package org.apache.helix.webapp.resources;
   
   /*
    * 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.
   */
  
  import java.util.List;
  
  import org.apache.helix.ZNRecord;
  import org.apache.helix.manager.zk.ZkClient;
  import org.apache.helix.webapp.RestAdminApplication;
  import org.apache.log4j.Logger;
  import org.apache.zookeeper.data.Stat;
  import org.restlet.Context;
  import org.restlet.data.MediaType;
  import org.restlet.data.Request;
  import org.restlet.data.Response;
  import org.restlet.data.Status;
  import org.restlet.resource.Representation;
  import org.restlet.resource.Resource;
  import org.restlet.resource.StringRepresentation;
  import org.restlet.resource.Variant;
  
  
  public class ZkChildResource extends Resource
  {
    private final static Logger LOG = Logger.getLogger(ZkChildResource.class);
  
    public ZkChildResource(Context context, Request request, Response response)
    {
      super(context, request, response);
      getVariants().add(new Variant(MediaType.TEXT_PLAIN));
      getVariants().add(new Variant(MediaType.APPLICATION_JSON));
    }
  
    @Override
    public boolean allowGet()
    {
      return true;
    }
  
    @Override
    public boolean allowPost()
    {
      return false;
    }
  
    @Override
    public boolean allowPut()
    {
      return false;
    }
  
    @Override
    public boolean allowDelete()
    {
      return true;
    }
  
    private String getZKPath()
    {
      String relativeRef = getRequest().getResourceRef().getRelativeRef().toString();
      if (relativeRef.equals("."))
      {
        relativeRef = "";
      }
  
      // strip off trailing "/"
      while (relativeRef.endsWith("/"))
      {
        relativeRef = relativeRef.substring(0, relativeRef.length() - 1);
      }
  
      return "/" + relativeRef;
    }
  
    @Override
    public Representation represent(Variant variant)
    {
      StringRepresentation presentation = null;
      String zkPath = getZKPath();
  
      try
      {
       ZkClient zkClient =
           (ZkClient) getContext().getAttributes().get(RestAdminApplication.ZKCLIENT);
       ZNRecord result = readZkChild(zkPath, zkClient);
 
       presentation =
           new StringRepresentation(ClusterRepresentationUtil.ZNRecordToJson(result),
                                    MediaType.APPLICATION_JSON);
     }
     catch (Exception e)
     {
       String error = ClusterRepresentationUtil.getErrorAsJsonStringFromException(e);
       presentation = new StringRepresentation(error, MediaType.APPLICATION_JSON);
 
       LOG.error("Error in read zkPath: " + zkPath, e);
     }
 
     return presentation;
   }
 
   private ZNRecord readZkChild(String zkPath, ZkClient zkClient)
   {
     ZNRecord result = null;
 
     // read data and stat
     Stat stat = new Stat();
     ZNRecord data = zkClient.readDataAndStat(zkPath, stat, true);
     if (data != null)
     {
       result = data;
     }
     else
     {
       result = new ZNRecord("");
     }
 
     // read childrenList
     List<String> children = zkClient.getChildren(zkPath);
     if (children != null && children.size() > 0)
     {
       result.setSimpleField("numChildren", "" + children.size());
       result.setListField("childrenList", children);
     } else
     {
       result.setSimpleField("numChildren", "" + 0);
     }
     return result;
   }
 
   @Override
   public void removeRepresentations()
   {
     String zkPath = getZKPath();
     try
     {
       ZkClient zkClient =
           (ZkClient) getContext().getAttributes().get(RestAdminApplication.ZKCLIENT);
       
       List<String> childNames = zkClient.getChildren(zkPath);
       if (childNames != null)
       {
         for (String childName : childNames)
         {
           String childPath = zkPath.equals("/")? "/" + childName : zkPath + "/" + childName;
           zkClient.deleteRecursive(childPath);
         }
       }
       
       getResponse().setStatus(Status.SUCCESS_OK);
     }
     catch (Exception e)
     {
       getResponse().setEntity(ClusterRepresentationUtil.getErrorAsJsonStringFromException(e),
                               MediaType.APPLICATION_JSON);
       getResponse().setStatus(Status.SUCCESS_OK);
       LOG.error("Error in delete zkChild: " + zkPath, e);
     }
   }
 }