/*
 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/HttpVersion.java $
 * $Revision: 609106 $
 * $Date: 2008-01-05 01:15:42 -0800 (Sat, 05 Jan 2008) $
 *
 * ====================================================================
 * 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;

import java.io.Serializable;

/**
 * Represents an HTTP version, as specified in RFC 2616.
 * 
 * @author <a href="mailto:oleg@ural.ru">Oleg Kalnichevski</a>
 * 
 * @version $Revision: 609106 $ $Date: 2008-01-05 01:15:42 -0800 (Sat, 05 Jan 2008) $
 */
public final class HttpVersion extends ProtocolVersion
    implements Serializable {

    private static final long serialVersionUID = -5856653513894415344L;

    /** The protocol name. */
    public static final String HTTP = "HTTP";
    
    /** HTTP protocol version 0.9 */
    public static final HttpVersion HTTP_0_9 = new HttpVersion(0, 9);  

    /** HTTP protocol version 1.0 */
    public static final HttpVersion HTTP_1_0 = new HttpVersion(1, 0);  

    /** HTTP protocol version 1.1 */
    public static final HttpVersion HTTP_1_1 = new HttpVersion(1, 1);  

    
    /**
     * Create an HTTP protocol version designator.
     *
     * @param major   the major version number of the HTTP protocol
     * @param minor   the minor version number of the HTTP protocol
     * 
     * @throws IllegalArgumentException if either major or minor version number is negative
     */
    public HttpVersion(int major, int minor) {
        super(HTTP, major, minor);
    }


    /**
     * Obtains a specific HTTP version.
     *
     * @param major     the major version
     * @param minor     the minor version
     *
     * @return  an instance of {@link HttpVersion} with the argument version
     */
    public ProtocolVersion forVersion(int major, int minor) {

        if ((major == this.major) && (minor == this.minor)) {
            return this;
        }

        if (major == 1) {
            if (minor == 0) {
                return HTTP_1_0;
            }
            if (minor == 1) {
                return HTTP_1_1;
            }
        }
        if ((major == 0) && (minor == 9)) {
            return HTTP_0_9;
        }

        // argument checking is done in the constructor
        return new HttpVersion(major, minor);
    }

}