feat: 좋아요 취소 API 구현

Author: dnzp75

src/main/java/com/example/log4u/domain/diary/entity/Diary.java

@@ -46,8 +46,13 @@ public class Diary extends BaseEntity {
 	@Column(nullable = false)
 	private Long likeCount;
 
-	public Long updateLikeCount() {
+	public Long incrementLikeCount() {
 		this.likeCount++;
 		return this.likeCount;
 	}
+
+	public Long decreaseLikeCount() {
+		this.likeCount--;
+		return this.likeCount;
+	}
 }

src/main/java/com/example/log4u/domain/diary/service/DiaryService.java

@@ -22,6 +22,16 @@ public Diary getDiary(Long diaryId) {
 
 	public Long incrementLikeCount(Long diaryId) {
 		Diary diary = getDiary(diaryId);
-		return diary.updateLikeCount();
+		return diary.incrementLikeCount();
+	}
+
+	public Long decreaseLikeCount(Long diaryId) {
+		Diary diary = getDiary(diaryId);
+		return diary.decreaseLikeCount();
+	}
+
+	public Long getLikeCount(Long diaryId) {
+		Diary diary = getDiary(diaryId);
+		return diary.getLikeCount();
 	}
 }

src/main/java/com/example/log4u/domain/like/controller/LikeController.java

@@ -1,13 +1,16 @@
 package com.example.log4u.domain.like.controller;
 
 import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
 import com.example.log4u.domain.like.dto.request.LikeAddRequestDto;
 import com.example.log4u.domain.like.dto.response.LikeAddResponseDto;
+import com.example.log4u.domain.like.dto.response.LikeCancelResponseDto;
 import com.example.log4u.domain.like.service.LikeService;
 
 import io.swagger.v3.oas.annotations.tags.Tag;
@@ -29,4 +32,12 @@ public ResponseEntity<LikeAddResponseDto> addLike(@Valid @RequestBody LikeAddReq
 		LikeAddResponseDto response = likeService.addLike(userId, requestDto);
 		return ResponseEntity.ok(response);
 	}
+
+	@DeleteMapping("/{diaryId}")
+	public ResponseEntity<LikeCancelResponseDto> cancelLike(@PathVariable Long diaryId){
+		Long userId = 1L;// 실제 구현에서는 토큰에서 추출
+
+		LikeCancelResponseDto response = likeService.cancelLike(userId, diaryId);
+		return ResponseEntity.ok(response);
+	}
 }

src/main/java/com/example/log4u/domain/like/dto/response/LikeCancelResponseDto.java

@@ -0,0 +1,10 @@
+package com.example.log4u.domain.like.dto.response;
+
+public record LikeCancelResponseDto(
+	boolean liked,
+	Long likeCount) {
+
+	public static LikeCancelResponseDto of(boolean liked, Long likeCount) {
+		return new LikeCancelResponseDto(liked, likeCount);
+	}
+}

src/main/java/com/example/log4u/domain/like/repository/LikeRepository.java

@@ -1,9 +1,14 @@
 package com.example.log4u.domain.like.repository;
 
+import java.util.List;
+import java.util.Optional;
+
 import org.springframework.data.jpa.repository.JpaRepository;
 
 import com.example.log4u.domain.like.entity.Like;
 
 public interface LikeRepository extends JpaRepository<Like, Long> {
 	boolean existsByUserIdAndDiaryId(Long userId, Long diaryId);
+
+	Optional<Like> findByUserIdAndDiaryId(Long userId, Long diaryId);
 }

src/main/java/com/example/log4u/domain/like/service/LikeService.java

@@ -1,11 +1,14 @@
 package com.example.log4u.domain.like.service;
 
+import java.util.Optional;
+
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
 import com.example.log4u.domain.diary.service.DiaryService;
 import com.example.log4u.domain.like.dto.request.LikeAddRequestDto;
 import com.example.log4u.domain.like.dto.response.LikeAddResponseDto;
+import com.example.log4u.domain.like.dto.response.LikeCancelResponseDto;
 import com.example.log4u.domain.like.entity.Like;
 import com.example.log4u.domain.like.exception.DuplicateLikeException;
 import com.example.log4u.domain.like.repository.LikeRepository;
@@ -30,6 +33,20 @@ public LikeAddResponseDto addLike(Long userId, LikeAddRequestDto requestDto) {
 		return LikeAddResponseDto.of(true, likeCount);
 	}
 
+	@Transactional
+	public LikeCancelResponseDto cancelLike(Long userId, Long diaryId) {
+		return likeRepository.findByUserIdAndDiaryId(userId, diaryId)
+			.map(like -> {
+				likeRepository.delete(like);
+				Long likeCount = diaryService.decreaseLikeCount(diaryId);
+				return LikeCancelResponseDto.of(false, likeCount);
+			})
+			.orElseGet(() -> {
+				Long currentCount = diaryService.getLikeCount(diaryId);
+				return LikeCancelResponseDto.of(false, currentCount);
+			});
+	}
+
 	private void validateDuplicateLike(Long userId, Long diaryId) {
 		if (likeRepository.existsByUserIdAndDiaryId(userId, diaryId)) {
 			throw new DuplicateLikeException();