///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   UdpExpConnection.sg
//
//  Note:   Provider-side helper for the Udp Channel Contract
//

// #define DEBUG_UDPEXPCONNECTION

using System.Threading;
using System.Net.IP;
using Microsoft.SingSharp;
using Microsoft.Singularity;
using Microsoft.Singularity.Channels;
using NetStack.Contracts;
using NetStack.Runtime;
using System.Collections;
using System;

namespace NetStack.Channels.Private
{
    public class UdpConnectionExpThread
    {
        private TRef<UdpConnectionContract.Exp:Start>! chanEP;
        private UdpSession! session;

        [ System.Diagnostics.Conditional("DEBUG_UDPEXPCONNECTION") ]
        static void DebugPrint(string format, params object [] args)
        {
            DebugStub.Print(
                "UdpConnectionExpThread [{0}]: {1}",
                __arglist(
                    Thread.CurrentThread.GetThreadId(),
                    string.Format(format, args)
                    )
                );
        }

        public void Run()
        {
            UdpConnectionContract.Exp! ep = chanEP.Acquire();

            while(true) {
                switch receive {
                    case ep.BindLocalEndPoint(uint srcIP, ushort srcPort) :
                    {
                        DebugPrint("BindLocalEndPoint ({0:x8}/{1} ->)\n",
                                   srcIP, srcPort);
                        IPv4 srcAddr = new IPv4(srcIP);
                        if (srcAddr != IPv4.Any &&
                            session.IsLocalAddress(srcAddr) == false) {
                            ep.SendInvalidEndPoint(srcIP, srcPort);
                        }
                        else {
                            session.BindLocalEndPoint(srcAddr, srcPort);
                            ep.SendOK();
                        }
                    }
                    break;

                    case ep.ConnectWithAnyLocalEndPoint(uint   dstIP,
                                                        ushort dstPort) :
                    {
                        DebugPrint(
                            "ConnectWithAnyLocalEndPoint (-> {0:x8}/{1})\n",
                            dstIP, dstPort
                            );

                        session.BindRemoteEndPoint(new IPv4(dstIP), dstPort);
                        ep.SendOK();
                    }
                    break;

                    case ep.Connect(uint srcIP, ushort srcPort,
                                    uint dstIP, ushort dstPort) :
                    {
                        DebugPrint(
                            "BindLocalEndPoint ({0:x8}/{1} -> {2:x8}/{3})\n",
                            srcIP, srcPort, dstIP, dstPort
                            );

                        session.BindEndPoints(new IPv4(srcIP), srcPort,
                                              new IPv4(dstIP), dstPort);
                        ep.SendOK();
                    }
                    break;

                    case ep.PollSelectRead(int millis) :
                    {
                        if (ep.InState(UdpConnectionContract.Start.Value)) {
                            ep.SendPollSelectResult(false);
                        }
                        else {
                            bool result = session.PollSelectRead(millis);
                            ep.SendPollSelectResult(result);
                        }
                    }
                    break;

                    case ep.PollSelectWrite(int millis) :
                    {
                        bool result = session.PollSelectWrite(millis);
                        ep.SendPollSelectResult(result);
                    }
                    break;

                    case ep.Read() :
                    {
                        byte[] in ExHeap data = session.ReadData();

                        // Currently, there is no way of
                        // detecting that the connection has
                        // been closed underneath us. We should
                        // fix that.
                        if (data == null) {
                            ep.SendNoData();
                        }
                        else {
                            ep.SendData(0, 0, data);
                        }
                    }
                    break;

                    case ep.PollRead(int timeoutMillis) :
                    {
                        byte[] in ExHeap data = session.PollData(timeoutMillis);
                        // Currently, there is no way of
                        // detecting that the connection has
                        // been closed underneath us. We should
                        // fix that.
                        if (data == null) {
                            ep.SendNoData();
                        }
                        else {
                            ep.SendData(0, 0, data);
                        }
                    }
                    break;

                    case ep.Write(byte[]! in ExHeap data) :
                    {
                        DebugPrint("Write {0} bytes.\n", data.Length);
                        if (session.WriteData(data) == data.Length) {
                            ep.SendOK();
                        }
                        else {
                            ep.SendDataTooLarge();
                        }
                        delete data;
                    }
                    break;

                    case ep.WriteTo(uint dstIP, dstPort, byte[]! in ExHeap data) :
                    {
                        DebugPrint("WriteTo {0} bytes -> {1:x8}/{2}.\n",
                                   data.Length, dstIP, dstPort);
                        int written = session.WriteDataTo(new IPv4(dstIP),
                                                          dstPort, data);
                        if (written == data.Length) {
                            ep.SendOK();
                        }
                        else {
                            ep.SendDataTooLarge();
                        }
                        delete data;
                    }
                    break;

                    case ep.Close() :
                        session.Close();
                        break;

                    case ep.GetLocalAddress() :
                        ep.SendIPAddress((uint)session.LocalAddress);
                        break;

                    case ep.GetLocalPort() :
                        ep.SendPort(session.LocalPort);
                        break;

                    case ep.GetRemoteAddress() :
                        ep.SendIPAddress((uint)session.RemoteAddress);
                        break;

                    case ep.GetRemotePort() :
                        ep.SendPort(session.RemotePort);
                        break;

                    case unsatisfiable :
                        // Exit this thread
                        session.Dispose();
                        delete ep;
                        return;
                        break;
                }
            }
        }

        public UdpConnectionExpThread([Claims]UdpConnectionContract.Exp:Start! ep)
        {
            chanEP = new TRef<UdpConnectionContract.Exp:Start>(ep);
            session = (UdpSession!)Core.Instance().CreateSession("UDP");
        }

        private UdpConnectionExpThread([Claims]UdpConnectionContract.Exp:Connected! ep,
                                       UdpSession! newSession)
        {
            chanEP = new TRef<UdpConnectionContract.Exp:Start>(ep);
            this.session = newSession;
        }

        public void Start()
        {
            Thread newThread = new Thread(new ThreadStart(Run));
            newThread.Start();
        }
    }
}