[REFACTOR] 메세지 제한 횟수 5개로 제한

src/main/java/doldol_server/doldol/common/exception/errorCode/MessageErrorCode.java

@@ -16,7 +16,10 @@ public enum MessageErrorCode implements ErrorCode {
 	MESSAGE_ACCESS_DENIED(HttpStatus.FORBIDDEN, "M-002", "메시지에 접근할 권한이 없습니다."),
 
 	// 409
-	MESSAGE_ALREADY_EXISTS(HttpStatus.CONFLICT,"M-003", "이미 해당 사용자에게 보낸 메시지가 존재합니다.");
+	MESSAGE_ALREADY_EXISTS(HttpStatus.CONFLICT, "M-003", "이미 해당 사용자에게 보낸 메시지가 존재합니다."),
+
+	// 400
+	MESSAGE_LIMIT_EXCEEDED(HttpStatus.BAD_REQUEST, "M-004", "메시지는 최대 5개까지만 작성할 수 있습니다."),
 	;
 
 	private HttpStatus httpStatus;

src/main/java/doldol_server/doldol/rollingPaper/repository/MessageRepository.java

@@ -8,5 +8,5 @@
 import doldol_server.doldol.user.entity.User;
 
 public interface MessageRepository extends JpaRepository<Message, Long>, MessageRepositoryCustom {
-	boolean existsByPaperAndFromAndToAndIsDeletedFalse(Paper paper, User from, User to);
+	long countByPaperAndFromAndToAndIsDeletedFalse(Paper paper, User fromUser, User toUser);
 }

src/main/java/doldol_server/doldol/rollingPaper/service/MessageService.java

@@ -87,12 +87,7 @@ public void createMessage(CreateMessageRequest request, Long userId) {
 		Paper paper = paperRepository.findById(request.paperId())
 			.orElseThrow(() -> new CustomException(PaperErrorCode.PAPER_NOT_FOUND));
 
-		boolean messageExists = messageRepository.existsByPaperAndFromAndToAndIsDeletedFalse(
-			paper, fromUser, toUser);
-
-		if (messageExists) {
-			throw new CustomException(MessageErrorCode.MESSAGE_ALREADY_EXISTS);
-		}
+		validateMessageCount(paper, fromUser, toUser);
 
 		paper.addMessage();
 
@@ -159,4 +154,12 @@ private MessageResponse decryptMessageContent(MessageResponse messageResponse) {
 		String decryptedContent = encryptor.decrypt(messageResponse.content());
 		return messageResponse.withDecryptedContent(decryptedContent);
 	}
+
+	private void validateMessageCount(Paper paper, User fromUser, User toUser) {
+		long messageCount = messageRepository.countByPaperAndFromAndToAndIsDeletedFalse(
+			paper, fromUser, toUser);
+		if (messageCount >= 5) {
+			throw new CustomException(MessageErrorCode.MESSAGE_LIMIT_EXCEEDED);
+		}
+	}
 }