/*
 
Copyright (c) 2017 Ahmed Kh. Zamil

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

*/

using System;
using System.Threading;
using System.Collections.Generic;
using Esiur.Data;
using Esiur.Misc;
using Esiur.Engine;
using Esiur.Net.Sockets;
using Esiur.Resource;
using System.Threading.Tasks;

namespace Esiur.Net
{

    public abstract class NetworkServer<TConnection>: IDestructible where TConnection : NetworkConnection, new()
    {
        //private bool isRunning;
        uint clock;
        private ISocket listener;
        private AutoList<TConnection, NetworkServer<TConnection>> connections;

        //private Thread thread;

        protected abstract void DataReceived(TConnection sender, NetworkBuffer data);
        protected abstract void ClientConnected(TConnection sender);
        protected abstract void ClientDisconnected(TConnection sender);


        private uint timeout;
        private Timer timer;
        //public KeyList<string, TSession> Sessions = new KeyList<string, TSession>();

        public event DestroyedEvent OnDestroy;

        public AutoList<TConnection, NetworkServer<TConnection>> Connections
        {
            get
            {
                return connections;
            }
        }

        /*
        public void RemoveSession(string ID)
        {
            Sessions.Remove(ID);
        }

        public void RemoveSession(TSession Session)
        {
            if (Session != null)
                Sessions.Remove(Session.Id);
        }
        */

        /*
        public TSession CreateSession(string ID, int Timeout)
        {
            TSession s = new TSession();

            s.SetSession(ID, Timeout, new NetworkSession.SessionModifiedEvent(SessionModified)
                            , new NetworkSession.SessionEndedEvent(SessionEnded));


            Sessions.Add(ID, s);
            return s;
        }
        */

        /*
        private void pSessionModified(TSession session, string key, object oldValue, object newValue)
        {
            SessionModified((TSession)session, key, oldValue, newValue);
        }

        private void pSessionEnded(NetworkSession session)
        {
            SessionEnded((TSession)session);
        }
        */

            /*
        protected virtual void SessionModified(NetworkSession session, string key, object oldValue, object newValue)
        {

        }

        protected virtual void SessionEnded(NetworkSession session)
        {
            Sessions.Remove(session.Id);
            session.Destroy();
        }
        */

        private void MinuteThread(object state)
        {
            List<TConnection> ToBeClosed = null;


            lock (connections.SyncRoot)
            {
                foreach (TConnection c in connections)
                {
                    if (DateTime.Now.Subtract(c.LastAction).TotalSeconds >= timeout)
                    {
                        if (ToBeClosed == null)
                            ToBeClosed = new List<TConnection>();
                        ToBeClosed.Add(c);
                    }
                }
            }

            //Console.WriteLine("UnLock MinuteThread");

            if (ToBeClosed != null)
            {
                //Console.WriteLine("Term: " + ToBeClosed.Count + " " + this.listener.LocalEndPoint.ToString());
                foreach (TConnection c in ToBeClosed)
                    c.Close();// CloseAndWait();

                ToBeClosed.Clear();
                ToBeClosed = null;
            }
        }

        public void Start(ISocket socket, uint timeout, uint clock)
        {
            if (listener != null)
                return;

            //if (socket.State == SocketState.Listening)
            //  return;

            //if (isRunning)
            //  return;

            connections = new AutoList<TConnection, NetworkServer<TConnection>>(this);


            if (timeout > 0 & clock > 0)
            {
                timer = new Timer(MinuteThread, null, TimeSpan.FromMinutes(0), TimeSpan.FromSeconds(clock));
                this.timeout = timeout;
            }

            //this.ip = ip;
            //this.port = port;
            this.clock = clock;


            // start a new thread for the server to live on
            //isRunning = true;



            listener = socket;

            // Start accepting
            listener.Accept().Then(NewConnection);

            //var rt = listener.Accept().Then()
            //thread = new Thread(new System.Threading.ThreadStart(ListenForConnections));

            //thread.Start();

        }

        /*
        public int LocalPort
        {
            get
            {
                return port;
            }
        }
        */


        public uint Clock
        {
            get { return clock; }
        }

        public void Stop()
        {
            var port = 0;

            try
            {
                if (listener != null)
                {
                    port = listener.LocalEndPoint.Port;
                    listener.Close();
                }

                // wait until the listener stops
                //while (isRunning)
                //{
                  //  Thread.Sleep(100);
                //}

                //Console.WriteLine("Listener stopped");

                var cons = connections.ToArray();

                //lock (connections.SyncRoot)
                //{
                    foreach (TConnection con in cons)
                        con.Close();
                //}

                //Console.WriteLine("Sockets Closed");

                //while (connections.Count > 0)
                //{
                //    Console.WriteLine("Waiting... " + connections.Count);  
                //    Thread.Sleep(1000);
                //}

            }
            finally
            {
                Console.WriteLine("Server@{0} is down", port);
            }
        }


        public virtual void RemoveConnection(TConnection connection)
        {
            connection.OnDataReceived -= OnDataReceived;
            connection.OnConnect -= OnClientConnect;
            connection.OnClose -= OnClientClose;
            connections.Remove(connection);
        }

        public virtual void AddConnection(TConnection connection)
        {
            connection.OnDataReceived += OnDataReceived;
            connection.OnConnect += OnClientConnect;
            connection.OnClose += OnClientClose;
            connections.Add(connection);
        }

        private void NewConnection(ISocket sock)
        {

            try
            {

                /*
                    if (listener.State == SocketState.Closed || listener.State == SocketState.Terminated)
                    {
                           Console.WriteLine("Listen socket break ");
                           Console.WriteLine(listener.LocalEndPoint.Port);
                           break;
                    }
                    */

                    if (sock == null)
                    {
                        //Console.Write("sock == null");
                        return;
                    }

                //sock.ReceiveBufferSize = 102400;
                //sock.SendBufferSize = 102400;


                    TConnection c = new TConnection();
                    AddConnection(c);

                    c.Assign(sock);

                    ClientConnected(c);

                    // Accept more
                    listener.Accept().Then(NewConnection);

                    sock.Begin();


            }
            catch (Exception ex)
            {
                //Console.WriteLine("TSERVER " + ex.ToString());
                Global.Log("NetworkServer", LogType.Error, ex.ToString());
            }

            //isRunning = false;


        }

        public bool IsRunning
        {
            get
            {
                return listener.State == SocketState.Listening;
                //isRunning; 
            }
        }
 
        public void OnDataReceived(NetworkConnection sender, NetworkBuffer data)
        {
            DataReceived((TConnection)sender, data);
        }

        public void OnClientConnect(NetworkConnection sender)
        {
            if (sender == null)
                return;

            if (sender.RemoteEndPoint == null || sender.LocalEndPoint == null)
            { }
            //Console.WriteLine("NULL");
            else
                Global.Log("Connections", LogType.Debug, sender.RemoteEndPoint.Address.ToString()
                    + "->" + sender.LocalEndPoint.Port + " at " + DateTime.UtcNow.ToString("d")
                    + " " + DateTime.UtcNow.ToString("d"), false);

            // Console.WriteLine("Connected " + sender.RemoteEndPoint.ToString());
            ClientConnected((TConnection)sender);
        }

        public void OnClientClose(NetworkConnection sender)
        {
            try
            {
                sender.Destroy();
                RemoveConnection((TConnection)sender);
                ClientDisconnected((TConnection)sender);
            }
            catch (Exception ex)
            {
                Global.Log("NetworkServer:OnClientDisconnect", LogType.Error, ex.ToString());
            }

            sender = null;
            GC.Collect();
        }

        
        public void Destroy()
        {
            Stop();
            OnDestroy?.Invoke(this);
        }

        ~NetworkServer()
        {
            Stop();
            //Connections = null;
            listener = null;
        }
    }

}