/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community License, Version 2.0 (the "License"); you may not use this file
    * except in compliance with the License. You may obtain a copy of the License
   * at:
   *
   *   http://opensource.org/licenses/ecl2.txt
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
   * License for the specific language governing permissions and limitations under
   * the License.
   *
   */
  
  
  package org.opencastproject.publication.youtube.auth;
  
  import com.google.api.client.auth.oauth2.Credential;
  import com.google.api.client.auth.oauth2.StoredCredential;
  import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp;
  import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
  import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
  import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
  import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
  import com.google.api.client.http.javanet.NetHttpTransport;
  import com.google.api.client.json.jackson2.JacksonFactory;
  import com.google.api.client.util.store.DataStore;
  import com.google.api.client.util.store.FileDataStoreFactory;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.File;
  import java.io.FileReader;
  import java.io.IOException;
  import java.text.MessageFormat;
  
  /**
   * @see com.google.api.client.googleapis.auth.oauth2.GoogleCredential
   */
  public final class OAuth2CredentialFactoryImpl implements OAuth2CredentialFactory {
  
    private final Logger logger = LoggerFactory.getLogger(this.getClass());
  
    public OAuth2CredentialFactoryImpl() {
    }
  
    @Override
    public GoogleCredential getGoogleCredential(final ClientCredentials credentials) throws IOException {
      // Use the default which is file-based; name and location are configurable
      final DataStore<StoredCredential> datastore = getDataStore(credentials.getCredentialDatastore(),
          credentials.getDataStoreDirectory());
      return getGoogleCredential(datastore, credentials);
    }
  
    @Override
    public DataStore<StoredCredential> getDataStore(final String id, final String dataStoreDirectory)
            throws IOException {
      return new FileDataStoreFactory(new File(dataStoreDirectory)).getDataStore(id);
    }
  
    @Override
    public GoogleCredential getGoogleCredential(
        final DataStore<StoredCredential> datastore,
        final ClientCredentials authContext
    ) throws IOException {
      final GoogleCredential gCred;
      final LocalServerReceiver localReceiver = new LocalServerReceiver();
      final String accessToken;
      final String refreshToken;
  
      try {
        // Reads the client id and client secret from a file name passed in authContext
        final GoogleClientSecrets gClientSecrets = GoogleClientSecrets.load(new JacksonFactory(),
                new FileReader(authContext.getClientSecrets()));
  
        // Obtain tokens from credential in data store, or obtains a new one from
        // Google if one doesn't exist
        final StoredCredential sCred = datastore.get(authContext.getClientId());
        if (sCred != null) {
          accessToken = sCred.getAccessToken();
          refreshToken = sCred.getRefreshToken();
          logger.debug(MessageFormat.format(
              "Found credential for client {0} in data store {1}", authContext.getClientId(), datastore.getId()));
        } else {
          // This flow supports installed applications
          final GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
                  new NetHttpTransport(), new JacksonFactory(), gClientSecrets, authContext.getScopes())
              .setCredentialDataStore(datastore)
              .setApprovalPrompt("auto")
              .setAccessType("offline")
              .build();
         final Credential cred = new AuthorizationCodeInstalledApp(flow, localReceiver)
             .authorize(authContext.getClientId());
         accessToken = cred.getAccessToken();
         refreshToken = cred.getRefreshToken();
         logger.debug(MessageFormat.format(
             "Created new credential for client {0} in data store {1}", authContext.getClientId(), datastore.getId()));
       }
       gCred = new GoogleCredential.Builder()
           .setClientSecrets(gClientSecrets).setJsonFactory(new JacksonFactory())
           .setTransport(new NetHttpTransport()).build();
       gCred.setAccessToken(accessToken);
       gCred.setRefreshToken(refreshToken);
       logger.debug(MessageFormat.format(
           "Found credential {0} using {1}", gCred.getRefreshToken(), authContext.toString()));
     } finally {
       localReceiver.stop();
     }
     return gCred;
   }
 }