refactor: 내 자치구 삭제시 대표 자치구 수정

Author: TaetaetaE01

src/main/java/com/trashheroesbe/feature/user/api/UserController.java

@@ -54,9 +54,10 @@ public ApiResponse<Void> createUserDistrict(
     @Override
     @DeleteMapping("/districts/{userDistrictId}")
     public ApiResponse<Void> deleteUserDistrict(
-        @PathVariable Long userDistrictId
+        @PathVariable Long userDistrictId,
+        @AuthenticationPrincipal CustomerDetails customerDetails
     ) {
-        userService.deleteUserDistrict(userDistrictId);
+        userService.deleteUserDistrict(userDistrictId, customerDetails.getUser().getId());
         return ApiResponse.success(OK);
     }
 

src/main/java/com/trashheroesbe/feature/user/api/UserControllerApi.java

@@ -36,11 +36,12 @@ ApiResponse<Long> updateUser(
     ApiResponse<Void> createUserDistrict(CustomerDetails customerDetails, String districtId);
 
     @Operation(summary = "유저 자치구 삭제하기", description = "유저의 자치구를 삭제합니다.")
-    ApiResponse<Void> deleteUserDistrict(Long userDistrictId);
+    ApiResponse<Void> deleteUserDistrict(Long userDistrictId, CustomerDetails customerDetails);
 
     @Operation(summary = "내 자치구 조회하기", description = "나의 등록된 자치구를 조회합니다.")
     ApiResponse<List<UserDistrictResponse>> getMyDistricts(CustomerDetails customerDetails);
 
-    @Operation(summary = "유저 대표 자치구 수정하기", description = "유저의 자치구를 수정합니다.")
-    ApiResponse<Void> updateDefaultUserDistrict(Long userDistrictId, CustomerDetails customerDetails);
+    @Operation(summary = "유저 대표(default) 자치구 수정하기", description = "유저 자치구의 default 값을 수정합니다.")
+    ApiResponse<Void> updateDefaultUserDistrict(Long userDistrictId,
+        CustomerDetails customerDetails);
 }

src/main/java/com/trashheroesbe/feature/user/application/UserService.java

@@ -96,10 +96,20 @@ public void createUserDistrict(Long userId, String districtId) {
     }
 
     @Transactional
-    public void deleteUserDistrict(Long userDistrictId) {
+    public void deleteUserDistrict(Long userDistrictId, Long userId) {
         if (!userDistrictFinder.existsByUserDistrictId(userDistrictId)) {
             throw new BusinessException(ENTITY_NOT_FOUND);
         }
+
+        List<UserDistrict> userDistricts = userDistrictFinder.findByUserId(userId);
+        if (userDistricts.size() == MAX_USER_DISTRICTS) {
+            UserDistrict userDistrict = userDistricts.stream()
+                .filter(defaultUserDistrict -> !defaultUserDistrict.getId().equals(userDistrictId))
+                .findFirst()
+                .orElseThrow(() -> new BusinessException(ENTITY_NOT_FOUND));
+            userDistrict.updateDefaultDistrict(true);
+        }
+
         userDistrictRepository.deleteById(userDistrictId);
     }