    }
+
+    public void setAdoptionId(Long adoptionId) {
+        this.adoptionId = adoptionId;
+    }
+
+    public Pet getPet() {
+        return pet;
+    }
+
+    public void setPet(Pet pet) {
+        this.pet = pet;
+    }
+
+    public Customer getCustomer() {
+        return customer;
+    }
+
+    public void setCustomer(Customer customer) {
+        this.customer = customer;
+    }
+
+    public LocalDate getAdoptionDate() {
+        return adoptionDate;
+    }
+
+    public void setAdoptionDate(LocalDate adoptionDate) {
+        this.adoptionDate = adoptionDate;
+    }
+
+    public String getAdoptionStatus() {
+        return adoptionStatus;
+    }
+
+    public void setAdoptionStatus(String adoptionStatus) {
+        this.adoptionStatus = adoptionStatus;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Adoption adoption = (Adoption) o;
+        return Objects.equals(adoptionId, adoption.adoptionId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(adoptionId);
+    }
+
+    @Override
+    public String toString() {
+        return "Adoption{" +
+                "adoptionId=" + adoptionId +
+                ", pet=" + pet +
+                ", customer=" + customer +
+                ", adoptionDate=" + adoptionDate +
+                ", adoptionStatus='" + adoptionStatus + '\'' +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Appointment.java

@@ -0,0 +1,183 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+
+@Entity
+@Table(name = "appointment")
+public class Appointment {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long appointmentId;
+
+    @ManyToOne
+    @JoinColumn(name = "customerId", nullable = false)
+    private Customer customer;
+
+    @ManyToOne
+    @JoinColumn(name = "storeId", nullable = false)
+    private StoreLocation store;
+
+    @ManyToOne
+    @JoinColumn(name = "serviceId", nullable = false)
+    private Service service;
+
+    @Column(nullable = false)
+    private LocalDate appointmentDate;
+
+    @Column(nullable = false)
+    private LocalTime appointmentTime;
+
+    @Column(nullable = false, length = 20)
+    private String appointmentStatus;
+
+    @ManyToMany
+    @JoinTable(
+        name = "appointmentPet",
+        joinColumns = @JoinColumn(name = "appointmentId"),
+        inverseJoinColumns = @JoinColumn(name = "petId")
+    )
+    private Set<Pet> pets = new HashSet<>();
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public Appointment() {
+    }
+
+    public Appointment(Long appointmentId, Customer customer, StoreLocation store, Service service, LocalDate appointmentDate, LocalTime appointmentTime, String appointmentStatus, Set<Pet> pets, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.appointmentId = appointmentId;
+        this.customer = customer;
+        this.store = store;
+        this.service = service;
+        this.appointmentDate = appointmentDate;
+        this.appointmentTime = appointmentTime;
+        this.appointmentStatus = appointmentStatus;
+        this.pets = pets;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getAppointmentId() {
+        return appointmentId;
+    }
+
+    public void setAppointmentId(Long appointmentId) {
+        this.appointmentId = appointmentId;
+    }
+
+    public Customer getCustomer() {
+        return customer;
+    }
+
+    public void setCustomer(Customer customer) {
+        this.customer = customer;
+    }
+
+    public StoreLocation getStore() {
+        return store;
+    }
+
+    public void setStore(StoreLocation store) {
+        this.store = store;
+    }
+
+    public Service getService() {
+        return service;
+    }
+
+    public void setService(Service service) {
+        this.service = service;
+    }
+
+    public LocalDate getAppointmentDate() {
+        return appointmentDate;
+    }
+
+    public void setAppointmentDate(LocalDate appointmentDate) {
+        this.appointmentDate = appointmentDate;
+    }
+
+    public LocalTime getAppointmentTime() {
+        return appointmentTime;
+    }
+
+    public void setAppointmentTime(LocalTime appointmentTime) {
+        this.appointmentTime = appointmentTime;
+    }
+
+    public String getAppointmentStatus() {
+        return appointmentStatus;
+    }
+
+    public void setAppointmentStatus(String appointmentStatus) {
+        this.appointmentStatus = appointmentStatus;
+    }
+
+    public Set<Pet> getPets() {
+        return pets;
+    }
+
+    public void setPets(Set<Pet> pets) {
+        this.pets = pets;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Appointment that = (Appointment) o;
+        return Objects.equals(appointmentId, that.appointmentId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(appointmentId);
+    }
+
+    @Override
+    public String toString() {
+        return "Appointment{" +
+                "appointmentId=" + appointmentId +
+                ", customer=" + customer +
+                ", store=" + store +
+                ", service=" + service +
+                ", appointmentDate=" + appointmentDate +
+                ", appointmentTime=" + appointmentTime +
+                ", appointmentStatus='" + appointmentStatus + '\'' +
+                ", pets=" + pets +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Category.java

@@ -0,0 +1,106 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "category")
+public class Category {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long categoryId;
+
+    @Column(nullable = false, length = 100)
+    private String categoryName;
+
+    @Column(nullable = false, length = 50)
+    private String categoryType;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public Category() {
+    }
+
+    public Category(Long categoryId, String categoryName, String categoryType, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.categoryId = categoryId;
+        this.categoryName = categoryName;
+        this.categoryType = categoryType;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getCategoryId() {
+        return categoryId;
+    }
+
+    public void setCategoryId(Long categoryId) {
+        this.categoryId = categoryId;
+    }
+
+    public String getCategoryName() {
+        return categoryName;
+    }
+
+    public void setCategoryName(String categoryName) {
+        this.categoryName = categoryName;
+    }
+
+    public String getCategoryType() {
+        return categoryType;
+    }
+
+    public void setCategoryType(String categoryType) {
+        this.categoryType = categoryType;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Category category = (Category) o;
+        return Objects.equals(categoryId, category.categoryId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(categoryId);
+    }
+
+    @Override
+    public String toString() {
+        return "Category{" +
+                "categoryId=" + categoryId +
+                ", categoryName='" + categoryName + '\'' +
+                ", categoryType='" + categoryType + '\'' +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Conversation.java

@@ -0,0 +1,127 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.time.LocalDateTime;
+
+@Entity
+@Table(name = "conversation")
+public class Conversation {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(nullable = false)
+    private Long customerId;
+
+    @Column
+    private Long staffId;
+
+    @Enumerated(EnumType.STRING)
+    @Column(length = 20, nullable = false, columnDefinition = "VARCHAR(20)")
+    private ConversationStatus status = ConversationStatus.OPEN;
+
+    @Enumerated(EnumType.STRING)
+    @Column(length = 20, nullable = false, columnDefinition = "VARCHAR(20)")
+    private ConversationMode mode = ConversationMode.AUTOMATED;
+
+    @Column
+    private LocalDateTime humanRequestedAt;
+
+    @CreationTimestamp
+    @Column(name = "created_at", nullable = false, updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at", nullable = false)
+    private LocalDateTime updatedAt;
+
+    public enum ConversationStatus {
+        OPEN, CLOSED
+    }
+
+    public enum ConversationMode {
+        AUTOMATED, HUMAN
+    }
+
+    public Conversation() {
+    }
+
+    public Conversation(Long id, Long customerId, Long staffId, ConversationStatus status, ConversationMode mode, LocalDateTime humanRequestedAt, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.id = id;
+        this.customerId = customerId;
+        this.staffId = staffId;
+        this.status = status;
+        this.mode = mode;
+        this.humanRequestedAt = humanRequestedAt;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public Long getStaffId() {
+        return staffId;
+    }
+
+    public void setStaffId(Long staffId) {
+        this.staffId = staffId;
+    }
+
+    public ConversationStatus getStatus() {
+        return status;
+    }
+
+    public void setStatus(ConversationStatus status) {
+        this.status = status;
+    }
+
+    public ConversationMode getMode() {
+        return mode;
+    }
+
+    public void setMode(ConversationMode mode) {
+        this.mode = mode;
+    }
+
+    public LocalDateTime getHumanRequestedAt() {
+        return humanRequestedAt;
+    }
+
+    public void setHumanRequestedAt(LocalDateTime humanRequestedAt) {
+        this.humanRequestedAt = humanRequestedAt;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Customer.java

@@ -0,0 +1,132 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "customer")
+public class Customer {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long customerId;
+
+    @Column(name = "user_id")
+    private Long userId;
+
+    @Column(nullable = false, length = 50)
+    private String firstName;
+
+    @Column(nullable = false, length = 50)
+    private String lastName;
+
+    @Column(nullable = false, length = 100)
+    private String email;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public Customer() {
+    }
+
+    public Customer(Long customerId, Long userId, String firstName, String lastName, String email, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.customerId = customerId;
+        this.userId = userId;
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.email = email;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public Long getUserId() {
+        return userId;
+    }
+
+    public void setUserId(Long userId) {
+        this.userId = userId;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Customer customer = (Customer) o;
+        return Objects.equals(customerId, customer.customerId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(customerId);
+    }
+
+    @Override
+    public String toString() {
+        return "Customer{" +
+                "customerId=" + customerId +
+                ", userId=" + userId +
+                ", firstName='" + firstName + '\'' +
+                ", lastName='" + lastName + '\'' +
+                ", email='" + email + '\'' +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Employee.java

@@ -0,0 +1,158 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "employee")
+public class Employee {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long employeeId;
+
+    @Column(name = "user_id")
+    private Long userId;
+
+    @Column(nullable = false, length = 50)
+    private String firstName;
+
+    @Column(nullable = false, length = 50)
+    private String lastName;
+
+    @Column(nullable = false, length = 100)
+    private String email;
+
+    @Column(nullable = false, length = 50)
+    private String role;
+
+    @Column(nullable = false)
+    private Boolean isActive = true;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public Employee() {
+    }
+
+    public Employee(Long employeeId, Long userId, String firstName, String lastName, String email, String role, Boolean isActive, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.employeeId = employeeId;
+        this.userId = userId;
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.email = email;
+        this.role = role;
+        this.isActive = isActive;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getEmployeeId() {
+        return employeeId;
+    }
+
+    public void setEmployeeId(Long employeeId) {
+        this.employeeId = employeeId;
+    }
+
+    public Long getUserId() {
+        return userId;
+    }
+
+    public void setUserId(Long userId) {
+        this.userId = userId;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getRole() {
+        return role;
+    }
+
+    public void setRole(String role) {
+        this.role = role;
+    }
+
+    public Boolean getIsActive() {
+        return isActive;
+    }
+
+    public void setIsActive(Boolean isActive) {
+        this.isActive = isActive;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Employee employee = (Employee) o;
+        return Objects.equals(employeeId, employee.employeeId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(employeeId);
+    }
+
+    @Override
+    public String toString() {
+        return "Employee{" +
+                "employeeId=" + employeeId +
+                ", userId=" + userId +
+                ", firstName='" + firstName + '\'' +
+                ", lastName='" + lastName + '\'' +
+                ", email='" + email + '\'' +
+                ", role='" + role + '\'' +
+                ", isActive=" + isActive +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/EmployeeStore.java

@@ -0,0 +1,117 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+
+import java.io.Serializable;
+import java.util.Objects;
+
+@Entity
+@Table(name = "employeeStore")
+@IdClass(EmployeeStore.EmployeeStoreId.class)
+public class EmployeeStore {
+
+    @Id
+    @ManyToOne
+    @JoinColumn(name = "employeeId", nullable = false)
+    private Employee employee;
+
+    @Id
+    @ManyToOne
+    @JoinColumn(name = "storeId", nullable = false)
+    private StoreLocation store;
+
+    public EmployeeStore() {
+    }
+
+    public EmployeeStore(Employee employee, StoreLocation store) {
+        this.employee = employee;
+        this.store = store;
+    }
+
+    public Employee getEmployee() {
+        return employee;
+    }
+
+    public void setEmployee(Employee employee) {
+        this.employee = employee;
+    }
+
+    public StoreLocation getStore() {
+        return store;
+    }
+
+    public void setStore(StoreLocation store) {
+        this.store = store;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        EmployeeStore that = (EmployeeStore) o;
+        return Objects.equals(employee, that.employee) && Objects.equals(store, that.store);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(employee, store);
+    }
+
+    @Override
+    public String toString() {
+        return "EmployeeStore{" +
+                "employee=" + employee +
+                ", store=" + store +
+                '}';
+    }
+
+    public static class EmployeeStoreId implements Serializable {
+        private Long employee;
+        private Long store;
+
+        public EmployeeStoreId() {
+        }
+
+        public EmployeeStoreId(Long employee, Long store) {
+            this.employee = employee;
+            this.store = store;
+        }
+
+        public Long getEmployee() {
+            return employee;
+        }
+
+        public void setEmployee(Long employee) {
+            this.employee = employee;
+        }
+
+        public Long getStore() {
+            return store;
+        }
+
+        public void setStore(Long store) {
+            this.store = store;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            EmployeeStoreId that = (EmployeeStoreId) o;
+            return Objects.equals(employee, that.employee) && Objects.equals(store, that.store);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(employee, store);
+        }
+
+        @Override
+        public String toString() {
+            return "EmployeeStoreId{" +
+                    "employee=" + employee +
+                    ", store=" + store +
+                    '}';
+        }
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Inventory.java

@@ -0,0 +1,107 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "inventory")
+public class Inventory {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long inventoryId;
+
+    @ManyToOne
+    @JoinColumn(name = "prodId", nullable = false)
+    private Product product;
+
+    @Column(nullable = false)
+    private Integer quantity = 0;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public Inventory() {
+    }
+
+    public Inventory(Long inventoryId, Product product, Integer quantity, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.inventoryId = inventoryId;
+        this.product = product;
+        this.quantity = quantity;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getInventoryId() {
+        return inventoryId;
+    }
+
+    public void setInventoryId(Long inventoryId) {
+        this.inventoryId = inventoryId;
+    }
+
+    public Product getProduct() {
+        return product;
+    }
+
+    public void setProduct(Product product) {
+        this.product = product;
+    }
+
+    public Integer getQuantity() {
+        return quantity;
+    }
+
+    public void setQuantity(Integer quantity) {
+        this.quantity = quantity;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Inventory inventory = (Inventory) o;
+        return Objects.equals(inventoryId, inventory.inventoryId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(inventoryId);
+    }
+
+    @Override
+    public String toString() {
+        return "Inventory{" +
+                "inventoryId=" + inventoryId +
+                ", product=" + product +
+                ", quantity=" + quantity +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Message.java

@@ -0,0 +1,91 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+
+import java.time.LocalDateTime;
+
+@Entity
+@Table(name = "message")
+public class Message {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(nullable = false)
+    private Long conversationId;
+
+    @Column(nullable = false)
+    private Long senderId;
+
+    @Column(nullable = false, columnDefinition = "TEXT")
+    private String content;
+
+    @CreationTimestamp
+    @Column(nullable = false, updatable = false)
+    private LocalDateTime timestamp;
+
+    @Column(nullable = false)
+    private Boolean isRead = false;
+
+    public Message() {
+    }
+
+    public Message(Long id, Long conversationId, Long senderId, String content, LocalDateTime timestamp, Boolean isRead) {
+        this.id = id;
+        this.conversationId = conversationId;
+        this.senderId = senderId;
+        this.content = content;
+        this.timestamp = timestamp;
+        this.isRead = isRead;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getConversationId() {
+        return conversationId;
+    }
+
+    public void setConversationId(Long conversationId) {
+        this.conversationId = conversationId;
+    }
+
+    public Long getSenderId() {
+        return senderId;
+    }
+
+    public void setSenderId(Long senderId) {
+        this.senderId = senderId;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+
+    public LocalDateTime getTimestamp() {
+        return timestamp;
+    }
+
+    public void setTimestamp(LocalDateTime timestamp) {
+        this.timestamp = timestamp;
+    }
+
+    public Boolean getIsRead() {
+        return isRead;
+    }
+
+    public void setIsRead(Boolean isRead) {
+        this.isRead = isRead;
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Pet.java

@@ -0,0 +1,160 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "pet")
+public class Pet {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    @Column(name = "petId")
+    private Long id;
+
+    @Column(nullable = false, length = 50)
+    private String petName;
+
+    @Column(nullable = false, length = 50)
+    private String petSpecies;
+
+    @Column(nullable = false, length = 50)
+    private String petBreed;
+
+    @Column(nullable = false)
+    private Integer petAge;
+
+    @Column(nullable = false, length = 20)
+    private String petStatus;
+
+    @Column(nullable = false, precision = 10, scale = 2)
+    private BigDecimal petPrice;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public Pet() {
+    }
+
+    public Pet(Long id, String petName, String petSpecies, String petBreed, Integer petAge, String petStatus, BigDecimal petPrice, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.id = id;
+        this.petName = petName;
+        this.petSpecies = petSpecies;
+        this.petBreed = petBreed;
+        this.petAge = petAge;
+        this.petStatus = petStatus;
+        this.petPrice = petPrice;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getPetId() {
+        return id;
+    }
+
+    public void setPetId(Long id) {
+        this.id = id;
+    }
+
+    public String getPetName() {
+        return petName;
+    }
+
+    public void setPetName(String petName) {
+        this.petName = petName;
+    }
+
+    public String getPetSpecies() {
+        return petSpecies;
+    }
+
+    public void setPetSpecies(String petSpecies) {
+        this.petSpecies = petSpecies;
+    }
+
+    public String getPetBreed() {
+        return petBreed;
+    }
+
+    public void setPetBreed(String petBreed) {
+        this.petBreed = petBreed;
+    }
+
+    public Integer getPetAge() {
+        return petAge;
+    }
+
+    public void setPetAge(Integer petAge) {
+        this.petAge = petAge;
+    }
+
+    public String getPetStatus() {
+        return petStatus;
+    }
+
+    public void setPetStatus(String petStatus) {
+        this.petStatus = petStatus;
+    }
+
+    public BigDecimal getPetPrice() {
+        return petPrice;
+    }
+
+    public void setPetPrice(BigDecimal petPrice) {
+        this.petPrice = petPrice;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Pet pet = (Pet) o;
+        return Objects.equals(id, pet.id);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id);
+    }
+
+    @Override
+    public String toString() {
+        return "Pet{" +
+                "id=" + id +
+                ", petName='" + petName + '\'' +
+                ", petSpecies='" + petSpecies + '\'' +
+                ", petBreed='" + petBreed + '\'' +
+                ", petAge=" + petAge +
+                ", petStatus='" + petStatus + '\'' +
+                ", petPrice=" + petPrice +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Product.java

@@ -0,0 +1,134 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "product")
+public class Product {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long prodId;
+
+    @Column(nullable = false, length = 100)
+    private String prodName;
+
+    @ManyToOne
+    @JoinColumn(name = "categoryId", nullable = false)
+    private Category category;
+
+    @Column(columnDefinition = "TEXT")
+    private String prodDesc;
+
+    @Column(nullable = false, precision = 10, scale = 2)
+    private BigDecimal prodPrice;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public Product() {
+    }
+
+    public Product(Long prodId, String prodName, Category category, String prodDesc, BigDecimal prodPrice, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.prodId = prodId;
+        this.prodName = prodName;
+        this.category = category;
+        this.prodDesc = prodDesc;
+        this.prodPrice = prodPrice;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getProdId() {
+        return prodId;
+    }
+
+    public void setProdId(Long prodId) {
+        this.prodId = prodId;
+    }
+
+    public String getProdName() {
+        return prodName;
+    }
+
+    public void setProdName(String prodName) {
+        this.prodName = prodName;
+    }
+
+    public Category getCategory() {
+        return category;
+    }
+
+    public void setCategory(Category category) {
+        this.category = category;
+    }
+
+    public String getProdDesc() {
+        return prodDesc;
+    }
+
+    public void setProdDesc(String prodDesc) {
+        this.prodDesc = prodDesc;
+    }
+
+    public BigDecimal getProdPrice() {
+        return prodPrice;
+    }
+
+    public void setProdPrice(BigDecimal prodPrice) {
+        this.prodPrice = prodPrice;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Product product = (Product) o;
+        return Objects.equals(prodId, product.prodId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(prodId);
+    }
+
+    @Override
+    public String toString() {
+        return "Product{" +
+                "prodId=" + prodId +
+                ", prodName='" + prodName + '\'' +
+                ", category=" + category +
+                ", prodDesc='" + prodDesc + '\'' +
+                ", prodPrice=" + prodPrice +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/ProductSupplier.java

@@ -0,0 +1,162 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.io.Serializable;
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "productSupplier")
+@IdClass(ProductSupplier.ProductSupplierId.class)
+public class ProductSupplier {
+
+    @Id
+    @ManyToOne
+    @JoinColumn(name = "prodId", nullable = false)
+    private Product product;
+
+    @Id
+    @ManyToOne
+    @JoinColumn(name = "supId", nullable = false)
+    private Supplier supplier;
+
+    @Column(nullable = false, precision = 10, scale = 2)
+    private BigDecimal cost;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public ProductSupplier() {
+    }
+
+    public ProductSupplier(Product product, Supplier supplier, BigDecimal cost, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.product = product;
+        this.supplier = supplier;
+        this.cost = cost;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Product getProduct() {
+        return product;
+    }
+
+    public void setProduct(Product product) {
+        this.product = product;
+    }
+
+    public Supplier getSupplier() {
+        return supplier;
+    }
+
+    public void setSupplier(Supplier supplier) {
+        this.supplier = supplier;
+    }
+
+    public BigDecimal getCost() {
+        return cost;
+    }
+
+    public void setCost(BigDecimal cost) {
+        this.cost = cost;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ProductSupplier that = (ProductSupplier) o;
+        return Objects.equals(product, that.product) && Objects.equals(supplier, that.supplier);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(product, supplier);
+    }
+
+    @Override
+    public String toString() {
+        return "ProductSupplier{" +
+                "product=" + product +
+                ", supplier=" + supplier +
+                ", cost=" + cost +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+
+    public static class ProductSupplierId implements Serializable {
+        private Long product;
+        private Long supplier;
+
+        public ProductSupplierId() {
+        }
+
+        public ProductSupplierId(Long product, Long supplier) {
+            this.product = product;
+            this.supplier = supplier;
+        }
+
+        public Long getProduct() {
+            return product;
+        }
+
+        public void setProduct(Long product) {
+            this.product = product;
+        }
+
+        public Long getSupplier() {
+            return supplier;
+        }
+
+        public void setSupplier(Long supplier) {
+            this.supplier = supplier;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            ProductSupplierId that = (ProductSupplierId) o;
+            return Objects.equals(product, that.product) && Objects.equals(supplier, that.supplier);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(product, supplier);
+        }
+
+        @Override
+        public String toString() {
+            return "ProductSupplierId{" +
+                    "product=" + product +
+                    ", supplier=" + supplier +
+                    '}';
+        }
+    }
+}

backend/src/main/java/com/petshop/backend/entity/PurchaseOrder.java

@@ -0,0 +1,124 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+@Entity
+@Table(name = "purchaseOrder")
+public class PurchaseOrder {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long purchaseOrderId;
+
+    @ManyToOne
+    @JoinColumn(name = "supId", nullable = false)
+    private Supplier supplier;
+
+    @Column(nullable = false)
+    private LocalDate orderDate;
+
+    @Column(nullable = false, length = 50)
+    private String status;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public PurchaseOrder() {
+    }
+
+    public PurchaseOrder(Long purchaseOrderId, Supplier supplier, LocalDate orderDate, String status, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.purchaseOrderId = purchaseOrderId;
+        this.supplier = supplier;
+        this.orderDate = orderDate;
+        this.status = status;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getPurchaseOrderId() {
+        return purchaseOrderId;
+    }
+
+    public void setPurchaseOrderId(Long purchaseOrderId) {
+        this.purchaseOrderId = purchaseOrderId;
+    }
+
+    public Supplier getSupplier() {
+        return supplier;
+    }
+
+    public void setSupplier(Supplier supplier) {
+        this.supplier = supplier;
+    }
+
+    public LocalDate getOrderDate() {
+        return orderDate;
+    }
+
+    public void setOrderDate(LocalDate orderDate) {
+        this.orderDate = orderDate;
+    }
+
+    public String getStatus() {
+        return status;
+    }
+
+    public void setStatus(String status) {
+        this.status = status;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        PurchaseOrder that = (PurchaseOrder) o;
+        return Objects.equals(purchaseOrderId, that.purchaseOrderId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(purchaseOrderId);
+    }
+
+    @Override
+    public String toString() {
+        return "PurchaseOrder{" +
+                "purchaseOrderId=" + purchaseOrderId +
+                ", supplier=" + supplier +
+                ", orderDate=" + orderDate +
+                ", status='" + status + '\'' +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Refund.java

@@ -0,0 +1,151 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "refund")
+public class Refund {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(nullable = false)
+    private Long saleId;
+
+    @Column(nullable = false)
+    private Long customerId;
+
+    @Column(nullable = false, precision = 10, scale = 2)
+    private BigDecimal amount;
+
+    @Column(nullable = false, length = 500)
+    private String reason;
+
+    @Enumerated(EnumType.STRING)
+    @Column(nullable = false, length = 20, columnDefinition = "VARCHAR(20)")
+    private RefundStatus status;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public enum RefundStatus {
+        PENDING, APPROVED, REJECTED
+    }
+
+    public Refund() {
+    }
+
+    public Refund(Long id, Long saleId, Long customerId, BigDecimal amount, String reason, RefundStatus status, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.id = id;
+        this.saleId = saleId;
+        this.customerId = customerId;
+        this.amount = amount;
+        this.reason = reason;
+        this.status = status;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getSaleId() {
+        return saleId;
+    }
+
+    public void setSaleId(Long saleId) {
+        this.saleId = saleId;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public BigDecimal getAmount() {
+        return amount;
+    }
+
+    public void setAmount(BigDecimal amount) {
+        this.amount = amount;
+    }
+
+    public String getReason() {
+        return reason;
+    }
+
+    public void setReason(String reason) {
+        this.reason = reason;
+    }
+
+    public RefundStatus getStatus() {
+        return status;
+    }
+
+    public void setStatus(RefundStatus status) {
+        this.status = status;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Refund refund = (Refund) o;
+        return Objects.equals(id, refund.id);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id);
+    }
+
+    @Override
+    public String toString() {
+        return "Refund{" +
+                "id=" + id +
+                ", saleId=" + saleId +
+                ", customerId=" + customerId +
+                ", amount=" + amount +
+                ", reason='" + reason + '\'' +
+                ", status=" + status +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Sale.java

@@ -0,0 +1,204 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+@Entity
+@Table(name = "sale")
+public class Sale {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long saleId;
+
+    @Column(nullable = false)
+    private LocalDateTime saleDate = LocalDateTime.now();
+
+    @ManyToOne
+    @JoinColumn(name = "employeeId", nullable = false)
+    private Employee employee;
+
+    @ManyToOne
+    @JoinColumn(name = "storeId", nullable = false)
+    private StoreLocation store;
+
+    @ManyToOne
+    @JoinColumn(name = "customerId")
+    private Customer customer;
+
+    @Column(nullable = false, precision = 10, scale = 2)
+    private BigDecimal totalAmount;
+
+    @Column(nullable = false, length = 50)
+    private String paymentMethod;
+
+    @Column(nullable = false)
+    private Boolean isRefund = false;
+
+    @ManyToOne
+    @JoinColumn(name = "originalSaleId")
+    private Sale originalSale;
+
+    @OneToMany(mappedBy = "sale", cascade = CascadeType.ALL)
+    private List<SaleItem> items = new ArrayList<>();
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public Sale() {
+    }
+
+    public Sale(Long saleId, LocalDateTime saleDate, Employee employee, StoreLocation store, Customer customer, BigDecimal totalAmount, String paymentMethod, Boolean isRefund, Sale originalSale, List<SaleItem> items, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.saleId = saleId;
+        this.saleDate = saleDate;
+        this.employee = employee;
+        this.store = store;
+        this.customer = customer;
+        this.totalAmount = totalAmount;
+        this.paymentMethod = paymentMethod;
+        this.isRefund = isRefund;
+        this.originalSale = originalSale;
+        this.items = items;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getSaleId() {
+        return saleId;
+    }
+
+    public void setSaleId(Long saleId) {
+        this.saleId = saleId;
+    }
+
+    public LocalDateTime getSaleDate() {
+        return saleDate;
+    }
+
+    public void setSaleDate(LocalDateTime saleDate) {
+        this.saleDate = saleDate;
+    }
+
+    public Employee getEmployee() {
+        return employee;
+    }
+
+    public void setEmployee(Employee employee) {
+        this.employee = employee;
+    }
+
+    public StoreLocation getStore() {
+        return store;
+    }
+
+    public void setStore(StoreLocation store) {
+        this.store = store;
+    }
+
+    public Customer getCustomer() {
+        return customer;
+    }
+
+    public void setCustomer(Customer customer) {
+        this.customer = customer;
+    }
+
+    public BigDecimal getTotalAmount() {
+        return totalAmount;
+    }
+
+    public void setTotalAmount(BigDecimal totalAmount) {
+        this.totalAmount = totalAmount;
+    }
+
+    public String getPaymentMethod() {
+        return paymentMethod;
+    }
+
+    public void setPaymentMethod(String paymentMethod) {
+        this.paymentMethod = paymentMethod;
+    }
+
+    public Boolean getIsRefund() {
+        return isRefund;
+    }
+
+    public void setIsRefund(Boolean isRefund) {
+        this.isRefund = isRefund;
+    }
+
+    public Sale getOriginalSale() {
+        return originalSale;
+    }
+
+    public void setOriginalSale(Sale originalSale) {
+        this.originalSale = originalSale;
+    }
+
+    public List<SaleItem> getItems() {
+        return items;
+    }
+
+    public void setItems(List<SaleItem> items) {
+        this.items = items;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Sale sale = (Sale) o;
+        return Objects.equals(saleId, sale.saleId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(saleId);
+    }
+
+    @Override
+    public String toString() {
+        return "Sale{" +
+                "saleId=" + saleId +
+                ", saleDate=" + saleDate +
+                ", employee=" + employee +
+                ", store=" + store +
+                ", customer=" + customer +
+                ", totalAmount=" + totalAmount +
+                ", paymentMethod='" + paymentMethod + '\'' +
+                ", isRefund=" + isRefund +
+                ", originalSale=" + originalSale +
+                ", items=" + items +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/SaleItem.java

@@ -0,0 +1,135 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "saleItem")
+public class SaleItem {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long saleItemId;
+
+    @ManyToOne
+    @JoinColumn(name = "saleId", nullable = false)
+    private Sale sale;
+
+    @ManyToOne
+    @JoinColumn(name = "prodId", nullable = false)
+    private Product product;
+
+    @Column(nullable = false)
+    private Integer quantity;
+
+    @Column(nullable = false, precision = 10, scale = 2)
+    private BigDecimal unitPrice;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public SaleItem() {
+    }
+
+    public SaleItem(Long saleItemId, Sale sale, Product product, Integer quantity, BigDecimal unitPrice, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.saleItemId = saleItemId;
+        this.sale = sale;
+        this.product = product;
+        this.quantity = quantity;
+        this.unitPrice = unitPrice;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getSaleItemId() {
+        return saleItemId;
+    }
+
+    public void setSaleItemId(Long saleItemId) {
+        this.saleItemId = saleItemId;
+    }
+
+    public Sale getSale() {
+        return sale;
+    }
+
+    public void setSale(Sale sale) {
+        this.sale = sale;
+    }
+
+    public Product getProduct() {
+        return product;
+    }
+
+    public void setProduct(Product product) {
+        this.product = product;
+    }
+
+    public Integer getQuantity() {
+        return quantity;
+    }
+
+    public void setQuantity(Integer quantity) {
+        this.quantity = quantity;
+    }
+
+    public BigDecimal getUnitPrice() {
+        return unitPrice;
+    }
+
+    public void setUnitPrice(BigDecimal unitPrice) {
+        this.unitPrice = unitPrice;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        SaleItem saleItem = (SaleItem) o;
+        return Objects.equals(saleItemId, saleItem.saleItemId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(saleItemId);
+    }
+
+    @Override
+    public String toString() {
+        return "SaleItem{" +
+                "saleItemId=" + saleItemId +
+                ", sale=" + sale +
+                ", product=" + product +
+                ", quantity=" + quantity +
+                ", unitPrice=" + unitPrice +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}

backend/src/main/java/com/petshop/backend/entity/Service.java

@@ -0,0 +1,133 @@
+package com.petshop.backend.entity;
+
+import jakarta.persistence.*;
+import org.hibernate.annotations.CreationTimestamp;
+import org.hibernate.annotations.UpdateTimestamp;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+@Entity
+@Table(name = "service")
+public class Service {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long serviceId;
+
+    @Column(nullable = false, length = 100)
+    private String serviceName;
+
+    @Column(columnDefinition = "TEXT")
+    private String serviceDesc;
+
+    @Column(nullable = false, precision = 10, scale = 2)
+    private BigDecimal servicePrice;
+
+    @Column(nullable = false)
+    private Integer serviceDuration;
+
+    @CreationTimestamp
+    @Column(name = "created_at", updatable = false)
+    private LocalDateTime createdAt;
+
+    @UpdateTimestamp
+    @Column(name = "updated_at")
+    private LocalDateTime updatedAt;
+
+    public Service() {
+    }
+
+    public Service(Long serviceId, String serviceName, String serviceDesc, BigDecimal servicePrice, Integer serviceDuration, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        this.serviceId = serviceId;
+        this.serviceName = serviceName;
+        this.serviceDesc = serviceDesc;
+        this.servicePrice = servicePrice;
+        this.serviceDuration = serviceDuration;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getServiceId() {
+        return serviceId;
+    }
+
+    public void setServiceId(Long serviceId) {
+        this.serviceId = serviceId;
+    }
+
+    public String getServiceName() {
+        return serviceName;
+    }
+
+    public void setServiceName(String serviceName) {
+        this.serviceName = serviceName;
+    }
+
+    public String getServiceDesc() {
+        return serviceDesc;
+    }
+
+    public void setServiceDesc(String serviceDesc) {
+        this.serviceDesc = serviceDesc;
+    }
+
+    public BigDecimal getServicePrice() {
+        return servicePrice;
+    }
+
+    public void setServicePrice(BigDecimal servicePrice) {
+        this.servicePrice = servicePrice;
+    }
+
+    public Integer getServiceDuration() {
+        return serviceDuration;
+    }
+
+    public void setServiceDuration(Integer serviceDuration) {
+        this.serviceDuration = serviceDuration;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Service service = (Service) o;
+        return Objects.equals(serviceId, service.serviceId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(serviceId);
+    }
+
+    @Override
+    public String toString() {
+        return "Service{" +
+                "serviceId=" + serviceId +
+                ", serviceName='" + serviceName + '\'' +
+                ", serviceDesc='" + serviceDesc + '\'' +
+                ", servicePrice=" + servicePrice +
+                ", serviceDuration=" + serviceDuration +
+                ", createdAt=" + createdAt +
+                ", updatedAt=" + updatedAt +
+                '}';
+    }
+}