//
//  ========================================================================
//  Copyright (c) 1995-2022 Mort Bay Consulting Pty Ltd and others.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.http;

import java.nio.ByteBuffer;

import org.eclipse.jetty.util.ArrayTrie;
import org.eclipse.jetty.util.StringUtil;
import org.eclipse.jetty.util.Trie;

public enum HttpVersion
{
    HTTP_0_9("HTTP/0.9", 9),
    HTTP_1_0("HTTP/1.0", 10),
    HTTP_1_1("HTTP/1.1", 11),
    HTTP_2("HTTP/2.0", 20);

    public static final Trie<HttpVersion> CACHE = new ArrayTrie<HttpVersion>();

    static
    {
        for (HttpVersion version : HttpVersion.values())
        {
            CACHE.put(version.toString(), version);
        }
    }

    /**
     * Optimised lookup to find an Http Version and whitespace in a byte array.
     *
     * @param bytes Array containing ISO-8859-1 characters
     * @param position The first valid index
     * @param limit The first non valid index
     * @return An HttpMethod if a match or null if no easy match.
     */
    public static HttpVersion lookAheadGet(byte[] bytes, int position, int limit)
    {
        int length = limit - position;
        if (length < 9)
            return null;

        if (bytes[position + 4] == '/' && bytes[position + 6] == '.' && Character.isWhitespace((char)bytes[position + 8]) &&
            ((bytes[position] == 'H' && bytes[position + 1] == 'T' && bytes[position + 2] == 'T' && bytes[position + 3] == 'P') ||
                (bytes[position] == 'h' && bytes[position + 1] == 't' && bytes[position + 2] == 't' && bytes[position + 3] == 'p')))
        {
            switch (bytes[position + 5])
            {
                case '1':
                    switch (bytes[position + 7])
                    {
                        case '0':
                            return HTTP_1_0;
                        case '1':
                            return HTTP_1_1;
                    }
                    break;
                case '2':
                    switch (bytes[position + 7])
                    {
                        case '0':
                            return HTTP_2;
                    }
                    break;
            }
        }

        return null;
    }

    /**
     * Optimised lookup to find an HTTP Version and trailing white space in a byte array.
     *
     * @param buffer buffer containing ISO-8859-1 characters
     * @return An HttpVersion if a match or null if no easy match.
     */
    public static HttpVersion lookAheadGet(ByteBuffer buffer)
    {
        if (buffer.hasArray())
            return lookAheadGet(buffer.array(), buffer.arrayOffset() + buffer.position(), buffer.arrayOffset() + buffer.limit());
        return null;
    }

    private final String _string;
    private final byte[] _bytes;
    private final ByteBuffer _buffer;
    private final int _version;

    HttpVersion(String s, int version)
    {
        _string = s;
        _bytes = StringUtil.getBytes(s);
        _buffer = ByteBuffer.wrap(_bytes);
        _version = version;
    }

    public byte[] toBytes()
    {
        return _bytes;
    }

    public ByteBuffer toBuffer()
    {
        return _buffer.asReadOnlyBuffer();
    }

    public int getVersion()
    {
        return _version;
    }

    public boolean is(String s)
    {
        return _string.equalsIgnoreCase(s);
    }

    public String asString()
    {
        return _string;
    }

    @Override
    public String toString()
    {
        return _string;
    }

    /**
     * Case insensitive fromString() conversion
     *
     * @param version the String to convert to enum constant
     * @return the enum constant or null if version unknown
     */
    public static HttpVersion fromString(String version)
    {
        return CACHE.get(version);
    }

    public static HttpVersion fromVersion(int version)
    {
        switch (version)
        {
            case 9:
                return HttpVersion.HTTP_0_9;
            case 10:
                return HttpVersion.HTTP_1_0;
            case 11:
                return HttpVersion.HTTP_1_1;
            case 20:
                return HttpVersion.HTTP_2;
            default:
                throw new IllegalArgumentException();
        }
    }
}
