using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Streaming;
using ErsatzTV.Core.Streaming;
using NUnit.Framework;
using Shouldly;

namespace ErsatzTV.Core.Tests.Streaming;

[TestFixture]
public class DirectStreamSessionTrackerTests
{
    [Test]
    public void Should_Track_Concurrent_Viewers_Per_Channel()
    {
        var tracker = new DirectStreamSessionTracker();

        using IDisposable session1 = tracker.Register("1", StreamingMode.TransportStream);
        using IDisposable session2 = tracker.Register("1", StreamingMode.HttpLiveStreamingDirect);
        using IDisposable session3 = tracker.Register("2", StreamingMode.TransportStream);

        tracker.IsActive("1").ShouldBeTrue();
        tracker.GetViewerCount("1").ShouldBe(2);
        tracker.GetViewerCount("2").ShouldBe(1);
        tracker.GetActiveSessions().Count.ShouldBe(3);
    }

    [Test]
    public void Should_Remove_Only_Disposed_Session()
    {
        var tracker = new DirectStreamSessionTracker();

        IDisposable session1 = tracker.Register("1", StreamingMode.TransportStream);
        IDisposable session2 = tracker.Register("1", StreamingMode.TransportStream);

        session1.Dispose();

        tracker.IsActive("1").ShouldBeTrue();
        tracker.GetViewerCount("1").ShouldBe(1);

        session2.Dispose();

        tracker.IsActive("1").ShouldBeFalse();
        tracker.GetViewerCount("1").ShouldBe(0);
    }

    [Test]
    public void Should_Dispose_Registration_Only_Once()
    {
        var tracker = new DirectStreamSessionTracker();

        IDisposable session = tracker.Register("1", StreamingMode.TransportStream);

        session.Dispose();
        session.Dispose();

        tracker.IsActive("1").ShouldBeFalse();
        tracker.GetViewerCount("1").ShouldBe(0);
    }

    [Test]
    public void Should_Filter_Active_Sessions_By_Channel()
    {
        var tracker = new DirectStreamSessionTracker();

        using IDisposable session1 = tracker.Register("1", StreamingMode.TransportStream);
        using IDisposable session2 = tracker.Register("2", StreamingMode.HttpLiveStreamingDirect);

        IReadOnlyCollection<DirectStreamSession> sessions = tracker.GetActiveSessions("2");

        sessions.Count.ShouldBe(1);
        sessions.Single().ChannelNumber.ShouldBe("2");
        sessions.Single().StreamingMode.ShouldBe(StreamingMode.HttpLiveStreamingDirect);
    }

    [Test]
    public void Should_Not_Orphan_Session_When_Last_Registration_Is_Removed_During_Register()
    {
        DirectStreamSessionTracker tracker = null;
        IDisposable existingSession = null;

        tracker = new TestDirectStreamSessionTracker(() => existingSession?.Dispose());
        existingSession = tracker.Register("1", StreamingMode.TransportStream);

        using IDisposable newSession = tracker.Register("1", StreamingMode.HttpLiveStreamingDirect);

        tracker.IsActive("1").ShouldBeTrue();
        tracker.GetViewerCount("1").ShouldBe(1);

        IReadOnlyCollection<DirectStreamSession> sessions = tracker.GetActiveSessions("1");
        sessions.Count.ShouldBe(1);
        sessions.Single().StreamingMode.ShouldBe(StreamingMode.HttpLiveStreamingDirect);
    }

    private sealed class TestDirectStreamSessionTracker(Action onRegisteringSession) : DirectStreamSessionTracker
    {
        protected override void OnRegisteringSession() => onRegisteringSession();
    }
}