/*
 * ====================================================================
 *
 *  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 ch.boye.httpclientandroidlib.client.protocol;

import java.io.IOException;

import ch.boye.httpclientandroidlib.HttpException;
import ch.boye.httpclientandroidlib.HttpRequest;
import ch.boye.httpclientandroidlib.HttpRequestInterceptor;
import ch.boye.httpclientandroidlib.annotation.Immutable;
import ch.boye.httpclientandroidlib.protocol.HttpContext;

/**
 * Class responsible for handling Content Encoding requests in HTTP.
 * <p>
 * Instances of this class are stateless, therefore they're thread-safe and immutable.
 *
 * @see "http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.5"
 *
 * @since 4.1
 */
@Immutable
public class RequestAcceptEncoding implements HttpRequestInterceptor {

    /**
     * Adds the header {@code "Accept-Encoding: gzip,deflate"} to the request.
     */
    public void process(
            final HttpRequest request,
            final HttpContext context) throws HttpException, IOException {

        /* Signal support for Accept-Encoding transfer encodings. */
        if (!request.containsHeader("Accept-Encoding")) {
            request.addHeader("Accept-Encoding", "gzip,deflate");
        } 
    }

}
