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

namespace MrGameEng.Net.Tests;

public class WebSocketLoopbackTests
{
    [Fact]
    public async Task ClientAndServer_ExchangeBinaryMessages_OverLoopback()
    {
        var port = FreePort();
        using var server = new WebSocketServer(port);
        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"
        );

        // Сервер → клиент.
        connection.Send([1, 2, 3, 250]);
        var received = await WaitFor(
            () => client.TryReceive(out var m) ? m : null,
            "client receive"
        );
        Assert.Equal(new byte[] { 1, 2, 3, 250 }, received);

        // Клиент → сервер (ClientWebSocket маскирует кадры — сервер обязан размаскировать).
        client.Send([9, 8, 7]);
        var echoed = await WaitFor(
            () => connection.TryReceive(out var m) ? m : null,
            "server receive"
        );
        Assert.Equal(new byte[] { 9, 8, 7 }, echoed);

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

    [Fact]
    public async Task ClosingTheClient_ClosesTheServerConnection()
    {
        var port = FreePort();
        using var server = new WebSocketServer(port);
        server.Start();

        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"
        );

        client.Close();

        await WaitFor(() => connection.IsOpen ? null : "closed", "server-side close");
        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;
    }
}