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
   * <p/>
   * http://www.apache.org/licenses/LICENSE-2.0
   * <p/>
   * 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.controller.internal;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.lang.reflect.Type;
  import java.util.Map;
  
  import org.apache.ambari.server.controller.spi.Resource;
  import org.apache.ambari.server.controller.spi.SystemException;
  import org.apache.commons.io.IOUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.google.gson.Gson;
  import com.google.gson.reflect.TypeToken;
  
  /**
   * Represents an HTTP request to another server for properties to be used to populate an Ambari resource.
   * The server response is expected to be JSON that can be deserialized into a <code>Map<String, Object>></code>
   * instance.
   */
  public abstract class JsonHttpPropertyRequest extends HttpPropertyProvider.HttpPropertyRequest {
    private static final Logger LOG = LoggerFactory.getLogger(JsonHttpPropertyRequest.class);
  
    private static final Type MAP_TYPE = new TypeToken<Map<String, Object>>() {}.getType();
  
    private static final Gson GSON = new Gson();
  
  
    // ----- Constructors ----------------------------------------------------
  
    /**
     * Create a property request.
     *
     * @param propertyMappings  the property name mapping
     */
    public JsonHttpPropertyRequest(Map<String, String> propertyMappings) {
      super(propertyMappings);
    }
  
  
    // ----- PropertyRequest -------------------------------------------------
  
    @Override
    public void populateResource(Resource resource, InputStream inputStream) throws SystemException {
  
      try {
        Map<String, Object> responseMap = GSON.fromJson(IOUtils.toString(inputStream, "UTF-8"), MAP_TYPE);
        if (responseMap == null){
          LOG.error("Properties map from HTTP response is null");
        }
        for (Map.Entry<String, String> entry : getPropertyMappings().entrySet()) {
          Object propertyValueToSet = getPropertyValue(responseMap, entry.getKey());
          resource.setProperty(entry.getValue(), propertyValueToSet);
        }
      } catch (IOException e) {
        throw new SystemException("Error setting properties.", e);
      }
    }
  
  
    // ----- helper methods --------------------------------------------------
  
    // get the property value from the response map for the given property name
    private Object getPropertyValue(Map<String, Object> responseMap, String property) throws SystemException {
      if (property == null || responseMap == null) {
        return null;
      }
  
      Object result = responseMap;
  
      try {
        for (String key : property.split("/")) {
          result = ((Map) result).get(key);
        }
      } catch (ClassCastException e) {
        String msg = String.format("Error getting property value for %s.", property);
        LOG.error(msg, e);
        throw new SystemException(msg, e);
      }
      return result;
    }
  }
  