///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File: NicManager.sg
//
//  Note:
//
//  When a network device comes up, it registers with the
//  NicManager, who places it in the namespace under
//  /dev/nicX and advertises its existence with the netstack
//  runtime core.  The netstack runtime core will be responsible
//  for notifying the NicManager when the device has gone away.
//
//  This is a lot of jiggery-pokery just so users can see the device names
//  under /dev and the names are sequential.
//

// #define DEBUG_NIC

using NetStack.Common;
using System;
using System.Collections;
using System.Diagnostics;
using System.Threading;
using Microsoft.SingSharp;
using Microsoft.Singularity;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Io;
using Microsoft.Singularity.Io.Net;
using Microsoft.Singularity.Directory;

using NetStack.Contracts;
using NetStack.Runtime;

using Drivers.Net;

namespace NetStack.Channels.Nic
{
    internal class Nic : IAdapter
    {
        // Upper bounds computed for 10Gbps with maximum sized
        // packets to give a small number of I/O requests per
        // second and be a power of 2.
        private const int MaxTxPacketsInDevice = 128 * 1024;
        private const int MaxRxPacketsInDevice = 128 * 1024;

        private TRef<NicDeviceContract.Imp:READY>!     nicChannel;
        private TRef<NicDeviceEventContract.Imp:READY> eventChannel;

        string!  driverName;
        string!  driverVersion;
        byte []! macAddress;
        int mtu;
        int maxTxPacketsInDevice;
        int maxRxPacketsInDevice;
        int maxTxFragmentsPerPacket;
        int maxRxFragmentsPerPacket;

        private AutoResetEvent !readHandle;
        private AutoResetEvent !writeHandle;

        private Queue! rxFreePacketQueue;

        private ExRef<PacketFifo>! rxToDeviceFifo;
        private ExRef<PacketFifo>! rxFromDeviceFifo;

        private ExRef<PacketFifo>! txToDeviceFifo;
        private ExRef<PacketFifo>! txFromDeviceFifo;
        private ExRef<PacketFifo>! txFreeFifo;

        private ulong txRequests = 0;
        private ulong txComplete = 0;
        private ulong rxTotal    = 0;

        [Microsoft.Contracts.NotDelayed]
        public Nic([Claims] NicDeviceContract.Imp:READY! nicImp,
                   NicDeviceProperties*! in ExHeap np)
        {
            this.readHandle  = new AutoResetEvent(false);
            this.writeHandle = new AutoResetEvent(false);

            this.nicChannel = new TRef<NicDeviceContract.Imp:READY>(nicImp);
            expose (np) {
                assume np->DriverName != null;
                assume np->MacAddress != null;
                this.driverName    = Bitter.ToString2(np->DriverName);
                this.driverVersion = Bitter.ToString2(np->DriverName);
                this.macAddress    = Bitter.ToByteArray(np->MacAddress);
            }
            this.mtu = np->MtuBytes;
            this.maxTxPacketsInDevice    = np->MaxTxPacketsInDevice;
            this.maxRxPacketsInDevice    = np->MaxRxPacketsInDevice;
            this.maxTxFragmentsPerPacket = np->MaxTxFragmentsPerPacket;
            this.maxRxFragmentsPerPacket = np->MaxRxFragmentsPerPacket;
            // The following attributes are both integers yet
            // sgc is complaining it doesn't know to use
            // Math.Min(sbyte, sbyte) or Math.Min(byte, byte).
            int rxFifoSize = Math.Min(np->MaxRxPacketsInDevice,
                                      (int)Nic.MaxRxPacketsInDevice);

            // Create a queue for NetPackets that we pass up to
            // the NetStack and it passes down to us.  And
            // create a Packet fifo that has a packet for each
            // NetPacket.

            this.rxFreePacketQueue = new Queue(rxFifoSize);
            this.rxToDeviceFifo =
                new ExRef<PacketFifo>(
                    new [ExHeap] PacketFifo(rxFifoSize),
                    false
                    );

            this.rxFromDeviceFifo =
                new ExRef<PacketFifo>(
                    new [ExHeap] PacketFifo(rxFifoSize),
                    false
                    );

            // The following attributes are both integers yet
            // sgc is complaining it doesn't know to use
            // Math.Min(sbyte, sbyte) or Math.Min(byte, byte).
            int txFifoSize = Math.Min(np->MaxTxPacketsInDevice,
                                      (int)Nic.MaxTxPacketsInDevice);

            this.txToDeviceFifo =
                new ExRef<PacketFifo>(
                    new [ExHeap] PacketFifo(txFifoSize),
                    false
                    );

            this.txFromDeviceFifo =
                new ExRef<PacketFifo>(
                    new [ExHeap] PacketFifo(txFifoSize),
                    false
                    );

            this.txFreeFifo =
                new ExRef<PacketFifo>(
                    new [ExHeap] PacketFifo(txFifoSize),
                    false
                    );

            base();

            TxProvision();
            RxProvision();
        }

        int MaxRxPackets { get { return this.maxRxPacketsInDevice; } }

        internal void ThreadMain()
        {
            StartIO();
            EventMessagePump();
        }

        internal void EventMessagePump()
        {
            Tracing.Log(Tracing.Debug, "Started event pump");

            NicDeviceEventContract.Imp imp = (eventChannel).Acquire();
            eventChannel = null;
            try {
                assert imp.InState(NicDeviceEventContract.READY.Value);
                imp.RecvSuccess();
                assert imp.InState(NicDeviceEventContract.RUNNING.Value);
                for (;;) {
                    NicEventType eventType;
                    imp.RecvNicDeviceEvent(out eventType);
                    if ((eventType & NicEventType.ReceiveEvent) != 0) {
                        Tracing.Log(Tracing.Debug, "Receive event");
                        readHandle.Set();
                    }
                    if ((eventType & NicEventType.TransmitEvent) != 0) {
                        Tracing.Log(Tracing.Debug, "Transmit event");
                        writeHandle.Set();
                    }
                    if ((eventType & NicEventType.LinkEvent) != 0) {
                        Tracing.Log(Tracing.Debug, "Link event");
                        DebugStub.Break();
                    }
                    imp.SendAckNicDeviceEvent();
                }
            }
            catch (ChannelClosedException) {
                Tracing.Log(Tracing.Debug, "NIC event channel closed.");
            }
            finally {
                delete imp;
            }
        }


        //
        // IAdapter interface
        //
        string  IAdapter.DriverName
        {
            get { return this.driverName; }
        }

        string  IAdapter.DriverVersion
        {
            get { return this.driverVersion; }
        }

        uint IAdapter.LinkSpeed { get { return 100000000; } }

        EthernetAddress IAdapter.HardwareAddress
        {
            get { return new EthernetAddress(this.macAddress); }
        }

        WaitHandle IAdapter.GetReadHandle()  { return readHandle;  }
        WaitHandle IAdapter.GetWriteHandle() { return writeHandle; }

        [Conditional("DEBUG_NIC")]
        internal static void DebugPrint(string format, __arglist)
        {
            DebugStub.Print(format, new ArgIterator(__arglist));
        }

        private void RxExchangeInternal(NicDeviceContract.Imp! imp)
        {
            int toCount, fromCount;
            PacketFifo*! in ExHeap exFifo = this.rxToDeviceFifo.Acquire();
            toCount = exFifo->Count;
            try {
                imp.SendGiveRxPacketsToDevice(exFifo);
                imp.RecvTakeRxPacketsFromDevice(out exFifo);
                fromCount = exFifo->Count;

                // Transfer packets received from the device
                // to the fromDevice fifo.
                PacketFifo*! in ExHeap fromDevice =
                    this.rxFromDeviceFifo.Acquire();

                try {
                    while (exFifo->Count > 0) {
                        fromDevice->Push(exFifo->Pop());
                    }
                }
                finally {
                    this.rxFromDeviceFifo.Release(fromDevice);
                }
            }
            finally {
                this.rxToDeviceFifo.Release(exFifo);
            }
            DebugPrint("RxExchange out: {0} in: {1}\n",
                       __arglist(toCount, fromCount));
        }

        private void RxExchange()
        {
            NicDeviceContract.Imp imp = nicChannel.Acquire();
            try {
                RxExchangeInternal(imp);
            }
            finally {
                this.nicChannel.Release(imp);
            }
        }

        // Get the received packets from the adapter
        void IAdapter.GetReceivedPackets(Queue! outQueue)
        {
            lock (this) {
                // REVIEW: Should be able to make a decision about
                // whether to RxExchange or not here.
                RxExchange();

                PacketFifo*! in ExHeap toDevice = this.rxToDeviceFifo.Acquire();
                try {
                    PacketFifo*! in ExHeap fromDevice = this.rxFromDeviceFifo.Acquire();
                    try {
                        while (rxFreePacketQueue.Count > 0 &&
                               fromDevice->Count > 0) {
                            // Take netstack packet from free queue
                            NetPacket! netPacket =
                                (NetPacket!)rxFreePacketQueue.Dequeue();

                            // Take packet from the device
                            Packet*! in ExHeap packet = fromDevice->Pop();

                            // If packet from device has an error
                            // recycle it right away, and try next
                            // packet.  Careful not to lose the
                            // packet from the rxFreePacketQueue!
                            FromDeviceFlags fromFlags = packet->FromDeviceFlags;
                            if ((fromFlags & FromDeviceFlags.ReceiveError) != 0) {
                                packet->UnsetFragmentLengths();
                                toDevice->Push(packet);
                                rxFreePacketQueue.Enqueue(netPacket);
                                continue;
                            }

                            // Copy data from device's packet into netstack's packet
                            netPacket.Reset(packet->GetLength());
                            packet->ToByteArray((!)netPacket.GetRawData());
                            netPacket.AdapterContext = this;

                            // Enqueue netstack's packet for upward processing
                            outQueue.Enqueue(netPacket);

                            // Reset packet from device and put in the queue
                            // of return candidates.
                            packet->UnsetFragmentLengths();
                            toDevice->Push(packet);
                        }
                    }
                    finally {
                        this.rxFromDeviceFifo.Release(fromDevice);
                    }
                }
                finally {
                    this.rxToDeviceFifo.Release(toDevice);
                }
            }
        }

        // populate the adapter's receive ring with new NetPackets
        void IAdapter.PopulateRxRing(NetPacket! freePacket)
        {
            lock (this) {
                this.rxFreePacketQueue.Enqueue(freePacket);

                bool sendPacketsToDevice = false;
                PacketFifo*! in ExHeap toDevice = this.rxToDeviceFifo.Acquire();
                try {
                    sendPacketsToDevice = toDevice->Count > MaxRxPacketsInDevice / 2;
                }
                finally {
                    this.rxToDeviceFifo.Release(toDevice);
                }

                if (sendPacketsToDevice) {
                    RxExchange();
                }
            }
        }

        private void TxExchange()
        {
            int toCount = 0;
            int fromCount = 0;
            NicDeviceContract.Imp imp = nicChannel.Acquire();
            try {
                PacketFifo*! in ExHeap src = this.txToDeviceFifo.Acquire();
                toCount = src->Count;
                try {
                    imp->SendGiveTxPacketsToDevice(src);
                    imp->RecvTakeTxPacketsFromDevice(out src);
                    fromCount = src->Count;
                    PacketFifo*! in ExHeap dst =
                        this.txFromDeviceFifo.Acquire();
                    try {
                        dst->Push(src);
                    }
                    finally {
                        this.txFromDeviceFifo.Release(dst);
                    }
                }
                finally {
                    this.txToDeviceFifo.Release(src);
                }
            }
            finally
            {
                nicChannel.Release(imp);
            }
            DebugPrint("TxExchange out: {0} in: {1}\n",
                       __arglist(toCount, fromCount));
        }

        uint IAdapter.GetTransmittedPackets()
        {
            lock (this) {
                TxExchange();

                PacketFifo*! in ExHeap src = this.txFromDeviceFifo.Acquire();
                int srcCount = src->Count;
                try {
                    PacketFifo*! in ExHeap dst = this.txFreeFifo.Acquire();
                    try {
                        dst->Push(src);
                    }
                    finally {
                        this.txFreeFifo.Release(dst);
                    }
                }
                finally {
                    this.txFromDeviceFifo.Release(src);
                }

                return (uint) srcCount;
            }
        }

        void IAdapter.PopulateTxRing(NetPacket[]! fromUser, uint count)
        {
            lock (this) {
                PacketFifo*! in ExHeap txFree = this.txFreeFifo.Acquire();
                try {
                    PacketFifo*! in ExHeap txToDevice = this.txToDeviceFifo.Acquire();
                    try {
                        for (int i = 0; i < count; i++) {
                            Packet*! in ExHeap packet = txFree->Pop();
                            byte []! data = (!)((!)fromUser[i]).GetRawData();
                            packet->SetFragment(0, data, 0, data.Length);
                            txToDevice->Push(packet);
                        }
                    }
                    finally {
                        this.txToDeviceFifo.Release(txToDevice);
                    }
                }
                finally {
                    this.txFreeFifo.Release(txFree);
                }

                TxExchange();

                // TODO: Recycle fromUser packets...
                // Making work for the GC da...da...
            }
        }

        int IAdapter.TxSlotsFree
        {
            get {
                lock (this) {
                    PacketFifo*! in ExHeap txFree = this.txFreeFifo.Acquire();
                    try {
                        return txFree->Count;
                    }
                    finally {
                        this.txFreeFifo.Release(txFree);
                    }
                }
            }
        }

        private bool
        ConfigureEventChannel(NicDeviceContract.Imp:IO_CONFIGURE_BEGIN! nicImp)
        {
            NicDeviceEventContract.Imp! imp;
            NicDeviceEventContract.Exp! exp;
            NicDeviceEventContract.NewChannel(out imp, out exp);

            nicImp.SendRegisterForEvents(exp);
            switch receive {
                case nicImp.Success():
                    eventChannel =
                        new TRef<NicDeviceEventContract.Imp:READY>(imp);
                    return true;

                case nicImp.ChannelClosed():
                    Tracing.Log(Tracing.Error, "NIC channel closed");
                    delete imp;
                    break;
            }
            return false;
        }

        private bool
        ConfigureChecksumProperties(NicDeviceContract.Imp! nicImp)
        {
            nicImp.SendSetChecksumProperties(0);
            switch receive {
                case nicImp.Success():
                    return true;

                case nicImp.UnsupportedChecksumProperties():
                    Tracing.Log(Tracing.Error, "NIC refused checksum configuration it advertised");
                    break;
            }
            return false;
        }

        private bool Configure()
        {
            NicDeviceContract.Imp! nicImp = nicChannel.Acquire();
            try {
                nicImp.SendConfigureIO();
                nicImp.RecvAckConfigureIO();
                if (ConfigureEventChannel(nicImp) == true &&
                    ConfigureChecksumProperties(nicImp) == true) {
                    return true;
                }
            }
            catch (ChannelClosedException) {
                Tracing.Log(Tracing.Error, "NIC channel closed.");
            }
            catch (SystemException e) {
                Console.WriteLine(e);
                DebugStub.Break();
            }
            finally {
                nicChannel.Release(nicImp);
            }
            DebugStub.Break();
            return false;
        }

        private void RxProvision()
        {
            PacketFifo*! in ExHeap toDevice = this.rxToDeviceFifo.Acquire();
            for (int i = 0; i < toDevice->Capacity; i++) {
                this.rxFreePacketQueue.Enqueue( new NetPacket(this.mtu) );
                toDevice->Push(
                    new [ExHeap] Packet(
                        new [ExHeap] byte [this.mtu]
                        )
                    );
            }
            this.rxToDeviceFifo.Release(toDevice);
        }

        private void TxProvision()
        {
            PacketFifo*! in ExHeap txFree = this.txFreeFifo.Acquire();
            for (int i = 0; i < txFree->Capacity; i++) {
                txFree->Push(
                    new [ExHeap] Packet(
                        new [ExHeap] byte [this.mtu]
                        )
                    );
            }
            this.txFreeFifo.Release(txFree);
        }

        private bool StartIO()
        {
            NicDeviceContract.Imp imp = nicChannel.Acquire();
            try {
                if (imp.InState(NicDeviceContract.IO_CONFIGURED.Value) == true) {
                    imp.SendStartIO();
                    imp.RecvAckStartIO();
                    RxExchangeInternal(imp);
                    return true;
                }
            }
            catch (ChannelClosedException) {
            }
            finally {
                nicChannel.Release(imp);
            }
            DebugStub.Break();
            return false;
        }

        private bool StopIO()
        {
            NicDeviceContract.Imp imp = nicChannel.Acquire();
            try
            {
                if (imp.InState(NicDeviceContract.IO_RUNNING.Value) == true)
                {
                    imp.SendStopIO();
                    imp.RecvAckStopIO();
                    return true;
                }
            }
            catch (ChannelClosedException)
            {
            }
            finally
            {
                nicChannel.Release(imp);
            }
            return false;
        }

        //
        // Factory methods
        //
        internal static NicDeviceProperties* in ExHeap
        GetNicProperties(NicDeviceContract.Imp:READY! imp)
        {
            try {
                NicDeviceProperties*! in ExHeap np =
                    new [ExHeap] NicDeviceProperties();
                imp.SendGetDeviceProperties(np);
                imp.RecvDeviceProperties(out np);
                return np;
            }
            catch (OutOfMemoryException) {
                Tracing.Log(Tracing.Debug,
                            "Out-of-memory getting NIC properties");
                return null;
            }
            catch (ChannelClosedException) {
                Tracing.Log(Tracing.Debug,
                            "Channel closed while getting NIC properties");
                return null;
            }
        }

        internal static bool
        CreateAndRegister([Claims] NicDeviceContract.Imp:Start! imp,
                          string! nicName)
        {
            Nic nic = null;
            try {
                imp.RecvSuccess();
                Tracing.Log(Tracing.Debug, "Nic channel transition");
                Tracing.Log(Tracing.Debug, imp.CurrentState());

                NicDeviceProperties* in ExHeap np = GetNicProperties(imp);
                if (np == null) {
                    delete imp;
                    return false;
                }

                nic = new Nic(imp, np);
                delete np;
                if (nic.Configure() == false) {
                    return false;
                }

                NetStack.Runtime.Core! ns = (!)NetStack.Runtime.Core.Instance();
                ns.RegisterAdapter(nic, nicName, nic.MaxRxPackets);

                Thread thread = new Thread(
                    new ThreadStart(nic.ThreadMain)
                    );
                thread.Start();

                return true;
            }
            catch {
                delete imp;
                DebugStub.Break();
                return false;
            }
        }
    }
}