using Microsoft.Extensions.Logging.Abstractions;
using NATS.Client.Core;
using NATS.Server.Auth;
using NATS.Server.Configuration;

namespace NATS.Server.Tests.Gateways;

public class GatewayAccountScopedDeliveryTests
{
    [Fact]
    public async Task Remote_message_delivery_uses_target_account_sublist_not_global_sublist()
    {
        const string subject = "orders.created";
        await using var fixture = await GatewayAccountDeliveryFixture.StartAsync();

        await using var remoteAccountA = await fixture.ConnectAsync(fixture.Remote, "a_sub");
        await using var remoteAccountB = await fixture.ConnectAsync(fixture.Remote, "b_sub");
        await using var publisher = await fixture.ConnectAsync(fixture.Local, "a_pub");

        await using var subA = await remoteAccountA.SubscribeCoreAsync<string>(subject);
        await using var subB = await remoteAccountB.SubscribeCoreAsync<string>(subject);
        await remoteAccountA.PingAsync();
        await remoteAccountB.PingAsync();
        await fixture.WaitForRemoteInterestOnLocalAsync("A", subject);

        await publisher.PublishAsync(subject, "from-gateway-a");

        using var receiveTimeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
        var msgA = await subA.Msgs.ReadAsync(receiveTimeout.Token);
        msgA.Data.ShouldBe("from-gateway-a");

        using var leakTimeout = new CancellationTokenSource(TimeSpan.FromMilliseconds(500));
        await Should.ThrowAsync<OperationCanceledException>(async () =>
            await subB.Msgs.ReadAsync(leakTimeout.Token));
    }
}

internal sealed class GatewayAccountDeliveryFixture : IAsyncDisposable
{
    private readonly CancellationTokenSource _localCts;
    private readonly CancellationTokenSource _remoteCts;

    private GatewayAccountDeliveryFixture(NatsServer local, NatsServer remote, CancellationTokenSource localCts, CancellationTokenSource remoteCts)
    {
        Local = local;
        Remote = remote;
        _localCts = localCts;
        _remoteCts = remoteCts;
    }

    public NatsServer Local { get; }
    public NatsServer Remote { get; }

    public static async Task<GatewayAccountDeliveryFixture> StartAsync()
    {
        var users = new User[]
        {
            new() { Username = "a_pub", Password = "pass", Account = "A" },
            new() { Username = "a_sub", Password = "pass", Account = "A" },
            new() { Username = "b_sub", Password = "pass", Account = "B" },
        };

        var localOptions = new NatsOptions
        {
            Host = "127.0.0.1",
            Port = 0,
            Users = users,
            Gateway = new GatewayOptions
            {
                Name = "LOCAL",
                Host = "127.0.0.1",
                Port = 0,
            },
        };

        var local = new NatsServer(localOptions, NullLoggerFactory.Instance);
        var localCts = new CancellationTokenSource();
        _ = local.StartAsync(localCts.Token);
        await local.WaitForReadyAsync();

        var remoteOptions = new NatsOptions
        {
            Host = "127.0.0.1",
            Port = 0,
            Users = users,
            Gateway = new GatewayOptions
            {
                Name = "REMOTE",
                Host = "127.0.0.1",
                Port = 0,
                Remotes = [local.GatewayListen!],
            },
        };

        var remote = new NatsServer(remoteOptions, NullLoggerFactory.Instance);
        var remoteCts = new CancellationTokenSource();
        _ = remote.StartAsync(remoteCts.Token);
        await remote.WaitForReadyAsync();

        using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
        while (!timeout.IsCancellationRequested && (local.Stats.Gateways == 0 || remote.Stats.Gateways == 0))
            await Task.Delay(50, timeout.Token).ContinueWith(_ => { }, TaskScheduler.Default);

        return new GatewayAccountDeliveryFixture(local, remote, localCts, remoteCts);
    }

    public async Task<NatsConnection> ConnectAsync(NatsServer server, string username)
    {
        var connection = new NatsConnection(new NatsOpts
        {
            Url = $"nats://{username}:pass@127.0.0.1:{server.Port}",
        });
        await connection.ConnectAsync();
        return connection;
    }

    public async Task WaitForRemoteInterestOnLocalAsync(string account, string subject)
    {
        using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
        while (!timeout.IsCancellationRequested)
        {
            if (Local.HasRemoteInterest(account, subject))
                return;

            await Task.Delay(50, timeout.Token).ContinueWith(_ => { }, TaskScheduler.Default);
        }

        throw new TimeoutException($"Timed out waiting for remote interest {account}:{subject}.");
    }

    public async ValueTask DisposeAsync()
    {
        await _localCts.CancelAsync();
        await _remoteCts.CancelAsync();
        Local.Dispose();
        Remote.Dispose();
        _localCts.Dispose();
        _remoteCts.Dispose();
    }
}