using System;
using System.Diagnostics;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Threading.Tasks;
using Domain;

namespace NetworkTest;

public class TcpServer : IServer
{
    private const uint MagicHeader = 0xDEADBEEF;
    private readonly TcpListener _listener;
    private readonly Func<Data?> _getPackage;
    private readonly Func<Data, byte[]> _prepareBytes;
    private readonly int _port;
    private CancellationTokenSource _cts = new CancellationTokenSource();

    public TcpServer(Func<Data?> getPackage, Func<Data, byte[]> prepareBytes, int port = 5555)
    {
        _getPackage = getPackage;
        _prepareBytes = prepareBytes;
        _port = port;
        _listener = new TcpListener(IPAddress.Any, _port);
    }

    public void Start()
    {
        _cts = new CancellationTokenSource();
        _listener.Start();
        Task.Run(() => ListenAsync(_cts.Token));
    }

    public void Stop()
    {
        _cts.Cancel();
        _listener.Stop();
    }

    private async Task ListenAsync(CancellationToken token)
    {
        while (!token.IsCancellationRequested)
        {
            try
            {
                var client = await _listener.AcceptTcpClientAsync(token);
                _ = Task.Run(() => HandleClientAsync(client, token));
            }
            catch (SocketException)
            {
                break;
            }
            catch (OperationCanceledException)
            {
                break;
            }
        }
    }

    private async Task HandleClientAsync(TcpClient client, CancellationToken token)
    {
        using (client)
        using (var stream = client.GetStream())
        {
            while (!token.IsCancellationRequested && client.Connected)
            {
                var data = _getPackage();
                if (data != null)
                {
                    var bytes = _prepareBytes(data);
                    var magicBytes = BitConverter.GetBytes(MagicHeader);
                    var lengthBytes = BitConverter.GetBytes(bytes.Length);
                    await stream.WriteAsync(magicBytes, 0, magicBytes.Length, token);
                    await stream.WriteAsync(lengthBytes, 0, lengthBytes.Length, token);
                    await stream.WriteAsync(bytes, 0, bytes.Length, token);
                }
                // await Task.Delay(50, token); // Removed delay to test maximum throughput
            }
        }
    }

    public override string ToString()
    {
        return $"TcpServer listening on port {_port}";
    }
}