/*
    * ====================================================================
    * 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.http.client.protocol;
  
  import java.io.IOException;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.http.annotation.Immutable;
  
  import org.apache.http.HttpException;
  import org.apache.http.HttpRequest;
  import org.apache.http.HttpRequestInterceptor;
  import org.apache.http.conn.HttpRoutedConnection;
  import org.apache.http.conn.routing.HttpRoute;
  import org.apache.http.protocol.ExecutionContext;
  import org.apache.http.protocol.HTTP;
  import org.apache.http.protocol.HttpContext;
  
  /**
   * This protocol interceptor is responsible for adding <code>Connection</code>
   * or <code>Proxy-Connection</code> headers to the outgoing requests, which
   * is essential for managing persistence of <code>HTTP/1.0</code> connections.
   *
   * @since 4.0
   */
  @Immutable
  public class RequestClientConnControl implements HttpRequestInterceptor {
  
      private final Log log = LogFactory.getLog(getClass());
  
      private static final String PROXY_CONN_DIRECTIVE = "Proxy-Connection";
  
      public RequestClientConnControl() {
          super();
      }
  
      public void process(final HttpRequest request, final HttpContext context)
              throws HttpException, IOException {
          if (request == null) {
              throw new IllegalArgumentException("HTTP request may not be null");
          }
  
          String method = request.getRequestLine().getMethod();
          if (method.equalsIgnoreCase("CONNECT")) {
              request.setHeader(PROXY_CONN_DIRECTIVE, HTTP.CONN_KEEP_ALIVE);
              return;
          }
  
          // Obtain the client connection (required)
          HttpRoutedConnection conn = (HttpRoutedConnection) context.getAttribute(
                  ExecutionContext.HTTP_CONNECTION);
          if (conn == null) {
              this.log.debug("HTTP connection not set in the context");
              return;
          }
  
          HttpRoute route = conn.getRoute();
  
          if (route.getHopCount() == 1 || route.isTunnelled()) {
              if (!request.containsHeader(HTTP.CONN_DIRECTIVE)) {
                  request.addHeader(HTTP.CONN_DIRECTIVE, HTTP.CONN_KEEP_ALIVE);
              }
          }
          if (route.getHopCount() == 2 && !route.isTunnelled()) {
              if (!request.containsHeader(PROXY_CONN_DIRECTIVE)) {
                  request.addHeader(PROXY_CONN_DIRECTIVE, HTTP.CONN_KEEP_ALIVE);
              }
          }
      }
  
  }