Refactor: 멘티의 기존 예약 시간 중복 확인

Author: sso0om

back/src/main/java/com/back/domain/mentoring/reservation/error/ReservationErrorCode.java

@@ -30,7 +30,8 @@ public enum ReservationErrorCode implements ErrorCode {
     NOT_AVAILABLE_SLOT("409-1", "이미 예약이 완료된 시간대입니다."),
     ALREADY_RESERVED_SLOT("409-2", "이미 예약한 시간대입니다. 예약 목록을 확인해 주세요."),
     CONCURRENT_RESERVATION_CONFLICT("409-3", "다른 사용자가 먼저 예약했습니다. 새로고침 후 다시 시도해 주세요."),
-    CONCURRENT_APPROVAL_CONFLICT("409-4", "이미 수락한 예약입니다.");
+    CONCURRENT_APPROVAL_CONFLICT("409-4", "이미 수락한 예약입니다."),
+    OVERLAPPING_TIME("409-5", "이미 해당 시간에 다른 예약이 있습니다. 예약 목록을 확인해 주세요.");
 
     private final String code;
     private final String message;

back/src/main/java/com/back/domain/mentoring/reservation/repository/ReservationRepository.java

@@ -9,6 +9,7 @@
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;
 
+import java.time.LocalDateTime;
 import java.util.List;
 import java.util.Optional;
 
@@ -58,4 +59,21 @@ Page<Reservation> findAllByMenteeMember(
      * - 취소/거절된 예약도 히스토리로 보존
      */
     boolean existsByMentorSlotId(Long slotId);
+
+    @Query("""
+        SELECT CASE WHEN COUNT(r) > 0
+            THEN TRUE
+            ELSE FALSE
+            END
+        FROM Reservation r
+        WHERE r.mentee.id = :menteeId
+        AND r.status NOT IN ('REJECTED', 'CANCELED')
+        AND r.mentorSlot.startDateTime < :end
+        AND r.mentorSlot.endDateTime > :start
+        """)
+    boolean existsOverlappingTimeForMentee(
+        @Param("menteeId") Long menteeId,
+        @Param("start") LocalDateTime start,
+        @Param("end") LocalDateTime end
+    );
 }

back/src/main/java/com/back/domain/mentoring/reservation/service/ReservationService.java

@@ -62,8 +62,9 @@ public ReservationResponse createReservation(Mentee mentee, ReservationRequest r
             Mentoring mentoring = mentoringStorage.findMentoring(reqDto.mentoringId());
             MentorSlot mentorSlot = mentoringStorage.findMentorSlot(reqDto.mentorSlotId());
 
-            validateMentorSlotStatus(mentorSlot, mentee);
             DateTimeValidator.validateStartTimeNotInPast(mentorSlot.getStartDateTime());
+            validateMentorSlotStatus(mentorSlot, mentee);
+            validateOverlappingTimeForMentee(mentee, mentorSlot);
 
             Reservation reservation = Reservation.builder()
                 .mentoring(mentoring)
@@ -131,4 +132,13 @@ private void validateMentorSlotStatus(MentorSlot mentorSlot, Mentee mentee) {
             throw new ServiceException(ReservationErrorCode.NOT_AVAILABLE_SLOT);
         }
     }
+
+    private void validateOverlappingTimeForMentee(Mentee mentee, MentorSlot mentorSlot) {
+        boolean isOverlapping = reservationRepository
+            .existsOverlappingTimeForMentee(mentee.getId(), mentorSlot.getStartDateTime(), mentorSlot.getEndDateTime());
+
+        if (isOverlapping) {
+            throw new ServiceException(ReservationErrorCode.OVERLAPPING_TIME);
+        }
+    }
 }

back/src/test/java/com/back/domain/mentoring/reservation/service/ReservationServiceTest.java

@@ -267,9 +267,6 @@ void throwExceptionWhenStartTimeInPast() {
                 .thenReturn(mentoring);
             when(mentoringStorage.findMentorSlot(pastRequest.mentorSlotId()))
                 .thenReturn(pastSlot);
-            when(reservationRepository.findByMentorSlotIdAndStatusIn(pastSlot.getId(),
-                List.of(ReservationStatus.PENDING, ReservationStatus.APPROVED, ReservationStatus.COMPLETED)))
-                .thenReturn(Optional.empty());
 
             // when & then
             assertThatThrownBy(() -> reservationService.createReservation(mentee, pastRequest))