feat: 토큰교환 로직 추가

src/main/java/com/dku/council/domain/oauth/service/OauthService.java

@@ -1,26 +1,32 @@
 package com.dku.council.domain.oauth.service;
 
+import com.dku.council.domain.oauth.exception.InvalidGrantTypeException;
 import com.dku.council.domain.oauth.exception.InvalidOauthResponseTypeException;
 import com.dku.council.domain.oauth.exception.OauthClientNotFoundException;
-import com.dku.council.domain.oauth.model.dto.request.OauthCachePayload;
-import com.dku.council.domain.oauth.model.dto.request.OauthRequest;
+import com.dku.council.domain.oauth.model.dto.request.*;
+import com.dku.council.domain.oauth.model.dto.response.OauthLoginResponse;
+import com.dku.council.domain.oauth.model.dto.response.TokenExchangeResponse;
+import com.dku.council.domain.oauth.model.entity.HashAlgorithm;
 import com.dku.council.domain.oauth.model.entity.OauthClient;
 import com.dku.council.domain.oauth.model.entity.OauthResponseType;
 import com.dku.council.domain.oauth.repository.OauthClientRepository;
 import com.dku.council.domain.oauth.repository.OauthRedisRepository;
+import com.dku.council.domain.oauth.util.CodeChallengeConverter;
 import com.dku.council.domain.user.exception.WrongPasswordException;
 import com.dku.council.domain.user.model.dto.request.RequestLoginDto;
 import com.dku.council.domain.user.model.entity.User;
 import com.dku.council.domain.user.repository.UserRepository;
 import com.dku.council.domain.user.util.CodeGenerator;
+import com.dku.council.global.auth.jwt.AuthenticationToken;
+import com.dku.council.global.auth.jwt.JwtProvider;
 import com.dku.council.global.error.exception.UserNotFoundException;
 import lombok.RequiredArgsConstructor;
 import org.springframework.security.crypto.password.PasswordEncoder;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.web.util.UriComponentsBuilder;
 
-import java.util.UUID;
+import java.util.Objects;
 
 @Service
 @Transactional(readOnly = true)
@@ -30,6 +36,8 @@ public class OauthService {
     private final OauthRedisRepository oauthRedisRepository;
     private final UserRepository userRepository;
     private final PasswordEncoder passwordEncoder;
+    private final CodeChallengeConverter codeChallengeConverter;
+    private final JwtProvider jwtProvider;
 
     public String authorize(OauthRequest oauthRequest) {
         String clientId = oauthRequest.getClientId();
@@ -58,10 +66,61 @@ public OauthLoginResponse login(RequestLoginDto loginInfo, OauthInfo oauthInfo)
         oauthRedisRepository.cacheOauth(authCode, cachePayload);
         return OauthLoginResponse.from(authCode);
     }
+
+    public TokenExchangeResponse exchangeToken(ClientInfo clientInfo, OAuthTarget target) {
+        checkGrantType(target.getGrantType());
+        OauthClient oauthClient = getOauthClient(clientInfo.getClientId());
+        oauthClient.checkClientSecret(clientInfo.getClientSecret());
+        oauthClient.checkRedirectUri(clientInfo.getRedirectUri());
+        OauthCachePayload payload = getPayload(target);
+        String codeVerifier = target.getCodeVerifier();
+        String codeChallengeMethod = getCodeChallengeMethod(payload.getCodeChallengeMethod());
+        checkCodeChallenge(codeVerifier, codeChallengeMethod, payload);
+        User user = userRepository.findById(payload.getUserId())
+                .orElseThrow(UserNotFoundException::new);
+        AuthenticationToken token = jwtProvider.issue(user);
+        return TokenExchangeResponse.of(token.getAccessToken(), token.getRefreshToken(), payload.getScope());
+    }
+
+    private String getCodeChallengeMethod(String codeChallengeMethod) {
+        if (Objects.equals(codeChallengeMethod, HashAlgorithm.SHA1.getShortenedAlgorithm())) {
+            codeChallengeMethod = HashAlgorithm.SHA1.getAlgorithm();
+        }
+        if (Objects.equals(codeChallengeMethod, HashAlgorithm.SHA256.getShortenedAlgorithm())) {
+            codeChallengeMethod = HashAlgorithm.SHA256.getAlgorithm();
+        }
+        if (Objects.equals(codeChallengeMethod, HashAlgorithm.SHA512.getShortenedAlgorithm())) {
+            codeChallengeMethod = HashAlgorithm.SHA512.getAlgorithm();
+        }
+        return codeChallengeMethod;
+    }
+
+    private void checkCodeChallenge(String codeVerifier, String codeChallengeMethod, OauthCachePayload payload) {
+        String convertedCode = codeChallengeConverter.convertToCodeChallenge(codeVerifier, codeChallengeMethod);
+        payload.checkCodeChallenge(convertedCode);
+    }
+
+    private OauthCachePayload getPayload(OAuthTarget target) {
+        return oauthRedisRepository.getOauth(target.getCode())
+                .orElseThrow(OauthClientNotFoundException::new);
+    }
+
+    private OauthClient getOauthClient(String clientId) {
+        return oauthClientRepository.findByClientId(clientId)
+                .orElseThrow(OauthClientNotFoundException::new);
+    }
+
     private void checkResponseType(String responseType) {
         String type = OauthResponseType.CODE.getValue();
         if (!responseType.equals(type)) {
             throw new InvalidOauthResponseTypeException(responseType);
         }
     }
+
+    private void checkGrantType(String grantType) {
+        if (!grantType.equals("authorization_code")) {
+            throw new InvalidGrantTypeException(grantType);
+        }
+    }
+
 }