content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements. See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache 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://www.apache.org/licenses/LICENSE-2.0
   *
   * 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.apache.kafka.common.security.oauthbearer;
  
  import org.apache.kafka.common.security.oauthbearer.internals.secured.CachedFile;
  import org.apache.kafka.common.security.oauthbearer.internals.secured.ConfigurationUtils;
  
  import java.io.File;
  import java.util.List;
  import java.util.Map;
  
  import javax.security.auth.login.AppConfigurationEntry;
  
  import static org.apache.kafka.common.config.SaslConfigs.SASL_OAUTHBEARER_TOKEN_ENDPOINT_URL;
  import static org.apache.kafka.common.security.oauthbearer.internals.secured.CachedFile.RefreshPolicy.lastModifiedPolicy;
  import static org.apache.kafka.common.security.oauthbearer.internals.secured.CachedFile.STRING_JSON_VALIDATING_TRANSFORMER;
  
  /**
   * <code>FileJwtRetriever</code> is an {@link JwtRetriever} that will load the contents
   * of a file, interpreting them as a JWT access key in the serialized form.
   */
  public class FileJwtRetriever implements JwtRetriever {
  
      private CachedFile<String> jwtFile;
  
      @Override
      public void configure(Map<String, ?> configs, String saslMechanism, List<AppConfigurationEntry> jaasConfigEntries) {
          ConfigurationUtils cu = new ConfigurationUtils(configs, saslMechanism);
          File file = cu.validateFileUrl(SASL_OAUTHBEARER_TOKEN_ENDPOINT_URL);
          jwtFile = new CachedFile<>(file, STRING_JSON_VALIDATING_TRANSFORMER, lastModifiedPolicy());
      }
  
      @Override
      public String retrieve() throws JwtRetrieverException {
          if (jwtFile == null)
              throw new IllegalStateException("JWT is null; please call configure() first");
  
          try {
              return jwtFile.transformed();
          } catch (Exception e) {
              throw new JwtRetrieverException(e);
          }
      }
  }
  