using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Net;
namespace NetFrame.Net.TCP.Listener.Asynchronous
{
    /// <summary>
    /// TcpListener實現非同步TCP伺服器
    /// </summary>
    public class AsyncTCPServer : IDisposable
    {
        #region Fields
        /// <summary>
        /// 伺服器程式允許的最大客戶端連線數
        /// </summary>
        private int _maxClient;

        /// <summary>
        /// 當前的連線的客戶端數
        /// </summary>
        private int _clientCount;

        /// <summary>
        /// 伺服器使用的非同步TcpListener
        /// </summary>
        private TcpListener _listener;

        /// <summary>
        /// 客戶端會話列表
        /// </summary>
        private List<Object> _clients;

        private bool disposed = false;

        #endregion

        #region Properties

        /// <summary>
        /// 伺服器是否正在執行
        /// </summary>
        public bool IsRunning { get; private set; }
        /// <summary>
        /// 監聽的IP地址
        /// </summary>
        public IPAddress Address { get; private set; }
        /// <summary>
        /// 監聽的埠
        /// </summary>
        public int Port { get; private set; }
        /// <summary>
        /// 通訊使用的編碼
        /// </summary>
        public Encoding Encoding { get; set; }


        #endregion

        #region 建構函式

        /// <summary>
        /// 非同步TCP伺服器
        /// </summary>
        /// <param name="listenPort">監聽的埠</param>
        public AsyncTCPServer(int listenPort)
            : this(IPAddress.Any, listenPort)
        {
        }

        /// <summary>
        /// 非同步TCP伺服器
        /// </summary>
        /// <param name="localEP">監聽的終結點</param>
        public AsyncTCPServer(IPEndPoint localEP)
            : this(localEP.Address, localEP.Port)
        {
        }

        /// <summary>
        /// 非同步TCP伺服器
        /// </summary>
        /// <param name="localIPAddress">監聽的IP地址</param>
        /// <param name="listenPort">監聽的埠</param>
        public AsyncTCPServer(IPAddress localIPAddress, int listenPort)
        {
            Address = localIPAddress;
            Port = listenPort;
            this.Encoding = Encoding.Default;

            _clients = new List<Object>();

            _listener = new TcpListener(Address, Port);
            _listener.AllowNatTraversal(true);
        }

        #endregion

        #region Method

        /// <summary>
        /// 啟動伺服器
        /// </summary>
        public void Start()
        {
            if (!IsRunning)
            {
                IsRunning = true;
                _listener.Start();
                _listener.BeginAcceptTcpClient(
                  new AsyncCallback(HandleTcpClientAccepted), _listener);
            }
        }


        /// <summary>
        /// 啟動伺服器
        /// </summary>
        /// <param name="backlog">
        /// 伺服器所允許的掛起連線序列的最大長度
        /// </param>
        public void Start(int backlog)
        {
            if (!IsRunning)
            {
                IsRunning = true;
                _listener.Start(backlog);
                _listener.BeginAcceptTcpClient(
                  new AsyncCallback(HandleTcpClientAccepted), _listener);
            }
        }

        /// <summary>
        /// 停止伺服器
        /// </summary>
        public void Stop()
        {
            if (IsRunning)
            {
                IsRunning = false;
                _listener.Stop();
                lock (_clients)
                {
                    //關閉所有客戶端連線
                    CloseAllClient();
                }
            }
        }

        /// <summary>
        /// 處理客戶端連線的函式
        /// </summary>
        /// <param name="ar"></param>
        private void HandleTcpClientAccepted(IAsyncResult ar)
        {
            if (IsRunning)
            {
                //TcpListener tcpListener = (TcpListener)ar.AsyncState;

                TcpClient client = _listener.EndAcceptTcpClient(ar);
                byte[] buffer = new byte[client.ReceiveBufferSize];

                TCPClientState state
                  = new TCPClientState(client, buffer);
                lock (_clients)
                {
                    _clients.Add(state);
                    RaiseClientConnected(state);
                }

                NetworkStream stream = state.NetworkStream;
                //開始非同步讀取資料
                stream.BeginRead(state.Buffer, 0, state.Buffer.Length, HandleDataReceived, state);

                _listener.BeginAcceptTcpClient(
                  new AsyncCallback(HandleTcpClientAccepted), ar.AsyncState);
            }
        }
        /// <summary>
        /// 資料接受回撥函式
        /// </summary>
        /// <param name="ar"></param>
        private void HandleDataReceived(IAsyncResult ar)
        {
            if (IsRunning)
            {
                TCPClientState state = (TCPClientState)ar.AsyncState;
                NetworkStream stream = state.NetworkStream;

                int recv = 0;
                try
                {
                    recv = stream.EndRead(ar);
                }
                catch
                {
                    recv = 0;
                }

                if (recv == 0)
                {
                    // connection has been closed
                    lock (_clients)
                    {
                        _clients.Remove(state);
                        //觸發客戶端連線斷開事件
                        RaiseClientDisconnected(state);
                        return;
                    }
                }

                // received byte and trigger event notification
                byte[] buff = new byte[recv];
                Buffer.BlockCopy(state.Buffer, 0, buff, 0, recv);
                //觸發資料收到事件
                RaiseDataReceived(state);

                // continue listening for tcp datagram packets
                stream.BeginRead(state.Buffer, 0, state.Buffer.Length, HandleDataReceived, state);
            }
        }

        /// <summary>
        /// 傳送資料
        /// </summary>
        /// <param name="state">接收資料的客戶端會話</param>
        /// <param name="data">資料報文</param>
        public void Send(TCPClientState state, byte[] data)
        {
            RaisePrepareSend(state);
            Send(state.TcpClient, data);
        }

        /// <summary>
        /// 非同步傳送資料至指定的客戶端
        /// </summary>
        /// <param name="client">客戶端</param>
        /// <param name="data">報文</param>
        public void Send(TcpClient client, byte[] data)
        {
            if (!IsRunning)
                throw new InvalidProgramException("This TCP Scoket server has not been started.");

            if (client == null)
                throw new ArgumentNullException("client");

            if (data == null)
                throw new ArgumentNullException("data");
            client.GetStream().BeginWrite(data, 0, data.Length, SendDataEnd, client);
        }

        /// <summary>
        /// 傳送資料完成處理函式
        /// </summary>
        /// <param name="ar">目標客戶端Socket</param>
        private void SendDataEnd(IAsyncResult ar)
        {
            ((TcpClient)ar.AsyncState).GetStream().EndWrite(ar);
            RaiseCompletedSend(null);
        }
        #endregion

        #region 事件

        /// <summary>
        /// 與客戶端的連線已建立事件
        /// </summary>
        public event EventHandler<AsyncEventArgs> ClientConnected;
        /// <summary>
        /// 與客戶端的連線已斷開事件
        /// </summary>
        public event EventHandler<AsyncEventArgs> ClientDisconnected;


        /// <summary>
        /// 觸發客戶端連線事件
        /// </summary>
        /// <param name="state"></param>
        private void RaiseClientConnected(TCPClientState state)
        {
            if (ClientConnected != null)
            {
                ClientConnected(this, new AsyncEventArgs(state));
            }
        }
        /// <summary>
        /// 觸發客戶端連線斷開事件
        /// </summary>
        /// <param name="client"></param>
        private void RaiseClientDisconnected(TCPClientState state)
        {
            if (ClientDisconnected != null)
            {
                ClientDisconnected(this, new AsyncEventArgs("連線斷開"));
            }
        }

        /// <summary>
        /// 接收到資料事件
        /// </summary>
        public event EventHandler<AsyncEventArgs> DataReceived;

        private void RaiseDataReceived(TCPClientState state)
        {
            if (DataReceived != null)
            {
                DataReceived(this, new AsyncEventArgs(state));
            }
        }

        /// <summary>
        /// 傳送資料前的事件
        /// </summary>
        public event EventHandler<AsyncEventArgs> PrepareSend;

        /// <summary>
        /// 觸發傳送資料前的事件
        /// </summary>
        /// <param name="state"></param>
        private void RaisePrepareSend(TCPClientState state)
        {
            if (PrepareSend != null)
            {
                PrepareSend(this, new AsyncEventArgs(state));
            }
        }

        /// <summary>
        /// 資料傳送完畢事件
        /// </summary>
        public event EventHandler<AsyncEventArgs> CompletedSend;

        /// <summary>
        /// 觸發資料傳送完畢的事件
        /// </summary>
        /// <param name="state"></param>
        private void RaiseCompletedSend(TCPClientState state)
        {
            if (CompletedSend != null)
            {
                CompletedSend(this, new AsyncEventArgs(state));
            }
        }

        /// <summary>
        /// 網路錯誤事件
        /// </summary>
        public event EventHandler<AsyncEventArgs> NetError;
        /// <summary>
        /// 觸發網路錯誤事件
        /// </summary>
        /// <param name="state"></param>
        private void RaiseNetError(TCPClientState state)
        {
            if (NetError != null)
            {
                NetError(this, new AsyncEventArgs(state));
            }
        }

        /// <summary>
        /// 異常事件
        /// </summary>
        public event EventHandler<AsyncEventArgs> OtherException;
        /// <summary>
        /// 觸發異常事件
        /// </summary>
        /// <param name="state"></param>
        private void RaiseOtherException(TCPClientState state, string descrip)
        {
            if (OtherException != null)
            {
                OtherException(this, new AsyncEventArgs(descrip, state));
            }
        }
        private void RaiseOtherException(TCPClientState state)
        {
            RaiseOtherException(state, "");
        }

        #endregion

        #region Close
        /// <summary>
        /// 關閉一個與客戶端之間的會話
        /// </summary>
        /// <param name="state">需要關閉的客戶端會話物件</param>
        public void Close(TCPClientState state)
        {
            if (state != null)
            {
                state.Close();
                _clients.Remove(state);
                _clientCount--;
                //TODO 觸發關閉事件
            }
        }
        /// <summary>
        /// 關閉所有的客戶端會話,與所有的客戶端連線會斷開
        /// </summary>
        public void CloseAllClient()
        {
            foreach (TCPClientState client in _clients)
            {
                Close(client);
            }
            _clientCount = 0;
            _clients.Clear();
        }
        #endregion

        #region 釋放
        /// <summary>
        /// Performs application-defined tasks associated with freeing, 
        /// releasing, or resetting unmanaged resources.
        /// </summary>
        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        /// <summary>
        /// Releases unmanaged and - optionally - managed resources
        /// </summary>
        /// <param name="disposing"><c>true</c> to release 
        /// both managed and unmanaged resources; <c>false</c> 
        /// to release only unmanaged resources.</param>
        protected virtual void Dispose(bool disposing)
        {
            if (!this.disposed)
            {
                if (disposing)
                {
                    try
                    {
                        Stop();
                        if (_listener != null)
                        {
                            _listener = null;
                        }
                    }
                    catch (SocketException)
                    {
                        //TODO
                        RaiseOtherException(null);
                    }
                }
                disposed = true;
            }
        }
        #endregion
    }
}