//
// Author: Atsushi Enomoto <atsushi@ximian.com>
//
// Copyright (C) 2010 Novell, Inc (http://www.novell.com)
//
// 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.
//
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.NetworkInformation;
using System.Net.Sockets;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Discovery;
using System.Threading;
using System.Xml;

namespace System.ServiceModel.Discovery.Udp
{
	internal class UdpDuplexChannel : ChannelBase, IDuplexChannel
	{
		// channel factory
		public UdpDuplexChannel (UdpChannelFactory factory, BindingContext context, EndpointAddress address, Uri via)
			: base (factory)
		{
			if (factory == null)
				throw new ArgumentNullException ("factory");
			if (context == null)
				throw new ArgumentNullException ("context");
			if (address == null)
				throw new ArgumentNullException ("address");

			binding_element = factory.Source;
			RemoteAddress = address;
			Via = via;
			FillMessageEncoder (context);
		}
		
		public UdpDuplexChannel (UdpChannelListener listener)
			: base (listener)
		{
			binding_element = listener.Source;
			LocalAddress = new EndpointAddress (listener.Uri);
			FillMessageEncoder (listener.Context);
		}
		
		MessageEncoder message_encoder;
		UdpClient client;
		IPAddress multicast_address;
		UdpTransportBindingElement binding_element;
		
		// for servers
		public EndpointAddress LocalAddress { get; private set; }
		// for clients
		public EndpointAddress RemoteAddress { get; private set; }
		
		public Uri Via { get; private set; }

		void FillMessageEncoder (BindingContext ctx)
		{
			var mbe = (MessageEncodingBindingElement) ctx.Binding.Elements.FirstOrDefault (be => be is MessageEncodingBindingElement);
			if (mbe == null)
				mbe = new TextMessageEncodingBindingElement ();
			message_encoder = mbe.CreateMessageEncoderFactory ().Encoder;
		}
		
		public void Send (Message message)
		{
			Send (message, DefaultSendTimeout);
		}

		static readonly Random rnd = new Random ();

		UdpClient GetSenderClient (Message message)
		{
			if (RemoteAddress != null)
				return client;
				
			var rmp = message.Properties [RemoteEndpointMessageProperty.Name] as RemoteEndpointMessageProperty;
			if (rmp == null)
				throw new ArgumentException ("This duplex channel from the channel listener cannot send messages without RemoteEndpointMessageProperty");
			var cli = new UdpClient ();
			cli.Connect (IPAddress.Parse (rmp.Address), rmp.Port);
			return cli;
		}

		public void Send (Message message, TimeSpan timeout)
		{
			if (State != CommunicationState.Opened)
				throw new InvalidOperationException ("The UDP channel must be opened before sending a message.");

			var cli = GetSenderClient (message);
			try {
				SendCore (cli, message, timeout);
			} finally {
				if (cli != client)
					cli.Close ();
			}
		}

		void SendCore (UdpClient cli, Message message, TimeSpan timeout)
		{
			var ms = new MemoryStream ();
			message_encoder.WriteMessage (message, ms);
			// It seems .NET sends the same Message a couple of times so that the receivers don't miss it. So, do the same hack.
			for (int i = 0; i < 6; i++) {
				// FIXME: use MaxAnnouncementDelay. It is fixed now.
				Thread.Sleep (rnd.Next (50, 500));
				cli.Send (ms.GetBuffer (), (int) ms.Length);
			}
		}

		public bool WaitForMessage (TimeSpan timeout)
		{
			throw new NotImplementedException ();
		}

		public Message Receive ()
		{
			return Receive (DefaultReceiveTimeout);
		}

		public Message Receive (TimeSpan timeout)
		{
			Message msg;
			if (!TryReceive (timeout, out msg))
				throw new TimeoutException ();
			return msg;
		}

		public bool TryReceive (TimeSpan timeout, out Message msg)
		{
			DateTime start = DateTime.Now;
			ThrowIfDisposedOrNotOpen ();
			msg = null;

			if (client == null) // could be invoked while being closed.
				return false;

			byte [] bytes = null;
			IPEndPoint ip = new IPEndPoint (IPAddress.Any, 0);
			var ar = client.BeginReceive (delegate (IAsyncResult result) {
if (result == null) throw new ArgumentNullException ("result");
				UdpClient cli = (UdpClient) result.AsyncState;
				try {
					bytes = cli.EndReceive (result, ref ip);
				} catch (ObjectDisposedException) {
					if (State == CommunicationState.Opened)
						throw;
					// Otherwise, called during shutdown. Ignore it.
				}
			}, client);

			if (!ar.IsCompleted && !ar.AsyncWaitHandle.WaitOne (timeout))
				return false;
			if (bytes == null || bytes.Length == 0)
				return false;

			// Clients will send the same message many times, and this receiver has to 

			// FIXME: give maxSizeOfHeaders
			msg = message_encoder.ReadMessage (new MemoryStream (bytes), int.MaxValue);
			var id = msg.Headers.MessageId;
			if (message_ids.Contains (id))
				return TryReceive (timeout - (DateTime.Now - start), out msg);
			if (id != null) {
				message_ids.Enqueue (id);
				if (message_ids.Count >= binding_element.TransportSettings.DuplicateMessageHistoryLength)
					message_ids.Dequeue ();
			}
			msg.Properties.Add ("Via", LocalAddress.Uri);
			msg.Properties.Add ("Encoder", message_encoder);
			msg.Properties.Add (RemoteEndpointMessageProperty.Name, new RemoteEndpointMessageProperty (ip.Address.ToString (), ip.Port));
			return true;
		}

		Queue<UniqueId> message_ids = new Queue<UniqueId> ();

		protected override void OnAbort ()
		{
			OnClose (TimeSpan.Zero);
		}
		
		Action<TimeSpan> open_delegate, close_delegate;
		
		protected override IAsyncResult OnBeginClose (TimeSpan timeout, AsyncCallback callback, object state)
		{
			if (close_delegate == null)
				close_delegate = new Action<TimeSpan> (OnClose);
			return close_delegate.BeginInvoke (timeout, callback, state);
		}
		
		protected override void OnEndClose (IAsyncResult result)
		{
			close_delegate.EndInvoke (result);
		}
		
		protected override IAsyncResult OnBeginOpen (TimeSpan timeout, AsyncCallback callback, object state)
		{
			if (open_delegate == null)
				open_delegate = new Action<TimeSpan> (OnOpen);
			return open_delegate.BeginInvoke (timeout, callback, state);
		}
		
		protected override void OnEndOpen (IAsyncResult result)
		{
			open_delegate.EndInvoke (result);
		}
		
		protected override void OnClose (TimeSpan timeout)
		{
			if (client != null) {
				if (multicast_address != null) {
					client.DropMulticastGroup (multicast_address, LocalAddress.Uri.Port);
					multicast_address = null;
				}
				client.Close ();
			}
			client = null;
		}
		
		protected override void OnOpen (TimeSpan timeout)
		{
			if (RemoteAddress != null) {
				client = new UdpClient ();
				var uri = Via ?? RemoteAddress.Uri;
				client.Connect (uri.Host, uri.Port);
			} else {
				var ip = IPAddress.Parse (LocalAddress.Uri.Host);
				bool isMulticast = NetworkInterface.GetAllNetworkInterfaces ().Any (nic => nic.SupportsMulticast && nic.GetIPProperties ().MulticastAddresses.Any (mca => mca.Address.Equals (ip)));
				int port = LocalAddress.Uri.Port;
				if (isMulticast) {
					multicast_address = ip;
					client = new UdpClient (new IPEndPoint (IPAddress.Any, port));
					client.ExclusiveAddressUse = false;
					client.JoinMulticastGroup (ip, binding_element.TransportSettings.TimeToLive);
				}
				else
					client = new UdpClient (new IPEndPoint (ip, port));
			}

			client.EnableBroadcast = true;

			// FIXME: apply UdpTransportSetting here.
		}
		
		Func<TimeSpan,Message> receive_delegate;
		
		public IAsyncResult BeginReceive (AsyncCallback callback, object state)
		{
			return BeginReceive (DefaultReceiveTimeout, callback, state);
		}
		
		public IAsyncResult BeginReceive (TimeSpan timeout, AsyncCallback callback, object state)
		{
			if (receive_delegate == null)
				receive_delegate = new Func<TimeSpan,Message> (Receive);
			return receive_delegate.BeginInvoke (timeout, callback, state);
		}
		
		public Message EndReceive (IAsyncResult result)
		{
			return receive_delegate.EndInvoke (result);
		}
		
		delegate bool TryReceiveDelegate (TimeSpan timeout, out Message msg);
		TryReceiveDelegate try_receive_delegate;

		public IAsyncResult BeginTryReceive (TimeSpan timeout, AsyncCallback callback, object state)
		{
			if (try_receive_delegate == null)
				try_receive_delegate = new TryReceiveDelegate (TryReceive);
			Message dummy;
			return try_receive_delegate.BeginInvoke (timeout, out dummy, callback, state);
		}
		
		public bool EndTryReceive (IAsyncResult result, out Message msg)
		{
			return try_receive_delegate.EndInvoke (out msg, result);
		}

		Func<TimeSpan,bool> wait_delegate;
		
		public IAsyncResult BeginWaitForMessage (TimeSpan timeout, AsyncCallback callback, object state)
		{
			if (wait_delegate == null)
				wait_delegate = new Func<TimeSpan,bool> (WaitForMessage);
			return wait_delegate.BeginInvoke (timeout, callback, state);
		}
		
		public bool EndWaitForMessage (IAsyncResult result)
		{
			return wait_delegate.EndInvoke (result);
		}

		Action<Message,TimeSpan> send_delegate;
		
		public IAsyncResult BeginSend (Message message, AsyncCallback callback, object state)
		{
			return BeginSend (message, DefaultSendTimeout, callback, state);
		}
		
		public IAsyncResult BeginSend (Message message, TimeSpan timeout, AsyncCallback callback, object state)
		{
			if (send_delegate == null)
				send_delegate = new Action<Message,TimeSpan> (Send);
			return send_delegate.BeginInvoke (message, timeout, callback, state);
		}
		
		public void EndSend (IAsyncResult result)
		{
			send_delegate.EndInvoke (result);
		}
	}
}