Feat: 제품 좋아요/취소 API 구현

src/main/java/com/DecodEat/domain/products/controller/ProductController.java

@@ -105,4 +105,12 @@ public ApiResponse<PageResponseDto<ProductRegisterHistoryDto>> getRegisterHistor
         return ApiResponse.onSuccess(productService.getRegisterHistory(user, pageable));
     }
 
+    @Operation(summary = "제품 좋아요 추가/취소", description = "좋아요를 누르면 추가, 다시 누르면 취소됩니다.")
+    @PostMapping("/{productId}/like")
+    public ApiResponse<ProductLikeResponseDTO> addOrUpdateLike(
+            @CurrentUser User user,
+            @Parameter(description = "제품 ID") @PathVariable Long productId
+    ) {
+        return ApiResponse.onSuccess(productService.addOrUpdateLike(user.getId(), productId));
+    }
 }

src/main/java/com/DecodEat/domain/products/converter/ProductConverter.java

@@ -3,6 +3,7 @@
 import com.DecodEat.domain.products.dto.request.ProductRegisterRequestDto;
 import com.DecodEat.domain.products.dto.response.*;
 import com.DecodEat.domain.products.entity.Product;
+import com.DecodEat.domain.products.entity.ProductInfoImage;
 import com.DecodEat.domain.products.entity.ProductNutrition;
 import com.DecodEat.domain.products.entity.RawMaterial.RawMaterialCategory;
 import org.springframework.data.domain.Slice;
@@ -121,4 +122,13 @@ public static ProductResponseDTO.ProductListResultDTO toProductListResultDTO(Sli
                 .nextCursorId(nextCursorId)
                 .build();
     }
+
+    public static ProductLikeResponseDTO toProductLikeDTO(Long productId, boolean isLiked) {
+
+        return ProductLikeResponseDTO.builder()
+                .productId(productId)
+                .isLiked(isLiked)
+                .build();
+
+    }
 }

src/main/java/com/DecodEat/domain/products/dto/response/ProductLikeResponseDTO.java

@@ -0,0 +1,22 @@
+package com.DecodEat.domain.products.dto.response;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Getter
+@Builder
+@AllArgsConstructor
+@NoArgsConstructor
+@Schema(description = "제품 좋아요 응답 정보")
+public class ProductLikeResponseDTO {
+
+    @Schema(description = "제품 ID", example = "1")
+    private Long productId;
+
+    @Schema(description = "좋아요 여부", example = "true")
+    private boolean isLiked;
+
+}

src/main/java/com/DecodEat/domain/products/entity/ProductLike.java

@@ -0,0 +1,34 @@
+package com.DecodEat.domain.products.entity;
+
+
+import com.DecodEat.domain.users.entity.User;
+import com.DecodEat.global.common.BaseEntity;
+import jakarta.persistence.*;
+import lombok.*;
+
+@Entity
+@Getter
+@AllArgsConstructor
+@NoArgsConstructor
+@Builder
+@Table(
+        name = "product_like",
+        uniqueConstraints = {
+                @UniqueConstraint(columnNames = {"user_id", "product_id"})
+        }
+)// 한 유저는 하나의 제품에 대해 한번의 좋아요만 하도록 유니크 제약조건 설정
+public class ProductLike extends BaseEntity {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "user_id", nullable = false)
+    private User user;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "product_id", nullable = false)
+    private Product product;
+
+}

src/main/java/com/DecodEat/domain/products/repository/ProductLikeRepository.java

@@ -0,0 +1,14 @@
+package com.DecodEat.domain.products.repository;
+
+import com.DecodEat.domain.products.entity.Product;
+import com.DecodEat.domain.products.entity.ProductLike;
+import com.DecodEat.domain.users.entity.User;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.Optional;
+
+public interface ProductLikeRepository extends JpaRepository<ProductLike, Long>  {
+
+    Optional<ProductLike> findByUserAndProduct(User user, Product product);
+
+}

src/main/java/com/DecodEat/domain/products/service/ProductService.java

@@ -5,21 +5,13 @@
 import com.DecodEat.domain.products.dto.request.AnalysisRequestDto;
 import com.DecodEat.domain.products.dto.request.ProductRegisterRequestDto;
 import com.DecodEat.domain.products.dto.response.*;
-import com.DecodEat.domain.products.entity.DecodeStatus;
-import com.DecodEat.domain.products.entity.Product;
-import com.DecodEat.domain.products.entity.ProductInfoImage;
-import com.DecodEat.domain.products.entity.ProductNutrition;
-import com.DecodEat.domain.products.entity.ProductRawMaterial;
+import com.DecodEat.domain.products.entity.*;
 import com.DecodEat.domain.products.entity.RawMaterial.RawMaterial;
 import com.DecodEat.domain.products.entity.RawMaterial.RawMaterialCategory;
-import com.DecodEat.domain.products.repository.ProductImageRepository;
-import com.DecodEat.domain.products.repository.ProductNutritionRepository;
-import com.DecodEat.domain.products.repository.ProductRawMaterialRepository;
-import com.DecodEat.domain.products.repository.ProductRepository;
-import com.DecodEat.domain.products.repository.RawMaterialRepository;
-import com.DecodEat.domain.products.repository.ProductSpecification;
+import com.DecodEat.domain.products.repository.*;
 import com.DecodEat.domain.users.entity.Behavior;
 import com.DecodEat.domain.users.entity.User;
+import com.DecodEat.domain.users.repository.UserRepository;
 import com.DecodEat.domain.users.service.UserBehaviorService;
 import com.DecodEat.global.aws.s3.AmazonS3Manager;
 import com.DecodEat.global.dto.PageResponseDto;
@@ -37,6 +29,7 @@
 import javax.swing.*;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 import java.util.UUID;
 import java.util.stream.Collectors;
 
@@ -55,9 +48,9 @@ public class ProductService {
     private final AmazonS3Manager amazonS3Manager;
     private final PythonAnalysisClient pythonAnalysisClient;
     private final UserBehaviorService userBehaviorService;
-
-
     private static final int PAGE_SIZE = 12;
+    private final UserRepository userRepository;
+    private final ProductLikeRepository productLikeRepository;
 
     public ProductDetailDto getDetail(Long id, User user) {
         Product product = productRepository.findById(id).orElseThrow(() -> new GeneralException(PRODUCT_NOT_EXISTED));
@@ -325,4 +318,36 @@ private Double parseDouble(String value) {
             return null;
         }
     }
+
+    @Transactional
+    public ProductLikeResponseDTO addOrUpdateLike(Long userId, Long productId) {
+
+        // 1. 유저 확인
+        User user = userRepository.findById(userId)
+                .orElseThrow(() -> new GeneralException(USER_NOT_EXISTED));
+
+        // 2. 제품 확인
+        Product product = productRepository.findById(productId)
+                .orElseThrow(() -> new GeneralException(PRODUCT_NOT_EXISTED));
+
+        // 3. 기존 좋아요 여부 확인
+        Optional<ProductLike> existingLike = productLikeRepository.findByUserAndProduct(user, product);
+
+        boolean isLiked;
+
+        if (existingLike.isPresent()) {
+            // 이미 눌렀으면 → 좋아요 취소
+            productLikeRepository.delete(existingLike.get());
+            isLiked = false;
+        } else {
+            // 처음 누르면 → 좋아요 추가
+            ProductLike productLike = ProductLike.builder()
+                    .user(user)
+                    .product(product)
+                    .build();
+            productLikeRepository.save(productLike);
+            isLiked = true;
+        }
+        return ProductConverter.toProductLikeDTO(productId, isLiked);
+    }
 }