/**
 * 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.hadoop.hdfsproxy;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.security.PrivilegedExceptionAction;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;

import org.apache.hadoop.hdfs.DFSClient;
import org.apache.hadoop.hdfs.server.namenode.StreamFile;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.conf.Configuration;

/** {@inheritDoc} */
public class ProxyStreamFile extends StreamFile {
  /** For java.io.Serializable */
  private static final long serialVersionUID = 1L;

  /** {@inheritDoc} */
  @Override
  protected DFSClient getDFSClient(HttpServletRequest request)
      throws IOException, InterruptedException {
    ServletContext context = getServletContext();
    final Configuration conf =
        (Configuration) context.getAttribute("name.conf");
    final InetSocketAddress nameNodeAddr =
        (InetSocketAddress) context.getAttribute("name.node.address");

    DFSClient client = getUGI(request, conf).doAs
        ( new PrivilegedExceptionAction<DFSClient>() {
          @Override
          public DFSClient run() throws IOException {
            return new DFSClient(nameNodeAddr, conf);
          }
        });

    return client;
  }

  /** {@inheritDoc} */
  @Override
  protected UserGroupInformation getUGI(HttpServletRequest request,
                                        Configuration conf) {
    String userID = (String) request
        .getAttribute("org.apache.hadoop.hdfsproxy.authorized.userID");
    return ProxyUtil.getProxyUGIFor(userID);
  }

}