Merge pull request #161 from kt-cloud-basic-project/SHOP-124

 feat: DiscountEventListener 개발

Author: DaveLee-b

src/main/java/com/kt/integration/eventlistener/DiscountEventListener.java

@@ -0,0 +1,50 @@
+package com.kt.integration.eventlistener;
+
+import com.kt.event.ProductDiscountEvent;
+import com.kt.notification.MailSendRequest;
+import com.kt.notification.MailSendService;
+import com.kt.repository.cart.CartRepository;
+import com.kt.repository.wishlist.WishlistRepository;
+import com.kt.service.discount.DiscountService;
+import jakarta.validation.Valid;
+import lombok.RequiredArgsConstructor;
+import org.springframework.context.event.EventListener;
+import org.springframework.stereotype.Component;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+@Component
+@RequiredArgsConstructor
+public class DiscountEventListener {
+
+    private final DiscountService discountService;
+    private final MailSendService mailSendService;
+    private final WishlistRepository wishlistRepository;
+    private final CartRepository cartRepository;
+
+    @EventListener
+    public void sendMail(ProductDiscountEvent event) {
+
+        List<String> wishlistEmails =
+                wishlistRepository.findDistinctEmailsByProductId(event.productId());
+        List<String> cartEmails =
+                cartRepository.findDistinctEmailsByProductId(event.productId());
+
+        Set<String> distinct_Emails = new HashSet<>(wishlistEmails);
+        distinct_Emails.addAll(cartEmails);
+
+        if (distinct_Emails.isEmpty()) return;
+
+        for (String email : distinct_Emails) {
+            MailSendRequest request = new MailSendRequest(
+                    email,
+                    "현재 상품 " + event.productName() + " 이(가) 할인중입니다.",
+                    "상품명: " + event.productName() + "\n할인금액: " + event.discountValue() + "\n할인가: 289,000원\n링크: https://your-shop.com/products/" + event.productId() + "\n\n지금 구매하면 혜택 적용됩니다."
+            );
+            mailSendService.sendEmail(request);
+        }
+    }
+}
+

src/main/java/com/kt/notification/FakeMailSendService.java

@@ -0,0 +1,18 @@
+package com.kt.notification;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.context.annotation.Profile;
+import org.springframework.stereotype.Component;
+
+@Slf4j
+@Component
+@Profile("test")
+public class FakeMailSendService implements MailSendService {
+
+    @Override
+    public void sendEmail(MailSendRequest mailSendRequest) {
+        log.info("[TEST] skip email send: to={}, subject={}",
+                mailSendRequest.email(), mailSendRequest.title());
+    }
+}
+

src/main/java/com/kt/repository/cart/CartRepository.java

@@ -10,6 +10,7 @@
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.jpa.repository.EntityGraph;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
 
 public interface CartRepository extends JpaRepository<Cart, Long> {
 	default Cart findByIdOrThrow(Long id, ErrorCode errorCode) {
@@ -20,4 +21,15 @@ default Cart findByIdOrThrow(Long id, ErrorCode errorCode) {
 
 	@EntityGraph(attributePaths = {"user", "product", "user.membership"})
 	Page<Cart> findByUserId(Long userId, Pageable pageable);
+
+    //상품을 찜한 유저 이메일만 뽑는 쿼리, jpa는 비효율적이라 사용x
+    @Query("""
+        select distinct u.email
+        from Wishlist w
+        join w.user u
+        where w.product.id = :productId
+          and u.isDeleted = false
+          and u.email is not null
+    """)
+    List<String> findDistinctEmailsByProductId(Long productId);
 }

src/main/java/com/kt/repository/wishlist/WishlistRepository.java

@@ -3,17 +3,29 @@
 import java.util.List;
 
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
 import org.springframework.stereotype.Repository;
 
 import com.kt.domain.wishlist.Wishlist;
 
 @Repository
 public interface WishlistRepository extends JpaRepository<Wishlist,Long> {
-		boolean existsByUserIdAndProductId(Long userId, Long productId);
-		List<Wishlist> findByUserId(Long userId);
-		List<Wishlist> findByProductId(Long productId);
+    boolean existsByUserIdAndProductId(Long userId, Long productId);
+    List<Wishlist> findByUserId(Long userId);
+    List<Wishlist> findByProductId(Long productId);
 
-		void deleteByUserIdAndProductId(Long userId, Long productId);
+    void deleteByUserIdAndProductId(Long userId, Long productId);
 
-		void deleteByUserId(Long userId);
+    void deleteByUserId(Long userId);
+
+    //상품을 찜한 유저 이메일만 뽑는 쿼리, jpa는 비효율적이라 사용x
+    @Query("""
+        select distinct u.email
+        from Wishlist w
+        join w.user u
+        where w.product.id = :productId
+          and u.isDeleted = false
+          and u.email is not null
+    """)
+    List<String> findDistinctEmailsByProductId(Long productId);
 }