using System.Net;
using System.Net.Sockets;
using System.Text;
using MrGameEng.Net;
using Xunit;

namespace MrGameEng.Net.Tests;

public class HeartbeatTests
{
    [Fact]
    public async Task HealthyClient_SurvivesPastIdleTimeout()
    {
        var port = FreePort();
        using var server = new WebSocketServer(
            port,
            heartbeatInterval: TimeSpan.FromMilliseconds(100),
            idleTimeout: TimeSpan.FromMilliseconds(400)
        );
        server.Start();

        using var client = await WebSocketClient.ConnectAsync(
            new Uri($"ws://localhost:{port}/"),
            new CancellationTokenSource(TimeSpan.FromSeconds(10)).Token
        );
        var connection = await WaitFor(
            () => server.TryAcceptConnection(out var c) ? c : null,
            "server accept"
        );

        // Дольше idleTimeout: живой клиент авто-отвечает pong на server-ping и остаётся открыт.
        await Task.Delay(900, TestContext.Current.CancellationToken);

        Assert.True(connection.IsOpen);
        Assert.True(client.IsOpen);
    }

    [Fact]
    public async Task SilentPeer_IsDroppedAfterIdleTimeout()
    {
        var port = FreePort();
        using var server = new WebSocketServer(
            port,
            heartbeatInterval: TimeSpan.FromMilliseconds(100),
            idleTimeout: TimeSpan.FromMilliseconds(400)
        );
        server.Start();

        // Сырой peer: проходит рукопожатие, но дальше молчит и не отвечает на ping.
        using var tcp = new TcpClient();
        await tcp.ConnectAsync(IPAddress.Loopback, port, TestContext.Current.CancellationToken);
        var request =
            "GET / HTTP/1.1\r\n"
            + "Host: localhost\r\n"
            + "Upgrade: websocket\r\n"
            + "Connection: Upgrade\r\n"
            + "Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==\r\n"
            + "Sec-WebSocket-Version: 13\r\n"
            + "\r\n";
        var bytes = Encoding.ASCII.GetBytes(request);
        await tcp.GetStream().WriteAsync(bytes, TestContext.Current.CancellationToken);

        var connection = await WaitFor(
            () => server.TryAcceptConnection(out var c) ? c : null,
            "server accept"
        );
        Assert.True(connection.IsOpen);

        // Peer не отвечает pong'ом → активность не обновляется → сервер закрывает по простою.
        await WaitFor(() => connection.IsOpen ? null : "closed", "idle drop");
        Assert.False(connection.IsOpen);
    }

    private static async Task<T> WaitFor<T>(Func<T?> poll, string what)
        where T : class
    {
        for (var i = 0; i < 200; i++)
        {
            if (poll() is { } result)
            {
                return result;
            }

            await Task.Delay(25);
        }

        throw new TimeoutException($"Timed out waiting for {what}.");
    }

    private static int FreePort()
    {
        var listener = new TcpListener(IPAddress.Loopback, 0);
        listener.Start();
        var port = ((IPEndPoint)listener.LocalEndpoint).Port;
        listener.Stop();
        return port;
    }
}