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

namespace TestWebSocket.Controllers
{
    [RoutePrefix("api/msg")]
    public class MsgApiController : ApiController
    {
        private static List<WebSocket> _sockets = new List<WebSocket>();

        [Route]
        [HttpGet]
        public HttpResponseMessage Connect()
        {
            HttpContext.Current.AcceptWebSocketRequest(ProcessRequest); //在服务器端接受Web Socket请求，传入的函数作为Web Socket的处理函数，待Web Socket建立后该函数会被调用，在该函数中可以对Web Socket进行消息收发

            return Request.CreateResponse(HttpStatusCode.SwitchingProtocols); //构造同意切换至Web Socket的Response.
        }

        public async Task ProcessRequest(AspNetWebSocketContext context)
        {
            var socket = context.WebSocket;//传入的context中有当前的web socket对象
            _sockets.Add(socket);//此处将web socket对象加入一个静态列表中

            //进入一个无限循环，当web socket close是循环结束
            while (true)
            {
                var buffer = new ArraySegment<byte>(new byte[1024]);
                var receivedResult = await socket.ReceiveAsync(buffer, CancellationToken.None);//对web socket进行异步接收数据
                if (receivedResult.MessageType == WebSocketMessageType.Close)
                {
                    await socket.CloseAsync(WebSocketCloseStatus.Empty, string.Empty, CancellationToken.None);//如果client发起close请求，对client进行ack
                    _sockets.Remove(socket);
                    break;
                }

                if (socket.State == System.Net.WebSockets.WebSocketState.Open)
                {
                    string recvMsg = Encoding.UTF8.GetString(buffer.Array, 0, receivedResult.Count);
                    var recvBytes = Encoding.UTF8.GetBytes(recvMsg);
                    var sendBuffer = new ArraySegment<byte>(recvBytes);
                    foreach (var innerSocket in _sockets)//当接收到文本消息时，对当前服务器上所有web socket连接进行广播
                    {
                        if (innerSocket != socket)
                        {
                            await innerSocket.SendAsync(sendBuffer, WebSocketMessageType.Text, true, CancellationToken.None);
                        }
                    }
                }
            }
        }
    }
}