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.ambari.server.state.kerberos;
  
  import java.io.File;
  import java.io.FileReader;
  import java.io.IOException;
  import java.util.Collections;
  import java.util.Map;
  
  import org.apache.ambari.server.AmbariException;
  
  import com.google.gson.Gson;
  import com.google.gson.JsonSyntaxException;
  import com.google.gson.reflect.TypeToken;
  
  /**
   * AbstractKerberosDescriptorFactory is an abstract class containing common functionality for
   * Kerberos descriptor factory classes.
   */
  abstract class AbstractKerberosDescriptorFactory {
  
    /**
     * Parses a file containing JSON-formatted text into a (generic) Map.
     *
     * @param file a File containing the JSON-formatted text to parse
     * @return a Map of the data
     * @throws java.io.FileNotFoundException            if the specified File does not point to a valid file
     * @throws java.io.IOException                      if the specified File is not a readable file
     * @throws org.apache.ambari.server.AmbariException if the specified File does not contain valid JSON data
     */
    protected Map<String, Object> parseFile(File file) throws IOException {
      if (file == null) {
        return Collections.emptyMap();
      } else if (!file.isFile() || !file.canRead()) {
        throw new IOException(String.format("%s is not a readable file", file.getAbsolutePath()));
      } else {
        try {
          return new Gson().fromJson(new FileReader(file),
              new TypeToken<Map<String, Object>>() {
              }.getType());
        } catch (JsonSyntaxException e) {
          throw new AmbariException(String.format("Failed to parse JSON-formatted file: %s", file.getAbsolutePath()), e);
        }
      }
    }
  
    /**
     * Parses a JSON-formatted String into a (generic) Map.
     *
     * @param json a String containing the JSON-formatted text to parse
     * @return a Map of the data
     * @throws AmbariException if an error occurs while parsing the JSON-formatted String
     */
    protected Map<String, Object> parseJSON(String json) throws AmbariException {
      if ((json == null) || json.isEmpty()) {
        return Collections.emptyMap();
      } else {
        try {
          return new Gson().fromJson(json,
              new TypeToken<Map<String, Object>>() {
              }.getType());
        } catch (JsonSyntaxException e) {
          throw new AmbariException("Failed to parse JSON-formatted string", e);
        }
      }
    }
  }
  