feat: 댓글 서비스 로직 구현

Author: larama-C

src/main/java/com/back/web7_9_codecrete_be/domain/community/comment/service/CommentService.java

@@ -0,0 +1,72 @@
+package com.back.web7_9_codecrete_be.domain.community.comment.service;
+
+import com.back.web7_9_codecrete_be.domain.community.comment.dto.request.CommentCreateRequest;
+import com.back.web7_9_codecrete_be.domain.community.comment.dto.response.CommentPageResponse;
+import com.back.web7_9_codecrete_be.domain.community.comment.dto.response.CommentResponse;
+import com.back.web7_9_codecrete_be.domain.community.comment.entity.Comment;
+import com.back.web7_9_codecrete_be.domain.community.comment.repository.CommentRepository;
+import com.back.web7_9_codecrete_be.domain.community.post.entity.Post;
+import com.back.web7_9_codecrete_be.domain.community.post.repository.PostRepository;
+import com.back.web7_9_codecrete_be.global.error.code.CommentErrorCode;
+import com.back.web7_9_codecrete_be.global.error.code.PostErrorCode;
+import com.back.web7_9_codecrete_be.global.error.exception.BusinessException;
+import lombok.RequiredArgsConstructor;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Sort;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@RequiredArgsConstructor
+@Transactional(readOnly = true)
+public class CommentService {
+
+    private final CommentRepository commentRepository;
+    private final PostRepository postRepository;
+
+    // 댓글 생성
+    @Transactional
+    public Long create(Long postId, CommentCreateRequest req, Long userId) {
+        Post post = postRepository.findById(postId)
+                .orElseThrow(() -> new BusinessException(PostErrorCode.POST_NOT_FOUND));
+
+        Comment comment = Comment.create(
+                post,
+                userId,
+                req.getContent()
+        );
+
+        return commentRepository.save(comment).getCommentId();
+    }
+
+    // 댓글 조회
+    public CommentPageResponse<CommentResponse> getComments(Long postId, int page) {
+
+        Pageable pageable = PageRequest.of(
+                page - 1,
+                20,
+                Sort.by(Sort.Direction.ASC, "createdDate")
+        );
+
+        Page<CommentResponse> result =
+                commentRepository.findByPost_PostId(postId, pageable)
+                        .map(CommentResponse::from);
+
+        return CommentPageResponse.from(result);
+    }
+
+    // 댓글 삭제
+    @Transactional
+    public void delete(Long commentId, Long userId) {
+        Comment comment = commentRepository.findById(commentId)
+                .orElseThrow(() -> new BusinessException(CommentErrorCode.COMMENT_NOT_FOUND));
+
+        if (!comment.getUserId().equals(userId)) {
+            throw new BusinessException(CommentErrorCode.NO_COMMENT_PERMISSION);
+        }
+
+        commentRepository.delete(comment);
+    }
+}

src/main/java/com/back/web7_9_codecrete_be/global/error/code/CommentErrorCode.java

@@ -0,0 +1,42 @@
+package com.back.web7_9_codecrete_be.global.error.code;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatus;
+
+@Getter
+@RequiredArgsConstructor
+public enum CommentErrorCode implements ErrorCode {
+
+    // 댓글 조회
+    COMMENT_NOT_FOUND(
+            HttpStatus.NOT_FOUND,
+            "C-100",
+            "댓글을 찾을 수 없습니다."
+    ),
+
+    // 댓글 작성
+    COMMENT_CONTENT_EMPTY(
+            HttpStatus.BAD_REQUEST,
+            "C-110",
+            "댓글 내용은 비어 있을 수 없습니다."
+    ),
+
+    // 권한 관련
+    NO_COMMENT_PERMISSION(
+            HttpStatus.FORBIDDEN,
+            "C-120",
+            "댓글에 대한 권한이 없습니다."
+    ),
+
+    // 삭제 관련
+    COMMENT_ALREADY_DELETED(
+            HttpStatus.BAD_REQUEST,
+            "C-130",
+            "이미 삭제된 댓글입니다."
+    );
+
+    private final HttpStatus status;
+    private final String code;
+    private final String message;
+}