using System;
using System.Collections.Concurrent;
using System.Net.WebSockets;
using System.Threading;
using System.Threading.Tasks;

namespace XGame.Framework.Network
{
    public class WSSession : IRemoteSession, IDisposable
    {
        readonly int TIMEOUT;

        private volatile SessionStatus _status = SessionStatus.FREE;
        public SessionStatus Status => _status;
        public SessionAddress Address { get; private set; }


        ClientWebSocket _webSocket;
        byte[] _buffer;
        CancellationTokenSource _sendSource;
        CancellationTokenSource _receiveSource;
        ConcurrentQueue<PendingCommand> _pendings;
        private ISessionContext _context;
        struct PendingCommand
        {
            public byte[] buffer;
            public int offset;
            public int length;
        }

        internal WSSession(int bufferSize, int timeout, ISessionContext context)
        {
            _buffer = new byte[bufferSize];
            TIMEOUT = timeout;
            _pendings = new ConcurrentQueue<PendingCommand>();
            _sendSource = new CancellationTokenSource();
            _receiveSource = new CancellationTokenSource();
            _context = context;
        }

        #region Connect Method

        public void Connect(AddressInfo info)
        {
            if (Status != SessionStatus.FREE)
            {
                Log.Warn($"[WSSession] SessionStatus:{Status}  已连接或者正在连接,又尝试连接");
                return;
            }

            OnStartConnect();

            if (Address == null ||
                Address.Domain != info.Address ||
                Address.PORT == info.Port ||
                Address.ProtocolType == info.ProtocolType)
            {
                Address = new SessionAddress(info);
            }
            var uri = GetUri(Address);

            if (uri == null)
            {
                OnConnectFail(new Exception($"[WSSession] ProtocolType {Address.ProtocolType} is not find"));
                return;
            }

            StartConnect(uri).ConfigureAwait(false);
        }
        Uri GetUri(SessionAddress info)
        {
            string url;
            switch (info.ProtocolType)
            {
                case ProtocolType.WS:
                    if (string.IsNullOrEmpty(info.URI))
                        url = $"ws://{info.Domain}:{info.PORT}";
                    else
                        url = info.URI;
                    break;
                case ProtocolType.WSS:
                    if (string.IsNullOrEmpty(info.URI))
                        url = $"wss://{info.Domain}:{info.PORT}";
                    else
                        url = info.URI;
                    break;
                default:
                    return null;
            }
            return new Uri(url);
        }

        async Task StartConnect(Uri uri)
        {
            await Task.Run(() =>
            {
                _status = SessionStatus.CONNECTING;

                var webSocket = new ClientWebSocket();
                webSocket.Options.KeepAliveInterval = new TimeSpan(0, 0, 30);
                webSocket.Options.Proxy = null;
                webSocket.Options.UseDefaultCredentials = true;

                try
                {
                    IAsyncResult asyncResult = webSocket.ConnectAsync(uri, CancellationToken.None);

                    var success = asyncResult.AsyncWaitHandle.WaitOne(TIMEOUT, true);

                    if (success && webSocket.State == WebSocketState.Open)
                    {
                        while (_pendings.TryDequeue(out var _)) ; // clear pendings

                        _webSocket = webSocket;

                        if (_sendSource != null)
                            try { _sendSource.Dispose(); } catch { }

                        if (_receiveSource != null)
                            try { _receiveSource.Dispose(); } catch { }

                        _sendSource = new CancellationTokenSource();
                        _receiveSource = new CancellationTokenSource();

                        _ = Task.Run(() => LoopSendAsync().ConfigureAwait(false));

                        _ = Task.Run(() => LoopReceiveAsync().ConfigureAwait(false));

                        OnConnected();
                    }
                    else
                    {
                        webSocket.Dispose();
                        OnConnectTimeout();
                    }
                }
                catch (Exception e)
                {
                    webSocket.Dispose();
                    OnConnectFail(e);
                }
            });
        }

        #endregion

        #region Disconnect Method
        public void Disconnect()
        {
            if (Status != SessionStatus.FREE)
            {
                Exception exception = null;

                _sendSource.Cancel();

                try
                {
                    if (_webSocket != null && _webSocket.State == WebSocketState.Open)
                    {
                        IAsyncResult resultAsync = _webSocket.CloseOutputAsync(WebSocketCloseStatus.NormalClosure, "Closing", CancellationToken.None);

                        resultAsync.AsyncWaitHandle.WaitOne(TIMEOUT, true);

                    }
                    else
                    {
                        Log.Debug($"[WSSession] CloseOutputAsync else!!!: Status: {Status}, Time: {DateTime.Now.ToLongTimeString()}:{DateTime.Now.Millisecond}, State: {_webSocket?.State}, IsNull: {_webSocket == null}");
                    }
                }
                catch (Exception e)
                {
                    exception = e;
                }
                finally
                {
                    _receiveSource.Cancel();

                    try { _webSocket?.Dispose(); } catch { }

                    _webSocket = null;

                    _status = SessionStatus.FREE;

                    if (exception != null)
                        OnDisconnectError(exception);
                    OnDisconnect();
                }
            }
        }

        #endregion

        public bool IsConnected(bool bPrecice)
        {
            return _webSocket != null && Status == SessionStatus.CONNECTED;
        }

        public bool Send(byte[] bytes, int offset, int length)
        {
            PendingCommand cmd = new PendingCommand()
            {
                buffer = bytes,
                offset = offset,
                length = length
            };

            _pendings.Enqueue(cmd);
            return true;
        }


        async Task LoopSendAsync()
        {
            var cancelToken = _sendSource.Token;

            Log.Debug($"[WSSession] LoopSendAsync Start: Status: {Status}, Time: {DateTime.Now.ToLongTimeString()}:{DateTime.Now.Millisecond}, State: {_webSocket?.State}, IsNull: {_webSocket == null}, SourceIsCanceled: {_sendSource.IsCancellationRequested}, TokenIsCanceled: {cancelToken.IsCancellationRequested}");

            try
            {
                while (_webSocket.State != WebSocketState.Closed && !cancelToken.IsCancellationRequested)
                {
                    cancelToken.ThrowIfCancellationRequested();

                    while (_pendings.TryDequeue(out var cmd))
                    {
                        var buffer = new ArraySegment<byte>(cmd.buffer, cmd.offset, cmd.length);

                        cancelToken.ThrowIfCancellationRequested();

                        await _webSocket.SendAsync(buffer, WebSocketMessageType.Binary, true, cancelToken).ConfigureAwait(false);

                        cancelToken.ThrowIfCancellationRequested();

                        SessionBufferPool.Recycle(cmd.buffer);
                    }
                    Thread.Sleep(1);
                }
            }
            catch (OperationCanceledException oce)
            {
                Log.WarnException("[WSSession] Normal upon task/token cancellation, disregard", oce);
            }
            catch (Exception e)
            {
                OnSendError(e);
            }
            finally
            {
                Log.Debug($"[WSSession] LoopSendAsync Exit: Status: {Status}, Time: {DateTime.Now.ToLongTimeString()}:{DateTime.Now.Millisecond}, State: {_webSocket?.State}, IsNull: {_webSocket == null}, SourceIsCanceled: {_sendSource.IsCancellationRequested}, TokenIsCanceled: {cancelToken.IsCancellationRequested}");
            }
        }

        async Task LoopReceiveAsync()
        {
            var cancelToken = _receiveSource.Token;

            Log.Debug($"[WSSession] LoopReceiveAsync Start: Status: {Status}, Time: {DateTime.Now.ToLongTimeString()}:{DateTime.Now.Millisecond}, State: {_webSocket?.State}, IsNull: {_webSocket == null}, SourceIsCanceled: {_receiveSource.IsCancellationRequested}, TokenIsCanceled: {cancelToken.IsCancellationRequested}");

            Exception exception = null;

            try
            {
                var buffer = new ArraySegment<byte>(_buffer, 0, _buffer.Length);

                while (_webSocket.State != WebSocketState.Closed && !cancelToken.IsCancellationRequested)
                {
                    cancelToken.ThrowIfCancellationRequested();

                    var receiveResult = await _webSocket.ReceiveAsync(buffer, cancelToken).ConfigureAwait(false);

                    if (!cancelToken.IsCancellationRequested)
                    {
                        if (_webSocket.State == WebSocketState.CloseReceived && receiveResult.MessageType == WebSocketMessageType.Close)
                        {
                            _sendSource.Cancel();

                            await _webSocket.CloseOutputAsync(WebSocketCloseStatus.NormalClosure, "Acknowledge Close frame", CancellationToken.None).ConfigureAwait(false);

                            OnRemoteClose();
                        }

                        if (_webSocket.State == WebSocketState.Open && receiveResult.MessageType != WebSocketMessageType.Close)
                        {
                            int length = receiveResult.Count;
                            if (length > 0)
                                OnRead(buffer.Array, buffer.Offset, length);
                        }
                    }

                    Thread.Sleep(1);

                    if (Status == SessionStatus.FREE)
                        throw new OperationCanceledException("No cancel after disconnected...");
                }
            }
            catch (OperationCanceledException oce)
            {
                Log.WarnException("[WSSession] Normal upon task/token cancellation, disregard", oce);
            }
            catch (Exception e)
            {
                exception = e;
            }
            finally
            {
                _sendSource.Cancel();

                if (exception != null)
                    OnReceiveError(exception);
            }
            Log.Debug($"[WSSession] LoopReceiveAsync Exit: Status: {Status}, Time: {DateTime.Now.ToLongTimeString()}:{DateTime.Now.Millisecond}, State: {_webSocket?.State}, IsNull: {_webSocket == null}, SourceIsCanceled: {_receiveSource.IsCancellationRequested}, TokenIsCanceled: {cancelToken.IsCancellationRequested}");
        }

        void OnRead(byte[] bytes, int offset, int length)
        {
            var buffer = SessionBufferPool.Acquire();
            Array.Copy(bytes, offset, buffer, 0, length);
            _context.Synchronizer.Enqueue(buffer, 0, length);
        }

        void IDisposable.Dispose()
        {
            Disconnect();
            _context = null;
        }

        #region Event
        private void OnConnectFail(Exception e)
        {
            _status = SessionStatus.CONNECT_FAIL;
            _context.Synchronizer.Enqueue(ESessionCode.ConnectFail, e);
        }

        private void OnConnectTimeout()
        {
            _status = SessionStatus.CONNECT_TIMEOUT;
            _context.Synchronizer.Enqueue(ESessionCode.ConnectTimeout, null);
        }

        private void OnConnected()
        {
            _status = SessionStatus.CONNECTED;
            _context.Synchronizer.Enqueue(ESessionCode.Connected, null);
        }

        private void OnStartConnect()
        {
            _context.Synchronizer.Enqueue(ESessionCode.StartConnect, null);
        }

        private void OnDisconnect()
        {
            _context.Synchronizer.Enqueue(ESessionCode.Disconnect, null);
        }

        private void OnDisconnectError(Exception e)
        {
            _context.Synchronizer.Enqueue(ESessionCode.DisconnectError, e);
        }

        private void OnSendError(Exception e)
        {
            _status = SessionStatus.SEND_ERROR;
            _context.Synchronizer.Enqueue(ESessionCode.SendException, e);
        }
        private void OnReceiveError(Exception e)
        {
            _status = SessionStatus.RECV_ERROR;
            _context.Synchronizer.Enqueue(ESessionCode.RecvError, e);
        }

        private void OnRemoteClose()
        {
            _status = SessionStatus.CLOSED;
            _context.Synchronizer.Enqueue(ESessionCode.SessionClose, null);
        }

        #endregion
    }
}