Refactor: 사용자 중복 OAuth 로그인 검증 로직

src/main/java/slvtwn/khu/toyouserver/common/authentication/social/strategy/KakaoAuthStrategy.java

@@ -2,6 +2,7 @@
 
 import static slvtwn.khu.toyouserver.domain.SocialAuthProvider.KAKAO;
 
+import java.util.Optional;
 import lombok.RequiredArgsConstructor;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.stereotype.Service;
@@ -13,59 +14,75 @@
 import slvtwn.khu.toyouserver.common.feign.auth.kakao.web.KakaoTokenResponse;
 import slvtwn.khu.toyouserver.common.feign.auth.kakao.web.KakaoUserResponse;
 import slvtwn.khu.toyouserver.domain.User;
+import slvtwn.khu.toyouserver.domain.UserSocialAccount;
 import slvtwn.khu.toyouserver.dto.SocialAuthRequest;
 import slvtwn.khu.toyouserver.dto.SocialAuthResponse;
-import slvtwn.khu.toyouserver.persistance.EventRepository;
 import slvtwn.khu.toyouserver.persistance.UserRepository;
+import slvtwn.khu.toyouserver.persistance.UserSocialAccountRepository;
 
 @Service
 @RequiredArgsConstructor
 public class KakaoAuthStrategy implements SocialAuthStrategy {
 
-    @Value("${oauth.kakao.client-id}")
-    private String kakaoClientId;
-    @Value("${oauth.kakao.redirect-uri}")
-    private String kakaoRedirectUri;
-    @Value("${oauth.kakao.grant-type}")
-    private String kakaoGrantType;
+	private final UserSocialAccountRepository userSocialAccountRepository;
+	@Value("${oauth.kakao.client-id}")
+	private String kakaoClientId;
+	@Value("${oauth.kakao.redirect-uri}")
+	private String kakaoRedirectUri;
+	@Value("${oauth.kakao.grant-type}")
+	private String kakaoGrantType;
 
-    private final KakaoAuthApiClient kakaoAuthApiClient;
-    private final KakaoResourceApiClient kakaoResourceApiClient;
+	private final KakaoAuthApiClient kakaoAuthApiClient;
+	private final KakaoResourceApiClient kakaoResourceApiClient;
 
-    private final UserRepository userRepository;
+	private final UserRepository userRepository;
 
-    private final JwtProvider jwtProvider;
+	private final JwtProvider jwtProvider;
 
-    // TODO: 파사드로 카카오 요청 + 유저 저장 부분 분리
-    // 현재 외부 네트워크에 트랜잭션이 의존하는 상태
-    @Override
-    @Transactional
-    public SocialAuthResponse login(SocialAuthRequest request) {
-        KakaoTokenResponse tokenResponse = kakaoAuthApiClient.getOAuth2AccessToken(
-                kakaoGrantType,
-                kakaoClientId,
-                kakaoRedirectUri,
-                request.authorizationCode()
-        );
-        KakaoUserResponse userResponse = kakaoResourceApiClient.getUserInformation(
-                "Bearer " + tokenResponse.accessToken());
-        User user = registerUser(userResponse);
-        Token token = jwtProvider.issueTokens(user.getId());
-        return SocialAuthResponse.of(user.getId(), user.getName(), KAKAO, token);
-    }
+	// TODO: 파사드로 카카오 요청 + 유저 저장 부분 분리
+	// 현재 외부 네트워크에 트랜잭션이 의존하는 상태
+	@Override
+	@Transactional
+	public SocialAuthResponse login(SocialAuthRequest request) {
+		KakaoTokenResponse tokenResponse = kakaoAuthApiClient.getOAuth2AccessToken(
+				kakaoGrantType,
+				kakaoClientId,
+				kakaoRedirectUri,
+				request.authorizationCode()
+		);
+		KakaoUserResponse userResponse = kakaoResourceApiClient.getUserInformation(
+				"Bearer " + tokenResponse.accessToken());
+		User user = findOrCreateUser(userResponse);
+		Token token = jwtProvider.issueTokens(user.getId());
+		return SocialAuthResponse.of(user.getId(), user.getName(), KAKAO, token);
+	}
 
-    @Override
-    public boolean support(String provider) {
-        return provider.equals("KAKAO");
-    }
+	@Override
+	public boolean support(String provider) {
+		return provider.equals("KAKAO");
+	}
 
-    private User registerUser(KakaoUserResponse userResponse) {
-        User user = userRepository.findById(Long.parseLong(userResponse.id())).orElse(null);
-        if (user == null) {
-            user = User.create(userResponse.kakaoAccount().profile().nickname(),
-                    userResponse.kakaoAccount().profile().profileImageUrl(), KAKAO);
-        }
-        userRepository.save(user);
-        return user;
-    }
-}
+	private User findOrCreateUser(KakaoUserResponse userResponse) {
+		Optional<UserSocialAccount> account = userSocialAccountRepository.findByProviderSerial(
+				userResponse.id());
+		if (account.isPresent()) {
+			UserSocialAccount verifiedSocialAccount = account.get();
+			return userRepository.findById(verifiedSocialAccount.getUserId()).orElseThrow(
+					() -> new IllegalStateException("등록된 카카오 계정에 해당하는 유저가 없습니다."));
+		} else {
+			return registerUser(userResponse);
+		}
+	}
+
+	private User registerUser(KakaoUserResponse userResponse) {
+		User user = User.create(
+				userResponse.kakaoAccount().profile().nickname(),
+				userResponse.kakaoAccount().profile().profileImageUrl(),
+				KAKAO
+		);
+		userRepository.save(user);
+		UserSocialAccount newAccount = UserSocialAccount.createAccountByKakao(user.getId(), userResponse.id());
+		userSocialAccountRepository.save(newAccount);
+		return user;
+	}
+}

src/main/java/slvtwn/khu/toyouserver/domain/UserSocialAccount.java

@@ -0,0 +1,36 @@
+package slvtwn.khu.toyouserver.domain;
+
+
+import static jakarta.persistence.GenerationType.IDENTITY;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.EnumType;
+import jakarta.persistence.Enumerated;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+import lombok.AccessLevel;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Entity
+@Table(name = "user_social_accounts")
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@AllArgsConstructor(access = AccessLevel.PRIVATE)
+@Getter
+public class UserSocialAccount {
+
+	@Id
+	@GeneratedValue(strategy = IDENTITY)
+	private Long id;
+
+	@Enumerated(EnumType.STRING)
+	private SocialAuthProvider provider;
+	private String providerSerial;
+	private Long userId;
+
+	public static UserSocialAccount createAccountByKakao(Long userId, String providerSerial) {
+		return new UserSocialAccount(null, SocialAuthProvider.KAKAO, providerSerial, userId);
+	}
+}

src/main/java/slvtwn/khu/toyouserver/persistance/UserSocialAccountRepository.java

@@ -0,0 +1,9 @@
+package slvtwn.khu.toyouserver.persistance;
+
+import java.util.Optional;
+import org.springframework.data.jpa.repository.JpaRepository;
+import slvtwn.khu.toyouserver.domain.UserSocialAccount;
+
+public interface UserSocialAccountRepository extends JpaRepository<UserSocialAccount, Long> {
+	Optional<UserSocialAccount> findByProviderSerial(String providerSerial);
+}