feat: 탈퇴 V2 구현(사유 저장) 및 탈퇴 통계 페이지 추가 (#176)

* feat(auth): 탈퇴 V2 API 및 탈퇴 사유 DB 저장/검증 추가

* feat: 탈퇴 V2 구현 - 사유 저장 기능과 탈퇴 통계 페이지 추가

* fix(db): user withdrawal 관련 마이그레이션 파일명 시간대 보정

실제 실행 순서에 맞게 버전 타임스탬프 조정

* test(auth): 탈퇴 V2 사유 저장 및 통계 테스트 추가

Author: 1Seob

src/main/java/com/devkor/ifive/nadab/domain/auth/api/AuthController.java

@@ -713,9 +713,11 @@ public ResponseEntity<ApiResponseDto<TokenResponse>> changePassword(
         );
     }
 
+    @Deprecated
     @PostMapping("/withdrawal")
     @PreAuthorize("isAuthenticated()")
     @Operation(
+            deprecated = true,
             summary = "회원 탈퇴",
             description = """
                     회원 탈퇴를 진행합니다.<br>

src/main/java/com/devkor/ifive/nadab/domain/auth/api/AuthControllerV2.java

@@ -0,0 +1,94 @@
+package com.devkor.ifive.nadab.domain.auth.api;
+
+import com.devkor.ifive.nadab.domain.auth.api.dto.request.WithdrawalRequestV2;
+import com.devkor.ifive.nadab.domain.auth.application.AuthServiceV2;
+import com.devkor.ifive.nadab.domain.auth.infra.cookie.CookieManager;
+import com.devkor.ifive.nadab.global.core.response.ApiResponseDto;
+import com.devkor.ifive.nadab.global.core.response.ApiResponseEntity;
+import com.devkor.ifive.nadab.global.security.principal.UserPrincipal;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.security.SecurityRequirement;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import jakarta.validation.Valid;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import jakarta.servlet.http.HttpServletResponse;
+
+@Tag(name = "인증 API V2", description = "인증 관련 API V2")
+@RestController
+@RequestMapping("/api/v2/auth")
+@RequiredArgsConstructor
+public class AuthControllerV2 {
+
+    private final AuthServiceV2 authServiceV2;
+    private final CookieManager cookieManager;
+
+    @PostMapping("/withdrawal")
+    @PreAuthorize("isAuthenticated()")
+    @Operation(
+            summary = "회원 탈퇴 V2",
+            description = """
+                    회원 탈퇴를 진행합니다.
+                    - 탈퇴 후 14일 동안 복구 가능합니다.<br>
+                    - 모든 기기에서 자동 로그아웃됩니다.<br>
+                    - 14일 후 자동으로 완전 삭제됩니다. <br>
+                    - 탈퇴 사유를 함께 저장합니다. <br>
+                    이때, reasons 필드에 OTHER가 포함된 경우 customReason 필드는 필수입니다. <br>
+                    
+                    **<reasons 필드 enum>** <br>
+                    DAILY_LOGGING_BURDEN,           // 매일 기록이 부담 <br>
+                    INSUFFICIENT_QUESTION_ANALYSIS, // 질문·분석 부족 <br>
+                    LOSS_OF_INTEREST_IN_WRITING,    // 글쓰기 흥미 상실 <br>
+                    PRIVACY_RECORD_CONCERN,         // 감정·기록 보안 우려 <br>
+                    APP_ERROR_OR_SLOWNESS,          // 오류·속도 문제 <br>
+                    OTHER                           // 기타(직접 입력) <br>
+                    """,
+            security = @SecurityRequirement(name = "bearerAuth"),
+            responses = {
+                    @ApiResponse(responseCode = "204", description = "탈퇴 성공"),
+                    @ApiResponse(
+                            responseCode = "400",
+                            description = """
+                                    - ErrorCode: AUTH_WITHDRAWAL_REASON_REQUIRED - 사유 미선택
+                                    - ErrorCode: AUTH_WITHDRAWAL_REASON_DUPLICATED - 사유 중복 선택
+                                    - ErrorCode: AUTH_WITHDRAWAL_OTHER_REASON_REQUIRED - OTHER 선택 후 기타 사유 미입력
+                                    - ErrorCode: AUTH_WITHDRAWAL_OTHER_REASON_TOO_LONG - 기타 사유 200자 초과
+                                    - ErrorCode: AUTH_WITHDRAWAL_OTHER_REASON_NOT_ALLOWED - OTHER 미선택인데 기타 사유 입력
+                                    - ErrorCode: AUTH_ALREADY_WITHDRAWN - 이미 탈퇴된 계정
+                                    """,
+                            content = @Content
+                    ),
+                    @ApiResponse(
+                            responseCode = "401",
+                            description = """
+                                    인증 실패 (JWT 토큰 관련)
+                                    - ErrorCode: AUTH_TOKEN_EXPIRED - JWT Access Token 만료
+                                    - ErrorCode: AUTH_TOKEN_SIGNATURE_INVALID - 토큰 서명 검증 실패
+                                    - ErrorCode: AUTH_TOKEN_MALFORMED - 토큰 형식 오류
+                                    - ErrorCode: AUTH_TOKEN_VERIFICATION_FAILED - 토큰 검증 실패
+                                    - ErrorCode: AUTH_TOKEN_USERID_INVALID - 토큰의 유저 ID 형식 오류
+                                    - ErrorCode: AUTH_TOKEN_ROLES_MISSING - 토큰에 권한 정보 없음
+                                    """,
+                            content = @Content
+                    )
+            }
+    )
+    public ResponseEntity<ApiResponseDto<Void>> withdrawUser(
+            @AuthenticationPrincipal UserPrincipal principal,
+            @RequestBody @Valid WithdrawalRequestV2 request,
+            HttpServletResponse response
+    ) {
+        authServiceV2.withdrawUser(principal.getId(), request.reasons(), request.customReason());
+        cookieManager.removeRefreshTokenCookie(response);
+        return ApiResponseEntity.noContent();
+    }
+}

src/main/java/com/devkor/ifive/nadab/domain/auth/api/dto/request/WithdrawalRequestV2.java

@@ -0,0 +1,25 @@
+package com.devkor.ifive.nadab.domain.auth.api.dto.request;
+
+import com.devkor.ifive.nadab.domain.auth.core.entity.WithdrawalReasonType;
+import io.swagger.v3.oas.annotations.media.Schema;
+import jakarta.validation.constraints.NotEmpty;
+import jakarta.validation.constraints.Size;
+
+import java.util.List;
+
+public record WithdrawalRequestV2(
+        @Schema(
+                description = "탈퇴 사유 목록 (다중 선택 가능)",
+                example = "[\"DAILY_LOGGING_BURDEN\", \"OTHER\"]"
+        )
+        @NotEmpty(message = "탈퇴 사유는 최소 1개 이상 선택해야 합니다.")
+        List<WithdrawalReasonType> reasons,
+
+        @Schema(
+                description = "기타 사유 직접 입력 (reasons에 OTHER가 포함된 경우 필수)",
+                example = "앱이 저에게 맞지 않았어요."
+        )
+        @Size(max = 200, message = "기타 사유는 최대 200자까지 입력할 수 있습니다.")
+        String customReason
+) {
+}

src/main/java/com/devkor/ifive/nadab/domain/auth/application/AuthServiceV2.java

@@ -0,0 +1,93 @@
+package com.devkor.ifive.nadab.domain.auth.application;
+
+import com.devkor.ifive.nadab.domain.auth.core.entity.UserWithdrawalReason;
+import com.devkor.ifive.nadab.domain.auth.core.entity.WithdrawalReasonType;
+import com.devkor.ifive.nadab.domain.auth.core.repository.UserWithdrawalReasonRepository;
+import com.devkor.ifive.nadab.domain.user.core.entity.User;
+import com.devkor.ifive.nadab.domain.user.core.repository.UserRepository;
+import com.devkor.ifive.nadab.global.core.response.ErrorCode;
+import com.devkor.ifive.nadab.global.exception.BadRequestException;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.time.OffsetDateTime;
+import java.util.ArrayList;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.Set;
+
+@Service
+@RequiredArgsConstructor
+@Transactional
+public class AuthServiceV2 {
+
+    private static final int MAX_CUSTOM_REASON_LENGTH = 200;
+
+    private final WithdrawalService withdrawalService;
+    private final UserRepository userRepository;
+    private final UserWithdrawalReasonRepository userWithdrawalReasonRepository;
+
+    public void withdrawUser(Long userId, List<WithdrawalReasonType> reasons, String customReason) {
+        List<WithdrawalReasonType> validatedReasons = validateReasons(reasons);
+        String normalizedCustomReason = normalizeCustomReason(customReason);
+        validateCustomReason(validatedReasons, normalizedCustomReason);
+
+        // 기존 탈퇴 처리(소프트 삭제/토큰 revoke/Apple revoke)
+        withdrawalService.withdrawUser(userId);
+
+        // 탈퇴 사유 저장(집계용)
+        User user = userRepository.getReferenceById(userId);
+        OffsetDateTime effectiveWithdrawnAt = user.getDeletedAt() != null
+                ? user.getDeletedAt()
+                : OffsetDateTime.now();
+        List<UserWithdrawalReason> entities = new ArrayList<>(validatedReasons.size());
+        for (WithdrawalReasonType reason : validatedReasons) {
+            String detail = reason == WithdrawalReasonType.OTHER ? normalizedCustomReason : null;
+            entities.add(UserWithdrawalReason.create(
+                    user,
+                    reason,
+                    detail,
+                    effectiveWithdrawnAt
+            ));
+        }
+        userWithdrawalReasonRepository.saveAll(entities);
+    }
+
+    private List<WithdrawalReasonType> validateReasons(List<WithdrawalReasonType> reasons) {
+        if (reasons == null || reasons.isEmpty()) {
+            throw new BadRequestException(ErrorCode.AUTH_WITHDRAWAL_REASON_REQUIRED);
+        }
+
+        Set<WithdrawalReasonType> uniqueReasons = EnumSet.copyOf(reasons);
+        if (uniqueReasons.size() != reasons.size()) {
+            throw new BadRequestException(ErrorCode.AUTH_WITHDRAWAL_REASON_DUPLICATED);
+        }
+        return reasons;
+    }
+
+    private void validateCustomReason(List<WithdrawalReasonType> reasons, String customReason) {
+        boolean hasOther = reasons.contains(WithdrawalReasonType.OTHER);
+
+        if (hasOther) {
+            if (customReason == null || customReason.isEmpty()) {
+                throw new BadRequestException(ErrorCode.AUTH_WITHDRAWAL_OTHER_REASON_REQUIRED);
+            }
+            if (customReason.length() > MAX_CUSTOM_REASON_LENGTH) {
+                throw new BadRequestException(ErrorCode.AUTH_WITHDRAWAL_OTHER_REASON_TOO_LONG);
+            }
+            return;
+        }
+
+        if (customReason != null && !customReason.isEmpty()) {
+            throw new BadRequestException(ErrorCode.AUTH_WITHDRAWAL_OTHER_REASON_NOT_ALLOWED);
+        }
+    }
+
+    private String normalizeCustomReason(String customReason) {
+        if (customReason == null) {
+            return null;
+        }
+        return customReason.trim();
+    }
+}

src/main/java/com/devkor/ifive/nadab/domain/auth/core/entity/UserWithdrawalReason.java

@@ -0,0 +1,49 @@
+package com.devkor.ifive.nadab.domain.auth.core.entity;
+
+import com.devkor.ifive.nadab.domain.user.core.entity.User;
+import com.devkor.ifive.nadab.global.shared.entity.CreatableEntity;
+import jakarta.persistence.*;
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import java.time.OffsetDateTime;
+
+@Entity
+@Table(name = "user_withdrawal_reasons")
+@Getter
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+public class UserWithdrawalReason extends CreatableEntity {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @ManyToOne(fetch = FetchType.LAZY, optional = false)
+    @JoinColumn(name = "user_id", nullable = false)
+    private User user;
+
+    @Enumerated(EnumType.STRING)
+    @Column(name = "reason", nullable = false, length = 50)
+    private WithdrawalReasonType reason;
+
+    @Column(name = "custom_reason", length = 200)
+    private String customReason;
+
+    @Column(name = "withdrawn_at", nullable = false)
+    private OffsetDateTime withdrawnAt;
+
+    public static UserWithdrawalReason create(
+            User user,
+            WithdrawalReasonType reason,
+            String customReason,
+            OffsetDateTime withdrawnAt
+    ) {
+        UserWithdrawalReason userWithdrawalReason = new UserWithdrawalReason();
+        userWithdrawalReason.user = user;
+        userWithdrawalReason.reason = reason;
+        userWithdrawalReason.customReason = customReason;
+        userWithdrawalReason.withdrawnAt = withdrawnAt;
+        return userWithdrawalReason;
+    }
+}

src/main/java/com/devkor/ifive/nadab/domain/auth/core/entity/WithdrawalReasonType.java

@@ -0,0 +1,10 @@
+package com.devkor.ifive.nadab.domain.auth.core.entity;
+
+public enum WithdrawalReasonType {
+    DAILY_LOGGING_BURDEN,           // 매일 기록이 부담
+    INSUFFICIENT_QUESTION_ANALYSIS, // 질문·분석 부족
+    LOSS_OF_INTEREST_IN_WRITING,    // 글쓰기 흥미 상실
+    PRIVACY_RECORD_CONCERN,         // 감정·기록 보안 우려
+    APP_ERROR_OR_SLOWNESS,          // 오류·속도 문제
+    OTHER                           // 기타(직접 입력)
+}

src/main/java/com/devkor/ifive/nadab/domain/auth/core/repository/UserWithdrawalReasonRepository.java

@@ -0,0 +1,7 @@
+package com.devkor.ifive.nadab.domain.auth.core.repository;
+
+import com.devkor.ifive.nadab.domain.auth.core.entity.UserWithdrawalReason;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface UserWithdrawalReasonRepository extends JpaRepository<UserWithdrawalReason, Long> {
+}