SimpleWebChat/SimpleWebChat.ConHost/SimpleVoiceChatServerModule.cs

using System.Collections.Concurrent;
using System.Net;
using System.Net.WebSockets;
using System.Text;

namespace SimpleWebChat.ConHost
{
    public static class SimpleVoiceChatServerModule
    {
        public class VoiceSession
        {
            public WebSocket Host { get; set; }
            public WebSocket Guest { get; set; }
        }

        private static readonly ConcurrentDictionary<string, VoiceSession> VoiceChatSessions = new();

        public static void ProcessRequest(HttpListenerContext context, int currentSessionId)
        {
            WebSocket sck = null;
            string num = null;
            var isHost = false;
            VoiceSession pair = null;
            try
            {
                sck = context.AcceptWebSocketAsync("svcp").Result.WebSocket;
                Console.WriteLine($"Request #{currentSessionId:00000} VoiceChat WebSocket Session Start");

                var buffer = new byte[16384];

                var r = sck.ReceiveAsync(buffer, default).Result;
                num = Encoding.UTF8.GetString(buffer, 0, r.Count);

                if (VoiceChatSessions.TryGetValue(num, out pair))
                {
                    RunAsGuest(pair, sck, buffer);
                }
                else
                {
                    pair = RunAsHost(num, sck, buffer);
                    isHost = true;
                }
            }
            catch (Exception)
            {
                try
                {
                    if (sck != null && sck.State != WebSocketState.Aborted)
                    {
                        sck.CloseAsync(WebSocketCloseStatus.InternalServerError, "Error", default).Wait();
                    }
                }
                catch (Exception e)
                {
                    Console.WriteLine(e);
                }
            }

            if (pair != null)
            {
                if (isHost)
                {
                    VoiceChatSessions.TryRemove(num, out _);
                    pair.Host = null;
                }
                else pair.Guest = null;
            }
        }

        private static VoiceSession RunAsHost(string num, WebSocket sck, byte[] buffer)
        {
            var pair = VoiceChatSessions[num] = new VoiceSession { Host = sck };
            sck.Send("CONNECTED AS HOST");

            while (true)
            {
                var r = sck.ReceiveAsync(buffer, default).Result;
                if (r.Count == 0) break;

                if (pair.Guest != null && pair.Guest.State == WebSocketState.Open)
                {
                    pair.Guest
                        .SendAsync(new ArraySegment<byte>(buffer, 0, r.Count), WebSocketMessageType.Binary, WebSocketMessageFlags.EndOfMessage, default)
                        .AsTask().Wait();
                }
            }

            return pair;
        }

        private static void RunAsGuest(VoiceSession pair, WebSocket sck, byte[] buffer)
        {
            if (pair.Guest != null) { sck.Send("BUSY"); return; }

            pair.Guest = sck;
            var host = pair.Host;

            sck.Send("CONNECTED AS GUEST");

            host.Send("GUEST CONNECTED");

            while (true)
            {
                var r = sck.ReceiveAsync(buffer, default).Result;
                if (r.Count == 0) break;

                if (host.State == WebSocketState.Open)
                {
                    host.Send(buffer, 0, r.Count);
                }
                else
                {
                    sck.Send("HOST DISCONNECTED");
                    return;
                }
            }

            host.Send("GUEST DISCONNECTED");
        }

        private static void Send(this WebSocket sck, string text) => sck.SendAsync(Encoding.UTF8.GetBytes(text), WebSocketMessageType.Text, true, default).Wait();

        private static void Send(this WebSocket sck, byte[] bin) => sck.SendAsync(bin, WebSocketMessageType.Binary, true, default).Wait();

        private static void Send(this WebSocket sck, byte[] bin, int offset, int count) => sck.SendAsync(new ArraySegment<byte>(bin, offset, count), WebSocketMessageType.Binary, true, default).Wait();
    }
}