[feat] 구매자는 장바구니에 담긴 상품을 주문할 수 있다

src/main/java/camp/woowak/lab/cart/domain/Cart.java

@@ -6,6 +6,7 @@
 import java.util.Set;
 import java.util.stream.Collectors;
 
+import camp.woowak.lab.cart.domain.vo.CartItem;
 import camp.woowak.lab.cart.exception.OtherStoreMenuException;
 import camp.woowak.lab.cart.exception.StoreNotOpenException;
 import camp.woowak.lab.menu.domain.Menu;
@@ -16,7 +17,7 @@
 @Getter
 public class Cart {
 	private final String customerId;
-	private final List<Menu> menuList;
+	private final List<CartItem> cartItems;
 
 	/**
 	 * 생성될 때 무조건 cart가 비어있도록 구현
@@ -31,27 +32,36 @@ public Cart(String customerId) {
 	 * 해당 Domain을 사용하는 같은 패키지내의 클래스, 혹은 자식 클래스는 List를 커스텀할 수 있습니다.
 	 *
 	 * @param customerId 장바구니 소유주의 ID값입니다.
-	 * @param menuList   장바구니에 사용될 List입니다.
+	 * @param cartItems   장바구니에 사용될 List입니다.
 	 */
-	protected Cart(String customerId, List<Menu> menuList) {
+	protected Cart(String customerId, List<CartItem> cartItems) {
 		this.customerId = customerId;
-		this.menuList = menuList;
+		this.cartItems = cartItems;
 	}
 
 	public void addMenu(Menu menu) {
+		addMenu(menu, 1);
+	}
+
+	public void addMenu(Menu menu, int amount) {
 		Store store = menu.getStore();
 		validateOtherStore(store.getId());
 		validateStoreOpenTime(store);
 
-		this.menuList.add(menu);
+		CartItem existingCartItem = getExistingCartItem(menu, store);
+		if (existingCartItem != null) {
+			CartItem updatedCartItem = existingCartItem.add(amount);
+			cartItems.set(cartItems.indexOf(existingCartItem), updatedCartItem);
+		} else {
+			this.cartItems.add(new CartItem(menu.getId(), store.getId(), amount));
+		}
 	}
 
-	public long getTotalPrice() {
-		return this.menuList.stream()
-			.map(Menu::getPrice)
-			.mapToLong(Long::valueOf)
-			.boxed()
-			.reduce(0L, Long::sum);
+	private CartItem getExistingCartItem(Menu menu, Store store) {
+		return cartItems.stream()
+			.filter(item -> item.getMenuId().equals(menu.getId()) && item.getStoreId().equals(store.getId()))
+			.findFirst()
+			.orElse(null);
 	}
 
 	private void validateStoreOpenTime(Store store) {
@@ -72,10 +82,8 @@ private void validateOtherStore(Long menuStoreId) {
 	}
 
 	private Set<Long> getStoreIds() {
-		return this.menuList.stream()
-			.map(Menu::getStore)
-			.mapToLong(Store::getId)
-			.boxed()
+		return this.cartItems.stream()
+			.map(CartItem::getStoreId)
 			.collect(Collectors.toSet());
 	}
 }

src/main/java/camp/woowak/lab/cart/domain/vo/CartItem.java

@@ -0,0 +1,46 @@
+package camp.woowak.lab.cart.domain.vo;
+
+import java.util.Objects;
+
+public class CartItem {
+	private final Long menuId;
+	private final Long storeId;
+	private final int amount;
+
+	public CartItem(Long menuId, Long storeId, Integer amount) {
+		this.menuId = menuId;
+		this.storeId = storeId;
+		this.amount = amount;
+	}
+
+	public Long getMenuId() {
+		return menuId;
+	}
+
+	public Long getStoreId() {
+		return storeId;
+	}
+
+	public int getAmount() {
+		return amount;
+	}
+
+	public CartItem add(Integer increment) {
+		return new CartItem(menuId, storeId, amount + increment);
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o)
+			return true;
+		if (!(o instanceof CartItem item))
+			return false;
+		return Objects.equals(menuId, item.menuId) && Objects.equals(storeId, item.storeId)
+			&& Objects.equals(amount, item.amount);
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(menuId, storeId, amount);
+	}
+}

src/main/java/camp/woowak/lab/cart/exception/CartErrorCode.java

@@ -6,8 +6,8 @@
 
 public enum CartErrorCode implements ErrorCode {
 	MENU_NOT_FOUND(HttpStatus.NOT_FOUND, "ca_1_1", "해당 메뉴가 존재하지 않습니다."),
-	OTHER_STORE_MENU(HttpStatus.BAD_REQUEST,"ca_1_2","다른 매장의 메뉴는 등록할 수 없습니다."),
-	STORE_NOT_OPEN(HttpStatus.BAD_REQUEST,"ca_1_3","주문 가능한 시간이 아닙니다.");
+	OTHER_STORE_MENU(HttpStatus.BAD_REQUEST, "ca_1_2", "다른 매장의 메뉴는 등록할 수 없습니다."),
+	STORE_NOT_OPEN(HttpStatus.BAD_REQUEST, "ca_1_3", "주문 가능한 시간이 아닙니다.");
 
 	private final int status;
 	private final String errorCode;

src/main/java/camp/woowak/lab/cart/service/CartService.java

@@ -1,8 +1,11 @@
 package camp.woowak.lab.cart.service;
 
+import java.util.List;
+
 import org.springframework.stereotype.Service;
 
 import camp.woowak.lab.cart.domain.Cart;
+import camp.woowak.lab.cart.domain.vo.CartItem;
 import camp.woowak.lab.cart.exception.MenuNotFoundException;
 import camp.woowak.lab.cart.repository.CartRepository;
 import camp.woowak.lab.cart.service.command.AddCartCommand;
@@ -36,8 +39,18 @@ public void addMenu(AddCartCommand command) {
 	}
 
 	public long getTotalPrice(CartTotalPriceCommand command) {
-		return getCart(command.customerId())
-			.getTotalPrice();
+		Cart cart = getCart(command.customerId());
+		List<Menu> findMenus = menuRepository.findAllById(
+			cart.getCartItems().stream().map(CartItem::getMenuId).toList());
+		long totalPrice = 0L;
+		for (Menu findMenu : findMenus) {
+			for (CartItem item : cart.getCartItems()) {
+				if (item.getMenuId().equals(findMenu.getId())) {
+					totalPrice += (long)findMenu.getPrice() * item.getAmount();
+				}
+			}
+		}
+		return totalPrice;
 	}
 
 	private Cart getCart(String customerId) {

src/main/java/camp/woowak/lab/customer/exception/CustomerErrorCode.java

@@ -7,7 +7,8 @@
 public enum CustomerErrorCode implements ErrorCode {
 	INVALID_CREATION(HttpStatus.BAD_REQUEST, "C1", "잘못된 요청입니다."),
 	DUPLICATE_EMAIL(HttpStatus.BAD_REQUEST, "C2", "이미 존재하는 이메일입니다."),
-	AUTHENTICATION_FAILED(HttpStatus.UNAUTHORIZED, "C3", "이메일 또는 비밀번호가 올바르지 않습니다.");
+	AUTHENTICATION_FAILED(HttpStatus.UNAUTHORIZED, "C3", "이메일 또는 비밀번호가 올바르지 않습니다."),
+	NOT_FOUND(HttpStatus.NOT_FOUND, "C4", "존재하지 않는 사용자입니다.");
 
 	private final HttpStatus status;
 	private final String errorCode;

src/main/java/camp/woowak/lab/customer/exception/NotFoundCustomerException.java

@@ -0,0 +1,9 @@
+package camp.woowak.lab.customer.exception;
+
+import camp.woowak.lab.common.exception.NotFoundException;
+
+public class NotFoundCustomerException extends NotFoundException {
+	public NotFoundCustomerException(String message) {
+		super(CustomerErrorCode.NOT_FOUND, message);
+	}
+}

src/main/java/camp/woowak/lab/customer/repository/CustomerRepository.java

@@ -6,7 +6,12 @@
 import org.springframework.data.jpa.repository.JpaRepository;
 
 import camp.woowak.lab.customer.domain.Customer;
+import camp.woowak.lab.customer.exception.NotFoundCustomerException;
 
 public interface CustomerRepository extends JpaRepository<Customer, UUID> {
 	Optional<Customer> findByEmail(String email);
+
+	default Customer findByIdOrThrow(UUID id) {
+		return findById(id).orElseThrow(() -> new NotFoundCustomerException("존재하지 않는 사용자(id=" + id + ")를 조회했습니다."));
+	}
 }

src/main/java/camp/woowak/lab/menu/domain/Menu.java

@@ -58,4 +58,7 @@ public Long getId() {
 		return id;
 	}
 
+	public void decrementStockCount(int amount) {
+		stockCount -= amount;
+	}
 }

src/main/java/camp/woowak/lab/menu/repository/MenuRepository.java

@@ -1,14 +1,21 @@
 package camp.woowak.lab.menu.repository;
 
+import java.util.List;
 import java.util.Optional;
 
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Lock;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;
 
 import camp.woowak.lab.menu.domain.Menu;
+import jakarta.persistence.LockModeType;
 
 public interface MenuRepository extends JpaRepository<Menu, Long> {
 	@Query("SELECT m FROM Menu m JOIN FETCH m.store WHERE m.id = :id")
 	Optional<Menu> findByIdWithStore(@Param("id") Long id);
+
+	@Lock(LockModeType.PESSIMISTIC_WRITE)
+	@Query("SELECT m FROM Menu m where m.id in :ids")
+	List<Menu> findAllByIdForUpdate(List<Long> ids);
 }

src/main/java/camp/woowak/lab/order/domain/Order.java

@@ -1,17 +1,28 @@
 package camp.woowak.lab.order.domain;
 
+import java.util.ArrayList;
+import java.util.List;
+
+import camp.woowak.lab.cart.domain.vo.CartItem;
 import camp.woowak.lab.customer.domain.Customer;
+import camp.woowak.lab.order.domain.vo.OrderItem;
 import camp.woowak.lab.store.domain.Store;
+import jakarta.persistence.CollectionTable;
+import jakarta.persistence.ElementCollection;
 import jakarta.persistence.Entity;
 import jakarta.persistence.FetchType;
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
+import jakarta.persistence.JoinColumn;
 import jakarta.persistence.ManyToOne;
 import jakarta.persistence.Table;
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
 
 @Entity
 @Table(name = "ORDERS")
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
 public class Order {
 	@Id
 	@GeneratedValue(strategy = GenerationType.IDENTITY)
@@ -20,4 +31,27 @@ public class Order {
 	private Customer requester;
 	@ManyToOne(fetch = FetchType.LAZY)
 	private Store store;
+	@CollectionTable(name = "ORDER_ITEMS", joinColumns = @JoinColumn(name = "order_id"))
+	@ElementCollection(fetch = FetchType.EAGER)
+	private List<OrderItem> orderItems = new ArrayList<>();
+
+	public Order(Customer requester, Store store, List<CartItem> cartItems,
+				 SingleStoreOrderValidator singleStoreOrderValidator,
+				 StockRequester stockRequester, PriceChecker priceChecker, WithdrawPointService withdrawPointService) {
+		singleStoreOrderValidator.check(store, cartItems);
+		stockRequester.request(cartItems);
+		List<OrderItem> orderItems = priceChecker.check(cartItems);
+		withdrawPointService.withdraw(requester, orderItems);
+		this.requester = requester;
+		this.store = store;
+		this.orderItems = orderItems;
+	}
+
+	public Long getId() {
+		return id;
+	}
+
+	public List<OrderItem> getOrderItems() {
+		return orderItems;
+	}
 }

src/main/java/camp/woowak/lab/order/domain/PriceChecker.java

@@ -0,0 +1,65 @@
+package camp.woowak.lab.order.domain;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import org.springframework.stereotype.Component;
+
+import camp.woowak.lab.cart.domain.vo.CartItem;
+import camp.woowak.lab.menu.domain.Menu;
+import camp.woowak.lab.menu.repository.MenuRepository;
+import camp.woowak.lab.order.domain.vo.OrderItem;
+import camp.woowak.lab.order.exception.NotFoundMenuException;
+
+@Component
+public class PriceChecker {
+	private final MenuRepository menuRepository;
+
+	public PriceChecker(MenuRepository menuRepository) {
+		this.menuRepository = menuRepository;
+	}
+
+	public List<OrderItem> check(List<CartItem> cartItems) {
+		Set<Long> cartItemMenuIds = extractMenuIds(cartItems);
+		List<Menu> menus = menuRepository.findAllById(cartItemMenuIds);
+		Map<Long, Menu> menuMap = listToMap(menus);
+		Set<Long> missingMenuIds = new HashSet<>();
+		for (Long menuId : cartItemMenuIds) {
+			if (!menuMap.containsKey(menuId)) {
+				missingMenuIds.add(menuId);
+			}
+		}
+		if (!missingMenuIds.isEmpty()) {
+			String missingIdsString = formatMissingIds(missingMenuIds);
+			throw new NotFoundMenuException("등록되지 않은 메뉴(id=" + missingIdsString + ")를 주문했습니다.");
+		}
+		List<OrderItem> orderItems = new ArrayList<>();
+		for (CartItem cartItem : cartItems) {
+			Menu menu = menuMap.get(cartItem.getMenuId());
+			orderItems.add(new OrderItem(menu.getId(), menu.getPrice(), cartItem.getAmount()));
+		}
+		return orderItems;
+	}
+
+	private String formatMissingIds(Set<Long> missingMenuIds) {
+		return missingMenuIds.stream()
+			.map(String::valueOf)
+			.collect(Collectors.joining(", "));
+	}
+
+	private Map<Long, Menu> listToMap(List<Menu> menus) {
+		return menus.stream()
+			.collect(Collectors.toMap(Menu::getId, Function.identity()));
+	}
+
+	private Set<Long> extractMenuIds(List<CartItem> cartItems) {
+		return cartItems.stream()
+			.map(CartItem::getMenuId)
+			.collect(Collectors.toSet());
+	}
+}

src/main/java/camp/woowak/lab/order/domain/SingleStoreOrderValidator.java

@@ -0,0 +1,24 @@
+package camp.woowak.lab.order.domain;
+
+import java.util.List;
+
+import org.springframework.stereotype.Component;
+
+import camp.woowak.lab.cart.domain.vo.CartItem;
+import camp.woowak.lab.order.exception.EmptyCartException;
+import camp.woowak.lab.order.exception.MultiStoreOrderException;
+import camp.woowak.lab.store.domain.Store;
+
+@Component
+public class SingleStoreOrderValidator {
+	public void check(Store store, List<CartItem> cartItems) {
+		if (cartItems == null || cartItems.isEmpty()) {
+			throw new EmptyCartException("최소 하나 이상의 메뉴를 주문해야 합니다.");
+		}
+		for (CartItem cartItem : cartItems) {
+			if (!cartItem.getStoreId().equals(store.getId())) {
+				throw new MultiStoreOrderException("다른 가게의 메뉴를 같이 주문할 수 없습니다.");
+			}
+		}
+	}
+}