//#
//# Corba Time Server
//# $Revision: 1.1 $
//# Copyright 2004 by Eric Y. Theriault
//# All Rights Reserved.
//# http://www.eyt.ca/CORBA
//#
using System;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Services;
using System.Runtime.Remoting.Channels;
using Ch.Elca.Iiop;
using Ch.Elca.Iiop.Services;
using omg.org.CosNaming;

namespace ca.eyt.corba
{
	/// <summary>
	/// Multicast Service.
	/// </summary>
	/// <remarks>
	/// For more information on Multicasting, please see Chapter 21 [549]
	/// of W. Richard Stevens, Bill Fenner, and Andrew M. Rudoff's UNIX
	/// Network Programming: Volume 1: The Sockets Networking API--Third
	/// Edition, Addison-Wesley, 2004.
	/// </remarks>
	class MulticastIORServer 
	{
		/// <summary>
		/// Port to multicast on.  This number is random. 
		/// </summary>
		public const int MulticastPort = 7007; 

		/// <summary>
		/// Address to multicast to.  The default is link-local, which is
		/// generally OK, but in the presence of a segmented network with
		/// routers, this address and the TTL will have to be changed.
		/// </summary>
		public const String MulticastAddress = "224.0.0.1";

		/// <summary>
		/// This is the message that is multicasted to discover the new
		/// server.
		/// </summary>
		public const String MulticastDiscoverServer = "DiscoverIOR";

		/// <summary>
		/// IOR to Multicast
		/// </summary>
		private string ior;

		/// <summary>
		/// Multicast Socket
		/// </summary>
		private MulticastSocket mcast;

		/// <summary>
		/// Thread Reference.
		/// </summary>
		System.Threading.Thread thread;

		/// <summary>
		/// Create the service to answer to inbound Multicasts
		/// </summary>
		/// <param name="ior">IOR of NameService</param>
		public MulticastIORServer( String ior ) 
		{
			this.ior = ior;

			// Please note that a real implementation would provide options
			// to set the bind address, Time To Live, etc., but this is
			// simply to demonstrate the functionality.
			mcast = new MulticastSocket( MulticastPort );
			mcast.bind();
			mcast.joinGroup( MulticastAddress );
		}

		/// <summary>
		/// Executes the thread.
		/// </summary>
		protected void run() 
		{
			while ( true ) {
				try {
					// Create a received String
					System.Net.IPEndPoint address = null;
					string receivedString = mcast.receive( ref address );

					// If the packet is good, reply
					//
					// In a real application, a checksum or something could
					// be used to validate the message, and the reply should
					// contain a more verbose message.
					if ( receivedString.StartsWith( MulticastDiscoverServer ) ) {
						// Unicast back to the sender the ior string.
						mcast.send( address, ior );
					}
				} 
				catch ( Exception e ) {
					// Log the message.
					System.Console.WriteLine( "Exception: " + e.Message );
					System.Console.WriteLine( e.StackTrace.ToString() );
				}
			}
		}

		/// <summary>
		/// Starts a thread.
		/// </summary>
		public void start() 
		{
			thread = new System.Threading.Thread( new System.Threading.ThreadStart( run ) );
			thread.Start();
		}
	}

	/// <summary>
	/// Implements a CORBA server to provide the local time.
	/// </summary>
	public class TimeServer
	{
		/// <summary>
		/// Server Port
		/// </summary>
		const int ServerPort = 7832;

		/// <summary>
		/// Main.
		/// </summary>
		[System.STAThread]
		public static void Main( string[] args )
		{
			try {
				String iorFile = "time.ior";

				// Create and Initialize the ORB
				CorbaInit orb = CorbaInit.GetInit();

				// Register server channel
				IiopChannel channel = new IiopChannel( ServerPort );
				ChannelServices.RegisterChannel( channel );

				// Create the time Servant and register it.
				ca.eyt.corba.TimeImpl timeImpl = new ca.eyt.corba.TimeImpl();

				// Create the object reference.
				string objectURI = "Time";
				ObjRef objrefWellKnown = RemotingServices.Marshal( timeImpl, objectURI );

				// Acquire the IOR for the object reference.
				//TODO: There is probably a nicer way to do this.
				omg.org.CORBA.OrbServices srv = omg.org.CORBA.OrbServices.GetSingleton();
				String[] url = channel.GetUrlsForUri( objrefWellKnown.URI );
				if ( url.Length != 1 ) {
					throw new Exception( "Unexpected input: " + url.Length );
				}
				object obj = srv.string_to_object( url[0] );
				String ior = srv.object_to_string( obj  );

				// Write out the file
				try {
					using ( System.IO.StreamWriter writer = new System.IO.StreamWriter( iorFile ) ) {
						writer.WriteLine( ior );
					}
				} catch ( Exception e ) {
					System.Console.Error.WriteLine( iorFile + " raised an exception: " + e.Message );
					System.Environment.Exit( 1 );
				}

				// Let's get the root naming context.
				NamingContext nameService = ORBHelper.resolveNameserviceReference( orb, args );

				// Bind the Time object to the reference.
				String Time = "Time";
				NameComponent[] path = new NameComponent[] { new NameComponent( Time, "" ) };
				nameService.rebind( path, timeImpl );

				// Start the Multicast Server
				MulticastIORServer mcast = new MulticastIORServer( srv.object_to_string( nameService  ) );
				mcast.start();

				// Server is now up and running
				System.Console.Out.WriteLine( "TimeServer is ready and waiting..." );
			}  catch ( System.Exception e ) {
				System.Console.WriteLine( "Exception: " + e.Message );
				System.Console.WriteLine( e.StackTrace.ToString() );
				System.Environment.Exit( 1 );
			}
		}
	}
}