[feat] redis용 dao를 임시로 inMemoryCartRepository를 이용해서 구현

src/main/java/camp/woowak/lab/web/dao/cart/RedisCartDao.java

@@ -0,0 +1,93 @@
+package camp.woowak.lab.web.dao.cart;
+
+import static camp.woowak.lab.menu.domain.QMenu.*;
+import static camp.woowak.lab.store.domain.QStore.*;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
+import java.util.stream.Collectors;
+
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.stereotype.Repository;
+
+import com.querydsl.core.Tuple;
+import com.querydsl.jpa.impl.JPAQueryFactory;
+
+import camp.woowak.lab.cart.domain.Cart;
+import camp.woowak.lab.cart.repository.CartRepository;
+import camp.woowak.lab.web.dto.response.CartResponse;
+
+@Repository
+public class RedisCartDao implements CartDao {
+	private final CartRepository cartRepository;
+	private final JPAQueryFactory queryFactory;
+
+	public RedisCartDao(@Qualifier("inMemoryCartRepository") CartRepository cartRepository,
+						JPAQueryFactory queryFactory) {
+		this.cartRepository = cartRepository;
+		this.queryFactory = queryFactory;
+	}
+
+	@Override
+	public CartResponse findByCustomerId(UUID customerId) {
+		Optional<Cart> optionalCart = cartRepository.findByCustomerId(customerId.toString());
+		if (optionalCart.isEmpty()) {
+			return new CartResponse();
+		}
+		Cart cart = optionalCart.get();
+
+		if (cart.getCartItems().isEmpty()) {
+			return new CartResponse();
+		}
+
+		Long sId = cart.getCartItems().stream().findAny().get().getStoreId();
+		Map<Long, Integer> menuIdsCount = new HashMap<>();
+		Set<Long> menuIds = cart.getCartItems().stream()
+			.map((cartItem) -> {
+				int amount = cartItem.getAmount();
+				menuIdsCount.put(cartItem.getMenuId(), amount);
+				return cartItem.getMenuId();
+			})
+			.collect(Collectors.toSet());
+
+		List<Tuple> results = queryFactory
+			.select(
+				store.id,
+				store.name,
+				store.minOrderPrice,
+				menu.id,
+				menu.name,
+				menu.price,
+				menu.stockCount
+			)
+			.from(store)
+			.join(menu).on(menu.store.id.eq(store.id))
+			.where(store.id.eq(sId).and(menu.id.in(menuIds)))
+			.fetch();
+
+		if (results.isEmpty()) {
+			return null; // 또는 적절한 예외 처리
+		}
+
+		Tuple firstResult = results.get(0);
+		Long storeId = firstResult.get(store.id);
+		String storeName = firstResult.get(store.name);
+		Integer minOrderPrice = firstResult.get(store.minOrderPrice);
+
+		List<CartResponse.CartItemInfo> menuList = results.stream()
+			.map(tuple -> new CartResponse.CartItemInfo(
+				tuple.get(menu.id),
+				tuple.get(menu.name),
+				tuple.get(menu.price),
+				Integer.toUnsignedLong(menuIdsCount.get(tuple.get(menu.id))), // amount 대신 stockCount 사용
+				tuple.get(menu.stockCount)
+			))
+			.collect(Collectors.toList());
+
+		return new CartResponse(storeId, storeName, minOrderPrice, menuList);
+	}
+}