/*
Copyright (c) OpenSim project, http://osgrid.org/
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*     * Redistributions of source code must retain the above copyright
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*     * Redistributions in binary form must reproduce the above copyright
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*       documentation and/or other materials provided with the distribution.
*     * Neither the name of the <organization> nor the
*       names of its contributors may be used to endorse or promote products
*       derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY <copyright holder> ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL <copyright holder> BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

using System;
using System.Collections;
using System.Collections.Generic;
using libsecondlife;
using libsecondlife.Packets;
using Nwc.XmlRpc;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Threading;
using System.Timers;
using OpenSim.Framework.Interfaces;
using OpenSim.Framework.Assets;
using OpenSim.Framework.Inventory;
using OpenSim.Framework.Utilities;
using OpenSim.world;
using OpenSim.Assets;

namespace OpenSim
{
    public delegate bool PacketMethod(SimComms remoteSim, Packet packet);

    /// <summary>
    /// Handles sim<->sim communications
    /// Constructor takes a single Packet and authenticates everything
    /// </summary>
    public class SimComms
    {
        public LLUUID SimUUID;
	public bool m_child;
        public uint CircuitCode;
        private UseCircuitCodePacket cirpack;
        public Thread ClientThread;
        public EndPoint simEP;
        private BlockingQueue<QueItem> PacketQueue;
        private Dictionary<uint, uint> PendingAcks = new Dictionary<uint, uint>();
        private Dictionary<uint, Packet> NeedAck = new Dictionary<uint, Packet>();
        private System.Timers.Timer AckTimer;
        private uint Sequence = 0;
        private object SequenceLock = new object();
        private const int MAX_APPENDED_ACKS = 10;
        private const int RESEND_TIMEOUT = 4000;
        private const int MAX_SEQUENCE = 0xFFFFFF;
        private bool debug = false;
        private World m_world;
        private Dictionary<uint, SimComms> m_simThreads;
        private IGridServer m_gridServer;
        private IUserServer m_userServer = null;
        private OpenSimNetworkHandler m_application;
        //private bool m_sandboxMode;	// I can think of no reason why we'd ever have this set in sandbox mode

        protected static Dictionary<PacketType, PacketMethod> PacketHandlers = new Dictionary<PacketType, PacketMethod>(); //Global/static handlers for all sims

        protected Dictionary<PacketType, PacketMethod> m_packetHandlers = new Dictionary<PacketType, PacketMethod>(); //local handlers for this instance 

        public IUserServer UserServer
        {
            set
            {
                this.m_userServer = value;
            }
        }

        public SimComms(EndPoint remoteEP, UseCircuitCodePacket initialcirpack, World world, Dictionary<uint, SimComms> simThreads, IGridServer gridServer, OpenSimNetworkHandler application)
        {
            m_world = world;
            m_clientThreads = clientThreads;
            m_gridServer = gridServer;
            m_application = application;

            OpenSim.Framework.Console.MainConsole.Instance.WriteLine("SimComms.cs - Started up new thread to handle incoming request");
            cirpack = initialcirpack;
            simEP = remoteEP;

            PacketQueue = new BlockingQueue<QueItem>();

            AckTimer = new System.Timers.Timer(500);
            AckTimer.Elapsed += new ElapsedEventHandler(AckTimer_Elapsed);
            AckTimer.Start();

            this.RegisterLocalPacketHandlers();

            ClientThread = new Thread(new ThreadStart(AuthUser));
            ClientThread.IsBackground = true;
            ClientThread.Start();
        }

        protected virtual void RegisterLocalPacketHandlers()
        {
/*            this.AddLocalPacketHandler(PacketType.LogoutRequest, this.Logout);
            this.AddLocalPacketHandler(PacketType.AgentCachedTexture, this.AgentTextureCached);
            this.AddLocalPacketHandler(PacketType.MultipleObjectUpdate, this.MultipleObjUpdate);*/
        }

        public static bool AddPacketHandler(PacketType packetType, PacketMethod handler)
        {
            bool result = false;
            lock (PacketHandlers)
            {
                if (!PacketHandlers.ContainsKey(packetType))
                {
                    PacketHandlers.Add(packetType, handler);
                    result = true;
                }
            }
            return result;
        }

        public bool AddLocalPacketHandler(PacketType packetType, PacketMethod handler)
        {
            bool result = false;
            lock (m_packetHandlers)
            {
                if (!m_packetHandlers.ContainsKey(packetType))
                {
                    m_packetHandlers.Add(packetType, handler);
                    result = true;
                }
            }
            return result;
        }

        protected virtual bool ProcessPacketMethod(Packet packet)
        {
            bool result = false;
            bool found = false;
            PacketMethod method;
            if (m_packetHandlers.TryGetValue(packet.Type, out method))
            {
                //there is a local handler for this packet type
                result = method(this, packet);
            }
            else
            {
                //there is not a local handler so see if there is a Global handler
                lock (PacketHandlers)
                {
                    found = PacketHandlers.TryGetValue(packet.Type, out method);
                }
                if (found)
                {
                    result = method(this, packet);
                }
            }
            return result;
        }

        private void ack_pack(Packet Pack)
        {
            if (Pack.Header.Reliable)
            {
                libsecondlife.Packets.PacketAckPacket ack_it = new PacketAckPacket();
                ack_it.Packets = new PacketAckPacket.PacketsBlock[1];
                ack_it.Packets[0] = new PacketAckPacket.PacketsBlock();
                ack_it.Packets[0].ID = Pack.Header.Sequence;
                ack_it.Header.Reliable = false;

                OutPacket(ack_it);

            }
            /*
            if (Pack.Header.Reliable)
            {
                lock (PendingAcks)
                {
                    uint sequence = (uint)Pack.Header.Sequence;
                    if (!PendingAcks.ContainsKey(sequence)) { PendingAcks[sequence] = sequence; }
                }
            }*/
        }

        protected virtual void ProcessInPacket(Packet Pack)
        {
            ack_pack(Pack);

            if (this.ProcessPacketMethod(Pack))
            {
                //there is a handler registered that handled this packet type 
                return;
            }
            else
            {
                System.Text.Encoding _enc = System.Text.Encoding.ASCII;

                switch (Pack.Type)
                {
                }
            }
        }

        private void ResendUnacked()
        {
            int now = Environment.TickCount;

            lock (NeedAck)
            {
                foreach (Packet packet in NeedAck.Values)
                {
                    if ((now - packet.TickCount > RESEND_TIMEOUT) && (!packet.Header.Resent))
                    {
                        OpenSim.Framework.Console.MainConsole.Instance.WriteLine("Resending " + packet.Type.ToString() + " packet, " +
                         (now - packet.TickCount) + "ms have passed");

                        packet.Header.Resent = true;
                        OutPacket(packet);
                    }
                }
            }
        }

        private void SendAcks()
        {
            lock (PendingAcks)
            {
                if (PendingAcks.Count > 0)
                {
                    if (PendingAcks.Count > 250)
                    {
                        // FIXME: Handle the odd case where we have too many pending ACKs queued up
                        OpenSim.Framework.Console.MainConsole.Instance.WriteLine("Too many ACKs queued up!");
                        return;
                    }

                    //OpenSim.Framework.Console.MainConsole.Instance.WriteLine("Sending PacketAck");


                    int i = 0;
                    PacketAckPacket acks = new PacketAckPacket();
                    acks.Packets = new PacketAckPacket.PacketsBlock[PendingAcks.Count];

                    foreach (uint ack in PendingAcks.Values)
                    {
                        acks.Packets[i] = new PacketAckPacket.PacketsBlock();
                        acks.Packets[i].ID = ack;
                        i++;
                    }

                    acks.Header.Reliable = false;
                    OutPacket(acks);

                    PendingAcks.Clear();
                }
            }
        }

        private void AckTimer_Elapsed(object sender, ElapsedEventArgs ea)
        {
            SendAcks();
            ResendUnacked();
        }

        protected virtual void ProcessOutPacket(Packet Pack)
        {

            // Keep track of when this packet was sent out
            Pack.TickCount = Environment.TickCount;

            if (!Pack.Header.Resent)
            {
                // Set the sequence number
                lock (SequenceLock)
                {
                    if (Sequence >= MAX_SEQUENCE)
                        Sequence = 1;
                    else
                        Sequence++;
                    Pack.Header.Sequence = Sequence;
                }

                if (Pack.Header.Reliable)  //DIRTY HACK
                {
                    lock (NeedAck)
                    {
                        if (!NeedAck.ContainsKey(Pack.Header.Sequence))
                        {
                            NeedAck.Add(Pack.Header.Sequence, Pack);
                        }
                        else
                        {
                            //  Client.Log("Attempted to add a duplicate sequence number (" +
                            //     packet.Header.Sequence + ") to the NeedAck dictionary for packet type " +
                            //      packet.Type.ToString(), Helpers.LogLevel.Warning);
                        }
                    }

                    // Don't append ACKs to resent packets, in case that's what was causing the
                    // delivery to fail
                    if (!Pack.Header.Resent)
                    {
                        // Append any ACKs that need to be sent out to this packet
                        lock (PendingAcks)
                        {
                            if (PendingAcks.Count > 0 && PendingAcks.Count < MAX_APPENDED_ACKS &&
                                Pack.Type != PacketType.PacketAck &&
                                Pack.Type != PacketType.LogoutRequest)
                            {
                                Pack.Header.AckList = new uint[PendingAcks.Count];
                                int i = 0;

                                foreach (uint ack in PendingAcks.Values)
                                {
                                    Pack.Header.AckList[i] = ack;
                                    i++;
                                }

                                PendingAcks.Clear();
                                Pack.Header.AppendedAcks = true;
                            }
                        }
                    }
                }
            }

            byte[] ZeroOutBuffer = new byte[4096];
            byte[] sendbuffer;
            sendbuffer = Pack.ToBytes();

            try
            {
                if (Pack.Header.Zerocoded)
                {
                    int packetsize = Helpers.ZeroEncode(sendbuffer, sendbuffer.Length, ZeroOutBuffer);
                    m_application.SendPacketTo(ZeroOutBuffer, packetsize, SocketFlags.None, CircuitCode);//userEP);
                }
                else
                {
                    m_application.SendPacketTo(sendbuffer, sendbuffer.Length, SocketFlags.None, CircuitCode); //userEP);
                }
            }
            catch (Exception)
            {
                OpenSim.Framework.Console.MainConsole.Instance.WriteLine("SimComms.cs:ProcessOutPacket() - WARNING: Socket exception occurred on connection " + simEP.ToString() + " - killing thread");
                ClientThread.Abort();
            }

        }

        public virtual void InPacket(Packet NewPack)
        {
            // Handle appended ACKs
            if (NewPack.Header.AppendedAcks)
            {
                lock (NeedAck)
                {
                    foreach (uint ack in NewPack.Header.AckList)
                    {
                        NeedAck.Remove(ack);
                    }
                }
            }

            // Handle PacketAck packets
            if (NewPack.Type == PacketType.PacketAck)
            {
                PacketAckPacket ackPacket = (PacketAckPacket)NewPack;

                lock (NeedAck)
                {
                    foreach (PacketAckPacket.PacketsBlock block in ackPacket.Packets)
                    {
                        NeedAck.Remove(block.ID);
                    }
                }
            }
            else if ((NewPack.Type == PacketType.StartPingCheck))
            {
                //reply to pingcheck
                libsecondlife.Packets.StartPingCheckPacket startPing = (libsecondlife.Packets.StartPingCheckPacket)NewPack;
                libsecondlife.Packets.CompletePingCheckPacket endPing = new CompletePingCheckPacket();
                endPing.PingID.PingID = startPing.PingID.PingID;
                OutPacket(endPing);
            }
            else
            {
                QueItem item = new QueItem();
                item.Packet = NewPack;
                item.Incoming = true;
                this.PacketQueue.Enqueue(item);
            }

        }

        public virtual void OutPacket(Packet NewPack)
        {
            QueItem item = new QueItem();
            item.Packet = NewPack;
            item.Incoming = false;
            this.PacketQueue.Enqueue(item);
        }

        protected virtual void ClientLoop()
        {
            OpenSim.Framework.Console.MainConsole.Instance.WriteLine("SimComms.cs:ClientLoop() - Entered loop");
            while (true)
            {
                QueItem nextPacket = PacketQueue.Dequeue();
                if (nextPacket.Incoming)
                {
                    //is a incoming packet
                    ProcessInPacket(nextPacket.Packet);
                }
                else
                {
                    //is a out going packet
                    ProcessOutPacket(nextPacket.Packet);
                }
            }
        }

    }
}