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

namespace LobbyClientTest
{
    internal class FakeGameHost
    {
        private Socket _socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
        private const int bufSize = 8 * 1024;
        private State state = new State();
        private EndPoint epFrom = new IPEndPoint(IPAddress.Any, 0);
        private AsyncCallback recv = null;
        public bool isHost;
        public class State
        {
            public byte[] buffer = new byte[bufSize];
        }

        public int Server(int port)
        {
            _socket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.ReuseAddress, true);
            _socket.ExclusiveAddressUse = false;
            _socket.Bind(new IPEndPoint(IPAddress.Any, port));
            Receive();
            return ((IPEndPoint)_socket.LocalEndPoint!).Port;
        }

        public void Send(EndPoint ep, string text)
        {
            byte[] data = Encoding.ASCII.GetBytes(text);
            _socket.SendTo(data, 0, data.Length, SocketFlags.None, ep);
        }

        private void Receive()
        {
            _socket.BeginReceiveFrom(state.buffer, 0, bufSize, SocketFlags.None, ref epFrom, recv = (ar) =>
            {
                State so = (State)ar.AsyncState;
                int bytes = _socket.EndReceiveFrom(ar, ref epFrom);
                _socket.BeginReceiveFrom(so.buffer, 0, bufSize, SocketFlags.None, ref epFrom, recv, so);
                Console.WriteLine($"Game {(isHost ? "host" : "client")} received: {epFrom.ToString()}: {bytes}, {Encoding.ASCII.GetString(so.buffer, 0, bytes)}");
                if (isHost)
                    Send(epFrom, "Hello from Game Server!");
            }, state);
        }
    }
}