using DyeingComputer.UserClass;
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Sockets;
using System.Reflection.Emit;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Diagnostics;

namespace DyeingComputer.UserClass
{/// <summary>
 /// 异步TCP服务器
 /// </summary>
    public class AsyncTcpServer : IDisposable
    {
        #region Fields

        private TcpListener listener;
        private List<TcpClientState> clients;
        private bool disposed = false;

        #endregion

        #region Ctors

        /// <summary>
        /// 异步TCP服务器
        /// </summary>
        /// <param name="listenPort">监听的端口</param>
        public AsyncTcpServer(int listenPort)
          : this(IPAddress.Any, listenPort)
        {
        }

        /// <summary>
        /// 异步TCP服务器
        /// </summary>
        /// <param name="localEP">监听的终结点</param>
        public AsyncTcpServer(IPEndPoint localEP)
          : this(localEP.Address, localEP.Port)
        {
        }

        /// <summary>
        /// 异步TCP服务器
        /// </summary>
        /// <param name="localIPAddress">监听的IP地址</param>
        /// <param name="listenPort">监听的端口</param>
        public AsyncTcpServer(IPAddress localIPAddress, int listenPort)
        {
            Address = localIPAddress;
            Port = listenPort;
            this.Encoding = Encoding.Default;

            clients = new List<TcpClientState>();

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

        #endregion

        #region Properties

        /// <summary>
        /// 服务器是否正在运行
        /// </summary>
        public bool IsRunning { get; private set; }
        /// <summary>
        /// 监听的IP地址
        /// </summary>
        public IPAddress Address { get; private set; }
        /// <summary>
        /// 监听的端口
        /// </summary>
        public int Port { get; private set; }
        /// <summary>
        /// 通信使用的编码
        /// </summary>
        public Encoding Encoding { get; set; }

        #endregion

        #region Server

        /// <summary>
        /// 启动服务器
        /// </summary>
        /// <returns>异步TCP服务器</returns>
        public AsyncTcpServer Start()
        {
            if (!IsRunning)
            {
                IsRunning = true;
                listener.Start();
                listener.BeginAcceptTcpClient(
                  new AsyncCallback(HandleTcpClientAccepted), listener);
            }
            return this;
        }

        /// <summary>
        /// 启动服务器
        /// </summary>
        /// <param name="backlog">
        /// 服务器所允许的挂起连接序列的最大长度
        /// </param>
        /// <returns>异步TCP服务器</returns>
        public AsyncTcpServer Start(int backlog)
        {
            if (!IsRunning)
            {
                IsRunning = true;
                listener.Start(backlog);
                listener.BeginAcceptTcpClient(
                  new AsyncCallback(HandleTcpClientAccepted), listener);
            }
            return this;
        }

        /// <summary>
        /// 停止服务器
        /// </summary>
        /// <returns>异步TCP服务器</returns>
        public AsyncTcpServer Stop()
        {
            if (IsRunning)
            {
                IsRunning = false;
                listener.Stop();

                lock (this.clients)
                {
                    for (int i = 0; i < this.clients.Count; i++)
                    {
                        this.clients[i].TcpClient.Client.Disconnect(false);
                    }
                    this.clients.Clear();
                }

            }
            return this;
        }

        #endregion

        #region Receive

        private void HandleTcpClientAccepted(IAsyncResult ar)
        {
            if (IsRunning)
            {
                TcpListener tcpListener = (TcpListener)ar.AsyncState;

                TcpClient tcpClient = tcpListener.EndAcceptTcpClient(ar);
                byte[] buffer = new byte[tcpClient.ReceiveBufferSize];

                TcpClientState internalClient
                  = new TcpClientState(tcpClient, buffer);
                lock (this.clients)
                {
                    this.clients.Add(internalClient);
                    RaiseClientConnected(tcpClient);
                }

                NetworkStream networkStream = internalClient.NetworkStream;
                networkStream.BeginRead(
                  internalClient.Buffer,
                  0,
                  internalClient.Buffer.Length,
                  HandleDatagramReceived,
                  internalClient);

                tcpListener.BeginAcceptTcpClient(
                  new AsyncCallback(HandleTcpClientAccepted), ar.AsyncState);
            }
        }

        private void HandleDatagramReceived(IAsyncResult ar)
        {
            if (IsRunning)
            {
                TcpClientState internalClient = (TcpClientState)ar.AsyncState;
                NetworkStream networkStream = internalClient.NetworkStream;

                int numberOfReadBytes = 0;
                try
                {
                    numberOfReadBytes = networkStream.EndRead(ar);
                }
                catch
                {
                    numberOfReadBytes = 0;
                }

                if (numberOfReadBytes == 0)
                {
                    // connection has been closed
                    lock (this.clients)
                    {
                        this.clients.Remove(internalClient);
                        RaiseClientDisconnected(internalClient.TcpClient);
                        return;
                    }
                }

                // received byte and trigger event notification
                byte[] receivedBytes = new byte[numberOfReadBytes];
                Buffer.BlockCopy(
                  internalClient.Buffer, 0,
                  receivedBytes, 0, numberOfReadBytes);
                RaiseDatagramReceived(internalClient.TcpClient, receivedBytes);
                RaisePlaintextReceived(internalClient.TcpClient, receivedBytes);

                // continue listening for tcp datagram packets
                networkStream.BeginRead(
                  internalClient.Buffer,
                  0,
                  internalClient.Buffer.Length,
                  HandleDatagramReceived,
                  internalClient);
            }
        }

        #endregion

        #region Events

        /// <summary>
        /// 接收到数据报文事件
        /// </summary>
        public event EventHandler<TcpDatagramReceivedEventArgs<byte[]>> DatagramReceived;
        /// <summary>
        /// 接收到数据报文明文事件
        /// </summary>
        public event EventHandler<TcpDatagramReceivedEventArgs<string>> PlaintextReceived;

        private void RaiseDatagramReceived(TcpClient sender, byte[] datagram)
        {
            if (DatagramReceived != null)
            {
                DatagramReceived(this, new TcpDatagramReceivedEventArgs<byte[]>(sender, datagram));
            }
        }

        private void RaisePlaintextReceived(TcpClient sender, byte[] datagram)
        {
            if (PlaintextReceived != null)
            {
                PlaintextReceived(this, new TcpDatagramReceivedEventArgs<string>(
                  sender, this.Encoding.GetString(datagram, 0, datagram.Length)));
            }
        }

        /// <summary>
        /// 与客户端的连接已建立事件
        /// </summary>
        public event EventHandler<TcpClientConnectedEventArgs> ClientConnected;
        /// <summary>
        /// 与客户端的连接已断开事件
        /// </summary>
        public event EventHandler<TcpClientDisconnectedEventArgs> ClientDisconnected;

        private void RaiseClientConnected(TcpClient tcpClient)
        {
            if (ClientConnected != null)
            {
                ClientConnected(this, new TcpClientConnectedEventArgs(tcpClient));
            }
        }

        private void RaiseClientDisconnected(TcpClient tcpClient)
        {
            if (ClientDisconnected != null)
            {
                ClientDisconnected(this, new TcpClientDisconnectedEventArgs(tcpClient));
            }
        }

        #endregion

        #region Send

        /// <summary>
        /// 发送报文至指定的客户端
        /// </summary>
        /// <param name="tcpClient">客户端</param>
        /// <param name="datagram">报文</param>
        public void Send(TcpClient tcpClient, byte[] datagram)
        {
            if (!IsRunning)
                throw new InvalidProgramException("This TCP server has not been started.");

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

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

            tcpClient.GetStream().BeginWrite(
              datagram, 0, datagram.Length, HandleDatagramWritten, tcpClient);
        }

        private void HandleDatagramWritten(IAsyncResult ar)
        {
            ((TcpClient)ar.AsyncState).GetStream().EndWrite(ar);
        }

        /// <summary>
        /// 发送报文至指定的客户端
        /// </summary>
        /// <param name="tcpClient">客户端</param>
        /// <param name="datagram">报文</param>
        public void Send(TcpClient tcpClient, string datagram)
        {
            Send(tcpClient, this.Encoding.GetBytes(datagram));
        }

        /// <summary>
        /// 发送报文至所有客户端
        /// </summary>
        /// <param name="datagram">报文</param>
        public void SendAll(byte[] datagram)
        {
            if (!IsRunning)
                throw new InvalidProgramException("This TCP server has not been started.");

            for (int i = 0; i < this.clients.Count; i++)
            {
                Send(this.clients[i].TcpClient, datagram);
            }
        }

        /// <summary>
        /// 发送报文至所有客户端
        /// </summary>
        /// <param name="datagram">报文</param>
        public void SendAll(string datagram)
        {
            if (!IsRunning)
                throw new InvalidProgramException("This TCP server has not been started.");

            SendAll(this.Encoding.GetBytes(datagram));
        }

        #endregion

        #region IDisposable Members

        /// <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 ex)
                    {
                        ExceptionHandler.Handle(ex);
                    }
                }

                disposed = true;
            }
        }

        #endregion
    }
}