/// 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;
	
	/// <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 bool isMulticastAddress = false;
		private Ivy bus; /* master bus controler */
		private Socket broadcast; /* supervision socket */// To do reuseaddr we must use a Socket not a udp client
		private String domainaddr;
		private int port;
		private volatile Thread listenThread;
		private IPAddress group;
		
		/// <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.domainaddr = domainaddr;
			this.port = port;
			listenThread = new Thread(new ThreadStart(this.Run));
			// create the MulticastSocket
			try
			{
				group = Dns.GetHostByName(domainaddr).AddressList[0];
				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.Address & 0xf0000000) == 0xe0000000)
				{
					isMulticastAddress = true;
					broadcast.SetSocketOption(SocketOptionLevel.Udp, SocketOptionName.AddMembership, new MulticastOption( group ));					
				}
			}
			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");
			byte[] buf = new byte[4096];
			int len;
			IPEndPoint remoteEP =  new IPEndPoint(IPAddress.Any, 0);
			EndPoint tempRemoteEP = (EndPoint)remoteEP;

			remoteEP = null;
			try
			{
				bool running = true;
				while (running)
				{
					int port;
					try
					{
						len = broadcast.ReceiveFrom(buf, ref tempRemoteEP);
						// I was summoned to leave during the receive
						String msg = Encoding.ASCII.GetString(buf);
						remoteEP = (IPEndPoint)tempRemoteEP;
						IPAddress remotehost = remoteEP.Address;
						traceDebug("BUSWATCHER Receive Broadcast from " + Dns.GetHostName() + ":" + remoteEP.Port);
						// TODO if ( !isInDomain( remotehost ) ) continue;
						String[] st = msg.Split(new char[]{' ','\n'},3);
						if (st.Length != 3)
						{
							Console.Error.WriteLine("Bad format " + msg);
							continue;
						}
						
						int version = Int32.Parse(st[0]);
						port = Int32.Parse(st[1]);
						if (version != Ivy.PROCOCOLVERSION)
						{
							Console.Error.WriteLine("Ignoring bad protocol version broadcast");
							continue;
						}
						
						if ((bus.applicationPort == port))
							continue;
						traceDebug("BUSWATCHER Broadcast de " + Dns.GetHostName() + ":" + remoteEP.Port + " port " + port + " version " + version);
						try
						{
							MyTcpClient socket = new MyTcpClient(remoteEP.Address.ToString(),port);
							bus.addClient(socket);
						}
						catch (Exception e)
						{
							Console.Error.WriteLine("can't connect to " + remotehost + " port " + port + " \n"+ e.Message);
						}
					}
					catch (IOException jii)
					{
						running = false;
					}
				} // while
			}
			catch (SocketException se)
			{
				traceDebug( "watcher socket closed" );
			}
			catch (IOException ioe)
			{
				Console.Error.WriteLine( ioe.StackTrace );
			}
			traceDebug("end of a watcher thread");
		}
		
		/// <summary> stops the thread waiting on the broadcast socket
		/// </summary>
		internal virtual void  stop()
		{
			lock(this)
			{
				traceDebug("begining stopping an IvyWatcher");
				Thread t = listenThread;
				listenThread = null;
				broadcast.Close();
				if (t != null)
				{
					t.Interrupt();
				}
				// it might not even have been created
				traceDebug("ending stopping an IvyWatcher");
			}
		}
		
		internal virtual void  start()
		{
			lock(this)
			{
				String hello = Ivy.PROCOCOLVERSION + " " + bus.applicationPort + "\n";
				listenThread.Start();
				byte[] hellob = Encoding.ASCII.GetBytes( hello );
				IPEndPoint EPhost = new IPEndPoint(group, port);
				broadcast.SendTo(hellob,0,EPhost); // 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)
			{
				Console.Out.WriteLine("Bad broascat addr " + net);
				return null;
			}
			// out.println("net: "+net);
			return net;
		}
		
		internal static int getPort(String net)
		{
			int sep_index = net.LastIndexOf(":");
			int port = (sep_index == - 1)?Ivy.DEFAULT_PORT:Int32.Parse(net.Substring(sep_index + 1));
			// out.println("net: ["+net+"]\nsep_index: "+sep_index+"\nport: "+port);
			return port;
		}
		
		
		private void  traceDebug(String s)
		{
			if (bus.Debug)
				Console.Out.WriteLine("-->ivywatcher<-- " + s);
		}
	}
	// class IvyWatcher
	/* EOF */
}