using System;

using System.Collections.Generic;

using System.Linq;

using System.Net.WebSockets;

using System.Text;

using System.Threading;

using System.Threading.Tasks;

using System.Web;

using System.Web.WebSockets;

namespace WebApplicationWebsocketHandler

{

    /// <summary>

    /// 离线消息

    /// </summary>

    public class MessageInfo

    {

        public MessageInfo(DateTime _MsgTime, ArraySegment<byte> _MsgContent)

        {

            MsgTime = _MsgTime;

            MsgContent = _MsgContent;

        }

        public DateTime MsgTime { get; set; }

        public ArraySegment<byte> MsgContent { get; set; }

    }

    /// <summary>

    /// Handler1 的摘要说明

    /// </summary>

    public class Handler1 : IHttpHandler

    {

        private static Dictionary<string, WebSocket> CONNECT_POOL = new Dictionary<string, WebSocket>();//用户连接池

        private static Dictionary<string, List<MessageInfo>> MESSAGE_POOL = new Dictionary<string, List<MessageInfo>>();//离线消息池

        public void ProcessRequest(HttpContext context)

        {

            //context.Response.ContentType = "text/plain";

            //context.Response.Write("Hello World");

            if (context.IsWebSocketRequest)

            {

                context.AcceptWebSocketRequest(ProcessChat);

            }

        }

        private async Task ProcessChat(AspNetWebSocketContext context)

        {

            WebSocket socket = context.WebSocket;

            string user = context.QueryString["user"].ToString();

            try

            {

                #region 用户添加连接池

                //第一次open时，添加到连接池中

                if (!CONNECT_POOL.ContainsKey(user))

                    CONNECT_POOL.Add(user, socket);//不存在，添加

                else

                    if (socket != CONNECT_POOL[user])//当前对象不一致，更新

                        CONNECT_POOL[user] = socket;

                #endregion

                #region 离线消息处理

                if (MESSAGE_POOL.ContainsKey(user))

                {

                    List<MessageInfo> msgs = MESSAGE_POOL[user];

                    foreach (MessageInfo item in msgs)

                    {

                        await socket.SendAsync(item.MsgContent, WebSocketMessageType.Text, true, CancellationToken.None);

                    }

                    MESSAGE_POOL.Remove(user);//移除离线消息

                }

                #endregion

                string descUser = string.Empty;//目的用户

                while (true)

                {

                    if (socket.State == WebSocketState.Open)

                    {

                        ArraySegment<byte> buffer = new ArraySegment<byte>(new byte[2048]);

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

                        #region 消息处理（字符截取、消息转发）

                        try

                        {

                            #region 关闭Socket处理，删除连接池

                            if (socket.State != WebSocketState.Open)//连接关闭

                            {

                                if (CONNECT_POOL.ContainsKey(user)) CONNECT_POOL.Remove(user);//删除连接池

                                break;

                            }

                            #endregion

                            string userMsg = Encoding.UTF8.GetString(buffer.Array, 0, result.Count);//发送过来的消息

                            string[] msgList = userMsg.Split('|');

                            if (msgList.Length == 2)

                            {

                                if (msgList[0].Trim().Length > 0)

                                    descUser = msgList[0].Trim();//记录消息目的用户

                                buffer = new ArraySegment<byte>(Encoding.UTF8.GetBytes(msgList[1]));

                            }

                            else

                                buffer = new ArraySegment<byte>(Encoding.UTF8.GetBytes(userMsg));

                            if (CONNECT_POOL.ContainsKey(descUser))//判断客户端是否在线

                            {

                                WebSocket destSocket = CONNECT_POOL[descUser];//目的客户端

                                if (destSocket != null && destSocket.State == WebSocketState.Open)

                                    await destSocket.SendAsync(buffer, WebSocketMessageType.Text, true, CancellationToken.None);

                            }

                            else

                            {

                                Task.Run(() =>

                                {

                                    if (!MESSAGE_POOL.ContainsKey(descUser))//将用户添加至离线消息池中

                                        MESSAGE_POOL.Add(descUser, new List<MessageInfo>());

                                    MESSAGE_POOL[descUser].Add(new MessageInfo(DateTime.Now, buffer));//添加离线消息

                                });

                            }

                        }

                        catch (Exception exs)

                        {

                            //消息转发异常处理，本次消息忽略 继续监听接下来的消息

                        }

                        #endregion

                    }

                    else

                    {

                        break;

                    }

                }//while end

            }

            catch (Exception ex)

            {

                //整体异常处理

                if (CONNECT_POOL.ContainsKey(user)) CONNECT_POOL.Remove(user);

            }

        }

        public bool IsReusable

        {

            get

            {

                return false;

            }

        }

    }

}