Feature/#83 댓글 대댓글 crud api 구현

backend/emm-sale/src/docs/asciidoc/index.adoc

@@ -167,3 +167,58 @@ include::{snippets}/find-event/http-response.adoc[]
 
 .HTTP response 설명
 include::{snippets}/find-event/response-fields.adoc[]
+
+== Comment
+
+=== `GET` : 댓글 모두 조회
+
+.HTTP request 설명
+include::{snippets}/get-comment/request-parameters.adoc[]
+
+.HTTP request
+include::{snippets}/get-comment/http-request.adoc[]
+
+.HTTP response
+include::{snippets}/get-comment/http-response.adoc[]
+
+.HTTP response 설명
+include::{snippets}/get-comment/response-fields.adoc[]
+
+=== `POST` : 댓글 및 대댓글 생성
+
+.HTTP request
+include::{snippets}/add-comment/http-request.adoc[]
+
+.HTTP response
+include::{snippets}/add-comment/http-response.adoc[]
+
+.HTTP response 설명
+include::{snippets}/add-comment/response-fields.adoc[]
+
+=== `DELETE` : 댓글 삭제
+
+.HTTP request
+include::{snippets}/delete-comment/http-request.adoc[]
+
+.HTTP request 설명
+include::{snippets}/delete-comment/path-parameters.adoc[]
+
+.HTTP response
+include::{snippets}/delete-comment/http-response.adoc[]
+
+=== `PATCH` : 댓글 수정
+
+.HTTP request
+include::{snippets}/modify-comment/http-request.adoc[]
+
+.HTTP request 설명
+include::{snippets}/modify-comment/request-fields.adoc[]
+
+.PathVariable 설명
+include::{snippets}/modify-comment/path-parameters.adoc[]
+
+.HTTP response
+include::{snippets}/modify-comment/http-response.adoc[]
+
+.HTTP response 설명
+include::{snippets}/modify-comment/response-fields.adoc[]

backend/emm-sale/src/main/java/com/emmsale/base/BaseEntity.java

@@ -12,10 +12,17 @@
 @MappedSuperclass
 public abstract class BaseEntity {
 
-  @Column(updatable = false, nullable = false)
+  @Column(updatable = false)
   @CreatedDate
   private LocalDateTime createdAt;
-  @Column(nullable = false)
   @LastModifiedDate
   private LocalDateTime updatedAt;
+
+  public LocalDateTime getCreatedAt() {
+    return createdAt;
+  }
+
+  public LocalDateTime getUpdatedAt() {
+    return updatedAt;
+  }
 }

backend/emm-sale/src/main/java/com/emmsale/comment/api/CommentApi.java

@@ -0,0 +1,57 @@
+package com.emmsale.comment.api;
+
+import com.emmsale.comment.application.CommentCommandService;
+import com.emmsale.comment.application.CommentQueryService;
+import com.emmsale.comment.application.dto.CommentAddRequest;
+import com.emmsale.comment.application.dto.CommentHierarchyResponse;
+import com.emmsale.comment.application.dto.CommentModifyRequest;
+import com.emmsale.comment.application.dto.CommentResponse;
+import com.emmsale.member.domain.Member;
+import java.util.List;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PatchMapping;
+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.RequestParam;
+import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequiredArgsConstructor
+public class CommentApi {
+
+  private final CommentCommandService commentCommandService;
+  private final CommentQueryService commentQueryService;
+
+  @PostMapping("/comments")
+  public CommentResponse create(
+      @RequestBody final CommentAddRequest commentAddRequest,
+      final Member member
+  ) {
+    return commentCommandService.create(commentAddRequest, member);
+  }
+
+  @GetMapping("/comments")
+  public List<CommentHierarchyResponse> findAll(@RequestParam final Long eventId) {
+    return commentQueryService.findAllCommentsByEventId(eventId);
+  }
+
+  @DeleteMapping("/comments/{comment-id}")
+  @ResponseStatus(HttpStatus.NO_CONTENT)
+  public void delete(@PathVariable("comment-id") final Long commentId, final Member member) {
+    commentCommandService.delete(commentId, member);
+  }
+
+  @PatchMapping("/comments/{comment-id}")
+  public CommentResponse modify(
+      @PathVariable("comment-id") final Long commentId,
+      final Member member,
+      @RequestBody final CommentModifyRequest commentModifyRequest
+  ) {
+    return commentCommandService.modify(commentId, member, commentModifyRequest);
+  }
+}

backend/emm-sale/src/main/java/com/emmsale/comment/application/CommentCommandService.java

@@ -0,0 +1,97 @@
+package com.emmsale.comment.application;
+
+import static com.emmsale.comment.exception.CommentExceptionType.FORBIDDEN_DELETE_COMMENT;
+import static com.emmsale.comment.exception.CommentExceptionType.FORBIDDEN_MODIFY_COMMENT;
+import static com.emmsale.comment.exception.CommentExceptionType.FORBIDDEN_MODIFY_DELETED_COMMENT;
+import static com.emmsale.comment.exception.CommentExceptionType.NOT_FOUND_COMMENT;
+
+import com.emmsale.comment.application.dto.CommentAddRequest;
+import com.emmsale.comment.application.dto.CommentModifyRequest;
+import com.emmsale.comment.application.dto.CommentResponse;
+import com.emmsale.comment.domain.Comment;
+import com.emmsale.comment.domain.CommentRepository;
+import com.emmsale.comment.exception.CommentException;
+import com.emmsale.comment.exception.CommentExceptionType;
+import com.emmsale.event.domain.Event;
+import com.emmsale.event.domain.repository.EventRepository;
+import com.emmsale.event.exception.EventException;
+import com.emmsale.event.exception.EventExceptionType;
+import com.emmsale.member.domain.Member;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@RequiredArgsConstructor
+@Transactional
+public class CommentCommandService {
+
+  private final CommentRepository commentRepository;
+  private final EventRepository eventRepository;
+
+  public CommentResponse create(
+      final CommentAddRequest commentAddRequest,
+      final Member member
+  ) {
+    final Event savedEvent = eventRepository.findById(commentAddRequest.getEventId())
+        .orElseThrow(() -> new EventException(EventExceptionType.EVENT_NOT_FOUND_EXCEPTION));
+    final String content = commentAddRequest.getContent();
+
+    final Comment comment = commentAddRequest.optionalParentId()
+        .map(commentId -> Comment.createChild(
+            savedEvent,
+            findSavedComment(commentId),
+            member,
+            content)
+        )
+        .orElseGet(() -> Comment.createRoot(savedEvent, member, content));
+
+    return CommentResponse.from(commentRepository.save(comment));
+  }
+
+  private Comment findSavedComment(final Long commentId) {
+    return commentRepository.findById(commentId)
+        .orElseThrow(() -> new CommentException(NOT_FOUND_COMMENT));
+  }
+
+  public void delete(final Long commentId, final Member loginMember) {
+
+    final Comment comment = findSavedComment(commentId);
+
+    validateSameWriter(loginMember, comment, FORBIDDEN_DELETE_COMMENT);
+
+    comment.delete();
+  }
+
+  private void validateSameWriter(
+      final Member loginMember,
+      final Comment comment,
+      final CommentExceptionType commentExceptionType
+  ) {
+    if (loginMember.isNotMe(comment.getMember())) {
+      throw new CommentException(commentExceptionType);
+    }
+  }
+
+  public CommentResponse modify(
+      final Long commentId,
+      final Member loginMember,
+      final CommentModifyRequest commentModifyRequest
+  ) {
+
+    final Comment comment = findSavedComment(commentId);
+
+    validateAlreadyDeleted(comment);
+    validateSameWriter(loginMember, comment, FORBIDDEN_MODIFY_COMMENT);
+
+    comment.modify(commentModifyRequest.getContent());
+
+    return CommentResponse.from(comment);
+  }
+
+  private void validateAlreadyDeleted(final Comment comment) {
+    if (comment.isDeleted()) {
+      throw new CommentException(FORBIDDEN_MODIFY_DELETED_COMMENT);
+    }
+  }
+}

backend/emm-sale/src/main/java/com/emmsale/comment/application/CommentQueryService.java

@@ -0,0 +1,24 @@
+package com.emmsale.comment.application;
+
+import com.emmsale.comment.application.dto.CommentHierarchyResponse;
+import com.emmsale.comment.domain.Comment;
+import com.emmsale.comment.domain.CommentRepository;
+import java.util.List;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@RequiredArgsConstructor
+@Transactional(readOnly = true)
+public class CommentQueryService {
+
+  private final CommentRepository commentRepository;
+
+  public List<CommentHierarchyResponse> findAllCommentsByEventId(final Long eventId) {
+
+    final List<Comment> comments = commentRepository.findByEventId(eventId);
+
+    return CommentHierarchyResponse.from(comments);
+  }
+}

backend/emm-sale/src/main/java/com/emmsale/comment/application/dto/CommentAddRequest.java

@@ -0,0 +1,18 @@
+package com.emmsale.comment.application.dto;
+
+import java.util.Optional;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+@Getter
+public class CommentAddRequest {
+
+  private final String content;
+  private final Long eventId;
+  private final Long parentId;
+
+  public Optional<Long> optionalParentId() {
+    return Optional.ofNullable(parentId);
+  }
+}

backend/emm-sale/src/main/java/com/emmsale/comment/application/dto/CommentHierarchyResponse.java

@@ -0,0 +1,67 @@
+package com.emmsale.comment.application.dto;
+
+import com.emmsale.base.BaseEntity;
+import com.emmsale.comment.domain.Comment;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.stream.Collectors;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+@Getter
+public class CommentHierarchyResponse {
+
+  private final CommentResponse parentComment;
+  private final List<CommentResponse> childComments;
+
+  public static List<CommentHierarchyResponse> from(final List<Comment> comments) {
+
+    final Map<Comment, List<Comment>> groupedByParent =
+        groupingByParentAndSortedByCreatedAt(comments);
+
+    final List<CommentHierarchyResponse> result = new ArrayList<>();
+
+    for (final Entry<Comment, List<Comment>> entry : groupedByParent.entrySet()) {
+      final Comment parentComment = entry.getKey();
+      final List<CommentResponse> childCommentResponses =
+          mapToCommentResponse(entry, parentComment);
+
+      result.add(
+          new CommentHierarchyResponse(CommentResponse.from(parentComment), childCommentResponses)
+      );
+    }
+
+    return result;
+  }
+
+  private static LinkedHashMap<Comment, List<Comment>> groupingByParentAndSortedByCreatedAt(
+      final List<Comment> comments
+  ) {
+    return comments.stream()
+        .sorted(Comparator.comparing(BaseEntity::getCreatedAt))
+        .collect(Collectors.groupingBy(
+            it -> it.getParent().orElse(it),
+            LinkedHashMap::new, Collectors.toList())
+        );
+  }
+
+  private static List<CommentResponse> mapToCommentResponse(
+      final Entry<Comment, List<Comment>> entry,
+      final Comment parentComment
+  ) {
+    return entry.getValue().stream()
+        .filter(it -> isNotSameKeyAndValue(parentComment, it))
+        .map(CommentResponse::from)
+        .sorted(Comparator.comparing(CommentResponse::getCreatedAt))
+        .collect(Collectors.toList());
+  }
+
+  private static boolean isNotSameKeyAndValue(final Comment parentComment, final Comment target) {
+    return !target.equals(parentComment);
+  }
+}

backend/emm-sale/src/main/java/com/emmsale/comment/application/dto/CommentModifyRequest.java

@@ -0,0 +1,15 @@
+package com.emmsale.comment.application.dto;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+@Getter
+public class CommentModifyRequest {
+
+  private final String content;
+
+  private CommentModifyRequest() {
+    this(null);
+  }
+}