/// 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;
	
	/// <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
	{
		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)
		{
			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,1);
				broadcast.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress,1);
				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.Udp, 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("IvyWatcher I/O error" + e);
			}
		}
		
		/// <summary> the behaviour of each thread watching the UDP socket.
		/// </summary>
		public void  Run()
		{
			traceDebug("beginning of a watcher Thread");
			
			try
			{
				bool running = true;
				while (running)
				{
                    ushort version;
                    ushort appPort;
                    string appId;
                    string appName;
                    IPEndPoint remoteEP;

                    stream.receiveMsg(out remoteEP, out version, out appPort, out appId, out appName);
                    IPAddress remotehost = remoteEP.Address;
                    traceDebug("BUSWATCHER Receive Broadcast from " + Dns.GetHostEntry(remotehost).HostName + ":" + remoteEP.Port);

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

                    if (version != stream.ProtocolVersion)
                    {
                        traceDebug("Ignoring bad protocol version " + version + " expected " + stream.ProtocolVersion);
                        continue;
                    }

                    // filtrage des self Broadcast 
                    if (appId == bus.AppId)
                        continue;
                    if ((appPort == bus.applicationPort) && (remotehost.Equals(bus.applicationHost)))
                        continue;
                    traceDebug("BUSWATCHER 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.Connect(hostEndPoint);
                        bus.addClient(socket, appName);
                    }
                    catch (Exception e)
                    {
                        traceDebug("can't connect to " + remotehost + " port " + appPort + " \n" + e.Message);
                    }
					
				} // while
			}
			catch (SocketException se)
			{
                traceDebug("watcher socket closed: " + se.Message);
			}
			catch (IOException ioe)
			{
                traceDebug("watcher thread ended: " + ioe.Message);
			}
            traceDebug("end of a watcher thread");
		}
		
		/// <summary> stops the thread waiting on the broadcast socket
		/// </summary>
		internal virtual void  stop()
		{
            lock (stream)
			{
                traceDebug("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
                traceDebug("ending stopping an IvyWatcher");
			}
		}
		
		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
			}
		}
		
		
		internal static String getDomain(string net)
		{
			int sep_index = net.LastIndexOf(":");
			if (sep_index != - 1)
			{
				net = net.Substring(0, (sep_index) - (0));
			}
			try
			{
				net += ".255.255.255";
				Regex exp = new Regex("^(\\d+\\.\\d+\\.\\d+\\.\\d+).*");
				net = exp.Replace(net, "$1");
			}
			catch (ArgumentException e)
			{
                traceDebug("Bad broascat addr " + net + "error " + e.Message);
				return null;
			}
			return net;
		}
		
		internal static int getPort(string net)
		{
            if (net == null) return Ivy.DEFAULT_PORT;
			int sep_index = net.LastIndexOf(":");
			int port = (sep_index == - 1)?Ivy.DEFAULT_PORT:Int32.Parse(net.Substring(sep_index + 1));
            return port;
        }
        [Conditional("DEBUG")]
        private static void traceDebug(string s)
        {
            Trace.Assert(!Ivy.VerboseDebug, "-->ivywatcher<-- " + s);
        }
		
	}
	// class IvyWatcher
	/* EOF */
}