using System;
using System.Collections.Generic;
using System.Net.WebSockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Web;
using System.Web.WebSockets;

namespace DemoWebSockets
{
    public class CustomWS : IHttpHandler
    {
        static List<WebSocket> clients = new List<WebSocket>();

        public void ProcessRequest(HttpContext context)
        {
            if (context.IsWebSocketRequest)
            {
                context.AcceptWebSocketRequest(ProcessWSChat);
            }
        }

        private async Task ProcessWSChat(AspNetWebSocketContext context)
        {
            WebSocket socket = context.WebSocket;

            clients.Add(socket);

            bool isEnabled = true;

            while (isEnabled)
            {
                ArraySegment<byte> buffer = new ArraySegment<byte>(new byte[1024]);

                WebSocketReceiveResult result = await socket.ReceiveAsync(buffer, CancellationToken.None);

                if (result.MessageType == WebSocketMessageType.Close)
                {
                    isEnabled = false;

                    clients.Remove(socket);
                }
                else
                {
                    string userMessage = string.Format("You sent: {0} at {1:mm:ss.fff}", Encoding.UTF8.GetString(buffer.Array, 0, result.Count), DateTime.Now);

                    byte[] messageBytes = Encoding.UTF8.GetBytes(userMessage);

                    buffer = new ArraySegment<byte>(messageBytes);

                    Parallel.ForEach(clients, p =>
                    {
                        if (p.State == WebSocketState.Open)
                        {
                            p.SendAsync(buffer, WebSocketMessageType.Text, true, CancellationToken.None);
                        }
                    });
                }
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}