Add API infrastructure and DTOs

src/main/java/org/example/petshopdesktop/api/ApiClient.java

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+package org.example.petshopdesktop.api;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
+import org.example.petshopdesktop.auth.UserSession;
+
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.time.Duration;
+
+public class ApiClient {
+    private static final ApiClient INSTANCE = new ApiClient();
+    private final HttpClient httpClient;
+    private final ObjectMapper objectMapper;
+    private final String baseUrl;
+
+    private ApiClient() {
+        this.httpClient = HttpClient.newBuilder()
+                .connectTimeout(Duration.ofSeconds(10))
+                .build();
+        this.objectMapper = new ObjectMapper();
+        this.objectMapper.registerModule(new JavaTimeModule());
+        this.baseUrl = ApiConfig.getInstance().getBaseUrl();
+    }
+
+    public static ApiClient getInstance() {
+        return INSTANCE;
+    }
+
+    public <T> T get(String path, Class<T> responseClass) throws Exception {
+        HttpRequest.Builder builder = HttpRequest.newBuilder()
+                .uri(URI.create(baseUrl + path))
+                .GET()
+                .timeout(Duration.ofSeconds(30));
+
+        addAuthHeader(builder);
+
+        HttpRequest request = builder.build();
+        HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
+
+        return handleResponse(response, responseClass);
+    }
+
+    public <T> T post(String path, Object requestBody, Class<T> responseClass) throws Exception {
+        String jsonBody = objectMapper.writeValueAsString(requestBody);
+
+        HttpRequest.Builder builder = HttpRequest.newBuilder()
+                .uri(URI.create(baseUrl + path))
+                .header("Content-Type", "application/json")
+                .POST(HttpRequest.BodyPublishers.ofString(jsonBody))
+                .timeout(Duration.ofSeconds(30));
+
+        addAuthHeader(builder);
+
+        HttpRequest request = builder.build();
+        HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
+
+        return handleResponse(response, responseClass);
+    }
+
+    public <T> T put(String path, Object requestBody, Class<T> responseClass) throws Exception {
+        String jsonBody = objectMapper.writeValueAsString(requestBody);
+
+        HttpRequest.Builder builder = HttpRequest.newBuilder()
+                .uri(URI.create(baseUrl + path))
+                .header("Content-Type", "application/json")
+                .PUT(HttpRequest.BodyPublishers.ofString(jsonBody))
+                .timeout(Duration.ofSeconds(30));
+
+        addAuthHeader(builder);
+
+        HttpRequest request = builder.build();
+        HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
+
+        return handleResponse(response, responseClass);
+    }
+
+    public void delete(String path) throws Exception {
+        HttpRequest.Builder builder = HttpRequest.newBuilder()
+                .uri(URI.create(baseUrl + path))
+                .DELETE()
+                .timeout(Duration.ofSeconds(30));
+
+        addAuthHeader(builder);
+
+        HttpRequest request = builder.build();
+        HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
+
+        if (response.statusCode() != 204 && response.statusCode() != 200) {
+            throw new RuntimeException(parseErrorMessage(response));
+        }
+    }
+
+    public void deleteWithBody(String path, Object requestBody) throws Exception {
+        String jsonBody = objectMapper.writeValueAsString(requestBody);
+
+        HttpRequest.Builder builder = HttpRequest.newBuilder()
+                .uri(URI.create(baseUrl + path))
+                .header("Content-Type", "application/json")
+                .method("DELETE", HttpRequest.BodyPublishers.ofString(jsonBody))
+                .timeout(Duration.ofSeconds(30));
+
+        addAuthHeader(builder);
+
+        HttpRequest request = builder.build();
+        HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());
+
+        if (response.statusCode() != 204 && response.statusCode() != 200) {
+            throw new RuntimeException(parseErrorMessage(response));
+        }
+    }
+
+    private void addAuthHeader(HttpRequest.Builder builder) {
+        String token = UserSession.getInstance().getJwtToken();
+        if (token != null && !token.isEmpty()) {
+            builder.header("Authorization", "Bearer " + token);
+        }
+    }
+
+    private <T> T handleResponse(HttpResponse<String> response, Class<T> responseClass) throws Exception {
+        int statusCode = response.statusCode();
+
+        if (statusCode == 200 || statusCode == 201) {
+            if (response.body() == null || response.body().isEmpty()) {
+                return null;
+            }
+            return objectMapper.readValue(response.body(), responseClass);
+        } else if (statusCode == 204) {
+            return null;
+        } else if (statusCode == 401) {
+            throw new RuntimeException("Authentication failed. Please log in again.");
+        } else if (statusCode == 403) {
+            throw new RuntimeException("Access restricted. You don't have permission to perform this action.");
+        } else {
+            throw new RuntimeException(parseErrorMessage(response));
+        }
+    }
+
+    private String parseErrorMessage(HttpResponse<String> response) {
+        try {
+            if (response.body() != null && !response.body().isEmpty()) {
+                var errorNode = objectMapper.readTree(response.body());
+                if (errorNode.has("message")) {
+                    return errorNode.get("message").asText();
+                }
+                if (errorNode.has("errors")) {
+                    StringBuilder sb = new StringBuilder();
+                    errorNode.get("errors").fields().forEachRemaining(entry -> {
+                        sb.append(entry.getValue().asText()).append("\n");
+                    });
+                    return sb.toString().trim();
+                }
+            }
+        } catch (Exception e) {
+        }
+        return "Request failed with status " + response.statusCode();
+    }
+
+    public ObjectMapper getObjectMapper() {
+        return objectMapper;
+    }
+}

src/main/java/org/example/petshopdesktop/api/ApiConfig.java

@@ -0,0 +1,34 @@
+package org.example.petshopdesktop.api;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Properties;
+
+public class ApiConfig {
+    private static final ApiConfig INSTANCE = new ApiConfig();
+    private final String baseUrl;
+
+    private ApiConfig() {
+        Properties props = new Properties();
+        String url = "http://localhost:8080";
+
+        try (InputStream input = getClass().getClassLoader().getResourceAsStream("connectionpetstore.properties")) {
+            if (input != null) {
+                props.load(input);
+                url = props.getProperty("api.baseUrl", "http://localhost:8080");
+            }
+        } catch (IOException e) {
+            System.err.println("Failed to load api.baseUrl from properties: " + e.getMessage());
+        }
+
+        this.baseUrl = url;
+    }
+
+    public static ApiConfig getInstance() {
+        return INSTANCE;
+    }
+
+    public String getBaseUrl() {
+        return baseUrl;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/adoption/AdoptionRequest.java

@@ -0,0 +1,42 @@
+package org.example.petshopdesktop.api.dto.adoption;
+
+import java.time.LocalDate;
+
+public class AdoptionRequest {
+    private Long petId;
+    private Long customerId;
+    private LocalDate adoptionDate;
+    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;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/adoption/AdoptionResponse.java

@@ -0,0 +1,51 @@
+package org.example.petshopdesktop.api.dto.adoption;
+
+import java.time.LocalDate;
+
+public class AdoptionResponse {
+    private Long id;
+    private String petName;
+    private String customerName;
+    private LocalDate adoptionDate;
+    private String adoptionStatus;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getPetName() {
+        return petName;
+    }
+
+    public void setPetName(String petName) {
+        this.petName = petName;
+    }
+
+    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;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/analytics/DailySales.java

@@ -0,0 +1,25 @@
+package org.example.petshopdesktop.api.dto.analytics;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+
+public class DailySales {
+    private LocalDate date;
+    private BigDecimal totalSales;
+
+    public LocalDate getDate() {
+        return date;
+    }
+
+    public void setDate(LocalDate date) {
+        this.date = date;
+    }
+
+    public BigDecimal getTotalSales() {
+        return totalSales;
+    }
+
+    public void setTotalSales(BigDecimal totalSales) {
+        this.totalSales = totalSales;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/analytics/DashboardResponse.java

@@ -0,0 +1,61 @@
+package org.example.petshopdesktop.api.dto.analytics;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+public class DashboardResponse {
+    private BigDecimal totalRevenue;
+    private Long totalSales;
+    private Long totalCustomers;
+    private Long totalProducts;
+    private List<DailySales> dailySales;
+    private List<TopProduct> topProducts;
+
+    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 Long getTotalCustomers() {
+        return totalCustomers;
+    }
+
+    public void setTotalCustomers(Long totalCustomers) {
+        this.totalCustomers = totalCustomers;
+    }
+
+    public Long getTotalProducts() {
+        return totalProducts;
+    }
+
+    public void setTotalProducts(Long totalProducts) {
+        this.totalProducts = totalProducts;
+    }
+
+    public List<DailySales> getDailySales() {
+        return dailySales;
+    }
+
+    public void setDailySales(List<DailySales> dailySales) {
+        this.dailySales = dailySales;
+    }
+
+    public List<TopProduct> getTopProducts() {
+        return topProducts;
+    }
+
+    public void setTopProducts(List<TopProduct> topProducts) {
+        this.topProducts = topProducts;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/analytics/TopProduct.java

@@ -0,0 +1,33 @@
+package org.example.petshopdesktop.api.dto.analytics;
+
+import java.math.BigDecimal;
+
+public class TopProduct {
+    private String productName;
+    private Integer quantitySold;
+    private BigDecimal totalRevenue;
+
+    public String getProductName() {
+        return productName;
+    }
+
+    public void setProductName(String productName) {
+        this.productName = productName;
+    }
+
+    public Integer getQuantitySold() {
+        return quantitySold;
+    }
+
+    public void setQuantitySold(Integer quantitySold) {
+        this.quantitySold = quantitySold;
+    }
+
+    public BigDecimal getTotalRevenue() {
+        return totalRevenue;
+    }
+
+    public void setTotalRevenue(BigDecimal totalRevenue) {
+        this.totalRevenue = totalRevenue;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/appointment/AppointmentRequest.java

@@ -0,0 +1,62 @@
+package org.example.petshopdesktop.api.dto.appointment;
+
+import java.time.LocalDate;
+import java.time.LocalTime;
+import java.util.List;
+
+public class AppointmentRequest {
+    private List<Long> petIds;
+    private Long customerId;
+    private Long serviceId;
+    private LocalDate appointmentDate;
+    private LocalTime appointmentTime;
+    private String appointmentStatus;
+
+    public List<Long> getPetIds() {
+        return petIds;
+    }
+
+    public void setPetIds(List<Long> petIds) {
+        this.petIds = petIds;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    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;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/appointment/AppointmentResponse.java

@@ -0,0 +1,70 @@
+package org.example.petshopdesktop.api.dto.appointment;
+
+import java.time.LocalDate;
+import java.time.LocalTime;
+
+public class AppointmentResponse {
+    private Long id;
+    private String customerName;
+    private String petNames;
+    private String serviceName;
+    private LocalDate appointmentDate;
+    private LocalTime appointmentTime;
+    private String appointmentStatus;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getCustomerName() {
+        return customerName;
+    }
+
+    public void setCustomerName(String customerName) {
+        this.customerName = customerName;
+    }
+
+    public String getPetNames() {
+        return petNames;
+    }
+
+    public void setPetNames(String petNames) {
+        this.petNames = petNames;
+    }
+
+    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;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/auth/LoginRequest.java

@@ -0,0 +1,30 @@
+package org.example.petshopdesktop.api.dto.auth;
+
+public class LoginRequest {
+    private String username;
+    private String password;
+
+    public LoginRequest() {
+    }
+
+    public LoginRequest(String username, String password) {
+        this.username = username;
+        this.password = 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;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/auth/LoginResponse.java

@@ -0,0 +1,31 @@
+package org.example.petshopdesktop.api.dto.auth;
+
+public class LoginResponse {
+    private String token;
+    private String username;
+    private String 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;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/auth/UserInfoResponse.java

@@ -0,0 +1,31 @@
+package org.example.petshopdesktop.api.dto.auth;
+
+public class UserInfoResponse {
+    private Long id;
+    private String username;
+    private String role;
+
+    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 getRole() {
+        return role;
+    }
+
+    public void setRole(String role) {
+        this.role = role;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/common/BulkDeleteRequest.java

@@ -0,0 +1,22 @@
+package org.example.petshopdesktop.api.dto.common;
+
+import java.util.List;
+
+public class BulkDeleteRequest {
+    private List<Long> ids;
+
+    public BulkDeleteRequest() {
+    }
+
+    public BulkDeleteRequest(List<Long> ids) {
+        this.ids = ids;
+    }
+
+    public List<Long> getIds() {
+        return ids;
+    }
+
+    public void setIds(List<Long> ids) {
+        this.ids = ids;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/common/DropdownOption.java

@@ -0,0 +1,22 @@
+package org.example.petshopdesktop.api.dto.common;
+
+public class DropdownOption {
+    private Long id;
+    private String 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;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/common/PageResponse.java

@@ -0,0 +1,60 @@
+package org.example.petshopdesktop.api.dto.common;
+
+import java.util.List;
+
+public class PageResponse<T> {
+    private List<T> content;
+    private int pageNumber;
+    private int pageSize;
+    private long totalElements;
+    private int totalPages;
+    private boolean last;
+
+    public List<T> getContent() {
+        return content;
+    }
+
+    public void setContent(List<T> content) {
+        this.content = content;
+    }
+
+    public int getPageNumber() {
+        return pageNumber;
+    }
+
+    public void setPageNumber(int pageNumber) {
+        this.pageNumber = pageNumber;
+    }
+
+    public int getPageSize() {
+        return pageSize;
+    }
+
+    public void setPageSize(int pageSize) {
+        this.pageSize = pageSize;
+    }
+
+    public long getTotalElements() {
+        return totalElements;
+    }
+
+    public void setTotalElements(long totalElements) {
+        this.totalElements = totalElements;
+    }
+
+    public int getTotalPages() {
+        return totalPages;
+    }
+
+    public void setTotalPages(int totalPages) {
+        this.totalPages = totalPages;
+    }
+
+    public boolean isLast() {
+        return last;
+    }
+
+    public void setLast(boolean last) {
+        this.last = last;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/inventory/InventoryRequest.java

@@ -0,0 +1,40 @@
+package org.example.petshopdesktop.api.dto.inventory;
+
+public class InventoryRequest {
+    private Long productId;
+    private Long storeId;
+    private Integer stockQuantity;
+    private Integer reorderLevel;
+
+    public Long getProductId() {
+        return productId;
+    }
+
+    public void setProductId(Long productId) {
+        this.productId = productId;
+    }
+
+    public Long getStoreId() {
+        return storeId;
+    }
+
+    public void setStoreId(Long storeId) {
+        this.storeId = storeId;
+    }
+
+    public Integer getStockQuantity() {
+        return stockQuantity;
+    }
+
+    public void setStockQuantity(Integer stockQuantity) {
+        this.stockQuantity = stockQuantity;
+    }
+
+    public Integer getReorderLevel() {
+        return reorderLevel;
+    }
+
+    public void setReorderLevel(Integer reorderLevel) {
+        this.reorderLevel = reorderLevel;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/inventory/InventoryResponse.java

@@ -0,0 +1,58 @@
+package org.example.petshopdesktop.api.dto.inventory;
+
+public class InventoryResponse {
+    private Long id;
+    private String productName;
+    private String categoryName;
+    private String storeName;
+    private Integer stockQuantity;
+    private Integer reorderLevel;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    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 String getStoreName() {
+        return storeName;
+    }
+
+    public void setStoreName(String storeName) {
+        this.storeName = storeName;
+    }
+
+    public Integer getStockQuantity() {
+        return stockQuantity;
+    }
+
+    public void setStockQuantity(Integer stockQuantity) {
+        this.stockQuantity = stockQuantity;
+    }
+
+    public Integer getReorderLevel() {
+        return reorderLevel;
+    }
+
+    public void setReorderLevel(Integer reorderLevel) {
+        this.reorderLevel = reorderLevel;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/pet/PetRequest.java

@@ -0,0 +1,79 @@
+package org.example.petshopdesktop.api.dto.pet;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+
+public class PetRequest {
+    private String petName;
+    private String species;
+    private String breed;
+    private LocalDate dateOfBirth;
+    private String gender;
+    private String color;
+    private BigDecimal price;
+    private String petStatus;
+
+    public String getPetName() {
+        return petName;
+    }
+
+    public void setPetName(String petName) {
+        this.petName = petName;
+    }
+
+    public String getSpecies() {
+        return species;
+    }
+
+    public void setSpecies(String species) {
+        this.species = species;
+    }
+
+    public String getBreed() {
+        return breed;
+    }
+
+    public void setBreed(String breed) {
+        this.breed = breed;
+    }
+
+    public LocalDate getDateOfBirth() {
+        return dateOfBirth;
+    }
+
+    public void setDateOfBirth(LocalDate dateOfBirth) {
+        this.dateOfBirth = dateOfBirth;
+    }
+
+    public String getGender() {
+        return gender;
+    }
+
+    public void setGender(String gender) {
+        this.gender = gender;
+    }
+
+    public String getColor() {
+        return color;
+    }
+
+    public void setColor(String color) {
+        this.color = color;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    public String getPetStatus() {
+        return petStatus;
+    }
+
+    public void setPetStatus(String petStatus) {
+        this.petStatus = petStatus;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/pet/PetResponse.java

@@ -0,0 +1,88 @@
+package org.example.petshopdesktop.api.dto.pet;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+
+public class PetResponse {
+    private Long id;
+    private String petName;
+    private String species;
+    private String breed;
+    private LocalDate dateOfBirth;
+    private String gender;
+    private String color;
+    private BigDecimal price;
+    private String petStatus;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getPetName() {
+        return petName;
+    }
+
+    public void setPetName(String petName) {
+        this.petName = petName;
+    }
+
+    public String getSpecies() {
+        return species;
+    }
+
+    public void setSpecies(String species) {
+        this.species = species;
+    }
+
+    public String getBreed() {
+        return breed;
+    }
+
+    public void setBreed(String breed) {
+        this.breed = breed;
+    }
+
+    public LocalDate getDateOfBirth() {
+        return dateOfBirth;
+    }
+
+    public void setDateOfBirth(LocalDate dateOfBirth) {
+        this.dateOfBirth = dateOfBirth;
+    }
+
+    public String getGender() {
+        return gender;
+    }
+
+    public void setGender(String gender) {
+        this.gender = gender;
+    }
+
+    public String getColor() {
+        return color;
+    }
+
+    public void setColor(String color) {
+        this.color = color;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    public String getPetStatus() {
+        return petStatus;
+    }
+
+    public void setPetStatus(String petStatus) {
+        this.petStatus = petStatus;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/product/ProductRequest.java

@@ -0,0 +1,42 @@
+package org.example.petshopdesktop.api.dto.product;
+
+import java.math.BigDecimal;
+
+public class ProductRequest {
+    private String productName;
+    private Long categoryId;
+    private BigDecimal price;
+    private String description;
+
+    public String getProductName() {
+        return productName;
+    }
+
+    public void setProductName(String productName) {
+        this.productName = productName;
+    }
+
+    public Long getCategoryId() {
+        return categoryId;
+    }
+
+    public void setCategoryId(Long categoryId) {
+        this.categoryId = categoryId;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/product/ProductResponse.java

@@ -0,0 +1,51 @@
+package org.example.petshopdesktop.api.dto.product;
+
+import java.math.BigDecimal;
+
+public class ProductResponse {
+    private Long id;
+    private String productName;
+    private String categoryName;
+    private BigDecimal price;
+    private String description;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    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 BigDecimal getPrice() {
+        return price;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/productsupplier/ProductSupplierRequest.java

@@ -0,0 +1,33 @@
+package org.example.petshopdesktop.api.dto.productsupplier;
+
+import java.math.BigDecimal;
+
+public class ProductSupplierRequest {
+    private Long productId;
+    private Long supplierId;
+    private BigDecimal supplierPrice;
+
+    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 getSupplierPrice() {
+        return supplierPrice;
+    }
+
+    public void setSupplierPrice(BigDecimal supplierPrice) {
+        this.supplierPrice = supplierPrice;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/productsupplier/ProductSupplierResponse.java

@@ -0,0 +1,42 @@
+package org.example.petshopdesktop.api.dto.productsupplier;
+
+import java.math.BigDecimal;
+
+public class ProductSupplierResponse {
+    private Long id;
+    private String productName;
+    private String supplierName;
+    private BigDecimal supplierPrice;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getProductName() {
+        return productName;
+    }
+
+    public void setProductName(String productName) {
+        this.productName = productName;
+    }
+
+    public String getSupplierName() {
+        return supplierName;
+    }
+
+    public void setSupplierName(String supplierName) {
+        this.supplierName = supplierName;
+    }
+
+    public BigDecimal getSupplierPrice() {
+        return supplierPrice;
+    }
+
+    public void setSupplierPrice(BigDecimal supplierPrice) {
+        this.supplierPrice = supplierPrice;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/purchaseorder/PurchaseOrderResponse.java

@@ -0,0 +1,61 @@
+package org.example.petshopdesktop.api.dto.purchaseorder;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+
+public class PurchaseOrderResponse {
+    private Long id;
+    private String supplierName;
+    private LocalDate orderDate;
+    private LocalDate expectedDeliveryDate;
+    private String orderStatus;
+    private BigDecimal totalAmount;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    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 LocalDate getExpectedDeliveryDate() {
+        return expectedDeliveryDate;
+    }
+
+    public void setExpectedDeliveryDate(LocalDate expectedDeliveryDate) {
+        this.expectedDeliveryDate = expectedDeliveryDate;
+    }
+
+    public String getOrderStatus() {
+        return orderStatus;
+    }
+
+    public void setOrderStatus(String orderStatus) {
+        this.orderStatus = orderStatus;
+    }
+
+    public BigDecimal getTotalAmount() {
+        return totalAmount;
+    }
+
+    public void setTotalAmount(BigDecimal totalAmount) {
+        this.totalAmount = totalAmount;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/sale/SaleItemRequest.java

@@ -0,0 +1,33 @@
+package org.example.petshopdesktop.api.dto.sale;
+
+import java.math.BigDecimal;
+
+public class SaleItemRequest {
+    private Long productId;
+    private Integer quantity;
+    private BigDecimal unitPrice;
+
+    public Long getProductId() {
+        return productId;
+    }
+
+    public void setProductId(Long productId) {
+        this.productId = productId;
+    }
+
+    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;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/sale/SaleItemResponse.java

@@ -0,0 +1,51 @@
+package org.example.petshopdesktop.api.dto.sale;
+
+import java.math.BigDecimal;
+
+public class SaleItemResponse {
+    private Long id;
+    private String productName;
+    private Integer quantity;
+    private BigDecimal unitPrice;
+    private BigDecimal lineTotal;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    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;
+    }
+
+    public BigDecimal getLineTotal() {
+        return lineTotal;
+    }
+
+    public void setLineTotal(BigDecimal lineTotal) {
+        this.lineTotal = lineTotal;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/sale/SaleRequest.java

@@ -0,0 +1,51 @@
+package org.example.petshopdesktop.api.dto.sale;
+
+import java.util.List;
+
+public class SaleRequest {
+    private Long storeId;
+    private String paymentMethod;
+    private List<SaleItemRequest> items;
+    private Boolean isRefund;
+    private Long originalSaleId;
+
+    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;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/sale/SaleResponse.java

@@ -0,0 +1,89 @@
+package org.example.petshopdesktop.api.dto.sale;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.List;
+
+public class SaleResponse {
+    private Long id;
+    private String employeeName;
+    private String storeName;
+    private LocalDateTime saleDate;
+    private BigDecimal totalAmount;
+    private String paymentMethod;
+    private Boolean isRefund;
+    private Long originalSaleId;
+    private List<SaleItemResponse> items;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getEmployeeName() {
+        return employeeName;
+    }
+
+    public void setEmployeeName(String employeeName) {
+        this.employeeName = employeeName;
+    }
+
+    public String getStoreName() {
+        return storeName;
+    }
+
+    public void setStoreName(String storeName) {
+        this.storeName = storeName;
+    }
+
+    public LocalDateTime getSaleDate() {
+        return saleDate;
+    }
+
+    public void setSaleDate(LocalDateTime saleDate) {
+        this.saleDate = saleDate;
+    }
+
+    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;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/service/ServiceRequest.java

@@ -0,0 +1,33 @@
+package org.example.petshopdesktop.api.dto.service;
+
+import java.math.BigDecimal;
+
+public class ServiceRequest {
+    private String serviceName;
+    private BigDecimal price;
+    private String description;
+
+    public String getServiceName() {
+        return serviceName;
+    }
+
+    public void setServiceName(String serviceName) {
+        this.serviceName = serviceName;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/service/ServiceResponse.java

@@ -0,0 +1,42 @@
+package org.example.petshopdesktop.api.dto.service;
+
+import java.math.BigDecimal;
+
+public class ServiceResponse {
+    private Long id;
+    private String serviceName;
+    private BigDecimal price;
+    private String description;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getServiceName() {
+        return serviceName;
+    }
+
+    public void setServiceName(String serviceName) {
+        this.serviceName = serviceName;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/supplier/SupplierRequest.java

@@ -0,0 +1,49 @@
+package org.example.petshopdesktop.api.dto.supplier;
+
+public class SupplierRequest {
+    private String supplierName;
+    private String contactPerson;
+    private String phone;
+    private String email;
+    private String address;
+
+    public String getSupplierName() {
+        return supplierName;
+    }
+
+    public void setSupplierName(String supplierName) {
+        this.supplierName = supplierName;
+    }
+
+    public String getContactPerson() {
+        return contactPerson;
+    }
+
+    public void setContactPerson(String contactPerson) {
+        this.contactPerson = contactPerson;
+    }
+
+    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 String getAddress() {
+        return address;
+    }
+
+    public void setAddress(String address) {
+        this.address = address;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/supplier/SupplierResponse.java

@@ -0,0 +1,58 @@
+package org.example.petshopdesktop.api.dto.supplier;
+
+public class SupplierResponse {
+    private Long id;
+    private String supplierName;
+    private String contactPerson;
+    private String phone;
+    private String email;
+    private String address;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getSupplierName() {
+        return supplierName;
+    }
+
+    public void setSupplierName(String supplierName) {
+        this.supplierName = supplierName;
+    }
+
+    public String getContactPerson() {
+        return contactPerson;
+    }
+
+    public void setContactPerson(String contactPerson) {
+        this.contactPerson = contactPerson;
+    }
+
+    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 String getAddress() {
+        return address;
+    }
+
+    public void setAddress(String address) {
+        this.address = address;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/user/UserRequest.java

@@ -0,0 +1,58 @@
+package org.example.petshopdesktop.api.dto.user;
+
+public class UserRequest {
+    private String username;
+    private String password;
+    private String firstName;
+    private String lastName;
+    private String role;
+    private Boolean active;
+
+    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 getRole() {
+        return role;
+    }
+
+    public void setRole(String role) {
+        this.role = role;
+    }
+
+    public Boolean getActive() {
+        return active;
+    }
+
+    public void setActive(Boolean active) {
+        this.active = active;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/user/UserResponse.java

@@ -0,0 +1,60 @@
+package org.example.petshopdesktop.api.dto.user;
+
+import java.time.LocalDateTime;
+
+public class UserResponse {
+    private Long id;
+    private String username;
+    private String fullName;
+    private String role;
+    private Boolean active;
+    private LocalDateTime createdAt;
+
+    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 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;
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/AdoptionApi.java

@@ -0,0 +1,43 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.adoption.AdoptionRequest;
+import org.example.petshopdesktop.api.dto.adoption.AdoptionResponse;
+import org.example.petshopdesktop.api.dto.common.BulkDeleteRequest;
+
+import java.util.List;
+
+public class AdoptionApi {
+    private static final AdoptionApi INSTANCE = new AdoptionApi();
+    private final ApiClient apiClient;
+
+    private AdoptionApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static AdoptionApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<AdoptionResponse> listAdoptions(String query) throws Exception {
+        String path = "/api/v1/adoptions?page=0&size=1000";
+        if (query != null && !query.isEmpty()) {
+            path += "&q=" + query;
+        }
+        String response = apiClient.get(path, String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<AdoptionResponse>>() {});
+    }
+
+    public AdoptionResponse createAdoption(AdoptionRequest request) throws Exception {
+        return apiClient.post("/api/v1/adoptions", request, AdoptionResponse.class);
+    }
+
+    public AdoptionResponse updateAdoption(Long id, AdoptionRequest request) throws Exception {
+        return apiClient.put("/api/v1/adoptions/" + id, request, AdoptionResponse.class);
+    }
+
+    public void deleteAdoptions(List<Long> ids) throws Exception {
+        apiClient.deleteWithBody("/api/v1/adoptions", new BulkDeleteRequest(ids));
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/AnalyticsApi.java

@@ -0,0 +1,22 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.analytics.DashboardResponse;
+
+public class AnalyticsApi {
+    private static final AnalyticsApi INSTANCE = new AnalyticsApi();
+    private final ApiClient apiClient;
+
+    private AnalyticsApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static AnalyticsApi getInstance() {
+        return INSTANCE;
+    }
+
+    public DashboardResponse getDashboard(int days, int top) throws Exception {
+        String path = "/api/v1/analytics/dashboard?days=" + days + "&top=" + top;
+        return apiClient.get(path, DashboardResponse.class);
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/AppointmentApi.java

@@ -0,0 +1,43 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.appointment.AppointmentRequest;
+import org.example.petshopdesktop.api.dto.appointment.AppointmentResponse;
+import org.example.petshopdesktop.api.dto.common.BulkDeleteRequest;
+
+import java.util.List;
+
+public class AppointmentApi {
+    private static final AppointmentApi INSTANCE = new AppointmentApi();
+    private final ApiClient apiClient;
+
+    private AppointmentApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static AppointmentApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<AppointmentResponse> listAppointments(String query) throws Exception {
+        String path = "/api/v1/appointments?page=0&size=1000";
+        if (query != null && !query.isEmpty()) {
+            path += "&q=" + query;
+        }
+        String response = apiClient.get(path, String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<AppointmentResponse>>() {});
+    }
+
+    public AppointmentResponse createAppointment(AppointmentRequest request) throws Exception {
+        return apiClient.post("/api/v1/appointments", request, AppointmentResponse.class);
+    }
+
+    public AppointmentResponse updateAppointment(Long id, AppointmentRequest request) throws Exception {
+        return apiClient.put("/api/v1/appointments/" + id, request, AppointmentResponse.class);
+    }
+
+    public void deleteAppointments(List<Long> ids) throws Exception {
+        apiClient.deleteWithBody("/api/v1/appointments", new BulkDeleteRequest(ids));
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/DropdownApi.java

@@ -0,0 +1,55 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.common.DropdownOption;
+
+import java.util.List;
+
+public class DropdownApi {
+    private static final DropdownApi INSTANCE = new DropdownApi();
+    private final ApiClient apiClient;
+
+    private DropdownApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static DropdownApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<DropdownOption> getCategories() throws Exception {
+        String response = apiClient.get("/api/v1/dropdowns/categories", String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<DropdownOption>>() {});
+    }
+
+    public List<DropdownOption> getProducts() throws Exception {
+        String response = apiClient.get("/api/v1/dropdowns/products", String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<DropdownOption>>() {});
+    }
+
+    public List<DropdownOption> getSuppliers() throws Exception {
+        String response = apiClient.get("/api/v1/dropdowns/suppliers", String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<DropdownOption>>() {});
+    }
+
+    public List<DropdownOption> getServices() throws Exception {
+        String response = apiClient.get("/api/v1/dropdowns/services", String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<DropdownOption>>() {});
+    }
+
+    public List<DropdownOption> getCustomers() throws Exception {
+        String response = apiClient.get("/api/v1/dropdowns/customers", String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<DropdownOption>>() {});
+    }
+
+    public List<DropdownOption> getPets() throws Exception {
+        String response = apiClient.get("/api/v1/dropdowns/pets", String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<DropdownOption>>() {});
+    }
+
+    public List<DropdownOption> getStores() throws Exception {
+        String response = apiClient.get("/api/v1/dropdowns/stores", String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<DropdownOption>>() {});
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/InventoryApi.java

@@ -0,0 +1,42 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.inventory.InventoryRequest;
+import org.example.petshopdesktop.api.dto.inventory.InventoryResponse;
+
+import java.util.List;
+
+public class InventoryApi {
+    private static final InventoryApi INSTANCE = new InventoryApi();
+    private final ApiClient apiClient;
+
+    private InventoryApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static InventoryApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<InventoryResponse> listInventory(String query) throws Exception {
+        String path = "/api/v1/inventory?page=0&size=1000";
+        if (query != null && !query.isEmpty()) {
+            path += "&q=" + query;
+        }
+        String response = apiClient.get(path, String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<InventoryResponse>>() {});
+    }
+
+    public InventoryResponse createInventory(InventoryRequest request) throws Exception {
+        return apiClient.post("/api/v1/inventory", request, InventoryResponse.class);
+    }
+
+    public InventoryResponse updateInventory(Long id, InventoryRequest request) throws Exception {
+        return apiClient.put("/api/v1/inventory/" + id, request, InventoryResponse.class);
+    }
+
+    public void deleteInventory(Long id) throws Exception {
+        apiClient.delete("/api/v1/inventory/" + id);
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/PetApi.java

@@ -0,0 +1,43 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.common.BulkDeleteRequest;
+import org.example.petshopdesktop.api.dto.pet.PetRequest;
+import org.example.petshopdesktop.api.dto.pet.PetResponse;
+
+import java.util.List;
+
+public class PetApi {
+    private static final PetApi INSTANCE = new PetApi();
+    private final ApiClient apiClient;
+
+    private PetApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static PetApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<PetResponse> listPets(String query) throws Exception {
+        String path = "/api/v1/pets?page=0&size=1000";
+        if (query != null && !query.isEmpty()) {
+            path += "&q=" + query;
+        }
+        String response = apiClient.get(path, String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<PetResponse>>() {});
+    }
+
+    public PetResponse createPet(PetRequest request) throws Exception {
+        return apiClient.post("/api/v1/pets", request, PetResponse.class);
+    }
+
+    public PetResponse updatePet(Long id, PetRequest request) throws Exception {
+        return apiClient.put("/api/v1/pets/" + id, request, PetResponse.class);
+    }
+
+    public void deletePets(List<Long> ids) throws Exception {
+        apiClient.deleteWithBody("/api/v1/pets", new BulkDeleteRequest(ids));
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/ProductApi.java

@@ -0,0 +1,43 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.common.BulkDeleteRequest;
+import org.example.petshopdesktop.api.dto.product.ProductRequest;
+import org.example.petshopdesktop.api.dto.product.ProductResponse;
+
+import java.util.List;
+
+public class ProductApi {
+    private static final ProductApi INSTANCE = new ProductApi();
+    private final ApiClient apiClient;
+
+    private ProductApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static ProductApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<ProductResponse> listProducts(String query) throws Exception {
+        String path = "/api/v1/products?page=0&size=1000";
+        if (query != null && !query.isEmpty()) {
+            path += "&q=" + query;
+        }
+        String response = apiClient.get(path, String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<ProductResponse>>() {});
+    }
+
+    public ProductResponse createProduct(ProductRequest request) throws Exception {
+        return apiClient.post("/api/v1/products", request, ProductResponse.class);
+    }
+
+    public ProductResponse updateProduct(Long id, ProductRequest request) throws Exception {
+        return apiClient.put("/api/v1/products/" + id, request, ProductResponse.class);
+    }
+
+    public void deleteProducts(List<Long> ids) throws Exception {
+        apiClient.deleteWithBody("/api/v1/products", new BulkDeleteRequest(ids));
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/ProductSupplierApi.java

@@ -0,0 +1,43 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.common.BulkDeleteRequest;
+import org.example.petshopdesktop.api.dto.productsupplier.ProductSupplierRequest;
+import org.example.petshopdesktop.api.dto.productsupplier.ProductSupplierResponse;
+
+import java.util.List;
+
+public class ProductSupplierApi {
+    private static final ProductSupplierApi INSTANCE = new ProductSupplierApi();
+    private final ApiClient apiClient;
+
+    private ProductSupplierApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static ProductSupplierApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<ProductSupplierResponse> listProductSuppliers(String query) throws Exception {
+        String path = "/api/v1/product-suppliers?page=0&size=1000";
+        if (query != null && !query.isEmpty()) {
+            path += "&q=" + query;
+        }
+        String response = apiClient.get(path, String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<ProductSupplierResponse>>() {});
+    }
+
+    public ProductSupplierResponse createProductSupplier(ProductSupplierRequest request) throws Exception {
+        return apiClient.post("/api/v1/product-suppliers", request, ProductSupplierResponse.class);
+    }
+
+    public ProductSupplierResponse updateProductSupplier(Long id, ProductSupplierRequest request) throws Exception {
+        return apiClient.put("/api/v1/product-suppliers/" + id, request, ProductSupplierResponse.class);
+    }
+
+    public void deleteProductSuppliers(List<Long> ids) throws Exception {
+        apiClient.deleteWithBody("/api/v1/product-suppliers", new BulkDeleteRequest(ids));
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/PurchaseOrderApi.java

@@ -0,0 +1,29 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.purchaseorder.PurchaseOrderResponse;
+
+import java.util.List;
+
+public class PurchaseOrderApi {
+    private static final PurchaseOrderApi INSTANCE = new PurchaseOrderApi();
+    private final ApiClient apiClient;
+
+    private PurchaseOrderApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static PurchaseOrderApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<PurchaseOrderResponse> listPurchaseOrders(String query) throws Exception {
+        String path = "/api/v1/purchase-orders?page=0&size=1000";
+        if (query != null && !query.isEmpty()) {
+            path += "&q=" + query;
+        }
+        String response = apiClient.get(path, String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<PurchaseOrderResponse>>() {});
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/SaleApi.java

@@ -0,0 +1,38 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.sale.SaleRequest;
+import org.example.petshopdesktop.api.dto.sale.SaleResponse;
+
+import java.util.List;
+
+public class SaleApi {
+    private static final SaleApi INSTANCE = new SaleApi();
+    private final ApiClient apiClient;
+
+    private SaleApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static SaleApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<SaleResponse> listSales(int page, int size, String query) throws Exception {
+        String path = "/api/v1/sales?page=" + page + "&size=" + size;
+        if (query != null && !query.isEmpty()) {
+            path += "&q=" + query;
+        }
+        String response = apiClient.get(path, String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<SaleResponse>>() {});
+    }
+
+    public SaleResponse getSale(Long id) throws Exception {
+        return apiClient.get("/api/v1/sales/" + id, SaleResponse.class);
+    }
+
+    public SaleResponse createSale(SaleRequest request) throws Exception {
+        return apiClient.post("/api/v1/sales", request, SaleResponse.class);
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/ServiceApi.java

@@ -0,0 +1,43 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.common.BulkDeleteRequest;
+import org.example.petshopdesktop.api.dto.service.ServiceRequest;
+import org.example.petshopdesktop.api.dto.service.ServiceResponse;
+
+import java.util.List;
+
+public class ServiceApi {
+    private static final ServiceApi INSTANCE = new ServiceApi();
+    private final ApiClient apiClient;
+
+    private ServiceApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static ServiceApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<ServiceResponse> listServices(String query) throws Exception {
+        String path = "/api/v1/services?page=0&size=1000";
+        if (query != null && !query.isEmpty()) {
+            path += "&q=" + query;
+        }
+        String response = apiClient.get(path, String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<ServiceResponse>>() {});
+    }
+
+    public ServiceResponse createService(ServiceRequest request) throws Exception {
+        return apiClient.post("/api/v1/services", request, ServiceResponse.class);
+    }
+
+    public ServiceResponse updateService(Long id, ServiceRequest request) throws Exception {
+        return apiClient.put("/api/v1/services/" + id, request, ServiceResponse.class);
+    }
+
+    public void deleteServices(List<Long> ids) throws Exception {
+        apiClient.deleteWithBody("/api/v1/services", new BulkDeleteRequest(ids));
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/SupplierApi.java

@@ -0,0 +1,43 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.common.BulkDeleteRequest;
+import org.example.petshopdesktop.api.dto.supplier.SupplierRequest;
+import org.example.petshopdesktop.api.dto.supplier.SupplierResponse;
+
+import java.util.List;
+
+public class SupplierApi {
+    private static final SupplierApi INSTANCE = new SupplierApi();
+    private final ApiClient apiClient;
+
+    private SupplierApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static SupplierApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<SupplierResponse> listSuppliers(String query) throws Exception {
+        String path = "/api/v1/suppliers?page=0&size=1000";
+        if (query != null && !query.isEmpty()) {
+            path += "&q=" + query;
+        }
+        String response = apiClient.get(path, String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<SupplierResponse>>() {});
+    }
+
+    public SupplierResponse createSupplier(SupplierRequest request) throws Exception {
+        return apiClient.post("/api/v1/suppliers", request, SupplierResponse.class);
+    }
+
+    public SupplierResponse updateSupplier(Long id, SupplierRequest request) throws Exception {
+        return apiClient.put("/api/v1/suppliers/" + id, request, SupplierResponse.class);
+    }
+
+    public void deleteSuppliers(List<Long> ids) throws Exception {
+        apiClient.deleteWithBody("/api/v1/suppliers", new BulkDeleteRequest(ids));
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/UserApi.java

@@ -0,0 +1,34 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.user.UserRequest;
+import org.example.petshopdesktop.api.dto.user.UserResponse;
+
+import java.util.List;
+
+public class UserApi {
+    private static final UserApi INSTANCE = new UserApi();
+    private final ApiClient apiClient;
+
+    private UserApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static UserApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<UserResponse> listUsers(String query) throws Exception {
+        String path = "/api/v1/users?page=0&size=1000";
+        if (query != null && !query.isEmpty()) {
+            path += "&q=" + query;
+        }
+        String response = apiClient.get(path, String.class);
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<UserResponse>>() {});
+    }
+
+    public UserResponse createUser(UserRequest request) throws Exception {
+        return apiClient.post("/api/v1/users", request, UserResponse.class);
+    }
+}