using System.Net;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using Fleet.Core;

namespace MoShiro.Measurement.Tests;

public sealed class QuicSettingsTests
{
    [Theory]
    [InlineData(1100, null, false)]
    [InlineData(null, 70_000, false)]
    [InlineData(1400, 1300, false)]
    [InlineData(1280, 1500, true)]
    [InlineData(null, null, true)]
    public void Validate_RejectsMtuOutsideTheSupportedRangeOrOutOfOrder(int? min, int? max, bool valid) =>
        Assert.Equal(valid, new QuicSettings { MinMtu = min, MaxMtu = max }.Validate() is null);

    /// <summary>设置真的写进了 MsQuic：最大 MTU 压低后数据报上限随之变小，最小 MTU 抬高后一连上就是大包（不用等路径探测）。</summary>
    [Theory]
    [InlineData(1200, 1280, 1200, 1280)]
    [InlineData(1500, 1500, 1400, 1500)]
    public async Task Settings_ChangeTheDatagramLimitOfTheConnection(int min, int max, int atLeast, int atMost)
    {
        var settings = new QuicSettings { MinMtu = min, MaxMtu = max };
        var log = new NullLog();
        using ECDsa key = ECDsa.Create(ECCurve.NamedCurves.nistP256);
        var request = new CertificateRequest("CN=localhost", key, HashAlgorithmName.SHA256);
        using X509Certificate2 certificate = request.CreateSelfSigned(DateTimeOffset.UnixEpoch, DateTimeOffset.UnixEpoch.AddYears(100));
        await using var listener = new MsQuicListener(IPAddress.Loopback, [0], certificate, (_, _) => { }, log, null, settings);
        listener.Start();
        using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(15));
        MsQuicConnection client = await MsQuicConnection.ConnectAsync(IPAddress.Loopback, listener.BoundPorts[0], 0, key.ExportSubjectPublicKeyInfo(), (_, _) => { }, log, timeout.Token, settings);
        try
        {
            while (!client.IsReady)
            {
                await Task.Delay(10, timeout.Token);
            }

            // 路径 MTU 探测还可能在往上走，给它一点时间；上限始终不能超过设置的最大 MTU
            await Task.Delay(1500, timeout.Token);
            Assert.InRange(client.MaxDatagramBytes, atLeast - 100, atMost);
        }
        finally
        {
            await client.DisposeAsync().AsTask().WaitAsync(TimeSpan.FromSeconds(3));
        }
    }

    private sealed class NullLog : INodeLog
    {
        public void Write(NodeLogLevel level, string message, params (string Key, object? Value)[] fields)
        {
        }
    }
}