using FFXIVClassic.Common;
using FFXIVClassic_World_Server.DataObjects;
using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;

namespace FFXIVClassic_World_Server
{
    class Server
    {
        public const int FFXIV_MAP_PORT = 54992;
        public const int BUFFER_SIZE = 0xFFFF; //Max basepacket size is 0xFFFF
        public const int BACKLOG = 100;
        public const int HEALTH_THREAD_SLEEP_TIME = 5;
        
        private static Server mSelf;

        private Socket mServerSocket;

        WorldManager worldManager;

        private List<ClientConnection> mConnectionList = new List<ClientConnection>();
        private Dictionary<uint, Session> mZoneSessionList = new Dictionary<uint, Session>();
        private Dictionary<uint, Session> mChatSessionList = new Dictionary<uint, Session>();

        public Server()
        {
            mSelf = this;
        }

        public static Server GetServer()
        {
            return mSelf;
        }

        public bool StartServer()
        {
            worldManager = new WorldManager(this);
            worldManager.LoadZoneServerList();
            worldManager.ConnectToZoneServers();

            IPEndPoint serverEndPoint = new System.Net.IPEndPoint(IPAddress.Parse(ConfigConstants.OPTIONS_BINDIP), int.Parse(ConfigConstants.OPTIONS_PORT));

            try
            {
                mServerSocket = new System.Net.Sockets.Socket(serverEndPoint.Address.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
            }
            catch (Exception e)
            {
                throw new ApplicationException("Could not Create socket, check to make sure not duplicating port", e);
            }
            try
            {
                mServerSocket.Bind(serverEndPoint);
                mServerSocket.Listen(BACKLOG);
            }
            catch (Exception e)
            {
                throw new ApplicationException("Error occured while binding socket, check inner exception", e);
            }
            try
            {
                mServerSocket.BeginAccept(new AsyncCallback(AcceptCallback), mServerSocket);
            }
            catch (Exception e)
            {
                throw new ApplicationException("Error occured starting listeners, check inner exception", e);
            }

            Console.ForegroundColor = ConsoleColor.White;
            Program.Log.Info("World Server accepting connections @ {0}:{1}", (mServerSocket.LocalEndPoint as IPEndPoint).Address, (mServerSocket.LocalEndPoint as IPEndPoint).Port);
            Console.ForegroundColor = ConsoleColor.Gray;
            
            return true;
        }        

        #region Socket Handling
        private void AcceptCallback(IAsyncResult result)
        {
            ClientConnection conn = null;
            Socket socket = (System.Net.Sockets.Socket)result.AsyncState;

            try
            {
                conn = new ClientConnection();
                conn.socket = socket.EndAccept(result);
                conn.buffer = new byte[BUFFER_SIZE];

                lock (mConnectionList)
                {
                    mConnectionList.Add(conn);
                }

                Program.Log.Info("Connection {0}:{1} has connected.", (conn.socket.RemoteEndPoint as IPEndPoint).Address, (conn.socket.RemoteEndPoint as IPEndPoint).Port);
                //Queue recieving of data from the connection
                conn.socket.BeginReceive(conn.buffer, 0, conn.buffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), conn);
                //Queue the accept of the next incomming connection
                mServerSocket.BeginAccept(new AsyncCallback(AcceptCallback), mServerSocket);
            }
            catch (SocketException)
            {
                if (conn != null)
                {

                    lock (mConnectionList)
                    {
                        mConnectionList.Remove(conn);
                    }
                }
                mServerSocket.BeginAccept(new AsyncCallback(AcceptCallback), mServerSocket);
            }
            catch (Exception)
            {
                if (conn != null)
                {
                    lock (mConnectionList)
                    {
                        mConnectionList.Remove(conn);
                    }
                }
                mServerSocket.BeginAccept(new AsyncCallback(AcceptCallback), mServerSocket);
            }
        }

        public void AddSession(uint id)
        {
            throw new NotImplementedException();
        }

        public void RemoveSession(uint id)
        {
            if (mChatSessionList.ContainsKey(id)) {
                mChatSessionList[id].clientSocket.Disconnect();
                mConnectionList.Remove(mChatSessionList[id].clientSocket);
                mChatSessionList.Remove(id);
            }

            if (mZoneSessionList.ContainsKey(id))
            {
                mZoneSessionList[id].clientSocket.Disconnect();
                mConnectionList.Remove(mZoneSessionList[id].clientSocket);
                mZoneSessionList.Remove(id);
            }
        }

        public Session GetSession(uint targetSession)
        {
            if (mZoneSessionList.ContainsKey(targetSession))
                return mZoneSessionList[targetSession];
            else
                return null;
        }

        /// <summary>
        /// Receive Callback. Reads in incoming data, converting them to base packets. Base packets are sent to be parsed. If not enough data at the end to build a basepacket, move to the beginning and prepend.
        /// </summary>
        /// <param name="result"></param>
        private void ReceiveCallback(IAsyncResult result)
        {
            ClientConnection conn = (ClientConnection)result.AsyncState;

            //Check if disconnected
            if ((conn.socket.Poll(1, SelectMode.SelectRead) && conn.socket.Available == 0))
            {
                lock (mConnectionList)
                {
                    mConnectionList.Remove(conn);
                }
                
                return;
            }

            try
            {
                int bytesRead = conn.socket.EndReceive(result);

                bytesRead += conn.lastPartialSize;

                if (bytesRead >= 0)
                {
                    int offset = 0;

                    //Build packets until can no longer or out of data
                    while (true)
                    {
                        BasePacket basePacket = BuildPacket(ref offset, conn.buffer, bytesRead);

                        //If can't build packet, break, else process another
                        if (basePacket == null)
                            break;
                        else
                        {
                            //mProcessor.ProcessPacket(conn, basePacket);
                        }
                            
                    }

                    //Not all bytes consumed, transfer leftover to beginning
                    if (offset < bytesRead)
                        Array.Copy(conn.buffer, offset, conn.buffer, 0, bytesRead - offset);

                    conn.lastPartialSize = bytesRead - offset;

                    //Build any queued subpackets into basepackets and send
                    conn.FlushQueuedSendPackets();

                    if (offset < bytesRead)
                        //Need offset since not all bytes consumed
                        conn.socket.BeginReceive(conn.buffer, bytesRead - offset, conn.buffer.Length - (bytesRead - offset), SocketFlags.None, new AsyncCallback(ReceiveCallback), conn);
                    else
                        //All bytes consumed, full buffer available
                        conn.socket.BeginReceive(conn.buffer, 0, conn.buffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), conn);
                }
                else
                {
                    
                    lock (mConnectionList)
                    {
                        mConnectionList.Remove(conn);
                    }
                }
            }
            catch (SocketException)
            {
                if (conn.socket != null)
                {
                   
                    lock (mConnectionList)
                    {
                        mConnectionList.Remove(conn);
                    }
                }
            }
        }     

        /// <summary>
        /// Builds a packet from the incoming buffer + offset. If a packet can be built, it is returned else null.
        /// </summary>
        /// <param name="offset">Current offset in buffer.</param>
        /// <param name="buffer">Incoming buffer.</param>
        /// <returns>Returns either a BasePacket or null if not enough data.</returns>
        public BasePacket BuildPacket(ref int offset, byte[] buffer, int bytesRead)
        {
            BasePacket newPacket = null;

            //Too small to even get length
            if (bytesRead <= offset)
                return null;

            ushort packetSize = BitConverter.ToUInt16(buffer, offset);

            //Too small to whole packet
            if (bytesRead < offset + packetSize)
                return null;

            if (buffer.Length < offset + packetSize)
                return null;

            try
            {
                newPacket = new BasePacket(buffer, ref offset);
            }
            catch (OverflowException)
            {
                return null;
            }

            return newPacket;
        }

        #endregion


        public WorldManager GetWorldManager()
        {
            return worldManager;
        }
        
    }
}