/// François-Régis Colin
/// http://www.tls.cena.fr/products/ivy/
/// *
/// (C) CENA
/// *

namespace IvyBus
{
	using System;
	using System.Threading;
	using System.IO;
	using System.Net;
	using System.Net.Sockets;
	using System.Text.RegularExpressions;
	using System.Configuration;
	using System.Text;
    using System.Diagnostics;
    using IvyBus.Properties;
	
	/// <summary> IvyWatcher, A private Class for the Ivy rendezvous
	/// </summary>
	/// <remarks> right now, the rendez vous is either an UDP socket or a TCP multicast.
	/// The watcher will answer to
	/// each peer advertising its arrival on the bus. The intrinsics of Unix are so
	/// that the broadcast is done using the same socket, which is not a good
	/// thing.
	/// </remarks>
	internal class IvyWatcher: IDisposable
	{
		private Ivy bus; /* master bus controler */
		private int port;
		private volatile Thread listenThread;
		private IPAddress group;
        private IvyUDPStream stream;
		
		/// <summary> creates an Ivy watcher
		/// </summary>
		/// <param name='bus'>the bus
		/// </param>
		/// <param name='domainaddr'>the domain
		/// </param>
		/// <param name='port'>the port number
		/// </param>
		internal IvyWatcher(Ivy bus, String domainaddr, int port)
		{
            int multicast_ttl = 64; // region
			this.bus = bus;
			this.port = port;
			listenThread = new Thread(new ThreadStart(this.Run));
			listenThread.Name = "Ivy UDP Listener Thread";
			try
			{
				group = IPAddress.Parse(domainaddr);
                /* supervision socket */
                // To do reuseaddr we must use a Socket not a udp client
                Socket broadcast = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
				IPEndPoint EPhost = new IPEndPoint(IPAddress.Any, port);
				broadcast.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast,true);
				broadcast.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress,true);
				broadcast.Bind(EPhost);
				
				//test isMulticastAddress // TODO better check  
                //if ( group.IsIPv6Multicast ) //yes but in IPV4 how to do
                byte[] addr = group.GetAddressBytes();
                if ((addr[0] & 0xf0) == 0xe0)
				{
					broadcast.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastTimeToLive, multicast_ttl);
                    broadcast.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, new MulticastOption(group));
                    
				}
                // TODO support the Two protocol 
                if (bus.protocolVersion == 4)
                    stream = new IvyUDPStreamV4(broadcast);
                else 
                    stream = new IvyUDPStreamV3(broadcast);
			}
			catch (IOException e)
			{
				throw new IvyException(Resources.WatcherIOError + e);
			}
		}
		
		/// <summary> 
        /// the behaviour of each thread watching the UDP socket.
		/// </summary>
		private void  Run()
		{
            Ivy.traceProtocol(Resources.IvyWatcher, "beginning of a watcher Thread");

            try
            {
                bool running = true;
                while (running)
                {
                    int version;
                    int appPort;
                    string appId;
                    string appName;
                    IPEndPoint remoteEP;

                    stream.receiveMsg(out remoteEP, out version, out appPort, out appId, out appName);
                    IPAddress remotehost = remoteEP.Address;

                    Ivy.traceProtocol(Resources.IvyWatcher, Resources.WatcherReceive + Dns.GetHostEntry(remotehost).HostName + ":" + remoteEP.Port);

                    //TODO if ( !isInDomain( remotehost ) ) continue;

                    if (version != stream.ProtocolVersion)
                    {
                        Ivy.traceError(Resources.IvyWatcher, Resources.BadVersion + version + " expected " + stream.ProtocolVersion);
                        continue;
                    }

                    /* check if we received our own message. SHOULD ALSO TEST THE HOST */
                    if (appId == bus.AppId)
                        continue;
                    if ((appPort == bus.applicationPort) && (remotehost.Equals(bus.applicationHost)))
                        continue;

                    Ivy.traceProtocol(Resources.IvyWatcher, "reponse au Broadcast de " + Dns.GetHostEntry(remotehost).HostName + ":" + remoteEP.Port + " port " + appPort +
                                " version " + version +
                                " id " + appId +
                                " name " + appName);

                    try
                    {
                        Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                        IPEndPoint hostEndPoint = new IPEndPoint(remoteEP.Address, appPort);
                        socket.Blocking = true;
                        socket.Connect(hostEndPoint);
                        IvyClient client = new IvyClient(this.bus, socket, appName, appPort);
                        client.SendBindings();
                    }
                    catch (SocketException e)
                    {
                        Ivy.traceError(Resources.IvyWatcher, Resources.WatcherConnectError + remotehost + " port " + appPort + " \n" + e.Message);
                    }

                } // while
            }
            catch (ObjectDisposedException ex)
            {
                Ivy.traceError(Resources.IvyWatcher, Resources.WatcherSocketClosed + ex.Message);
            }
            catch (SocketException se)
            {
                Ivy.traceError(Resources.IvyWatcher, Resources.WatcherSocketClosed + se.Message);
            }
            catch (IOException ioe)
            {
                Ivy.traceError(Resources.IvyWatcher, Resources.WatcherIOException + ioe.Message);
            }
            Ivy.traceProtocol(Resources.IvyWatcher, "end of a watcher thread");
		}
		
		/// <summary> stops the thread waiting on the broadcast socket
		/// </summary>
		internal virtual void  stop()
		{
            lock (stream)
			{
                Ivy.traceProtocol(Resources.IvyWatcher, "begining stopping an IvyWatcher");
				stream.Close();
				if (listenThread != null)
				{
                    // Wait for Thread to end.
                    bool term = listenThread.Join(10000);
                    if (!term && (listenThread != null)) listenThread.Abort();
					listenThread = null;
				}
				// it might not even have been created
                Ivy.traceProtocol(Resources.IvyWatcher, "ending stopping an IvyWatcher");
			}
		}
		/// <summary>
		/// send the boradcst message on all domains
		/// </summary>
		internal virtual void  start()
		{
            lock (stream)
			{
				listenThread.Start();
                IPEndPoint EPhost = new IPEndPoint(group, port);
                stream.sendMsg(EPhost, bus.applicationPort, bus.AppId, bus.AppName);// notifies our arrival on each domain: protocol version + port
			}
		}


        #region IDisposable Membres

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
            {
                // Free other state (managed objects).
                if (stream != null)
                {
                    stream.Close();
                    stream = null;
                }
            }
            // Free your own state (unmanaged objects).
            // Set large fields to null.
            
        }

        #endregion
    }
}