fixed the issues with main

src/main/java/org/example/petshopdesktop/controllers/MainLayoutController.java

@@ -190,8 +190,10 @@ public class MainLayoutController {
         btnPurchaseOrders.setVisible(isAdmin);
         btnPurchaseOrders.setManaged(isAdmin);
 
-        btnStaffAccounts.setVisible(isAdmin);
-        btnStaffAccounts.setManaged(isAdmin);
+        if (btnStaffAccounts != null) {
+            btnStaffAccounts.setVisible(isAdmin);
+            btnStaffAccounts.setManaged(isAdmin);
+        }
 
         btnSalesHistory.setText(isAdmin ? "Sales History" : "Sales");
 

src/main/java/org/example/petshopdesktop/controllers/dialogcontrollers/StaffRegisterDialogController.java

@@ -0,0 +1,117 @@
+package org.example.petshopdesktop.controllers.dialogcontrollers;
+
+import javafx.event.ActionEvent;
+import javafx.fxml.FXML;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
+import javafx.scene.control.PasswordField;
+import javafx.scene.control.TextField;
+import javafx.stage.Stage;
+import org.example.petshopdesktop.database.UserDB;
+import org.example.petshopdesktop.util.ActivityLogger;
+
+import java.sql.SQLException;
+
+public class StaffRegisterDialogController {
+
+    @FXML
+    private TextField txtFirstName;
+
+    @FXML
+    private TextField txtLastName;
+
+    @FXML
+    private TextField txtEmail;
+
+    @FXML
+    private TextField txtPhone;
+
+    @FXML
+    private TextField txtUsername;
+
+    @FXML
+    private PasswordField txtPassword;
+
+    @FXML
+    private PasswordField txtPasswordConfirm;
+
+    @FXML
+    private Label lblError;
+
+    @FXML
+    private Button btnCreate;
+
+    @FXML
+    void btnCreateClicked(ActionEvent event) {
+        lblError.setText("");
+
+        String firstName = value(txtFirstName);
+        String lastName = value(txtLastName);
+        String email = value(txtEmail);
+        String phone = value(txtPhone);
+        String username = value(txtUsername);
+        String password = txtPassword.getText() == null ? "" : txtPassword.getText();
+        String confirm = txtPasswordConfirm.getText() == null ? "" : txtPasswordConfirm.getText();
+
+        if (firstName.isBlank() || lastName.isBlank()) {
+            lblError.setText("First name and last name are required.");
+            return;
+        }
+        if (email.isBlank()) {
+            lblError.setText("Email is required.");
+            return;
+        }
+        if (phone.isBlank()) {
+            lblError.setText("Phone is required.");
+            return;
+        }
+        if (username.isBlank()) {
+            lblError.setText("Username is required.");
+            return;
+        }
+        if (password.isBlank()) {
+            lblError.setText("Password is required.");
+            return;
+        }
+        if (!password.equals(confirm)) {
+            lblError.setText("Passwords do not match.");
+            return;
+        }
+
+        try {
+            UserDB.createStaffAccount(firstName, lastName, email, phone, username, password);
+            Alert alert = new Alert(Alert.AlertType.INFORMATION);
+            alert.setTitle("Staff Account");
+            alert.setHeaderText(null);
+            alert.setContentText("Staff account created. You can log in now.");
+            alert.showAndWait();
+            close();
+        } catch (SQLException e) {
+            ActivityLogger.getInstance().logException("StaffRegisterDialogController.btnCreateClicked", e, "Creating staff account");
+            String msg = e.getMessage() == null ? "Could not create staff account." : e.getMessage();
+            if (msg.toLowerCase().contains("duplicate") || msg.toLowerCase().contains("unique")) {
+                lblError.setText("Username already exists.");
+            } else {
+                lblError.setText(msg);
+            }
+        } catch (RuntimeException e) {
+            ActivityLogger.getInstance().logException("StaffRegisterDialogController.btnCreateClicked", e, "Database connection");
+            lblError.setText("Database is not connected.");
+        }
+    }
+
+    @FXML
+    void btnCancelClicked(ActionEvent event) {
+        close();
+    }
+
+    private void close() {
+        Stage stage = (Stage) btnCreate.getScene().getWindow();
+        stage.close();
+    }
+
+    private static String value(TextField tf) {
+        return tf.getText() == null ? "" : tf.getText().trim();
+    }
+}

src/main/java/org/example/petshopdesktop/database/EmployeeDB.java

@@ -0,0 +1,132 @@
+package org.example.petshopdesktop.database;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+public class EmployeeDB {
+
+    public static int ensureDefaultEmployee(String firstName, String lastName, String email, String phone, String role, boolean isActive) throws SQLException {
+        Integer existingId = findEmployeeIdByEmail(email);
+        if (existingId != null) {
+            return existingId;
+        }
+
+        try (Connection conn = ConnectionDB.getConnection()) {
+            conn.setAutoCommit(false);
+            try {
+                int storeId = getDefaultStoreId(conn);
+                int employeeId = createEmployee(conn, firstName, lastName, email, phone, role, isActive);
+                assignEmployeeToStore(conn, employeeId, storeId);
+                conn.commit();
+                return employeeId;
+            } catch (SQLException e) {
+                conn.rollback();
+                throw e;
+            } finally {
+                conn.setAutoCommit(true);
+            }
+        }
+    }
+
+    public static Integer findEmployeeIdByEmail(String email) throws SQLException {
+        String sql = "SELECT employeeId FROM employee WHERE email = ? LIMIT 1";
+        try (Connection conn = ConnectionDB.getConnection();
+             PreparedStatement ps = conn.prepareStatement(sql)) {
+            ps.setString(1, email);
+            try (ResultSet rs = ps.executeQuery()) {
+                if (rs.next()) {
+                    return rs.getInt("employeeId");
+                }
+            }
+        }
+        return null;
+    }
+
+    public static int createEmployee(Connection conn, String firstName, String lastName, String email, String phone, String role, boolean isActive) throws SQLException {
+        String sql = "INSERT INTO employee (firstName, lastName, email, phone, role, isActive) VALUES (?, ?, ?, ?, ?, ?)";
+        try (PreparedStatement ps = conn.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)) {
+            ps.setString(1, firstName);
+            ps.setString(2, lastName);
+            ps.setString(3, email);
+            ps.setString(4, phone);
+            ps.setString(5, role);
+            ps.setBoolean(6, isActive);
+            ps.executeUpdate();
+
+            try (ResultSet keys = ps.getGeneratedKeys()) {
+                if (keys.next()) {
+                    return keys.getInt(1);
+                }
+            }
+        }
+
+        throw new SQLException("Could not create employee.");
+    }
+
+    public static void assignEmployeeToStore(Connection conn, int employeeId, int storeId) throws SQLException {
+        String sql = "INSERT IGNORE INTO employeeStore (employeeId, storeId) VALUES (?, ?)";
+        try (PreparedStatement ps = conn.prepareStatement(sql)) {
+            ps.setInt(1, employeeId);
+            ps.setInt(2, storeId);
+            ps.executeUpdate();
+        }
+    }
+
+    public static int getDefaultStoreId() throws SQLException {
+        try (Connection conn = ConnectionDB.getConnection()) {
+            return getDefaultStoreId(conn);
+        }
+    }
+
+    public static int getDefaultStoreId(Connection conn) throws SQLException {
+        Integer existing = firstStoreId(conn);
+        if (existing != null) {
+            return existing;
+        }
+
+        String insert = "INSERT INTO storeLocation (storeName, address, phone, email) VALUES ('Main Store', 'N/A', '000-000-0000', 'main@petshop.com')";
+        try (PreparedStatement ps = conn.prepareStatement(insert, Statement.RETURN_GENERATED_KEYS)) {
+            ps.executeUpdate();
+            try (ResultSet keys = ps.getGeneratedKeys()) {
+                if (keys.next()) {
+                    return keys.getInt(1);
+                }
+            }
+        }
+
+        Integer after = firstStoreId(conn);
+        if (after != null) {
+            return after;
+        }
+
+        return 1;
+    }
+
+    public static Integer getPrimaryStoreId(int employeeId) throws SQLException {
+        String sql = "SELECT storeId FROM employeeStore WHERE employeeId = ? ORDER BY storeId ASC LIMIT 1";
+        try (Connection conn = ConnectionDB.getConnection();
+             PreparedStatement ps = conn.prepareStatement(sql)) {
+            ps.setInt(1, employeeId);
+            try (ResultSet rs = ps.executeQuery()) {
+                if (rs.next()) {
+                    return rs.getInt("storeId");
+                }
+            }
+        }
+        return null;
+    }
+
+    private static Integer firstStoreId(Connection conn) throws SQLException {
+        String sql = "SELECT storeId FROM storeLocation ORDER BY storeId ASC LIMIT 1";
+        try (PreparedStatement ps = conn.prepareStatement(sql);
+             ResultSet rs = ps.executeQuery()) {
+            if (rs.next()) {
+                return rs.getInt("storeId");
+            }
+        }
+        return null;
+    }
+}

src/main/java/org/example/petshopdesktop/models/SaleCartItem.java

@@ -0,0 +1,39 @@
+package org.example.petshopdesktop.models;
+
+public class SaleCartItem {
+    private final int prodId;
+    private final String prodName;
+    private int quantity;
+    private final double unitPrice;
+
+    public SaleCartItem(int prodId, String prodName, int quantity, double unitPrice) {
+        this.prodId = prodId;
+        this.prodName = prodName;
+        this.quantity = quantity;
+        this.unitPrice = unitPrice;
+    }
+
+    public int getProdId() {
+        return prodId;
+    }
+
+    public String getProdName() {
+        return prodName;
+    }
+
+    public int getQuantity() {
+        return quantity;
+    }
+
+    public void setQuantity(int quantity) {
+        this.quantity = quantity;
+    }
+
+    public double getUnitPrice() {
+        return unitPrice;
+    }
+
+    public double getTotal() {
+        return unitPrice * quantity;
+    }
+}

src/main/java/org/example/petshopdesktop/models/SaleLineItem.java

@@ -0,0 +1,55 @@
+package org.example.petshopdesktop.models;
+
+public class SaleLineItem {
+    private final int saleId;
+    private final String saleDate;
+    private final String employeeName;
+    private final String itemName;
+    private final int quantity;
+    private final double unitPrice;
+    private final double total;
+    private final String paymentMethod;
+
+    public SaleLineItem(int saleId, String saleDate, String employeeName, String itemName, int quantity, double unitPrice, double total, String paymentMethod) {
+        this.saleId = saleId;
+        this.saleDate = saleDate;
+        this.employeeName = employeeName;
+        this.itemName = itemName;
+        this.quantity = quantity;
+        this.unitPrice = unitPrice;
+        this.total = total;
+        this.paymentMethod = paymentMethod;
+    }
+
+    public int getSaleId() {
+        return saleId;
+    }
+
+    public String getSaleDate() {
+        return saleDate;
+    }
+
+    public String getEmployeeName() {
+        return employeeName;
+    }
+
+    public String getItemName() {
+        return itemName;
+    }
+
+    public int getQuantity() {
+        return quantity;
+    }
+
+    public double getUnitPrice() {
+        return unitPrice;
+    }
+
+    public double getTotal() {
+        return total;
+    }
+
+    public String getPaymentMethod() {
+        return paymentMethod;
+    }
+}

src/main/java/org/example/petshopdesktop/models/StaffAccount.java

@@ -0,0 +1,73 @@
+package org.example.petshopdesktop.models;
+
+import java.sql.Timestamp;
+
+public class StaffAccount {
+    private final int userId;
+    private final int employeeId;
+    private final String username;
+    private final String firstName;
+    private final String lastName;
+    private final String email;
+    private final String phone;
+    private final boolean active;
+    private final Timestamp createdAt;
+
+    public StaffAccount(int userId, int employeeId, String username, String firstName, String lastName, String email, String phone, boolean active, Timestamp createdAt) {
+        this.userId = userId;
+        this.employeeId = employeeId;
+        this.username = username;
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.email = email;
+        this.phone = phone;
+        this.active = active;
+        this.createdAt = createdAt;
+    }
+
+    public int getUserId() {
+        return userId;
+    }
+
+    public int getEmployeeId() {
+        return employeeId;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public String getFullName() {
+        String fn = firstName == null ? "" : firstName.trim();
+        String ln = lastName == null ? "" : lastName.trim();
+        return (fn + " " + ln).trim();
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public String getPhone() {
+        return phone;
+    }
+
+    public boolean isActive() {
+        return active;
+    }
+
+    public Timestamp getCreatedAt() {
+        return createdAt;
+    }
+
+    public String getStatus() {
+        return active ? "Active" : "Inactive";
+    }
+}

src/main/java/org/example/petshopdesktop/util/ActivityLogger.java

@@ -0,0 +1,90 @@
+package org.example.petshopdesktop.util;
+
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+
+public final class ActivityLogger {
+
+    private static final ActivityLogger INSTANCE = new ActivityLogger();
+
+    private static final String LOG_FILE_NAME = "log.txt";
+    private static final DateTimeFormatter TS = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
+
+    private final Path logFilePath;
+
+    private ActivityLogger() {
+        this.logFilePath = resolveProjectRoot().resolve(LOG_FILE_NAME);
+    }
+
+    public static ActivityLogger getInstance() {
+        return INSTANCE;
+    }
+
+    public void logInsert(String tableName, String recordId, String details) {
+        write("INSERT", String.format("DB_INSERT | Table: %s | ID: %s | Details: %s", tableName, recordId, details));
+    }
+
+    public void logUpdate(String tableName, String recordId, String details) {
+        write("UPDATE", String.format("DB_UPDATE | Table: %s | ID: %s | Details: %s", tableName, recordId, details));
+    }
+
+    public void logDelete(String tableName, String recordId, String details) {
+        write("DELETE", String.format("DB_DELETE | Table: %s | ID: %s | Details: %s", tableName, recordId, details));
+    }
+
+    public void logException(String location, Exception exception, String context) {
+        write("ERROR", String.format(
+            "EXCEPTION | Location: %s | Type: %s | Message: %s | Context: %s",
+            location,
+            exception.getClass().getSimpleName(),
+            String.valueOf(exception.getMessage()),
+            context
+        ));
+    }
+
+    public void logInfo(String category, String message) {
+        write(category, message);
+    }
+
+    public Path getLogFilePath() {
+        return logFilePath;
+    }
+
+    private static Path resolveProjectRoot() {
+        Path start = Paths.get(System.getProperty("user.dir")).toAbsolutePath();
+        Path current = start;
+
+        for (int i = 0; i < 6 && current != null; i++) {
+            if (Files.exists(current.resolve("pom.xml"))
+                || Files.exists(current.resolve("mvnw"))
+                || Files.exists(current.resolve("connectionpetstore.properties.example"))) {
+                return current;
+            }
+            current = current.getParent();
+        }
+
+        return start;
+    }
+
+    private synchronized void write(String level, String message) {
+        String timestamp = LocalDateTime.now().format(TS);
+        String logEntry = String.format("[%s] [%s] %s%n", timestamp, level, message);
+
+        try {
+            Files.writeString(
+                logFilePath,
+                logEntry,
+                StandardCharsets.UTF_8,
+                StandardOpenOption.CREATE,
+                StandardOpenOption.APPEND
+            );
+        } catch (Exception e) {
+            System.err.println("Failed to write log entry: " + e.getMessage());
+        }
+    }
+}