[FEATURE #22]: comment 도메인 기본 구현

src/main/java/com/payper/server/comment/controller/CommentController.java

@@ -0,0 +1,78 @@
+package com.payper.server.comment.controller;
+
+import com.payper.server.comment.dto.CommentRequest;
+import com.payper.server.comment.dto.CommentResponse;
+import com.payper.server.comment.service.CommentService;
+import com.payper.server.global.response.ApiResponse;
+import com.payper.server.security.CustomUserDetails;
+import jakarta.validation.Valid;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/comments")
+@RequiredArgsConstructor
+public class CommentController {
+    private final CommentService commentService;
+
+    /**
+     * 댓글 수정
+     * 작성자만 수정 가능
+     */
+    @PutMapping("/{commentId}")
+    public ResponseEntity<ApiResponse<Void>> updateComment(
+            @AuthenticationPrincipal CustomUserDetails user,
+            @PathVariable Long commentId,
+            @RequestBody @Valid CommentRequest.UpdateComment request
+    ) {
+        commentService.updateComment(user.getId(), commentId, request);
+        return ResponseEntity.ok(ApiResponse.ok());
+    }
+
+    /**
+     * 댓글 삭제
+     * 작성자만 삭제 가능
+     *
+     * 자식 댓글은 삭제하지 않음
+     */
+    @DeleteMapping("/{commentId}")
+    public ResponseEntity<ApiResponse<Void>> deleteComment(
+            @AuthenticationPrincipal CustomUserDetails user,
+            @PathVariable Long commentId) {
+
+        commentService.deleteComment(user.getId(), commentId);
+        return ResponseEntity.ok(ApiResponse.ok());
+    }
+
+    /**
+     * 내가 쓴 댓글 조회
+     * 
+     * 무한 스크롤 방식
+     * 
+     * 정렬: 최신 순
+     */
+    @GetMapping("/me")
+    public ResponseEntity<ApiResponse<CommentResponse.MyCommentList>> getMyComments(
+            @AuthenticationPrincipal CustomUserDetails user,
+            @RequestParam(required = false) Long cursorId,
+            @RequestParam(defaultValue = "20") int size
+    ) {
+        CommentResponse.MyCommentList response = commentService.getMyComments(user.getId(), cursorId, size);
+        return ResponseEntity.ok(ApiResponse.ok(response));
+    }
+
+    /**
+     * 자식 댓글 조회
+     */
+    @GetMapping("/{parentId}/replies")
+    public ResponseEntity<ApiResponse<CommentResponse.CommentList>> getReplies(
+            @PathVariable Long parentId,
+            @RequestParam(required = false) Long cursorId,
+            @RequestParam(defaultValue = "20") int size
+    ) {
+        CommentResponse.CommentList response = commentService.getReplies(parentId, cursorId, size);
+        return ResponseEntity.ok(ApiResponse.ok(response));
+    }
+}

src/main/java/com/payper/server/comment/dto/CommentRequest.java

@@ -0,0 +1,29 @@
+package com.payper.server.comment.dto;
+
+import jakarta.annotation.Nullable;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
+
+public class CommentRequest {
+
+    /**
+     * 댓글 작성 DTO
+     */
+    public record CreateComment(
+            @NotBlank(message = "댓글을 적어주세요.")
+            @Size(max = 21800, message = "댓글은 21,800자 이하여야 합니다.")
+            String content,
+
+            @Nullable
+            Long parentCommentId
+    ) {}
+
+    /**
+     * 댓글 수정 DTO
+     */
+    public record UpdateComment(
+            @NotBlank(message = "댓글을 적어주세요.")
+            @Size(max = 21800, message = "댓글은 21,800자 이하여야 합니다.")
+            String content
+    ) {}
+}

src/main/java/com/payper/server/comment/dto/CommentResponse.java

@@ -0,0 +1,91 @@
+package com.payper.server.comment.dto;
+
+import com.payper.server.comment.entity.Comment;
+
+import java.time.LocalDateTime;
+import java.util.List;
+
+public class CommentResponse {
+
+    /**
+     * Post에 달린 Comment 리스트
+     */
+    public record CommentList(
+            List<CommentResponse.CommentItem> comments,
+            Long nextCursor,
+            boolean hasNext
+    ) {
+        public static CommentList from(List<Comment> comments, Long nextCursor, boolean hasNext) {
+            return new CommentList(
+                    comments.stream()
+                            .map(CommentResponse.CommentItem::from)
+                            .toList(),
+                    nextCursor,
+                    hasNext
+            );
+        }
+    }
+
+    /**
+     * Comment Item
+     */
+    public record CommentItem(
+            Long id,
+            String userName,
+            Long parentCommentId,
+            String content,
+            LocalDateTime createdAt,
+            LocalDateTime updatedAt
+    ) {
+        public static CommentItem from(Comment comment) {
+            return new CommentItem(
+                    comment.getId(),
+                    comment.getUser().getName(),
+                    comment.getParentComment() != null ? comment.getParentComment().getId() : null,
+                    comment.isDeleted() ? "[삭제된 댓글입니다]" : comment.getContent(),
+                    comment.getCreatedAt(),
+                    comment.getUpdatedAt()
+            );
+        }
+    }
+
+    /**
+     * 내가 작성한 Comment 리스트
+     */
+    public record MyCommentList(
+            List<CommentResponse.MyCommentItem> comments,
+            Long nextCursor,
+            boolean hasNext
+    ) {
+        public static MyCommentList from(List<Comment> comments, Long nextCursor, boolean hasNext) {
+            return new MyCommentList(
+                    comments.stream()
+                            .map(CommentResponse.MyCommentItem::from)
+                            .toList(),
+                    nextCursor,
+                    hasNext
+            );
+        }
+    }
+
+    /**
+     * 내가 작성한 Comment Item
+     */
+    public record MyCommentItem(
+            Long id,
+            Long postId,
+            String content,
+            LocalDateTime createdAt,
+            LocalDateTime updatedAt
+    ) {
+        public static MyCommentItem from(Comment comment) {
+            return new MyCommentItem(
+                    comment.getId(),
+                    comment.getPost().getId(),
+                    comment.getContent(),
+                    comment.getCreatedAt(),
+                    comment.getUpdatedAt()
+            );
+        }
+    }
+}

src/main/java/com/payper/server/comment/entity/Comment.java

@@ -71,7 +71,33 @@ public class Comment extends BaseTimeEntity {
      * soft delete
      */
     public void delete() {
+        if (this.isDeleted) { // 멱등성 고려
+            return;
+        }
+
         this.isDeleted = true;
-        this.deletedAt = LocalDateTime.now(ZoneId.of("Asia/Seoul"));
+        this.deletedAt = LocalDateTime.now();
+        this.post.decreaseCommentCount();
+    }
+
+    /**
+     * 댓글 생성
+     */
+    public static Comment create(Post post, User user, Comment parentComment, String content) {
+        return Comment.builder()
+                .post(post)
+                .user(user)
+                .parentComment(parentComment)
+                .content(content)
+                .isDeleted(false)
+                .deletedAt(null)
+                .build();
+    }
+
+    /**
+     * 댓글 수정
+     */
+    public void update(String content) {
+        this.content = content;
     }
 }

src/main/java/com/payper/server/comment/repository/CommentRepository.java

@@ -0,0 +1,124 @@
+package com.payper.server.comment.repository;
+
+import com.payper.server.comment.entity.Comment;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Slice;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+import org.springframework.stereotype.Repository;
+
+import java.time.LocalDateTime;
+import java.util.Optional;
+
+@Repository
+public interface CommentRepository extends JpaRepository<Comment, Long> {
+
+    Optional<Comment> findByIdAndIsDeletedFalse(Long id);
+
+    @Query("""
+        select c from Comment c
+        join fetch c.user
+        where c.post.id = :postId
+          and c.parentComment is null
+          and (
+            c.isDeleted = false
+            or exists (
+                select 1 from Comment child
+                where child.parentComment = c
+                  and child.isDeleted = false
+            )
+          )
+        order by c.createdAt asc, c.id asc
+    """)
+    Slice<Comment> findParent(@Param("postId") Long postId, Pageable pageable);
+
+    @Query("""
+        select c from Comment c
+        join fetch c.user
+        where c.post.id = :postId
+          and c.parentComment is null
+          and (
+                c.isDeleted = false
+                or exists (
+                    select 1 from Comment child
+                    where child.parentComment = c
+                      and child.isDeleted = false
+                )
+              )
+          and (
+                c.createdAt > :createdAt
+                or (c.createdAt = :createdAt and c.id > :cursorId)
+              )
+        order by c.createdAt asc, c.id asc
+    """)
+    Slice<Comment> findParentNext(
+            @Param("postId") Long postId,
+            @Param("cursorId") Long cursorId,
+            @Param("createdAt") LocalDateTime createdAt,
+            Pageable pageable
+    );
+
+    @Query("""
+        select c from Comment c
+        join fetch c.user
+        where c.parentComment.id = :parentId
+          and c.isDeleted = false
+        order by c.createdAt asc, c.id asc
+    """)
+    Slice<Comment> findReply(@Param("parentId") Long parentId, Pageable pageable);
+
+    @Query("""
+        select c from Comment c
+        join fetch c.user
+        where c.parentComment.id = :parentId
+          and c.isDeleted = false
+          and (
+                c.createdAt > :createdAt
+                or (c.createdAt = :createdAt and c.id > :cursorId)
+              )
+        order by c.createdAt asc, c.id asc
+    """)
+    Slice<Comment> findReplyNext(
+            @Param("parentId") Long parentId,
+            @Param("cursorId") Long cursorId,
+            @Param("createdAt") LocalDateTime createdAt,
+            Pageable pageable
+    );
+
+    @Query("""
+        select c from Comment c
+        where c.user.id = :userId
+          and c.isDeleted = false
+        order by c.createdAt desc, c.id desc
+    """)
+    Slice<Comment> findFirstMyCommentPage(@Param("userId") Long userId, Pageable pageable);
+
+    @Query("""
+        select c from Comment c
+        where c.user.id = :userId
+          and c.isDeleted = false
+          and (
+                c.createdAt < :createdAt
+                or (c.createdAt = :createdAt and c.id < :cursorId)
+              )
+        order by c.createdAt desc, c.id desc
+    """)
+    Slice<Comment> findNextMyCommentPage(
+            @Param("userId") Long userId,
+            @Param("cursorId") Long cursorId,
+            @Param("createdAt") LocalDateTime createdAt,
+            Pageable pageable
+    );
+
+    @Modifying
+    @Query("""
+        update Comment c
+        set c.isDeleted = true,
+            c.deletedAt = :now
+        where c.post.id = :postId
+          and c.isDeleted = false
+    """)
+    long softDeleteByPostId(@Param("postId") Long postId, @Param("now") LocalDateTime now);
+}