feat: 장바구니 조회 기능 구현

src/main/java/com/jangburich/domain/order/application/OrderService.java

@@ -4,13 +4,15 @@
 import com.jangburich.domain.menu.domain.repository.MenuRepository;
 import com.jangburich.domain.order.domain.Cart;
 import com.jangburich.domain.order.domain.repository.CartRepository;
-import com.jangburich.domain.order.domain.repository.OrdersRepository;
 import com.jangburich.domain.order.dto.request.AddCartRequest;
+import com.jangburich.domain.order.dto.response.CartResponse;
+import com.jangburich.domain.order.dto.response.CartResponse.GetCartItemsResponse;
 import com.jangburich.domain.store.domain.Store;
 import com.jangburich.domain.store.domain.repository.StoreRepository;
 import com.jangburich.domain.user.domain.User;
 import com.jangburich.domain.user.domain.repository.UserRepository;
 import com.jangburich.global.payload.Message;
+import java.util.List;
 import java.util.Optional;
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
@@ -65,4 +67,29 @@ public Message addCart(String userProviderId, AddCartRequest addCartRequest) {
                 .message("장바구니에 상품을 추가했습니다.")
                 .build();
     }
+
+    public CartResponse getCartItems(String userProviderId) {
+        User user = userRepository.findByProviderId(userProviderId)
+                .orElseThrow(() -> new NullPointerException());
+
+        List<Cart> carts = cartRepository.findAllByUser(user);
+
+        if (carts.isEmpty()) {
+            return CartResponse.of(List.of(), 0);
+        }
+
+        List<GetCartItemsResponse> cartItems = carts.stream()
+                .map(cart -> GetCartItemsResponse.of(
+                        cart.getMenu().getName(),
+                        cart.getMenu().getDescription(),
+                        cart.getQuantity(),
+                        cart.getMenu().getPrice()
+                ))
+                .toList();
+
+        int discountAmount = 0;
+        CartResponse cartResponse = CartResponse.of(cartItems, discountAmount);
+
+        return cartResponse;
+    }
 }

src/main/java/com/jangburich/domain/order/domain/repository/CartRepository.java

@@ -1,6 +1,8 @@
 package com.jangburich.domain.order.domain.repository;
 
 import com.jangburich.domain.order.domain.Cart;
+import com.jangburich.domain.user.domain.User;
+import java.util.List;
 import java.util.Optional;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
@@ -11,4 +13,6 @@
 public interface CartRepository extends JpaRepository<Cart, Long> {
     @Query("SELECT c FROM Cart c WHERE c.user.userId = :userId AND c.menu.id = :menuId")
     Optional<Cart> findByUserIdAndMenuId(@Param("userId") Long userId, @Param("menuId") Long menuId);
+
+    List<Cart> findAllByUser(User user);
 }

src/main/java/com/jangburich/domain/order/dto/response/CartResponse.java

@@ -0,0 +1,33 @@
+package com.jangburich.domain.order.dto.response;
+
+import java.util.List;
+
+public record CartResponse(
+        List<GetCartItemsResponse> cartItems,
+        Integer totalAmount,
+        Integer discountAmount,
+        Integer finalAmount
+) {
+    public static CartResponse of(List<GetCartItemsResponse> cartItems, Integer discountAmount) {
+        int totalAmount = cartItems.stream()
+                .mapToInt(item -> item.menuPrice * item.quantity)
+                .sum();
+
+        discountAmount = 0;
+
+        int finalAmount = totalAmount - discountAmount;
+
+        return new CartResponse(cartItems, totalAmount, discountAmount, finalAmount);
+    }
+
+    public record GetCartItemsResponse(
+            String menuName,
+            String menuDescription,
+            Integer quantity,
+            Integer menuPrice
+    ) {
+        public static GetCartItemsResponse of(String menuName, String menuDescription, Integer quantity, Integer menuPrice) {
+            return new GetCartItemsResponse(menuName, menuDescription, quantity, menuPrice);
+        }
+    }
+}

src/main/java/com/jangburich/domain/order/presentation/OrderController.java

@@ -2,13 +2,15 @@
 
 import com.jangburich.domain.order.application.OrderService;
 import com.jangburich.domain.order.dto.request.AddCartRequest;
+import com.jangburich.domain.order.dto.response.CartResponse;
 import com.jangburich.global.payload.Message;
 import com.jangburich.global.payload.ResponseCustom;
 import com.jangburich.utils.parser.AuthenticationParser;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.tags.Tag;
 import lombok.RequiredArgsConstructor;
 import org.springframework.security.core.Authentication;
+import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
@@ -23,11 +25,19 @@ public class OrderController {
     private final OrderService orderService;
 
     @Operation(summary = "장바구니 담기", description = "장바구니에 물건과 수량을 담습니다.")
-    @PostMapping("/cart")
+    @PostMapping("/carts")
     public ResponseCustom<Message> addCart(
             Authentication authentication,
             @RequestBody AddCartRequest addCartRequest
     ) {
         return ResponseCustom.OK(orderService.addCart(AuthenticationParser.parseUserId(authentication), addCartRequest));
     }
+
+    @Operation(summary = "장바구니 조회", description = "장바구니에 담은 상품을 조회합니다.")
+    @GetMapping("/carts")
+    public ResponseCustom<CartResponse> getCartItems(
+            Authentication authentication
+    ) {
+        return ResponseCustom.OK(orderService.getCartItems(AuthenticationParser.parseUserId(authentication)));
+    }
 }