complete dao classes

src/main/java/dev/dao/MenuItemDao.java

@@ -1,25 +1,59 @@
 package dev.dao;
 
+import dev.database.DatabaseConnection;
 import dev.model.MenuItem;
 
+import java.sql.*;
+import java.util.ArrayList;
 import java.util.List;
 
 public class MenuItemDao {
 
     public List<MenuItem> findAll() {
+        List<MenuItem> items = new ArrayList<>();
+        String sql = "SELECT * FROM menu_items ORDER BY category, name";
 
-        // TODO:
+        try (Connection conn = DatabaseConnection.getConnection();
-        // Retrieve all menu items
+             PreparedStatement ps = conn.prepareStatement(sql);
+             ResultSet rs = ps.executeQuery()) {
 
-        return null;
+            while (rs.next()) {
+                MenuItem item = new MenuItem();
+                item.setId(rs.getInt("id"));
+                item.setName(rs.getString("name"));
+                item.setDescription(rs.getString("description"));
+                item.setPrice(rs.getDouble("price"));
+                item.setCategory(rs.getString("category"));
+                items.add(item);
+            }
+
+        } catch (SQLException e) {
+            System.out.println("Error fetching menu: " + e.getMessage());
+        }
+        return items;
     }
 
     public MenuItem findById(int id) {
+        String sql = "SELECT * FROM menu_items WHERE id = ?";
+        try (Connection conn = DatabaseConnection.getConnection();
+             PreparedStatement ps = conn.prepareStatement(sql)) {
 
-        // TODO:
+            ps.setInt(1, id);
-        // Find menu item by id
+            ResultSet rs = ps.executeQuery();
 
+            if (rs.next()) {
+                MenuItem item = new MenuItem();
+                item.setId(rs.getInt("id"));
+                item.setName(rs.getString("name"));
+                item.setDescription(rs.getString("description"));
+                item.setPrice(rs.getDouble("price"));
+                item.setCategory(rs.getString("category"));
+                return item;
+            }
+
+        } catch (SQLException e) {
+            System.out.println("Error finding menu item: " + e.getMessage());
+        }
         return null;
     }
-
 }

src/main/java/dev/dao/OrderDao.java

@@ -1,25 +1,53 @@
 package dev.dao;
 
+import dev.database.DatabaseConnection;
 import dev.model.Order;
 
+import java.sql.*;
+import java.util.ArrayList;
 import java.util.List;
 
 public class OrderDao {
 
     public int save(Order order) {
+        String sql = "INSERT INTO orders (user_id, total_price) VALUES (?, ?) RETURNING id";
+        try (Connection conn = DatabaseConnection.getConnection();
+             PreparedStatement ps = conn.prepareStatement(sql)) {
 
-        // TODO:
+            ps.setInt(1, order.getUserId());
-        // Insert order and return generated id
+            ps.setDouble(2, order.getTotalPrice());
+            ResultSet rs = ps.executeQuery();
 
+            if (rs.next()) return rs.getInt(1);  // return generated id
+
+        } catch (SQLException e) {
+            System.out.println("Error saving order: " + e.getMessage());
+        }
         return -1;
     }
 
     public List<Order> findByUserId(int userId) {
+        List<Order> orders = new ArrayList<>();
+        String sql = "SELECT * FROM orders WHERE user_id = ? ORDER BY created_at DESC";
 
-        // TODO:
+        try (Connection conn = DatabaseConnection.getConnection();
-        // Retrieve all orders of a user
+             PreparedStatement ps = conn.prepareStatement(sql)) {
 
-        return null;
+            ps.setInt(1, userId);
+            ResultSet rs = ps.executeQuery();
+
+            while (rs.next()) {
+                Order order = new Order();
+                order.setId(rs.getInt("id"));
+                order.setUserId(rs.getInt("user_id"));
+                order.setCreatedAt(rs.getTimestamp("created_at").toLocalDateTime());
+                order.setTotalPrice(rs.getDouble("total_price"));
+                orders.add(order);
+            }
+
+        } catch (SQLException e) {
+            System.out.println("Error fetching orders: " + e.getMessage());
+        }
+        return orders;
     }
-
 }

src/main/java/dev/dao/OrderDetailDao.java

@@ -1,24 +1,53 @@
 package dev.dao;
 
+import dev.database.DatabaseConnection;
 import dev.model.OrderDetail;
 
+import java.sql.*;
+import java.util.ArrayList;
 import java.util.List;
 
 public class OrderDetailDao {
 
     public void save(OrderDetail detail) {
+        String sql = "INSERT INTO order_details (order_id, menu_item_id, quantity, unit_price) VALUES (?, ?, ?, ?)";
+        try (Connection conn = DatabaseConnection.getConnection();
+             PreparedStatement ps = conn.prepareStatement(sql)) {
 
-        // TODO:
+            ps.setInt(1, detail.getOrderId());
-        // Insert order detail
+            ps.setInt(2, detail.getMenuItemId());
+            ps.setInt(3, detail.getQuantity());
+            ps.setDouble(4, detail.getPrice());
+            ps.executeUpdate();
 
+        } catch (SQLException e) {
+            System.out.println("Error saving order detail: " + e.getMessage());
+        }
     }
 
     public List<OrderDetail> findByOrderId(int orderId) {
+        List<OrderDetail> details = new ArrayList<>();
+        String sql = "SELECT * FROM order_details WHERE order_id = ?";
 
-        // TODO:
+        try (Connection conn = DatabaseConnection.getConnection();
-        // Retrieve order details
+             PreparedStatement ps = conn.prepareStatement(sql)) {
 
-        return null;
+            ps.setInt(1, orderId);
+            ResultSet rs = ps.executeQuery();
+
+            while (rs.next()) {
+                OrderDetail d = new OrderDetail();
+                d.setId(rs.getInt("id"));
+                d.setOrderId(rs.getInt("order_id"));
+                d.setMenuItemId(rs.getInt("menu_item_id"));
+                d.setQuantity(rs.getInt("quantity"));
+                d.setPrice(rs.getDouble("unit_price"));
+                details.add(d);
+            }
+
+        } catch (SQLException e) {
+            System.out.println("Error fetching order details: " + e.getMessage());
+        }
+        return details;
     }
-
 }

src/main/java/dev/dao/UserDao.java

@@ -1,23 +1,48 @@
 package dev.dao;
 
+import dev.database.DatabaseConnection;
 import dev.model.User;
 
+import java.sql.*;
+
 public class UserDao {
 
     public boolean save(User user) {
+        String sql = "INSERT INTO users (username, password_hash, email) VALUES (?, ?, ?)";
+        try (Connection conn = DatabaseConnection.getConnection();
+             PreparedStatement ps = conn.prepareStatement(sql)) {
 
-        // TODO:
+            ps.setString(1, user.getUsername());
-        // Insert user into database
+            ps.setString(2, user.getPassword());
+            ps.setString(3, user.getEmail());
+            return ps.executeUpdate() > 0;
 
-        return false;
+        } catch (SQLException e) {
+            System.out.println("Error saving user: " + e.getMessage());
+            return false;
+        }
     }
 
     public User findByUsername(String username) {
+        String sql = "SELECT * FROM users WHERE username = ?";
+        try (Connection conn = DatabaseConnection.getConnection();
+             PreparedStatement ps = conn.prepareStatement(sql)) {
 
-        // TODO:
+            ps.setString(1, username);
-        // Find a user by username
+            ResultSet rs = ps.executeQuery();
 
+            if (rs.next()) {
+                User user = new User();
+                user.setId(rs.getInt("id"));
+                user.setUsername(rs.getString("username"));
+                user.setPassword(rs.getString("password_hash"));
+                user.setEmail(rs.getString("email"));
+                return user;
+            }
+
+        } catch (SQLException e) {
+            System.out.println("Error finding user: " + e.getMessage());
+        }
         return null;
     }
-
 }