Refactor: 게시판(Post/Comment) 레포지토리 및 패키지 구조 개선 (#166) (#172)

* Ref: PostRespositoryImpl 개선

* Ref: CommentRepositoryImpl 개선

* Ref: board 패키지 구조 개선

---------

Co-authored-by: loseminho <[email protected]>

Author: joyewon0705

src/main/java/com/back/domain/board/controller/CommentController.java renamed to src/main/java/com/back/domain/board/comment/controller/CommentController.java

@@ -1,10 +1,10 @@
-package com.back.domain.board.controller;
+package com.back.domain.board.comment.controller;
 
-import com.back.domain.board.dto.CommentListResponse;
-import com.back.domain.board.dto.CommentRequest;
-import com.back.domain.board.dto.CommentResponse;
-import com.back.domain.board.dto.PageResponse;
-import com.back.domain.board.service.CommentService;
+import com.back.domain.board.comment.dto.CommentListResponse;
+import com.back.domain.board.comment.dto.CommentRequest;
+import com.back.domain.board.comment.dto.CommentResponse;
+import com.back.domain.board.common.dto.PageResponse;
+import com.back.domain.board.comment.service.CommentService;
 import com.back.global.common.dto.RsData;
 import com.back.global.security.user.CustomUserDetails;
 import jakarta.validation.Valid;

src/main/java/com/back/domain/board/controller/CommentControllerDocs.java renamed to src/main/java/com/back/domain/board/comment/controller/CommentControllerDocs.java

@@ -1,9 +1,9 @@
-package com.back.domain.board.controller;
+package com.back.domain.board.comment.controller;
 
-import com.back.domain.board.dto.CommentListResponse;
-import com.back.domain.board.dto.CommentRequest;
-import com.back.domain.board.dto.CommentResponse;
-import com.back.domain.board.dto.PageResponse;
+import com.back.domain.board.comment.dto.CommentListResponse;
+import com.back.domain.board.comment.dto.CommentRequest;
+import com.back.domain.board.comment.dto.CommentResponse;
+import com.back.domain.board.common.dto.PageResponse;
 import com.back.global.common.dto.RsData;
 import com.back.global.security.user.CustomUserDetails;
 import io.swagger.v3.oas.annotations.Operation;

src/main/java/com/back/domain/board/dto/CommentListResponse.java renamed to src/main/java/com/back/domain/board/comment/dto/CommentListResponse.java

@@ -1,5 +1,6 @@
-package com.back.domain.board.dto;
+package com.back.domain.board.comment.dto;
 
+import com.back.domain.board.common.dto.AuthorResponse;
 import com.querydsl.core.annotations.QueryProjection;
 import lombok.Getter;
 import lombok.Setter;

src/main/java/com/back/domain/board/dto/CommentRequest.java renamed to src/main/java/com/back/domain/board/comment/dto/CommentRequest.java

@@ -1,4 +1,4 @@
-package com.back.domain.board.dto;
+package com.back.domain.board.comment.dto;
 
 import jakarta.validation.constraints.NotBlank;
 

src/main/java/com/back/domain/board/dto/CommentResponse.java renamed to src/main/java/com/back/domain/board/comment/dto/CommentResponse.java

@@ -1,6 +1,7 @@
-package com.back.domain.board.dto;
+package com.back.domain.board.comment.dto;
 
-import com.back.domain.board.entity.Comment;
+import com.back.domain.board.common.dto.AuthorResponse;
+import com.back.domain.board.comment.entity.Comment;
 
 import java.time.LocalDateTime;
 

src/main/java/com/back/domain/board/entity/Comment.java renamed to src/main/java/com/back/domain/board/comment/entity/Comment.java

@@ -1,5 +1,6 @@
-package com.back.domain.board.entity;
+package com.back.domain.board.comment.entity;
 
+import com.back.domain.board.post.entity.Post;
 import com.back.domain.user.entity.User;
 import com.back.global.entity.BaseEntity;
 import jakarta.persistence.*;

src/main/java/com/back/domain/board/entity/CommentLike.java renamed to src/main/java/com/back/domain/board/comment/entity/CommentLike.java

@@ -1,4 +1,4 @@
-package com.back.domain.board.entity;
+package com.back.domain.board.comment.entity;
 
 import com.back.domain.user.entity.User;
 import com.back.global.entity.BaseEntity;

src/main/java/com/back/domain/board/repository/CommentRepository.java renamed to src/main/java/com/back/domain/board/comment/repository/CommentRepository.java

@@ -1,6 +1,6 @@
-package com.back.domain.board.repository;
+package com.back.domain.board.comment.repository;
 
-import com.back.domain.board.entity.Comment;
+import com.back.domain.board.comment.entity.Comment;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.stereotype.Repository;
 

src/main/java/com/back/domain/board/repository/CommentRepositoryCustom.java renamed to src/main/java/com/back/domain/board/comment/repository/CommentRepositoryCustom.java

@@ -1,6 +1,6 @@
-package com.back.domain.board.repository;
+package com.back.domain.board.comment.repository;
 
-import com.back.domain.board.dto.CommentListResponse;
+import com.back.domain.board.comment.dto.CommentListResponse;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 

src/main/java/com/back/domain/board/repository/CommentRepositoryImpl.java renamed to src/main/java/com/back/domain/board/comment/repository/CommentRepositoryImpl.java

@@ -1,11 +1,11 @@
-package com.back.domain.board.repository;
-
-import com.back.domain.board.dto.CommentListResponse;
-import com.back.domain.board.dto.QAuthorResponse;
-import com.back.domain.board.dto.QCommentListResponse;
-import com.back.domain.board.entity.Comment;
-import com.back.domain.board.entity.QComment;
-import com.back.domain.board.entity.QCommentLike;
+package com.back.domain.board.comment.repository;
+
+import com.back.domain.board.comment.dto.CommentListResponse;
+import com.back.domain.board.comment.dto.QCommentListResponse;
+import com.back.domain.board.comment.entity.Comment;
+import com.back.domain.board.comment.entity.QComment;
+import com.back.domain.board.comment.entity.QCommentLike;
+import com.back.domain.board.common.dto.QAuthorResponse;
 import com.back.domain.user.entity.QUser;
 import com.back.domain.user.entity.QUserProfile;
 import com.querydsl.core.types.Order;
@@ -15,27 +15,34 @@
 import com.querydsl.core.types.dsl.PathBuilder;
 import com.querydsl.jpa.impl.JPAQueryFactory;
 import lombok.RequiredArgsConstructor;
-import org.springframework.data.domain.Page;
-import org.springframework.data.domain.PageImpl;
-import org.springframework.data.domain.Pageable;
-import org.springframework.data.domain.Sort;
-
+import org.springframework.data.domain.*;
 import java.util.*;
 import java.util.stream.Collectors;
 
 @RequiredArgsConstructor
 public class CommentRepositoryImpl implements CommentRepositoryCustom {
+
     private final JPAQueryFactory queryFactory;
 
+    /**
+     * 게시글 ID로 댓글 목록 조회
+     * - 부모 댓글 페이징 + 자식 댓글 전체 조회
+     * - likeCount는 부모/자식 댓글을 한 번에 조회 후 주입
+     * - likeCount 정렬은 메모리에서 처리
+     * - 총 쿼리 수: 4회 (부모조회 + 자식조회 + likeCount + count)
+     *
+     * @param postId 게시글 Id
+     * @param pageable 페이징 + 정렬 조건
+     */
     @Override
     public Page<CommentListResponse> getCommentsByPostId(Long postId, Pageable pageable) {
         QComment comment = QComment.comment;
         QCommentLike commentLike = QCommentLike.commentLike;
 
-        // 정렬 조건
-        List<OrderSpecifier<?>> orders = buildOrderSpecifiers(pageable, comment, commentLike);
+        // 1. 정렬 조건 생성 (엔티티 필드 기반)
+        List<OrderSpecifier<?>> orders = buildOrderSpecifiers(pageable, comment);
 
-        // 부모 댓글 조회
+        // 2. 부모 댓글 조회 (페이징)
         List<CommentListResponse> parents = fetchComments(
                 comment.post.id.eq(postId).and(comment.parent.isNull()),
                 orders,
@@ -47,48 +54,33 @@ public Page<CommentListResponse> getCommentsByPostId(Long postId, Pageable pagea
             return new PageImpl<>(parents, pageable, 0);
         }
 
-        // 부모 id 수집
+        // 3. 부모 ID 목록 수집
         List<Long> parentIds = parents.stream()
                 .map(CommentListResponse::getCommentId)
                 .toList();
 
-        // 자식 댓글 조회
+        // 4. 자식 댓글 조회 (부모 ID 기준)
         List<CommentListResponse> children = fetchComments(
                 comment.parent.id.in(parentIds),
                 List.of(comment.createdAt.asc()),
                 null,
                 null
         );
 
-        // 부모 + 자식 id 합쳐서 likeCount 한 번에 조회
-        List<Long> allIds = new ArrayList<>(parentIds);
-        allIds.addAll(children.stream().map(CommentListResponse::getCommentId).toList());
-
-        Map<Long, Long> likeCountMap = queryFactory
-                .select(commentLike.comment.id, commentLike.count())
-                .from(commentLike)
-                .where(commentLike.comment.id.in(allIds))
-                .groupBy(commentLike.comment.id)
-                .fetch()
-                .stream()
-                .collect(Collectors.toMap(
-                        tuple -> tuple.get(commentLike.comment.id),
-                        tuple -> tuple.get(commentLike.count())
-                ));
+        // 5. 부모 + 자식 댓글 ID 합쳐 likeCount 조회 (쿼리 1회)
+        Map<Long, Long> likeCountMap = fetchLikeCounts(parentIds, children);
 
-        // likeCount 세팅
+        // 6. likeCount 주입
         parents.forEach(p -> p.setLikeCount(likeCountMap.getOrDefault(p.getCommentId(), 0L)));
         children.forEach(c -> c.setLikeCount(likeCountMap.getOrDefault(c.getCommentId(), 0L)));
 
-        // parentId → children 매핑
-        Map<Long, List<CommentListResponse>> childMap = children.stream()
-                .collect(Collectors.groupingBy(CommentListResponse::getParentId));
+        // 7. 부모-자식 매핑
+        mapChildrenToParents(parents, children);
 
-        parents.forEach(p ->
-                p.setChildren(childMap.getOrDefault(p.getCommentId(), List.of()))
-        );
+        // 8. 정렬 후처리 (통계 필드 기반)
+        parents = sortInMemoryIfNeeded(parents, pageable);
 
-        // 총 개수 (부모 댓글만 카운트)
+        // 9. 전체 부모 댓글 수 조회
         Long total = queryFactory
                 .select(comment.count())
                 .from(comment)
@@ -98,8 +90,12 @@ public Page<CommentListResponse> getCommentsByPostId(Long postId, Pageable pagea
         return new PageImpl<>(parents, pageable, total != null ? total : 0L);
     }
 
+    // -------------------- 내부 메서드 --------------------
+
     /**
-     * 공통 댓글 조회 메서드 (부모/자식 공통)
+     * 댓글 조회
+     * - User / UserProfile join (N+1 방지)
+     * - likeCount는 이후 주입
      */
     private List<CommentListResponse> fetchComments(
             BooleanExpression condition,
@@ -118,10 +114,10 @@ private List<CommentListResponse> fetchComments(
                         comment.parent.id,
                         new QAuthorResponse(user.id, profile.nickname),
                         comment.content,
-                        Expressions.constant(0L), // likeCount placeholder
+                        Expressions.constant(0L), // likeCount는 별도 주입
                         comment.createdAt,
                         comment.updatedAt,
-                        Expressions.constant(Collections.emptyList())
+                        Expressions.constant(Collections.emptyList()) // children은 별도 주입
                 ))
                 .from(comment)
                 .leftJoin(comment.user, user)
@@ -137,22 +133,89 @@ private List<CommentListResponse> fetchComments(
     }
 
     /**
-     * 정렬 조건 처리
+     * likeCount 일괄 조회
+     * - IN 조건 기반 groupBy 쿼리 1회
+     * - 부모/자식 댓글을 한 번에 조회
      */
-    private List<OrderSpecifier<?>> buildOrderSpecifiers(Pageable pageable, QComment comment, QCommentLike commentLike) {
+    private Map<Long, Long> fetchLikeCounts(List<Long> parentIds, List<CommentListResponse> children) {
+        QCommentLike commentLike = QCommentLike.commentLike;
+
+        List<Long> allIds = new ArrayList<>(parentIds);
+        allIds.addAll(children.stream().map(CommentListResponse::getCommentId).toList());
+
+        if (allIds.isEmpty()) return Map.of();
+
+        return queryFactory
+                .select(commentLike.comment.id, commentLike.count())
+                .from(commentLike)
+                .where(commentLike.comment.id.in(allIds))
+                .groupBy(commentLike.comment.id)
+                .fetch()
+                .stream()
+                .collect(Collectors.toMap(
+                        tuple -> tuple.get(commentLike.comment.id),
+                        tuple -> tuple.get(commentLike.count())
+                ));
+    }
+
+    /**
+     * 부모/자식 관계 매핑
+     * - childMap을 parentId 기준으로 그룹화 후 children 필드에 set
+     */
+    private void mapChildrenToParents(List<CommentListResponse> parents, List<CommentListResponse> children) {
+        if (children.isEmpty()) return;
+
+        Map<Long, List<CommentListResponse>> childMap = children.stream()
+                .collect(Collectors.groupingBy(CommentListResponse::getParentId));
+
+        parents.forEach(parent ->
+                parent.setChildren(childMap.getOrDefault(parent.getCommentId(), List.of()))
+        );
+    }
+
+    /**
+     * 정렬 처리 (DB 정렬)
+     * - createdAt, updatedAt 등 엔티티 필드
+     */
+    private List<OrderSpecifier<?>> buildOrderSpecifiers(Pageable pageable, QComment comment) {
         PathBuilder<Comment> entityPath = new PathBuilder<>(Comment.class, comment.getMetadata());
         List<OrderSpecifier<?>> orders = new ArrayList<>();
 
         for (Sort.Order order : pageable.getSort()) {
-            Order direction = order.isAscending() ? Order.ASC : Order.DESC;
             String prop = order.getProperty();
 
-            switch (prop) {
-                case "likeCount" -> orders.add(new OrderSpecifier<>(direction, commentLike.id.countDistinct()));
-                default -> orders.add(new OrderSpecifier<>(direction,
-                        entityPath.getComparable(prop, Comparable.class)));
+            // 통계 필드는 메모리 정렬에서 처리
+            if (prop.equals("likeCount")) {
+                continue;
             }
+            Order direction = order.isAscending() ? Order.ASC : Order.DESC;
+            orders.add(new OrderSpecifier<>(direction, entityPath.getComparable(prop, Comparable.class)));
         }
+
         return orders;
     }
+
+    /**
+     * 통계 기반 정렬 처리 (메모리)
+     * - likeCount 등 통계 필드
+     * - 페이지 단위라 성능에 영향 없음
+     */
+    private List<CommentListResponse> sortInMemoryIfNeeded(List<CommentListResponse> results, Pageable pageable) {
+        if (results.isEmpty() || !pageable.getSort().isSorted()) return results;
+
+        for (Sort.Order order : pageable.getSort()) {
+            Comparator<CommentListResponse> comparator = null;
+
+            if ("likeCount".equals(order.getProperty())) {
+                comparator = Comparator.comparing(CommentListResponse::getLikeCount);
+            }
+
+            if (comparator != null) {
+                if (order.isDescending()) comparator = comparator.reversed();
+                results.sort(comparator);
+            }
+        }
+
+        return results;
+    }
 }