/*
    * ====================================================================
    * 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 java.util.Locale;
  
  import org.apache.http.Header;
  import org.apache.http.HeaderElement;
  import org.apache.http.HttpEntity;
  import org.apache.http.HttpException;
  import org.apache.http.HttpResponse;
  import org.apache.http.HttpResponseInterceptor;
  import org.apache.http.annotation.Contract;
  import org.apache.http.annotation.ThreadingBehavior;
  import org.apache.http.client.config.RequestConfig;
  import org.apache.http.client.entity.DecompressingEntity;
  import org.apache.http.client.entity.DeflateInputStreamFactory;
  import org.apache.http.client.entity.GZIPInputStreamFactory;
  import org.apache.http.client.entity.InputStreamFactory;
  import org.apache.http.config.Lookup;
  import org.apache.http.config.RegistryBuilder;
  import org.apache.http.protocol.HttpContext;
  
  /**
   * {@link HttpResponseInterceptor} responsible for processing Content-Encoding
   * responses.
   * <p>
   * Instances of this class are stateless and immutable, therefore threadsafe.
   *
   * @since 4.1
   *
   */
  @Contract(threading = ThreadingBehavior.IMMUTABLE_CONDITIONAL)
  public class ResponseContentEncoding implements HttpResponseInterceptor {
  
      public static final String UNCOMPRESSED = "http.client.response.uncompressed";
  
      private final Lookup<InputStreamFactory> decoderRegistry;
      private final boolean ignoreUnknown;
  
      /**
       * @since 4.5
       */
      public ResponseContentEncoding(final Lookup<InputStreamFactory> decoderRegistry, final boolean ignoreUnknown) {
          this.decoderRegistry = decoderRegistry != null ? decoderRegistry :
              RegistryBuilder.<InputStreamFactory>create()
                      .register("gzip", GZIPInputStreamFactory.getInstance())
                      .register("x-gzip", GZIPInputStreamFactory.getInstance())
                      .register("deflate", DeflateInputStreamFactory.getInstance())
                      .build();
          this.ignoreUnknown = ignoreUnknown;
      }
  
      /**
       * @since 4.5
       */
      public ResponseContentEncoding(final boolean ignoreUnknown) {
          this(null, ignoreUnknown);
      }
  
      /**
       * @since 4.4
       */
      public ResponseContentEncoding(final Lookup<InputStreamFactory> decoderRegistry) {
          this(decoderRegistry, true);
      }
  
      /**
       * Handles {@code gzip} and {@code deflate} compressed entities by using the following
       * decoders:
       * <ul>
       * <li>gzip - see {@link java.util.zip.GZIPInputStream}</li>
       * <li>deflate - see {@link org.apache.http.client.entity.DeflateInputStream}</li>
       * </ul>
      */
     public ResponseContentEncoding() {
         this(null);
     }
 
     @Override
     public void process(
             final HttpResponse response,
             final HttpContext context) throws HttpException, IOException {
         final HttpEntity entity = response.getEntity();
 
         final HttpClientContext clientContext = HttpClientContext.adapt(context);
         final RequestConfig requestConfig = clientContext.getRequestConfig();
         // entity can be null in case of 304 Not Modified, 204 No Content or similar
         // check for zero length entity.
         if (requestConfig.isContentCompressionEnabled() && entity != null && entity.getContentLength() != 0) {
             final Header ceheader = entity.getContentEncoding();
             if (ceheader != null) {
                 final HeaderElement[] codecs = ceheader.getElements();
                 for (final HeaderElement codec : codecs) {
                     final String codecname = codec.getName().toLowerCase(Locale.ROOT);
                     final InputStreamFactory decoderFactory = decoderRegistry.lookup(codecname);
                     if (decoderFactory != null) {
                         response.setEntity(new DecompressingEntity(response.getEntity(), decoderFactory));
                         response.removeHeaders("Content-Length");
                         response.removeHeaders("Content-Encoding");
                         response.removeHeaders("Content-MD5");
                     } else {
                         if (!"identity".equals(codecname) && !ignoreUnknown) {
                             throw new HttpException("Unsupported Content-Encoding: " + codec.getName());
                         }
                     }
                 }
             }
         }
     }
 
 }