/*
 Sog 游戏基础库
 2016 by zouwei
 */


using System;
using System.Collections.Concurrent;
using System.Collections.Generic;

using System.Net;
using System.Net.Sockets;


namespace SogClient
{
    public class TcpSession :NetSession
    {
        const int TCP_BUFFER_SIZE = 1024 * 64;

        private bool m_recvAsyncPending;
        private bool m_sendAsyncPending;
        private object m_recvAsyncLocker;
        private object m_sendAsyncLocker;
        private SocketAsyncEventArgs m_recvAsyncEventArgs;
        private SocketAsyncEventArgs m_sendAsyncEventArgs;

        // todo shutdown和dontlinger有什么区别？
        private bool needShutdown;  // 只是为了判断是否需要socket.shutdown

        public TcpSession(Socket socket):base(socket)
        {
            m_recvBuffer = new byte[TCP_BUFFER_SIZE];
            m_sendBuffer = new byte[TCP_BUFFER_SIZE];

            InitRecvSendAsyncObject();
            m_remoteEndPoint = (IPEndPoint)m_socket.RemoteEndPoint;
            m_localEndPoint = (IPEndPoint)m_socket.LocalEndPoint;
            // socket.Connected表示最近一次IO操作时的socket状态
            // 这里Connected说明是server.accept成功时
            if (m_socket.Connected)
            {
                needShutdown = true;
            }
        }

        protected override void OnBindSocket()
        {
            InitRecvSendAsyncObject();
            m_remoteEndPoint = (IPEndPoint)m_socket.RemoteEndPoint;
            m_localEndPoint = (IPEndPoint)m_socket.LocalEndPoint;
            needShutdown = true;
        }

        private void InitRecvSendAsyncObject()
        {
            m_recvAsyncLocker = new object();
            m_sendAsyncLocker = new object();

            m_recvAsyncEventArgs = new SocketAsyncEventArgs();
            m_recvAsyncEventArgs.Completed += OnRecvAsyncCallback;

            m_sendAsyncEventArgs = new SocketAsyncEventArgs();
            m_sendAsyncEventArgs.Completed += OnSendAsyncCallback;
        }

        protected override void CloseSocket()
        {
            try
            {
                // 在调用Accept和Connect之前访问socket.RemoteEndPoint会抛出异常
                TraceLog.Trace("TcpSession.CloseSocket remote {0}", m_remoteEndPoint);

                if (m_socket != null && needShutdown)
                {
                    needShutdown = false;
                    m_socket.Shutdown(SocketShutdown.Both);
                }
            }
            catch (SocketException ex)
            {
                TraceLog.Trace("TcpSession.CloseSocket SocketException errcode {0} msg {1}"
                    , ex.ErrorCode, ex.Message);
            }
            catch (Exception ex)
            {
                TraceLog.Exception(ex);
            }
            finally
            {
                if(m_socket != null)
                {
                    m_socket.Close();
                    m_socket = null;
                }
            }
        }

        public override void CheckSocketAndSendKeepAlive()
        {
            if (m_socket == null)
            {
                return;
            }

            //发送0字节是没有效果的，这里发一个空包,这个功能增大网络流量，可以将时间设置大点
            //需要客户端兼容
            TimeSpan span = DateTime.Now - LastDataTime;
            if(span.TotalSeconds > 10)
            {
//                LastSendDataTimeSecond = AppTime.GetNowSysSecond();

                LastDataTime = DateTime.Now;

                try
                {
                    if (m_socket.Poll(0, SelectMode.SelectWrite))
                    {
                        m_noWriteableCheckCount = 0;

                        //有数据不能发送，会破坏结构
                        if (m_sendDataLeft == 0)
                        {
                            m_socket.Send(m_zeroLengthBytes, 0, m_zeroLengthBytes.Length, SocketFlags.None);
                        }
                    }
//                    else
//                    {
//                        CheckNoWriteableSocket();
//                    }
                }
                catch (SocketException ex)
                {
                    TraceLog.Error("TcpSession.CheckSocketAndSendKeepAlive remote {0} SocketException err {1}"
                        , m_remoteEndPoint, ex.SocketErrorCode);

                    if (ex.SocketErrorCode != SocketError.WouldBlock)
                    {
                        Close();
                    }
                }
                catch (Exception ex)
                {
                    TraceLog.Error("TcpSession.CheckSocketAndSendKeepAlive remote {0} SocketException message {1}"
                        , m_remoteEndPoint, ex.Message);

                    Close();
                }
            }
        }

        private void CheckNoWriteableSocket()
        {
            if (m_socket == null)
            {
                return;
            }

            // 通过send来判断socket是否还有效，万一成功时m_sendDataLeft!=0，就把消息打断了 
            // 改为count++; 后续只要socket有一次成功的recv/send就把计数清0

            m_noWriteableCheckCount++;

            TraceLog.Trace("TcpSession.CheckNoWriteableSocket socket no writeable, remote {0}, noWriteableCheckCount {1}"
                , m_remoteEndPoint, m_noWriteableCheckCount);

//            LastSendDataTimeSecond = AppTime.GetNowSysSecond();

            //如果连续多个5秒socket不可写，可以认为是断线了
            if (m_noWriteableCheckCount >= 5)
            {
                TraceLog.Error("TcpSession.CheckNoWriteableSocket socket no writeable, need close it remote {0}, noWriteableCheckCount {1} to much"
                    , m_remoteEndPoint, m_noWriteableCheckCount);

                Close();
            }
        }

       
        public override void RecvReadableSocket()
        {
            if(m_socket == null)
            {
                return;
            }

            try
            {
                int iRecvLen = m_socket.Receive(m_recvBuffer, m_alreadyRecvLength, m_recvBuffer.Length - m_alreadyRecvLength,SocketFlags.None);
                if(iRecvLen > 0)
                {
                    TotalRecvLength += iRecvLen;
//                    LastRecvDataTimeSecond = AppTime.GetNowSysSecond();
                    m_alreadyRecvLength += iRecvLen;

                    if (WriteSendRecvLog)
                    {
                        TraceLog.Trace("TcpSession.RecvReadableSocket sessionid {0} try recv from remote {1} to local {4},realy recv length {2} left length {3} "
                            , SessionID, m_remoteEndPoint, iRecvLen, m_alreadyRecvLength, m_localEndPoint);
                    }

                    TryReadMessageFromBuffer(false,false);
                }
            }
            catch(SocketException socketex)
            {
                TraceLog.Debug("TcpSession.RecvReadableSocket socket session {0} receive error HResult {1} message {2}"
                    , SessionID, socketex.HResult, socketex.Message);

                Close();
            }
            catch(Exception ex)
            {
                TraceLog.Error("TcpSession.RecvReadableSocket socket session {0} receive unkonw error, message {1}"
                    , SessionID, ex.Message);

                Close();
            }
        }


        public override void WriteWriteableSocket()
        {
            if (m_socket == null)
            {
                return;
            }

            m_noWriteableCheckCount = 0;

            try
            {
                if(m_sendDataLeft == 0)
                {
                    CopySendBuffer();
                }

                if(m_sendDataLeft > 0)
                {
                    int requestSendLength = m_sendDataLeft;

                    int iSendBytes = m_socket.Send(m_sendBuffer, m_sendDataPos, requestSendLength, SocketFlags.None);
                    if(iSendBytes > 0)
                    {
                        TotalSendLength += iSendBytes;
//                        LastSendDataTimeSecond = AppTime.GetNowSysSecond();

                        m_sendDataLeft -= iSendBytes;
                        m_sendDataPos += iSendBytes;

                        if(m_sendDataLeft == 0)
                        {
                            m_sendDataPos = 0;
                        }

                        if (WriteSendRecvLog)
                        {
                            TraceLog.Trace("TcpSession.WriteWriteableSocket sessionid {5} try send from local : {6} to remote :{0} length {1},realy send length {2} left length {3} dataLengthInSendQueue {4}"
                                , m_remoteEndPoint, requestSendLength, iSendBytes, m_sendDataLeft, m_dataLengthInSendQueue, SessionID, m_localEndPoint);
                        }
                    }
                    else
                    {
                        if (WriteSendRecvLog)
                        {
                            TraceLog.Trace("TcpSession.WriteWriteableSocket send no data length 0 from local : {6} to remote {0} request length {1} send length {2} left length {3}"
                                , m_remoteEndPoint, requestSendLength, iSendBytes, m_sendDataLeft, m_localEndPoint);
                        }
                    }
                }
                else
                {
                    if (WriteSendRecvLog)
                    {
                        TraceLog.Trace("TcpSession.WriteWriteableSocket send  from local : {1} to remote {0} no data", m_remoteEndPoint, m_localEndPoint);
                    }
                }
            }
            catch(SocketException ex)
            {
                // 正常
                if (ex.SocketErrorCode == SocketError.WouldBlock)
                {
                    TraceLog.Trace("TcpSession.WriteWriteableSocket session {0} send erro, errorcode WouldBlock"
                        , SessionID);
                }
                else
                {
                    TraceLog.Error("TcpSession.WriteWriteableSocket session {0} send erro, errorcode {1} message {2}"
                        , SessionID, ex.SocketErrorCode, ex.Message);

                    Close();
                }
            }
            catch (Exception ex)
            {
                TraceLog.Error("TcpSession.WriteWriteableSocket socket session {0} send erro, message {1}", SessionID, ex.Message);

                Close();
            }
        }


        public override void StartSendAsync()
        {
            if (m_socket == null)
            {
                return;
            }

            TraceLog.Trace("TcpSession.StartSendAsync socket session {0}", SessionID);

            lock (m_sendAsyncLocker)
            {
                if (m_sendAsyncPending)
                {
                    return;
                }

                m_sendAsyncPending = true;
            }

            DoSendAsync();
        }

        private void DoSendAsync()
        {
            try
            {
                if (m_sendDataLeft == 0)
                {
                    CopySendBuffer();
                }

                if (m_sendDataLeft > 0)
                {
                    int requestSendLength = m_sendDataLeft;
                    TraceLog.Trace("TcpSession.DoSendAsync session {0} remote {1} requestSendLength {2}"
                        , SessionID, m_remoteEndPoint, requestSendLength);

                    m_sendAsyncEventArgs.SetBuffer(m_sendBuffer, m_sendDataPos, requestSendLength);
                    bool pending = m_socket.SendAsync(m_sendAsyncEventArgs);
                    if (!pending)
                    {
                        OnSendAsyncCallback(null, m_sendAsyncEventArgs);
                    }
                }// keep alive
                else if((DateTime.Now - LastDataTime).TotalSeconds >= 60)
                {
                    TraceLog.Trace("TcpSession.DoSendAsync socket session {0} keep alive, send empty message", SessionID);

//                    LastSendDataTimeSecond = AppTime.GetNowSysSecond();

                    m_sendAsyncEventArgs.SetBuffer(m_zeroLengthBytes, 0, m_zeroLengthBytes.Length);
                    bool pending = m_socket.SendAsync(m_sendAsyncEventArgs);
                    if (!pending)
                    {
                        OnSendAsyncCallback(null, m_sendAsyncEventArgs);
                    }

                    if (WriteSendRecvLog)
                    {
                        TraceLog.Trace("TcpSession.DoSendAsync send remote {0} no data", m_remoteEndPoint);
                    }
                }
                else
                {
                    lock (m_sendAsyncLocker)
                    {
                        m_sendAsyncPending = false;
                    }

                    if (WriteSendRecvLog)
                    {
                        TraceLog.Trace("TcpSession.DoSendAsync send remote {0} no data"
                        , m_remoteEndPoint);
                    }
                }
            }
            catch (SocketException ex)
            {
                TraceLog.Error("TcpSession.DoSendAsync socket session {0} send erro, errorcode {1} message {2}"
                    , SessionID, ex.SocketErrorCode, ex.Message);

                Close();

                lock (m_sendAsyncLocker)
                {
                    m_sendAsyncPending = false;
                }

            }
            catch (Exception ex)
            {
                TraceLog.Error("TcpSession.DoSendAsync socket session {0} send erro, message {1}", SessionID, ex.Message);

                Close();

                lock (m_sendAsyncLocker)
                {
                    m_sendAsyncPending = false;
                }
            }
        }

        private void OnSendAsyncCallback(object sender, SocketAsyncEventArgs args)
        {
            int iSendBytes = args.BytesTransferred;

//            TraceLog.Trace("TcpSession.OnSendAsyncCallback sessionid {0} send length {1} "
//                , SessionID, iSendBytes);

            if (args.SocketError != SocketError.Success || args.BytesTransferred <= 0)
            {
                TraceLog.Trace("TcpSession.OnSendAsyncCallback session {0} receive error {1}"
                    , SessionID, args.SocketError);

                Close();

                lock (m_sendAsyncLocker)
                {
                    m_sendAsyncPending = false;
                }
                return;
            }

            m_noWriteableCheckCount = 0;
//            LastSendDataTimeSecond = AppTime.GetNowSysSecond();

            if(args.Buffer == m_sendBuffer)
            {
                TotalSendLength += iSendBytes;

                m_sendDataLeft -= iSendBytes;
                m_sendDataPos += iSendBytes;

                if (m_sendDataLeft == 0)
                {
                    m_sendDataPos = 0;
                }
            }
            else if(args.Buffer == m_zeroLengthBytes)
            {
                //keep alive
            }


            if (WriteSendRecvLog)
            {
                TraceLog.Trace("TcpSession.OnSendAsyncCallback sessionid {5} try send remote {0} length {1},realy send length {2} left length {3} dataLengthInSendQueue {4}"
                    , m_remoteEndPoint, iSendBytes, iSendBytes, m_sendDataLeft, m_dataLengthInSendQueue, SessionID);
            }

            DoSendAsync();
        }
        

        public override void StartRecvAsync()
        {
            if (m_socket == null)
            {
                return;
            }

            TraceLog.Trace("TcpSession.StartRecvAsync socket session {0}" , SessionID);

            lock (m_recvAsyncLocker)
            {
                if (m_recvAsyncPending)
                {
                    return;
                }

                m_recvAsyncPending = true;
            }

            DoRecvAsync();
        }

        private void DoRecvAsync()
        {
            try
            {
                TraceLog.Trace("TcpSession.DoRecvAsync socket session {0} m_alreadyRecvLength {1}", SessionID, m_alreadyRecvLength);

                m_recvAsyncEventArgs.SetBuffer(m_recvBuffer, m_alreadyRecvLength, m_recvBuffer.Length - m_alreadyRecvLength);

                bool pending = m_socket.ReceiveAsync(m_recvAsyncEventArgs);
                if (!pending)
                {
                    OnRecvAsyncCallback(null, m_recvAsyncEventArgs);
                }
            }
            catch (SocketException socketex)
            {
                TraceLog.Trace("TcpSession.DoRecvAsync socket session {0} receive error HResult {1} message {2}"
                    , SessionID, socketex.HResult, socketex.Message);

                Close();

                lock (m_recvAsyncLocker)
                {
                    m_recvAsyncPending = false;
                }
            }
            catch (Exception ex)
            {
                TraceLog.Error("TcpSession.DoRecvAsync socket session {0} receive unkonw error, message {1}"
                    , SessionID, ex.Message);

                Close();

                lock (m_recvAsyncLocker)
                {
                    m_recvAsyncPending = false;
                }
            }
        }

        private void OnRecvAsyncCallback(object sender, SocketAsyncEventArgs args)
        {
            int iRecvLen = args.BytesTransferred;

            if (args.SocketError != SocketError.Success || args.BytesTransferred <= 0)
            {
                TraceLog.Trace("TcpSession.OnRecvAsyncCallback socket session {0} SocketError {1}"
                    , SessionID, args.SocketError);

                Close();

                lock (m_recvAsyncLocker)
                {
                    m_recvAsyncPending = false;
                }

                return;
            }

            TotalRecvLength += iRecvLen;
//            LastRecvDataTimeSecond = AppTime.GetNowSysSecond();
            m_alreadyRecvLength += iRecvLen;

            if (WriteSendRecvLog)
            {
                TraceLog.Trace("TcpSession.OnRecvAsyncCallback sessionid {0} try recv remote {1},realy recv length {2} m_alreadyRecvLength {3} "
                    , SessionID, m_remoteEndPoint, iRecvLen, m_alreadyRecvLength);
            }

            TryReadMessageFromBuffer(false,true);

            //继续接收消息
            DoRecvAsync();
        }

    }
}