/***************************************************************************
 *                               MessagePump.cs
 *                            -------------------
 *   begin                : May 1, 2002
 *   copyright            : (C) The RunUO Software Team
 *   email                : info@runuo.com
 *
 *   $Id$
 *
 ***************************************************************************/

/***************************************************************************
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 ***************************************************************************/

using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using Server.Diagnostics;

namespace Server.Network
{
  public class MessagePump
  {
    private const int BufferSize = 4096;
    private BufferPool m_Buffers = new BufferPool("Processor", 4, BufferSize);
    private Queue<NetState> m_Queue;
    private Queue<NetState> m_Throttled;
    private Queue<NetState> m_WorkingQueue;

    public MessagePump()
    {
      IPEndPoint[] ipep = Listener.EndPoints;

      Listeners = new Listener[ipep.Length];

      bool success = false;

      do
      {
        for (int i = 0; i < ipep.Length; i++)
        {
          Listener l = new Listener(ipep[i]);
          if (!success)
            success = true;
          Listeners[i] = l;
        }

        if (!success)
        {
          Console.WriteLine("Retrying...");
          Thread.Sleep(10000);
        }
      } while (!success);

      m_Queue = new Queue<NetState>();
      m_WorkingQueue = new Queue<NetState>();
      m_Throttled = new Queue<NetState>();
    }

    public Listener[] Listeners{ get; set; }

    public void AddListener(Listener l)
    {
      Listener[] old = Listeners;

      Listeners = new Listener[old.Length + 1];

      for (int i = 0; i < old.Length; ++i)
        Listeners[i] = old[i];

      Listeners[old.Length] = l;
    }

    private void CheckListener()
    {
      for (int j = 0; j < Listeners.Length; ++j)
      {
        Socket[] accepted = Listeners[j].Slice();

        for (int i = 0; i < accepted.Length; ++i)
        {
          NetState ns = new NetState(accepted[i], this);
          ns.Start();

          if (ns.Running)
            Console.WriteLine("Client: {0}: Connected. [{1} Online]", ns, NetState.Instances.Count);
        }
      }
    }

    public void OnReceive(NetState ns)
    {
      lock (this)
      {
        m_Queue.Enqueue(ns);
      }

      Core.Set();
    }

    public void Slice()
    {
      CheckListener();

      lock (this)
      {
        Queue<NetState> temp = m_WorkingQueue;
        m_WorkingQueue = m_Queue;
        m_Queue = temp;
      }

      while (m_WorkingQueue.Count > 0)
      {
        NetState ns = m_WorkingQueue.Dequeue();

        if (ns.Running)
          HandleReceive(ns);
      }

      lock (this)
      {
        while (m_Throttled.Count > 0)
          m_Queue.Enqueue(m_Throttled.Dequeue());
      }
    }

    private bool HandleSeed(NetState ns, ByteQueue buffer)
    {
      if (buffer.GetPacketID() == 0xEF)
      {
        // new packet in client	6.0.5.0	replaces the traditional seed method with a	seed packet
        // 0xEF	= 239 =	multicast IP, so this should never appear in a normal seed.	 So	this is	backwards compatible with older	clients.
        ns.Seeded = true;
        return true;
      }

      if (buffer.Length >= 4)
      {
        byte[] m_Peek = new byte[4];

        buffer.Dequeue(m_Peek, 0, 4);

        int seed = (m_Peek[0] << 24) | (m_Peek[1] << 16) | (m_Peek[2] << 8) | m_Peek[3];

        if (seed == 0)
        {
          Console.WriteLine("Login: {0}: Invalid client detected, disconnecting", ns);
          ns.Dispose();
          return false;
        }

        ns.m_Seed = seed;
        ns.Seeded = true;
        return true;
      }

      return false;
    }

    private bool CheckEncrypted(NetState ns, int packetID)
    {
      if (!ns.SentFirstPacket && packetID != 0xF0 && packetID != 0xF1 && packetID != 0xCF && packetID != 0x80 &&
          packetID != 0x91 && packetID != 0xA4 && packetID != 0xEF)
      {
        Console.WriteLine("Client: {0}: Encrypted client detected, disconnecting", ns);
        ns.Dispose();
        return true;
      }

      return false;
    }

    public void HandleReceive(NetState ns)
    {
      ByteQueue buffer = ns.Buffer;

      if (buffer == null || buffer.Length <= 0)
        return;

      lock (buffer)
      {
        if (!ns.Seeded)
          if (!HandleSeed(ns, buffer))
            return;

        int length = buffer.Length;

        while (length > 0 && ns.Running)
        {
          int packetID = buffer.GetPacketID();

          if (CheckEncrypted(ns, packetID))
            break;

          PacketHandler handler = ns.GetHandler(packetID);

          if (handler == null)
          {
            byte[] data = new byte[length];
            length = buffer.Dequeue(data, 0, length);
            new PacketReader(data, length, false).Trace(ns);
            break;
          }

          int packetLength = handler.Length;

          if (packetLength <= 0)
          {
            if (length >= 3)
            {
              packetLength = buffer.GetPacketLength();

              if (packetLength < 3)
              {
                ns.Dispose();
                break;
              }
            }
            else
            {
              break;
            }
          }

          if (length >= packetLength)
          {
            if (handler.Ingame)
            {
              if (ns.Mobile == null)
              {
                Console.WriteLine(
                  "Client: {0}: Sent ingame packet (0x{1:X2}) before having been attached to a mobile", ns,
                  packetID);
                ns.Dispose();
                break;
              }

              if (ns.Mobile.Deleted)
              {
                ns.Dispose();
                break;
              }
            }

            ThrottlePacketCallback throttler = handler.ThrottleCallback;

            if (throttler != null && !throttler(ns))
            {
              m_Throttled.Enqueue(ns);
              return;
            }

            PacketReceiveProfile prof = null;

            if (Core.Profiling) prof = PacketReceiveProfile.Acquire(packetID);

            prof?.Start();

            byte[] packetBuffer = BufferSize >= packetLength ? m_Buffers.AcquireBuffer() : new byte[packetLength];

            packetLength = buffer.Dequeue(packetBuffer, 0, packetLength);

            PacketReader r = new PacketReader(packetBuffer, packetLength, handler.Length != 0);

            handler.OnReceive(ns, r);
            length = buffer.Length;

            if (BufferSize >= packetLength)
              m_Buffers.ReleaseBuffer(packetBuffer);

            prof?.Finish(packetLength);
          }
          else
          {
            break;
          }
        }
      }
    }
  }
}