/*
 * Copyright (c) OpenSim project, http://sim.opensecondlife.org/
* All rights reserved.
*
* 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
*       notice, this list of conditions and the following disclaimer.
*     * Redistributions in binary form must reproduce the above copyright
*       notice, this list of conditions and the following disclaimer in the
*       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.Generic;
using libsecondlife;
using System.Collections;
using libsecondlife.Packets;
using libsecondlife.AssetSystem;
using System.Net;
using System.Net.Sockets;
using System.Timers;

//really hacked , messy code

namespace OpenSim
{
	/// <summary>
	/// Description of Server.
	/// </summary>
	public interface ServerCallback
    {
	 	//should replace with delegates
    	void MainCallback(Packet pack, User_Agent_info User_info);
    	void NewUserCallback(User_Agent_info User_info);
    	void ErrorCallback(string text);
    }
	public class Server
    {
        /// <summary>A public reference to the client that this Simulator object
        /// is attached to</summary>
        //public SecondLife Client;

        /// <summary>The Region class that this Simulator wraps</summary>
       // public Region Region;

        /// <summary>
        /// Used internally to track sim disconnections, do not modify this 
        /// variable
        /// </summary>
        public bool DisconnectCandidate = false;

        /// <summary>
        /// The ID number associated with this particular connection to the 
        /// simulator, used to emulate TCP connections. This is used 
        /// internally for packets that have a CircuitCode field
        /// </summary>
        public uint CircuitCode
        {
            get { return circuitCode; }
            set { circuitCode = value; }
        }

        /// <summary>
        /// The IP address and port of the server
        /// </summary>
        public IPEndPoint IPEndPoint
        {
            get { return ipEndPoint; }
        }

        /// <summary>
        /// A boolean representing whether there is a working connection to the
        /// simulator or not
        /// </summary>
        public bool Connected
        {
            get { return connected; }
        }
		
        private ServerCallback CallbackObject;
        private uint Sequence = 0;
        private object SequenceLock = new object();
        private byte[] RecvBuffer = new byte[4096];
        private byte[] ZeroBuffer = new byte[8192];
        private byte[] ZeroOutBuffer = new byte[4096];
        private Socket Connection = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
        private AsyncCallback ReceivedData;
        private bool connected = false;
        private uint circuitCode;
        private IPEndPoint ipEndPoint;
        private EndPoint endPoint;
        private IPEndPoint ipeSender;
        private EndPoint epSender;
        private System.Timers.Timer AckTimer;
        private Server_Settings Settings=new Server_Settings();
        public ArrayList User_agents=new ArrayList();

        /// <summary>
        /// Constructor for Simulator
        /// </summary>
        /// <param name="client"></param>
        /// <param name="callbacks"></param>
        /// <param name="circuit"></param>
        /// <param name="ip"></param>
        /// <param name="port"></param>
        public Server(ServerCallback s_callback)
        {
        	
        	this.CallbackObject=s_callback;  //should be using delegate
        	AckTimer = new System.Timers.Timer(Settings.NETWORK_TICK_LENGTH);
        	AckTimer.Elapsed += new ElapsedEventHandler(AckTimer_Elapsed);

        	// Initialize the callback for receiving a new packet
        	ReceivedData = new AsyncCallback(this.OnReceivedData);

        	// Client.Log("Connecting to " + ip.ToString() + ":" + port, Helpers.LogLevel.Info);

        	try
        	{
        		// Create an endpoint that we will be communicating with (need it in two
        		// types due to .NET weirdness)
        		// ipEndPoint = new IPEndPoint(ip, port);
        		ipEndPoint = new IPEndPoint(IPAddress.Any, Globals.Instance.IpPort);
        		endPoint = (EndPoint)ipEndPoint;

        		// Associate this simulator's socket with the given ip/port and start listening
        		Connection.Bind(endPoint);
        		ipeSender = new IPEndPoint(IPAddress.Any, 0);
        		//The epSender identifies the incoming clients
        		epSender = (EndPoint) ipeSender;
        		Connection.BeginReceiveFrom(RecvBuffer, 0, RecvBuffer.Length, SocketFlags.None, ref epSender, ReceivedData, null);

        		// Start the ACK timer
        		AckTimer.Start();       		
        	}
        	catch (Exception e)
        	{
        		
        		System.Console.WriteLine(e.Message);
        	}
        }

        /// <summary>
        /// Disconnect a Simulator
        /// </summary>
        public void Disconnect()
        {
            if (connected)
            {
                connected = false;
                AckTimer.Stop();

                // Send the CloseCircuit notice
                CloseCircuitPacket close = new CloseCircuitPacket();

                if (Connection.Connected)
                {
                    try
                    {
                      //  Connection.Send(close.ToBytes());
                    }
                    catch (SocketException)
                    {
                        // There's a high probability of this failing if the network is
                        // disconnecting, so don't even bother logging the error
                    }
                }

                try
                {
                    // Shut the socket communication down
                  //  Connection.Shutdown(SocketShutdown.Both);
                }
                catch (SocketException)
                {
                }
            }
        }

        /// <summary>
        /// Sends a packet
        /// </summary>
        /// <param name="packet">Packet to be sent</param>
        /// <param name="incrementSequence">Increment sequence number?</param>
        public void SendPacket(Packet packet, bool incrementSequence, User_Agent_info User_info)
        {
            byte[] buffer;
            int bytes;

            if (!connected && packet.Type != PacketType.UseCircuitCode)
            {
               // Client.Log("Trying to send a " + packet.Type.ToString() + " packet when the socket is closed",
              //      Helpers.LogLevel.Info);

                return;
            }

            if (packet.Header.AckList.Length > 0)
            {
                // Scrub any appended ACKs since all of the ACK handling is done here
                packet.Header.AckList = new uint[0];
            }
            packet.Header.AppendedAcks = false;

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

            if (incrementSequence)
            {
                // Set the sequence number
                lock (SequenceLock)
                {
                    if (Sequence > Settings.MAX_SEQUENCE)
                        Sequence = 1;
                    else
                        Sequence++;
                    packet.Header.Sequence = Sequence;
                }

                if (packet.Header.Reliable)
                {
                    lock (User_info.NeedAck)
                    {
                        if (!User_info.NeedAck.ContainsKey(packet.Header.Sequence))
                        {
                            User_info.NeedAck.Add(packet.Header.Sequence, packet);
                        }
                        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 (!packet.Header.Resent)
                    {
                        // Append any ACKs that need to be sent out to this packet
                        lock (User_info.PendingAcks)
                        {
                            if (User_info.PendingAcks.Count > 0 && User_info.PendingAcks.Count < Settings.MAX_APPENDED_ACKS &&
                                packet.Type != PacketType.PacketAck &&
                                packet.Type != PacketType.LogoutRequest)
                            {
                                packet.Header.AckList = new uint[User_info.PendingAcks.Count];
                                int i = 0;
                                
                                foreach (uint ack in User_info.PendingAcks.Values)
                                {
                                    packet.Header.AckList[i] = ack;
                                    i++;
                                }

                                User_info.PendingAcks.Clear();
                                packet.Header.AppendedAcks = true;
                            }
                        }
                    }
                }
            }

            // Serialize the packet
            buffer = packet.ToBytes();
            bytes = buffer.Length;

            try
            {
                // Zerocode if needed
                if (packet.Header.Zerocoded)
                {
                    lock (ZeroOutBuffer)
                    {
                        bytes = Helpers.ZeroEncode(buffer, bytes, ZeroOutBuffer);
                        Connection.SendTo(ZeroOutBuffer, bytes, SocketFlags.None,User_info.endpoint);
                    }
                }
                else
                {	
                	
                    Connection.SendTo(buffer, bytes, SocketFlags.None,User_info.endpoint);
                }
            }
            catch (SocketException)
            {
                //Client.Log("Tried to send a " + packet.Type.ToString() + " on a closed socket",
                 //   Helpers.LogLevel.Warning);

                Disconnect();
            }
        }

        /// <summary>
        /// Send a raw byte array payload as a packet
        /// </summary>
        /// <param name="payload">The packet payload</param>
        /// <param name="setSequence">Whether the second, third, and fourth bytes
        /// should be modified to the current stream sequence number</param>
        /// <summary>
        /// Returns Simulator Name as a String
        /// </summary>
        /// <returns></returns>
        public override string ToString()
        {
        	return( " (" + ipEndPoint.ToString() + ")");
        }

        /// <summary>
        /// Sends out pending acknowledgements
        /// </summary>
        private void SendAcks(User_Agent_info User_info)
        {
            lock (User_info.PendingAcks)
            {
                if (connected && User_info.PendingAcks.Count > 0)
                {
                    if (User_info.PendingAcks.Count > 250)
                    {
                        // FIXME: Handle the odd case where we have too many pending ACKs queued up
                        //Client.Log("Too many ACKs queued up!", Helpers.LogLevel.Error);
                        return;
                    }

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

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

                    acks.Header.Reliable = false;
                    SendPacket(acks, true,User_info);

                    User_info.PendingAcks.Clear();
                }
            }
        }
        /// <summary>
        /// Resend unacknowledged packets
        /// </summary>
        private void ResendUnacked(User_Agent_info User_info)
        {
            if (connected)
            {
                int now = Environment.TickCount;

                lock (User_info.NeedAck)
                {
                    foreach (Packet packet in User_info.NeedAck.Values)
                    {
                        if (now - packet.TickCount > Settings.RESEND_TIMEOUT)
                        {
                          //  Client.Log("Resending " + packet.Type.ToString() + " packet, " +
                           //     (now - packet.TickCount) + "ms have passed", Helpers.LogLevel.Info);

                            packet.Header.Resent = true;
                            SendPacket(packet, false,User_info);
                        }
                    }
                }
            }
        }
        /// <summary>
        /// Callback handler for incomming data
        /// </summary>
        /// <param name="result"></param>
        private void OnReceivedData(IAsyncResult result)
        {
        	
        	ipeSender = new IPEndPoint(IPAddress.Any, 0);
            epSender = (EndPoint)ipeSender;
            Packet packet = null;
            int numBytes;

            // If we're receiving data the sim connection is open
            connected = true;

            // Update the disconnect flag so this sim doesn't time out
            DisconnectCandidate = false;
            User_Agent_info User_info=null;

            lock (RecvBuffer)
            {
                // Retrieve the incoming packet
                try
                {
                    numBytes = Connection.EndReceiveFrom(result, ref epSender);
					
                    //find user_agent_info
                    
                    int packetEnd = numBytes - 1;
                    packet = Packet.BuildPacket(RecvBuffer, ref packetEnd, ZeroBuffer);
					
                    
                    //should check if login/useconnection packet first
                    if (packet.Type == PacketType.UseCircuitCode)
           			{
                    	UseCircuitCodePacket cir_pack=(UseCircuitCodePacket)packet;
                    	User_Agent_info new_user=new User_Agent_info();
                    	new_user.circuitCode=cir_pack.CircuitCode.Code;
                    	new_user.AgentID=cir_pack.CircuitCode.ID;
                    	new_user.SessionID=cir_pack.CircuitCode.SessionID;
                    	new_user.endpoint=epSender;
                    	new_user.Inbox = new Queue<uint>(Settings.INBOX_SIZE);
                    	
                    	this.CallbackObject.NewUserCallback(new_user);
                    	this.User_agents.Add(new_user);
                    	
                    }
                    
                    
                    User_Agent_info temp_agent=null;
                    	IPEndPoint send_ip=(IPEndPoint)epSender;
                    //	this.callback_object.error("incoming: address is "+send_ip.Address +"port number is: "+send_ip.Port.ToString());
                    	
                    for(int ii=0; ii<this.User_agents.Count ; ii++)
                    {
                    	temp_agent=(User_Agent_info)this.User_agents[ii];
                    	IPEndPoint ag_ip=(IPEndPoint)temp_agent.endpoint;
                    	//this.callback_object.error("searching: address is "+ag_ip.Address +"port number is: "+ag_ip.Port.ToString());
                    	
                    	if((ag_ip.Address.ToString()==send_ip.Address.ToString()) && (ag_ip.Port.ToString()==send_ip.Port.ToString()))
                    	{
                    		//this.callback_object.error("found user");
                    		User_info=temp_agent;
                    		break;
                    	}
                    }
                    
                    Connection.BeginReceiveFrom(RecvBuffer, 0, RecvBuffer.Length, SocketFlags.None, ref epSender, ReceivedData, null);
                }
                catch (SocketException)
                {
                   // Client.Log(endPoint.ToString() + " socket is closed, shutting down " + this.Region.Name,
                   //     Helpers.LogLevel.Info);

                    connected = false;
                    //Network.DisconnectSim(this);
                    return;
                }
            }
            if(User_info==null)
            {
            	
            	//error finding agent
            	this.CallbackObject.ErrorCallback("no user found");
            	return;
            }

            // Fail-safe check
            if (packet == null)
            {
            	this.CallbackObject.ErrorCallback("couldn't build packet");
               // Client.Log("Couldn't build a message from the incoming data", Helpers.LogLevel.Warning);
                return;
            }
            //this.callback_object.error("past tests");
            // Track the sequence number for this packet if it's marked as reliable
            if (packet.Header.Reliable)
            {
                if (User_info.PendingAcks.Count > Settings.MAX_PENDING_ACKS)
                {
                    SendAcks(User_info);
                }

                // Check if we already received this packet
                if (User_info.Inbox.Contains(packet.Header.Sequence))
                {
                    //Client.Log("Received a duplicate " + packet.Type.ToString() + ", sequence=" +
                    //    packet.Header.Sequence + ", resent=" + ((packet.Header.Resent) ? "Yes" : "No") +
                    //    ", Inbox.Count=" + Inbox.Count + ", NeedAck.Count=" + NeedAck.Count,
                    //    Helpers.LogLevel.Info);

                    // Send an ACK for this packet immediately
                    //SendAck(packet.Header.Sequence);

                    // TESTING: Try just queuing up ACKs for resent packets instead of immediately triggering an ACK
                    lock (User_info.PendingAcks)
                    {
                        uint sequence = (uint)packet.Header.Sequence;
                        if (!User_info.PendingAcks.ContainsKey(sequence)) { User_info.PendingAcks[sequence] = sequence; }
                    }

                    // Avoid firing a callback twice for the same packet
                   // this.callback_object.error("avoiding callback");
                    return;
                }
                else
                {
                    lock (User_info.PendingAcks)
                    {
                        uint sequence = (uint)packet.Header.Sequence;
                        if (!User_info.PendingAcks.ContainsKey(sequence)) { User_info.PendingAcks[sequence] = sequence; }
                    }
                }
            }

            // Add this packet to our inbox
            lock (User_info.Inbox)
            {
                while (User_info.Inbox.Count >= Settings.INBOX_SIZE)
                {
                    User_info.Inbox.Dequeue();
                }
                User_info.Inbox.Enqueue(packet.Header.Sequence);
            }

            // Handle appended ACKs
            if (packet.Header.AppendedAcks)
            {
                lock (User_info.NeedAck)
                {
                    foreach (uint ack in packet.Header.AckList)
                    {
                        User_info.NeedAck.Remove(ack);
                    }
                }
            }

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

                lock (User_info.NeedAck)
                {
                    foreach (PacketAckPacket.PacketsBlock block in ackPacket.Packets)
                    {
                        User_info.NeedAck.Remove(block.ID);
                    }
                }
            }
			
            this.CallbackObject.MainCallback(packet,User_info);
           
        }

        private void AckTimer_Elapsed(object sender, ElapsedEventArgs ea)
        {
            if (connected)
            {
            	
            	//TODO for each user_agent_info
            	for(int i=0; i<this.User_agents.Count; i++)
            	{
            		User_Agent_info user=(User_Agent_info)this.User_agents[i];
            	
                	SendAcks(user);
                	ResendUnacked(user);
            	}
            }
        }
    }
	  
	   public class Server_Settings
    {
        /// <summary>The version of libsecondlife (not the SL protocol itself)</summary>
        public string VERSION = "libsecondlife 0.0.9";
        /// <summary>XML-RPC login server to connect to</summary>
        public string LOGIN_SERVER = "https://login.agni.lindenlab.com/cgi-bin/login.cgi";

        /// <summary>Millisecond interval between ticks, where all ACKs are 
        /// sent out and the age of unACKed packets is checked</summary>
        public readonly int NETWORK_TICK_LENGTH = 500;
        /// <summary>The maximum value of a packet sequence number. After that 
        /// we assume the sequence number just rolls over? Or maybe the 
        /// protocol isn't able to sustain a connection past that</summary>
        public readonly int MAX_SEQUENCE = 0xFFFFFF;
        /// <summary>Number of milliseconds before a teleport attempt will time
        /// out</summary>
        public readonly int TELEPORT_TIMEOUT = 18 * 1000;
		
		/// <summary>Number of milliseconds before NetworkManager.Logout() will time out</summary>
		public int LOGOUT_TIMEOUT = 5 * 1000;
		/// <summary>Number of milliseconds for xml-rpc to timeout</summary>
		public int LOGIN_TIMEOUT = 30 * 1000;
        /// <summary>The maximum size of the sequence number inbox, used to
        /// check for resent and/or duplicate packets</summary>
        public int INBOX_SIZE = 100;
        /// <summary>Milliseconds before a packet is assumed lost and resent</summary>
        public int RESEND_TIMEOUT = 4000;
        /// <summary>Milliseconds before the connection to a simulator is 
        /// assumed lost</summary>
        public int SIMULATOR_TIMEOUT = 15000;
        /// <summary>Maximum number of queued ACKs to be sent before SendAcks()
        /// is forced</summary>
        public int MAX_PENDING_ACKS = 10;
        /// <summary>Maximum number of ACKs to append to a packet</summary>
        public int MAX_APPENDED_ACKS = 10;
        /// <summary>Cost of uploading an asset</summary>
        public int UPLOAD_COST { get { return priceUpload; } }

        
        private int priceUpload = 0;
        
        public Server_Settings()
        {
        	
        }
    }
	   
	public class User_Agent_info
    {
    	public EndPoint endpoint;
    	public LLUUID AgentID;
        public LLUUID SessionID;
        public uint circuitCode;
        public string name;
        public uint localID;
        public string first_name;
        public string last_name;
        
        public Dictionary<uint, Packet> NeedAck = new Dictionary<uint, Packet>();
        // Sequence numbers of packets we've received from the simulator
        public Queue<uint> Inbox;
        // ACKs that are queued up to be sent to the simulator
        public Dictionary<uint, uint> PendingAcks = new Dictionary<uint, uint>();
      
    	public User_Agent_info()
    	{
    		
    	}
    }

}