feat: 사용자 전역 유니크 핸들 적용

build.gradle

@@ -101,6 +101,10 @@ dependencies {
 	runtimeOnly 'com.h2database:h2'
 	runtimeOnly 'com.mysql:mysql-connector-j'
 
+	// Flyway: migration
+	implementation 'org.flywaydb:flyway-core'
+	implementation 'org.flywaydb:flyway-mysql'
+
 	// Caffeine
 	implementation 'com.github.ben-manes.caffeine:caffeine'
 

src/main/java/com/teamEWSN/gitdeun/common/oauth/service/CustomOAuth2UserService.java

@@ -7,12 +7,12 @@
 import com.teamEWSN.gitdeun.common.oauth.dto.provider.GoogleResponseDto;
 import com.teamEWSN.gitdeun.common.oauth.dto.provider.OAuth2ResponseDto;
 import com.teamEWSN.gitdeun.common.oauth.entity.OauthProvider;
-import com.teamEWSN.gitdeun.user.entity.Role;
 import com.teamEWSN.gitdeun.common.oauth.entity.SocialConnection;
 import com.teamEWSN.gitdeun.user.entity.User;
 import com.teamEWSN.gitdeun.common.oauth.repository.SocialConnectionRepository;
 import com.teamEWSN.gitdeun.user.repository.UserRepository;
 import com.teamEWSN.gitdeun.common.oauth.dto.CustomOAuth2User;
+import com.teamEWSN.gitdeun.user.service.UserService;
 import jakarta.transaction.Transactional;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
@@ -22,10 +22,7 @@
 import org.springframework.security.oauth2.core.user.OAuth2User;
 import org.springframework.stereotype.Service;
 
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.UUID;
+import java.util.*;
 
 
 @Slf4j
@@ -35,6 +32,7 @@ public class CustomOAuth2UserService extends DefaultOAuth2UserService {
 
     private final GitHubApiHelper gitHubApiHelper;
     private final GoogleApiHelper googleApiHelper;
+    private final UserService userService;
     private final SocialTokenRefreshService socialTokenRefreshService;
     private final UserRepository userRepository;
     private final SocialConnectionRepository socialConnectionRepository;
@@ -63,18 +61,30 @@ public User processUser(OAuth2User oAuth2User, OAuth2UserRequest userRequest) {
         String accessToken  = userRequest.getAccessToken().getTokenValue();
         String refreshToken = (String) userRequest.getAdditionalParameters().get("refresh_token");
 
-        /* ② 이미 연결된 계정 → 토큰 갱신 로직 추상화  */
-        return socialConnectionRepository.findByProviderAndProviderId(provider, providerId)
-            .map(conn -> {
-                // provider 별 refresh 정책
-                socialTokenRefreshService.refreshSocialToken(conn, accessToken, refreshToken);
-
-                // 사용자 정보 갱신
-                User user = conn.getUser();
-                user.updateProfile(dto.getName(), dto.getProfileImageUrl());
-                return user;
-            })
-            .orElseGet(() -> createOrConnect(dto, provider, providerId, accessToken, refreshToken));
+        // 1) 이미 연결된 소셜 계정이면 토큰 갱신 + 프로필 갱신
+        var existingConnOpt = socialConnectionRepository.findByProviderAndProviderId(provider, providerId);
+        if (existingConnOpt.isPresent()) {
+            var conn = existingConnOpt.get();
+            socialTokenRefreshService.refreshSocialToken(conn, accessToken, refreshToken);
+
+            // 프로필 갱신 + (handle 보정 포함) — upsertAndGetId가 책임
+            Long userId = userService.upsertAndGetId(
+                dto.getEmail(), dto.getName(), dto.getProfileImageUrl(), dto.getNickname()
+            );
+            return userRepository.findById(userId)
+                .orElseThrow(() -> new GlobalException(ErrorCode.USER_NOT_FOUND_BY_ID));
+        }
+
+        // 2) 아직 연결 안된 계정 → upsertAndGetId로 (신규/기존) 저장/보정 먼저
+        Long userId = userService.upsertAndGetId(
+            dto.getEmail(), dto.getName(), dto.getProfileImageUrl(), dto.getNickname()
+        );
+        User user = userRepository.findById(userId)
+            .orElseThrow(() -> new GlobalException(ErrorCode.USER_NOT_FOUND_BY_ID));
+
+        // 3) 그 다음 소셜 계정 연결만 수행
+        connectSocialAccount(user, provider, providerId, accessToken, refreshToken);
+        return user;
     }
 
     // OAuth2 공급자로부터 받은 사용자 정보를 기반으로 OAuth2ResponseDto를 생성(인스턴스 메서드)
@@ -118,44 +128,6 @@ private OAuth2ResponseDto getOAuth2ResponseDto(OAuth2User oAuth2User, OAuth2User
         throw new GlobalException(ErrorCode.UNSUPPORTED_OAUTH_PROVIDER);
     }
 
-    /**
-     * 사용자가 존재하면 계정을 연결하고, 존재하지 않으면 새로 생성합니다.
-     */
-    private User createOrConnect(OAuth2ResponseDto response, OauthProvider provider, String providerId, String accessToken, String refreshToken) {
-        // 이메일로 기존 사용자를 찾습니다.
-        return userRepository.findByEmailAndDeletedAtIsNull(response.getEmail())
-            .map(user -> {
-                // 사용자가 존재하면, 새 소셜 계정을 연결
-                user.updateProfile(response.getName(), response.getProfileImageUrl());
-                connectSocialAccount(user, provider, providerId, accessToken, refreshToken);
-                return user;
-            })
-            .orElseGet(() -> {
-                // 사용자가 존재하지 않으면, 새 사용자를 생성
-                return createNewUser(response, provider, providerId, accessToken, refreshToken);
-            });
-    }
-
-    private User createNewUser(OAuth2ResponseDto response, OauthProvider provider, String providerId, String accessToken, String refreshToken) {
-        // provider별 다른 Nickname 처리 로직
-        String nickname = response.getNickname();
-        if (provider == OauthProvider.GOOGLE) {
-            nickname = nickname + "_" + UUID.randomUUID().toString().substring(0, 6);
-        }
-
-        User newUser = User.builder()
-            .email(response.getEmail())
-            .name(response.getName())   // GitHub의 경우 full name, Google의 경우 name
-            .nickname(nickname)
-            .profileImage(response.getProfileImageUrl())
-            .role(Role.USER)
-            .build();
-        User savedUser = userRepository.save(newUser);
-
-        connectSocialAccount(savedUser, provider, providerId, accessToken, refreshToken);
-        return savedUser;
-    }
-
     private void connectSocialAccount(User user, OauthProvider provider, String providerId, String accessToken, String refreshToken) {
         socialConnectionRepository.findByProviderAndProviderId(provider, providerId)
             .ifPresent(connection -> {

src/main/java/com/teamEWSN/gitdeun/common/oauth/service/GoogleApiHelper.java

@@ -6,6 +6,7 @@
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.beans.factory.annotation.Value;
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.MediaType;
 import org.springframework.stereotype.Component;
 import org.springframework.util.LinkedMultiValueMap;
@@ -108,7 +109,7 @@ public Map<String, Object> fetchLatestUserInfo(String accessToken) {
                 .uri("https://www.googleapis.com/oauth2/v2/userinfo")
                 .header("Authorization", "Bearer " + accessToken)
                 .retrieve()
-                .bodyToMono(Map.class)
+                .bodyToMono(new ParameterizedTypeReference<Map<String, Object>>() {})
                 .block();
         } catch (WebClientResponseException e) {
             log.error("Google userinfo 조회 실패: {}", e.getResponseBodyAsString());

src/main/java/com/teamEWSN/gitdeun/common/util/HandleGenerator.java

@@ -0,0 +1,102 @@
+package com.teamEWSN.gitdeun.common.util;
+
+import com.teamEWSN.gitdeun.user.repository.UserRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.dao.DataIntegrityViolationException;
+import org.springframework.stereotype.Component;
+
+import java.nio.ByteBuffer;
+import java.util.Base64;
+import java.util.concurrent.ThreadLocalRandom;
+
+@Component
+@RequiredArgsConstructor
+public class HandleGenerator {
+    private final UserRepository userRepository;
+
+    private static final int MAX_LEN = 30;
+    private static final int MAX_SEQ = 999;
+    private static final int MAX_RETRY = 3;
+
+    /**
+     * base를 받아 전역 유니크 핸들을 생성합니다.
+     * @param base 후보 문자열 (null 가능)
+     * @param selfId 본인 사용자 ID (신규 생성 시 null)
+     */
+    public String generateUniqueHandle(String base, Long selfId) {
+        String normalized = sanitize(base);
+        String candidate = normalized;
+        int seq = 0;
+
+        while (conflicts(candidate, selfId)) {
+            seq++;
+            if (seq <= MAX_SEQ) {
+                candidate = appendSeq(normalized, seq);
+            } else {
+                candidate = appendRandom(normalized);
+                // 랜덤도 충돌 가능하므로 계속 검사
+            }
+        }
+        return candidate;
+    }
+
+    /**
+     * UNIQUE 위반 발생 시 재시도하는 안전 래퍼
+     */
+    public <T> T withUniqueRetry(HandleSetter<T> action, String base, Long selfId) {
+        for (int attempt = 0; attempt < MAX_RETRY; attempt++) {
+            String handle = generateUniqueHandle(base, selfId);
+            try {
+                return action.apply(handle);
+            } catch (DataIntegrityViolationException e) {
+                if (attempt == MAX_RETRY - 1) {
+                    throw new IllegalStateException(
+                        "Failed to generate unique handle after " + MAX_RETRY + " attempts", e
+                    );
+                }
+            }
+        }
+        throw new IllegalStateException("Should not reach here");
+    }
+
+    private boolean conflicts(String handle, Long selfId) {
+        return (selfId == null)
+            ? userRepository.existsByHandle(handle)
+            : userRepository.existsByHandleAndIdNot(handle, selfId);
+    }
+
+    private String sanitize(String raw) {
+        String s = (raw == null ? "" : raw).trim().toLowerCase();
+        s = s.replaceAll("\\s+", "_");
+        s = s.replaceAll("[^a-z0-9_.-]", "");
+        s = s.replaceAll("_+", "_");
+        if (s.isBlank()) s = "user";
+        return s.length() > MAX_LEN ? s.substring(0, MAX_LEN) : s;
+    }
+
+    private String appendSeq(String base, int seq) {
+        String suffix = "_" + String.format("%03d", seq);
+        int room = MAX_LEN - suffix.length();
+        String head = base.length() > room ? base.substring(0, room) : base;
+        return head + suffix;
+    }
+
+    private String appendRandom(String base) {
+        String rand = random6();
+        String suffix = "_" + rand;
+        int room = MAX_LEN - suffix.length();
+        String head = base.length() > room ? base.substring(0, room) : base;
+        return head + suffix;
+    }
+
+    private String random6() {
+        long random = ThreadLocalRandom.current().nextLong() & 0xFFFFFFFFL;
+        return Base64.getUrlEncoder().withoutPadding()
+            .encodeToString(ByteBuffer.allocate(4).putInt((int)random).array());
+    }
+
+    @FunctionalInterface
+    public interface HandleSetter<T> {
+        T apply(String uniqueHandle);
+    }
+}

src/main/java/com/teamEWSN/gitdeun/user/entity/User.java

@@ -23,10 +23,13 @@ public class User extends AuditedEntity {
     @Column(length = 100)
     private String name;
 
-    @Column(nullable = false, length = 100, unique = true)
+    @Column(nullable = false, length = 100)
     private String nickname;
 
-    @Column(nullable = false, length = 256)
+    @Column(nullable = false, length = 50, unique = true)
+    private String handle;               // @menton / URL 용 전역 유니크 핸들
+
+    @Column(nullable = false, length = 256, unique = true)
     private String email;
 
     @Column(name="profile_image", length = 512)
@@ -49,29 +52,47 @@ public class User extends AuditedEntity {
 
 
     @Builder
-    public User(String name, String nickname, String email, String profileImage, Role role) {
+    public User(String name, String nickname, String handle, String email, String profileImage, Role role) {
         this.name = name;
         this.nickname = nickname;
+        this.handle = handle;
         this.email = email;
         this.profileImage = profileImage;
         this.role = role;
     }
 
-    public User updateProfile(String name, String profileImage) {
+    public void updateProfile(String name, String nickname, String profileImage) {
         this.name = name;
+        this.nickname = nickname;
         this.profileImage = profileImage;
-        return this; // 메소드 체이닝을 위해 this 반환
     }
 
     // 회원 탈퇴 처리
     public void markAsDeleted() {
         this.deletedAt = LocalDateTime.now();
     }
 
-    // 회원 닉네임 변경
-    public void updateNickname(String newNickname) {
-        this.nickname = newNickname;
-    }
 
+    /**
+     * handle이 아직 비어 있는(=최초 보정이 필요한) 계정에서만 1회 설정을 허용합니다.
+     * 이미 handle이 존재한다면 예외를 던져 서비스 내 불변성을 유지합니다.
+     */
+    public void setHandle(String newHandle) {
+        if (this.handle != null && !this.handle.isBlank()) {
+            throw new IllegalStateException("Handle is already set and cannot be changed.");
+        }
+        if (newHandle == null || newHandle.isBlank()) {
+            throw new IllegalArgumentException("Handle cannot be null or blank.");
+        }
+        // 길이·문자 정책은 HandleGenerator에서 보장하지만, 방어적으로 한 번 더 체크해도 됩니다.
+        if (newHandle.length() > 50) {
+            throw new IllegalArgumentException("Handle exceeds maximum length of 50 characters.");
+        }
+        this.handle = newHandle;
+    }
 
+    /** 편의 메서드: handle 존재 여부 */
+    public boolean hasHandle() {
+        return this.handle != null && !this.handle.isBlank();
+    }
 }

src/main/java/com/teamEWSN/gitdeun/user/repository/UserRepository.java

@@ -18,4 +18,9 @@ public interface UserRepository extends JpaRepository<User, Long> {
 
     // user email로 검색
     Optional<User> findByEmailAndDeletedAtIsNull(String email);
+
+    // 신규 생성/백필 시 충돌 검사
+    boolean existsByHandle(String handle);
+    // 수정·보정 시 “본인 제외” 충돌 검사
+    boolean existsByHandleAndIdNot(String handle, Long id);
 }