/*
    * ====================================================================
    * 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.impl.client;
  
  import java.io.IOException;
  import java.net.URI;
  
  import org.apache.http.HttpEntity;
  import org.apache.http.HttpEntityEnclosingRequest;
  import org.apache.http.HttpException;
  import org.apache.http.HttpHost;
  import org.apache.http.HttpRequest;
  import org.apache.http.HttpRequestInterceptor;
  import org.apache.http.HttpResponse;
  import org.apache.http.HttpResponseInterceptor;
  import org.apache.http.client.ClientProtocolException;
  import org.apache.http.client.HttpClient;
  import org.apache.http.client.ResponseHandler;
  import org.apache.http.client.methods.HttpUriRequest;
  import org.apache.http.client.protocol.RequestAcceptEncoding;
  import org.apache.http.client.protocol.ResponseContentEncoding;
  import org.apache.http.client.utils.URIUtils;
  import org.apache.http.conn.ClientConnectionManager;
  import org.apache.http.params.HttpParams;
  import org.apache.http.protocol.BasicHttpContext;
  import org.apache.http.protocol.HttpContext;
  import org.apache.http.util.EntityUtils;
  
  /**
   * <p>Decorator adding support for compressed responses. This class sets
   * the <code>Accept-Encoding</code> header on requests to indicate
   * support for the <code>gzip</code> and <code>deflate</code>
   * compression schemes; it then checks the <code>Content-Encoding</code>
   * header on the response to uncompress any compressed response bodies.
   * The {@link java.io.InputStream} of the entity will contain the uncompressed
   * content.</p>
   * 
   * <p><b>N.B.</b> Any upstream clients of this class need to be aware that
   * this effectively obscures visibility into the length of a server
   * response body, since the <code>Content-Length</code> header will
   * correspond to the compressed entity length received from the server,
   * but the content length experienced by reading the response body may
   * be different (hopefully higher!).</p>
   * 
   * <p>That said, this decorator is compatible with the 
   * <code>CachingHttpClient</code> in that the two decorators can be added 
   * in either order and still have cacheable responses be cached.</p> 
   * 
   * @since 4.2
   */
  public class DecompressingHttpClient implements HttpClient {
  
      private HttpClient backend;
      private HttpRequestInterceptor acceptEncodingInterceptor;
      private HttpResponseInterceptor contentEncodingInterceptor;
      
      /**
       * Constructs a decorator to ask for and handle compressed
       * entities on the fly.
       * @param backend the {@link HttpClient} to use for actually
       *   issuing requests
       */
      public DecompressingHttpClient(HttpClient backend) {
          this(backend, new RequestAcceptEncoding(), new ResponseContentEncoding());
      }
      
      DecompressingHttpClient(HttpClient backend, 
              HttpRequestInterceptor requestInterceptor, 
              HttpResponseInterceptor responseInterceptor) {
          this.backend = backend;
          this.acceptEncodingInterceptor = requestInterceptor;
          this.contentEncodingInterceptor = responseInterceptor;
      }
  
      public HttpParams getParams() {
          return backend.getParams();
     }
 
     public ClientConnectionManager getConnectionManager() {
         return backend.getConnectionManager();
     }
 
     public HttpResponse execute(HttpUriRequest request) throws IOException,
             ClientProtocolException {
         return execute(getHttpHost(request), request, (HttpContext)null);
     }
 
     HttpHost getHttpHost(HttpUriRequest request) {
         URI uri = request.getURI();
         return URIUtils.extractHost(uri);
     }
 
     public HttpResponse execute(HttpUriRequest request, HttpContext context)
             throws IOException, ClientProtocolException {
         return execute(getHttpHost(request), request, context);
     }
 
     public HttpResponse execute(HttpHost target, HttpRequest request)
             throws IOException, ClientProtocolException {
         return execute(target, request, (HttpContext)null);
     }
 
     public HttpResponse execute(HttpHost target, HttpRequest request,
             HttpContext context) throws IOException, ClientProtocolException {
         try {
             if (context == null) context = new BasicHttpContext();
             HttpRequest wrapped;
             if (request instanceof HttpEntityEnclosingRequest) {
                 wrapped = new EntityEnclosingRequestWrapper((HttpEntityEnclosingRequest) request);
             } else {
                 wrapped = new RequestWrapper(request);
             }
             acceptEncodingInterceptor.process(wrapped, context);
             HttpResponse response = backend.execute(target, wrapped, context);
             try {
                 contentEncodingInterceptor.process(response, context);
                 if (Boolean.TRUE.equals(context.getAttribute(ResponseContentEncoding.UNCOMPRESSED))) {
                     response.removeHeaders("Content-Length");
                     response.removeHeaders("Content-Encoding");
                     response.removeHeaders("Content-MD5");
                 }
                 return response;
             } catch (HttpException ex) {
                 EntityUtils.consume(response.getEntity());
                 throw ex;
             } catch (IOException ex) {
                 EntityUtils.consume(response.getEntity());
                 throw ex;
             } catch (RuntimeException ex) {
                 EntityUtils.consume(response.getEntity());
                 throw ex;
             }
         } catch (HttpException e) {
             throw new ClientProtocolException(e);
         }
     }
 
     public <T> T execute(HttpUriRequest request,
             ResponseHandler<? extends T> responseHandler) throws IOException,
             ClientProtocolException {
         return execute(getHttpHost(request), request, responseHandler);
     }
 
     public <T> T execute(HttpUriRequest request,
             ResponseHandler<? extends T> responseHandler, HttpContext context)
             throws IOException, ClientProtocolException {
         return execute(getHttpHost(request), request, responseHandler, context);
     }
 
     public <T> T execute(HttpHost target, HttpRequest request,
             ResponseHandler<? extends T> responseHandler) throws IOException,
             ClientProtocolException {
         return execute(target, request, responseHandler, null);
     }
 
     public <T> T execute(HttpHost target, HttpRequest request,
             ResponseHandler<? extends T> responseHandler, HttpContext context)
             throws IOException, ClientProtocolException {
         HttpResponse response = execute(target, request, context);
         try {
             return responseHandler.handleResponse(response);
         } finally {
             HttpEntity entity = response.getEntity();
             if (entity != null) EntityUtils.consume(entity);
         }
     }
 
 }