/*
    * ====================================================================
    * 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.protocol;
  
  import java.io.IOException;
  
  import org.apache.http.HttpEntity;
  import org.apache.http.HttpEntityEnclosingRequest;
  import org.apache.http.HttpException;
  import org.apache.http.HttpRequest;
  import org.apache.http.HttpRequestInterceptor;
  import org.apache.http.HttpVersion;
  import org.apache.http.ProtocolVersion;
  import org.apache.http.annotation.Immutable;
  import org.apache.http.params.CoreProtocolPNames;
  import org.apache.http.util.Args;
  
  /**
   * RequestExpectContinue is responsible for enabling the 'expect-continue'
   * handshake by adding <code>Expect</code> header. This interceptor is
   * recommended for client side protocol processors.
   *
   * @since 4.0
   */
  @Immutable
  @SuppressWarnings("deprecation")
  public class RequestExpectContinue implements HttpRequestInterceptor {
  
      public RequestExpectContinue() {
          super();
      }
  
      public void process(final HttpRequest request, final HttpContext context)
              throws HttpException, IOException {
          Args.notNull(request, "HTTP request");
  
          if (!request.containsHeader(HTTP.EXPECT_DIRECTIVE)) {
              if (request instanceof HttpEntityEnclosingRequest) {
                  final ProtocolVersion ver = request.getRequestLine().getProtocolVersion();
                  final HttpEntity entity = ((HttpEntityEnclosingRequest)request).getEntity();
                  // Do not send the expect header if request body is known to be empty
                  if (entity != null
                          && entity.getContentLength() != 0 && !ver.lessEquals(HttpVersion.HTTP_1_0)) {
                      final Boolean b = (Boolean) request.getParams().getParameter(
                              CoreProtocolPNames.USE_EXPECT_CONTINUE);
                      if (b == null || b.booleanValue() == true) {
                          request.addHeader(HTTP.EXPECT_DIRECTIVE, HTTP.EXPECT_CONTINUE);
                      }
                  }
              }
          }
      }
  
  }