using Akka.Actor;
using Akka.TestKit;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.Engines;
using ZB.MOM.WW.OtOpcUa.Commons.Types;
using ZB.MOM.WW.OtOpcUa.Runtime.Drivers;
using ZB.MOM.WW.OtOpcUa.Runtime.Tests.Harness;
using ZB.MOM.WW.OtOpcUa.Runtime.VirtualTags;

namespace ZB.MOM.WW.OtOpcUa.Runtime.Tests.Drivers;

/// <summary>
///     The dependency mux retains a ref's last value for replay-opting subscribers and evicts a driver's values on
///     <see cref="DependencyMuxActor.SourceRemoved"/>. Before this, nothing in production sent that message, so a
///     driver removed by a deploy kept its last Good in the mux and replayed it to the next replay-opting
///     subscriber as if it were current. <c>DriverHostActor.StopChild</c> now sends it. A supervision restart
///     re-uses the same driver and must NOT send it. All through a REAL mux and real driver children.
/// </summary>
public sealed class DriverHostActorSourceRemovedTests : RuntimeActorTestBase
{
    private static readonly NodeId TestNode = NodeId.Parse("driver-sourceremoved-test");
    private static readonly RevisionHash RevA = RevisionHash.Parse(new string('a', 64));
    private static readonly RevisionHash RevB = RevisionHash.Parse(new string('b', 64));
    private const string Path1 = "Plant/Modbus/dev1/speed";
    private const string Path2 = "Plant/Modbus2/dev2/flow";
    private static readonly (string, string, string, string, string?)[] NoRefs = [];

    private static readonly (string Driver, string DriverName, string Device, string Tag, string DataType, bool Writable)[] BothDrivers =
    [
        ("DI-1", "Modbus", "dev1", "speed", "Double", false),
        ("DI-2", "Modbus2", "dev2", "flow", "Double", false),
    ];

    /// <summary>Spawns a host over a real mux with two enabled drivers, waits for both children to subscribe,
    /// registers a replay-opting holder (so the mux retains both refs) and publishes one value per driver.</summary>
    private (IActorRef Host, TestProbe Coordinator, RecordingSubscribableDriverFactory Factory) ArrangeTwoDriversWithRetainedValues(
        Akka.TestKit.TestProbe holder)
    {
        var db = NewInMemoryDbFactory();
        _db = db;
        var revA = V3ArtifactSeeder.SeedV3Deployment(db, RevA, BothDrivers, NoRefs, enabled: true);
        var factory = new RecordingSubscribableDriverFactory("Modbus");
        var mux = Sys.ActorOf(DependencyMuxActor.Props());
        var coordinator = CreateTestProbe();
        var host = Sys.ActorOf(DriverHostActor.Props(
            db, TestNode, coordinator.Ref,
            driverFactory: factory,
            localRoles: new HashSet<string> { "driver" },
            dependencyMux: mux,
            virtualTagEvaluator: NullVirtualTagEvaluator.Instance,
            virtualTagHostOverride: CreateTestProbe().Ref));
        V3ArtifactSeeder.Dispatch(host, coordinator, revA, RevA);
        AwaitAssert(() => factory.Created.Count.ShouldBe(2), PresenceBudget);
        foreach (var d in factory.Created) AwaitAssert(() => d.SubscribeCount.ShouldBeGreaterThanOrEqualTo(1), PresenceBudget);

        mux.Tell(new DependencyMuxActor.RegisterInterest(new[] { Path1, Path2 }, holder.Ref, ReplayRetained: true));
        Driver(factory, "DI-1").FireDataChange(Path1, 11.0);
        Driver(factory, "DI-2").FireDataChange(Path2, 22.0);
        var seen = new HashSet<string>();
        while (seen.Count < 2)
            foreach (var item in holder.ExpectMsg<VirtualTagActor.DependencyValueBatch>(PresenceBudget).Items)
                seen.Add(item.TagId);

        _mux = mux;
        return (host, coordinator, factory);
    }

    private IActorRef _mux = ActorRefs.Nobody;
    private Microsoft.EntityFrameworkCore.IDbContextFactory<ZB.MOM.WW.OtOpcUa.Configuration.OtOpcUaConfigDbContext> _db = null!;

    private static RecordingSubscribableDriver Driver(RecordingSubscribableDriverFactory f, string id) =>
        f.Created.Last(d => d.DriverInstanceId == id);

    /// <summary>A fresh replay-opting subscriber for both refs; returns the refs it was replayed.</summary>
    private string[] ReplayedRefs()
    {
        var probe = CreateTestProbe();
        _mux.Tell(new DependencyMuxActor.RegisterInterest(new[] { Path1, Path2 }, probe.Ref, ReplayRetained: true));
        return probe.ExpectMsg<VirtualTagActor.DependencyValueBatch>(PresenceBudget)
            .Items.Select(i => i.TagId).OrderBy(x => x, StringComparer.Ordinal).ToArray();
    }

    [Fact]
    public void A_driver_removed_by_a_deploy_is_no_longer_replayed_while_a_still_present_driver_is()
    {
        var holder = CreateTestProbe();
        var (host, coordinator, _) = ArrangeTwoDriversWithRetainedValues(holder);

        // Positive control before the removal: both values replay.
        ReplayedRefs().ShouldBe(new[] { Path2, Path1 }.OrderBy(x => x, StringComparer.Ordinal).ToArray());

        // Deploy B drops DI-1 (StopChild).
        var revB = V3ArtifactSeeder.SeedV3Deployment(
            _db, RevB, [("DI-2", "Modbus2", "dev2", "flow", "Double", false)], NoRefs, enabled: true);
        V3ArtifactSeeder.Dispatch(host, coordinator, revB, RevB);

        AwaitAssert(
            () => ReplayedRefs().ShouldBe(new[] { Path2 }, "DI-1 was removed: its last Good must not replay; DI-2's must"),
            PresenceBudget);
    }

    [Fact]
    public void A_supervision_restart_does_not_evict_the_drivers_retained_value()
    {
        var holder = CreateTestProbe();
        var (_, _, factory) = ArrangeTwoDriversWithRetainedValues(holder);
        var di1 = Driver(factory, "DI-1");

        // Crash DI-1's child: Akka restarts it around the SAME driver object, and the host reprovisions it.
        di1.FireMalformedDataChange(Path1);
        AwaitAssert(() => di1.InitializeCount.ShouldBe(2), PresenceBudget);
        factory.Created.Count.ShouldBe(2, "a supervision restart re-uses the driver; no new one is created");

        ReplayedRefs().ShouldBe(
            new[] { Path2, Path1 }.OrderBy(x => x, StringComparer.Ordinal).ToArray(),
            "a restart is the same driver instance: its last value stays replayable");
    }
}