using Akka.Actor;
using Akka.Cluster.Tools.PublishSubscribe;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Redundancy;
using ZB.MOM.WW.OtOpcUa.ControlPlane.Redundancy;
using ZB.MOM.WW.OtOpcUa.ControlPlane.Tests.Harness;

namespace ZB.MOM.WW.OtOpcUa.ControlPlane.Tests;

public sealed class RedundancyStateActorTests : ControlPlaneActorTestBase
{
    [Fact(Skip = "Single-node DistributedPubSub bootstrap is flaky in TestKit; tracked as F6.")]
    public void Self_join_triggers_RedundancyStateChanged_on_pubsub_topic()
    {
        // Subscribe a probe to the redundancy-state topic.
        var probe = CreateTestProbe("redundancy-listener");
        var mediator = DistributedPubSub.Get(Sys).Mediator;
        mediator.Tell(new Subscribe(RedundancyStateActor.Topic, probe.Ref));
        probe.ExpectMsg<SubscribeAck>(TimeSpan.FromSeconds(3));

        // Start the actor — its PreStart subscribes to cluster events, which immediately fires
        // a CurrentClusterState replay (InitialStateAsEvents). After the 250ms debounce window,
        // a RedundancyStateChanged should land on the topic.
        Sys.ActorOf(RedundancyStateActor.Props(), "redundancy-actor");

        var msg = probe.ExpectMsg<RedundancyStateChanged>(TimeSpan.FromSeconds(3));
        msg.Nodes.ShouldNotBeNull();
        msg.CorrelationId.Value.ShouldNotBe(Guid.Empty);
    }

    [Fact(Skip = "Same root cause as the prior test; tracked as F6.")]
    public void Multiple_back_to_back_events_debounce_to_single_publish()
    {
        var probe = CreateTestProbe("dedup-listener");
        var mediator = DistributedPubSub.Get(Sys).Mediator;
        mediator.Tell(new Subscribe(RedundancyStateActor.Topic, probe.Ref));
        probe.ExpectMsg<SubscribeAck>(TimeSpan.FromSeconds(3));

        Sys.ActorOf(RedundancyStateActor.Props(), "redundancy-debounce");

        // First publish should arrive within the debounce window.
        probe.ExpectMsg<RedundancyStateChanged>(TimeSpan.FromSeconds(3));

        // After debounce settles, no more events are fired by a quiescent cluster.
        probe.ExpectNoMsg(TimeSpan.FromMilliseconds(500));
    }
}