/*

 * ====================================================================

 * 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.HttpException;

import org.apache.http.HttpResponse;

import org.apache.http.HttpResponseInterceptor;

import org.apache.http.HttpStatus;



/**

 * ResponseDate is responsible for adding <code>Date<c/ode> header to the 

 * outgoing responses. This interceptor is recommended for server side protocol 

 * processors.

 * 

 * @since 4.0

 */

public class ResponseDate implements HttpResponseInterceptor {



    private static final HttpDateGenerator DATE_GENERATOR = new HttpDateGenerator(); 

    

    public ResponseDate() {

        super();

    }



    public void process(final HttpResponse response, final HttpContext context) 

            throws HttpException, IOException {

        if (response == null) {

            throw new IllegalArgumentException

                ("HTTP response may not be null.");

        }

        int status = response.getStatusLine().getStatusCode();

        if ((status >= HttpStatus.SC_OK) &&

            !response.containsHeader(HTTP.DATE_HEADER)) {

            String httpdate = DATE_GENERATOR.getCurrentDate();

            response.setHeader(HTTP.DATE_HEADER, httpdate); 

        }

    }

    

}