//
// UdpTrackerMessage.cs
//
// Authors:
//   Alan McGovern alan.mcgovern@gmail.com
//
// Copyright (C) 2008 Alan McGovern
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//



namespace MonoTorrent.Client.Messages.UdpTracker
{
    using System;
    using System.Collections.Generic;
    using System.Text;
    using MonoTorrent.Client.Tracker;

    public abstract class UdpTrackerMessage : Message
    {
        private int action;
        private int transactionId;

        public int Action
        {
            get { return action; }
        }

        public int TransactionId
        {
            get { return transactionId; }
            protected set { transactionId = value; }
        }

        public UdpTrackerMessage(int action, int transactionId)
        {
            this.action = action;
            this.transactionId = transactionId;
        }

        public static UdpTrackerMessage DecodeMessage(byte[] buffer, int offset, int count, MessageType type)
        {
            UdpTrackerMessage m = null;
            int action = type == MessageType.Request ? ReadInt(buffer, offset + 8) : ReadInt(buffer, offset);
            switch (action)
            {
                case 0:
                    if (type == MessageType.Request)
                        m = new ConnectMessage();
                    else
                        m = new ConnectResponseMessage();
                    break;
                case 1:
                    if (type == MessageType.Request)
                        m = new AnnounceMessage();
                    else
                        m = new AnnounceResponseMessage();
                    break;
                case 2:
                    if (type == MessageType.Request)
                        m = new ScrapeMessage();
                    else
                        m = new ScrapeResponseMessage();
                    break;
                case 3:
                    m = new ErrorMessage();
                    break;
                default:
                    throw new ProtocolException(string.Format("Invalid udp message received: {0}", buffer[offset]));
            }

            try
            {
                m.Decode(buffer, offset, count);
            }
            catch
            {
                m = new ErrorMessage(0, "Couldn't decode the tracker response");
            }
            return m;
        }

        protected static void ThrowInvalidActionException()
        {
            throw new MessageException("Invalid value for 'Action'");
        }
    }
}
