EVCB_OCPP.OCPPServer.16J/EVCB_OCPP.WSServer/Service/WsService/WsSession.cs

using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Primitives;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.WebSockets;
using System.Text;
using System.Threading.Tasks;
using System.Timers;
using Timer = System.Timers.Timer;

namespace EVCB_OCPP.WSServer.Service.WsService
{
    public class WsSession
    {
        public WsSession()
        {

        }

        public PathString? Path { get; set; }
        public string UriScheme { get; set; }
        public string AuthHeader { get; set; }
        public string SessionID { get; set; }
        public IPEndPoint Endpoint { get; internal set; }
        //public StringValues Origin { get; internal set; }
        public DateTime LastActiveTime { get; set; }


        private WebSocket _WebSocket;
        public WebSocket ClientWebSocket
        {
            get => _WebSocket;
            set
            {
                Init(value);
            }
        }

        public WebSocketState State => ClientWebSocket.State;
        public string SecWebSocketProtocol => ClientWebSocket.SubProtocol;

        public SemaphoreSlim EndConnSemaphore { get; } = new SemaphoreSlim(0);

        //public event OCPPClientDataEventHandler<WsSession, String> m_ReceiveData;

        public event EventHandler<string> SessionClosed;

        private CancellationTokenSource disconnectCancellationTokenSource = new CancellationTokenSource();
        private Task ReceiveLoopTask;

        private void Init(WebSocket webSocket)
        {
            _WebSocket = webSocket;
            ReceiveLoopTask = StartReceivd(webSocket, disconnectCancellationTokenSource.Token);
        }

        private async Task StartReceivd(WebSocket webSocket, CancellationToken token)
        {
            string received = string.Empty;
            while (!token.IsCancellationRequested)
            {
                var buffer = new byte[1024 * 4];
                WebSocketReceiveResult result = null;

                try
                {
                    result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), token);
                }
                catch (Exception e)
                {
                    _ = BruteClose(e.Message);
                    break;
                }

                if (result == null || result.CloseStatus.HasValue)
                {
                    //closed gracefully
                    _ = GracefulClose(result.CloseStatus.Value);
                    break;
                }

                received += Encoding.UTF8.GetString(buffer, 0, result.Count);
                //m_ReceiveData?.Invoke(this, received);
                LastActiveTime = DateTime.UtcNow;
                if (result.EndOfMessage)
                {
                    HandleReceivedData(received);
                    received = string.Empty;
                }
            }
        }

        internal virtual void HandleReceivedData(string data)
        {

        }

        internal Task Send(string dataString)
        {
            var data = Encoding.UTF8.GetBytes(dataString);
            return Send(data, 0 , data.Length);
        }

        internal async Task Send(byte[] data, int offset, int length)
        {
            await ClientWebSocket.SendAsync(data, WebSocketMessageType.Text, endOfMessage: true, cancellationToken: disconnectCancellationTokenSource.Token);
            if (ClientWebSocket.State == WebSocketState.Aborted ||
                ClientWebSocket.State == WebSocketState.Closed)
            {

            }
        }

        internal Task Close()
        {
            return ServerClose();
        }

        private Task ServerClose()
        {
            SessionClosed?.Invoke(this, "ServerShutdown");
            return InternalClose(WebSocketCloseStatus.NormalClosure, "ServerShutdown");
        }

        private  Task GracefulClose(WebSocketCloseStatus closeStatus)
        {
            SessionClosed?.Invoke(this, closeStatus.ToString());
            return InternalClose(closeStatus , null);
        }

        private Task BruteClose(string description)
        {
            SessionClosed?.Invoke(this, description);
            return InternalClose(WebSocketCloseStatus.EndpointUnavailable, description);
        }

        private async Task InternalClose(WebSocketCloseStatus closeStatus, string description)
        {
            try
            {
                await _WebSocket.CloseAsync(closeStatus, description, default);
            }
            catch
            { 
            }
            finally
            {
                _WebSocket.Dispose();
            }

            disconnectCancellationTokenSource.Cancel();
            EndConnSemaphore.Release();
        }
    }
}