using Akka.Actor;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.OpcUa;
using ZB.MOM.WW.OtOpcUa.Commons.Types;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Runtime.Drivers;
using ZB.MOM.WW.OtOpcUa.Runtime.Tests.Harness;

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

public sealed class DriverInstanceActorTests : RuntimeActorTestBase
{
    /// <summary>Verifies that initialize failure keeps the actor in Reconnecting state.</summary>
    [Fact]
    public void Initialize_failure_keeps_actor_in_Reconnecting_state()
    {
        var driver = new StubDriver { InitializeShouldThrow = true };
        var actor = Sys.ActorOf(DriverInstanceActor.Props(driver, reconnectInterval: TimeSpan.FromMilliseconds(50)));

        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));

        // The actor should keep trying — we expect multiple Initialize calls because the
        // reconnect timer fires every 50ms.
        AwaitCondition(() => driver.InitializeCount >= 3, TimeSpan.FromSeconds(2));
    }

    /// <summary>Verifies that writing to a non-IWritable driver returns failure.</summary>
    [Fact]
    public async Task Write_against_non_IWritable_driver_returns_failure()
    {
        var driver = new StubDriver(); // IDriver only, no IWritable.
        var actor = Sys.ActorOf(DriverInstanceActor.Props(driver));

        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
        AwaitCondition(() => driver.InitializeCount > 0, TimeSpan.FromSeconds(2));

        var reply = await actor.Ask<DriverInstanceActor.WriteAttributeResult>(
            new DriverInstanceActor.WriteAttribute("tag-1", 42),
            TimeSpan.FromSeconds(3));

        reply.Success.ShouldBeFalse();
        reply.Reason!.ShouldContain("IWritable");
    }

    /// <summary>Verifies that writing to an IWritable driver returns success when status is Good.</summary>
    [Fact]
    public async Task Write_against_IWritable_returns_success_when_status_is_Good()
    {
        var driver = new WritableStubDriver();
        var actor = Sys.ActorOf(DriverInstanceActor.Props(driver));

        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
        AwaitCondition(() => driver.InitializeCount > 0, TimeSpan.FromSeconds(2));

        var reply = await actor.Ask<DriverInstanceActor.WriteAttributeResult>(
            new DriverInstanceActor.WriteAttribute("tag-1", 42),
            TimeSpan.FromSeconds(3));

        reply.Success.ShouldBeTrue();
        driver.Writes.Single().FullReference.ShouldBe("tag-1");
        driver.Writes.Single().Value.ShouldBe(42);
    }

    /// <summary>Verifies that write propagates status code on Bad result.</summary>
    [Fact]
    public async Task Write_propagates_status_code_on_Bad_result()
    {
        const uint badStatus = 0x80340000; // BadNodeIdUnknown — top severity bits = 10b
        var driver = new WritableStubDriver { NextStatusCode = badStatus };
        var actor = Sys.ActorOf(DriverInstanceActor.Props(driver));

        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
        AwaitCondition(() => driver.InitializeCount > 0, TimeSpan.FromSeconds(2));

        var reply = await actor.Ask<DriverInstanceActor.WriteAttributeResult>(
            new DriverInstanceActor.WriteAttribute("tag-1", 42),
            TimeSpan.FromSeconds(3));

        reply.Success.ShouldBeFalse();
        reply.Reason!.ShouldContain("80340000");
    }

    /// <summary>Verifies that subscribing to an ISubscribable driver forwards OnDataChange to parent.</summary>
    [Fact]
    public async Task Subscribe_against_ISubscribable_forwards_OnDataChange_to_parent()
    {
        var driver = new SubscribableStubDriver();
        var parent = CreateTestProbe();
        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
        var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver));

        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
        AwaitCondition(() => driver.InitializeCount > 0, TimeSpan.FromSeconds(2));

        await actor.Ask<DriverInstanceActor.SubscriptionEstablished>(
            new DriverInstanceActor.Subscribe(new[] { "tag-a", "tag-b" }, TimeSpan.FromMilliseconds(250)),
            TimeSpan.FromSeconds(3));

        // Driver fires an OnDataChange — actor should forward it to its parent as an
        // AttributeValueBatchPublished (single-item, since this driver is per-tag-only) carrying the
        // driver's status code.
        driver.FireDataChange("tag-a", value: 3.14, statusCode: 0u);

        var published = parent.ExpectMsg<DriverInstanceActor.AttributeValueBatchPublished>(TimeSpan.FromSeconds(2));
        published.Items.Count.ShouldBe(1);
        published.Items[0].FullReference.ShouldBe("tag-a");
        published.Items[0].Value.ShouldBe(3.14);
        published.Items[0].StatusCode.ShouldBe(OpcUaStatus.Good);
    }

    /// <summary>
    ///     Gitea #519 — a driver's status code reaches the parent <b>with its sub-code intact</b>.
    ///     <para>This is the first of the two hops that used to destroy it: the actor projected the
    ///     driver's <c>uint</c> onto a 3-state Good/Uncertain/Bad enum, and the node manager then
    ///     re-expanded Bad to a bare <c>0x80000000</c>. The net effect was that no driver's sub-code ever
    ///     reached an OPC UA client — <c>BadNoCommunication</c>, <c>BadTypeMismatch</c> and
    ///     <c>BadNotSupported</c> were indistinguishable — while every driver maintained its own named
    ///     constants (16 of which #497 had just corrected) as if they mattered end to end.</para>
    ///     <para>The severity buckets are asserted too, since the bucket is still what
    ///     <see cref="OpcUaStatus.IsGood"/> and friends classify on; what changed is that the bucket is no
    ///     longer <em>all</em> that survives.</para>
    /// </summary>
    [Fact]
    public async Task Subscribe_forwards_the_drivers_status_sub_code_without_collapsing_it()
    {
        var driver = new SubscribableStubDriver();
        var parent = CreateTestProbe();
        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
        var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver));

        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
        AwaitCondition(() => driver.InitializeCount > 0, TimeSpan.FromSeconds(2));

        await actor.Ask<DriverInstanceActor.SubscriptionEstablished>(
            new DriverInstanceActor.Subscribe(new[] { "tag-1" }, TimeSpan.FromMilliseconds(100)),
            TimeSpan.FromSeconds(3));

        // Uncertain — severity bits 01 (top 2 bits = 01).
        driver.FireDataChange("tag-1", value: 1, statusCode: 0x40000000u);
        parent.ExpectMsg<DriverInstanceActor.AttributeValueBatchPublished>().Items[0].StatusCode
            .ShouldBe(OpcUaStatus.Uncertain);

        // Bad — severity bits 10.
        driver.FireDataChange("tag-1", value: 2, statusCode: 0x80000000u);
        parent.ExpectMsg<DriverInstanceActor.AttributeValueBatchPublished>().Items[0].StatusCode
            .ShouldBe(OpcUaStatus.Bad);

        // The regression itself: a Bad SUB-code must arrive intact, not flattened to OpcUaStatus.Bad.
        // This is the exact code MTConnect maps the Agent's UNAVAILABLE sentinel to, and the live gate
        // that opened #519 observed it reaching a client as 0x80000000.
        driver.FireDataChange("tag-1", value: null, statusCode: OpcUaStatus.BadNoCommunication);
        var noComms = parent.ExpectMsg<DriverInstanceActor.AttributeValueBatchPublished>().Items[0];
        noComms.StatusCode.ShouldBe(OpcUaStatus.BadNoCommunication);
        noComms.StatusCode.ShouldNotBe(OpcUaStatus.Bad, "the sub-code was collapsed to a generic Bad");
        OpcUaStatus.IsBad(noComms.StatusCode).ShouldBeTrue("it must still classify as Bad");

        // A second, DIFFERENT Bad sub-code — the two were indistinguishable before the fix, so asserting
        // one alone would not prove the sub-code is carried rather than hard-coded.
        driver.FireDataChange("tag-1", value: null, statusCode: 0x80740000u /* BadTypeMismatch */);
        parent.ExpectMsg<DriverInstanceActor.AttributeValueBatchPublished>().Items[0].StatusCode
            .ShouldBe(0x80740000u);
    }

    /// <summary>
    ///     Verifies the SubscribeBulk pass: SetDesiredSubscriptions retains the ref set and the actor
    ///     auto-subscribes when it (re)enters Connected — including a re-subscribe after a reconnect,
    ///     closing the F8b/#113 gap that previously left galaxy variables at BadWaitingForInitialData.
    /// </summary>
    [Fact]
    public async Task SetDesiredSubscriptions_auto_subscribes_on_connect_and_resubscribes_after_reconnect()
    {
        var driver = new SubscribableStubDriver();
        var parent = CreateTestProbe();
        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
        var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver, reconnectInterval: TimeSpan.FromMilliseconds(50)));

        // Desired set arrives BEFORE connect — retained, not yet applied.
        actor.Tell(new DriverInstanceActor.SetDesiredSubscriptions(
            new[] { "tag-a", "tag-b" }, TimeSpan.FromMilliseconds(100)));

        // Connecting → Connected triggers the auto-subscribe.
        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
        AwaitCondition(() => driver.SubscribeCount >= 1, TimeSpan.FromSeconds(2));
        driver.LastSubscribedRefs.ShouldBe(new[] { "tag-a", "tag-b" });

        // The auto-subscription is live — a data change reaches the parent.
        driver.FireDataChange("tag-a", value: 7, statusCode: 0u);
        parent.ExpectMsg<DriverInstanceActor.AttributeValueBatchPublished>(TimeSpan.FromSeconds(2))
            .Items[0].Value.ShouldBe(7);

        // Reconnect → the desired set is re-established without any new host message.
        actor.Tell(new DriverInstanceActor.DisconnectObserved("backend blip"));
        AwaitCondition(() => driver.SubscribeCount >= 2, TimeSpan.FromSeconds(3));
    }

    /// <summary>
    ///     Verifies the re-subscribe path (the second Subscribe finds a live handle and first awaits
    ///     UnsubscribeAsync) still replies SubscriptionEstablished. Regression for the no-ActorContext
    ///     race: reading Sender after `await UnsubscribeAsync().ConfigureAwait(false)` resumed off the
    ///     actor context and threw, so the reply never arrived. This drives the exact deploy-re-apply /
    ///     bootstrap-restore path where `_subscriptionHandle is not null`.
    /// </summary>
    [Fact]
    public async Task Subscribe_twice_replies_SubscriptionEstablished_on_resubscribe()
    {
        // UnsubscribeYields makes the inner UnsubscribeAsync genuinely suspend, so the second
        // Subscribe's `await UnsubscribeAsync()` resumes off the actor context if ConfigureAwait(false)
        // is used — the exact condition that throws NotSupportedException on the subsequent Sender read.
        var driver = new SubscribableStubDriver { UnsubscribeYields = true };
        var parent = CreateTestProbe();
        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
        var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver));

        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
        AwaitCondition(() => driver.InitializeCount > 0, TimeSpan.FromSeconds(2));

        // First subscribe — establishes the handle.
        await actor.Ask<DriverInstanceActor.SubscriptionEstablished>(
            new DriverInstanceActor.Subscribe(new[] { "tag-a", "tag-b" }, TimeSpan.FromMilliseconds(250)),
            TimeSpan.FromSeconds(3));

        // Second subscribe — `_subscriptionHandle is not null`, so the handler awaits
        // UnsubscribeAsync first, then reads Sender. Must still reply (today it threw → no reply).
        var reply = await actor.Ask<DriverInstanceActor.SubscriptionEstablished>(
            new DriverInstanceActor.Subscribe(new[] { "tag-a", "tag-b" }, TimeSpan.FromMilliseconds(250)),
            TimeSpan.FromSeconds(3));

        reply.ReferenceCount.ShouldBe(2);
        driver.SubscribeCount.ShouldBe(2);
        // Old handler must have been detached before the new one was attached — no leak.
        driver.OnDataChangeSubscriberCount.ShouldBe(1);
    }

    /// <summary>Verifies that subscribing to a non-ISubscribable driver replies with failure.</summary>
    [Fact]
    public async Task Subscribe_against_non_ISubscribable_replies_with_failure()
    {
        var driver = new StubDriver(); // IDriver only
        var actor = Sys.ActorOf(DriverInstanceActor.Props(driver));

        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
        AwaitCondition(() => driver.InitializeCount > 0, TimeSpan.FromSeconds(2));

        var reply = await actor.Ask<DriverInstanceActor.SubscriptionFailed>(
            new DriverInstanceActor.Subscribe(new[] { "tag-1" }, TimeSpan.FromMilliseconds(100)),
            TimeSpan.FromSeconds(3));

        reply.Reason.ShouldContain("ISubscribable");
    }

    /// <summary>Verifies that DisconnectObserved detaches subscription handler so late events are dropped.</summary>
    [Fact]
    public async Task DisconnectObserved_detaches_subscription_handler_so_late_events_are_dropped()
    {
        var driver = new SubscribableStubDriver();
        var parent = CreateTestProbe();
        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
        var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver, reconnectInterval: TimeSpan.FromSeconds(30)));

        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
        AwaitCondition(() => driver.InitializeCount > 0, TimeSpan.FromSeconds(2));
        await actor.Ask<DriverInstanceActor.SubscriptionEstablished>(
            new DriverInstanceActor.Subscribe(new[] { "tag-1" }, TimeSpan.FromMilliseconds(100)),
            TimeSpan.FromSeconds(3));

        actor.Tell(new DriverInstanceActor.DisconnectObserved("backend went away"));

        // Race window — once disconnect is processed, subsequent FireDataChange calls hit a
        // detached handler and don't push anything to the parent.
        AwaitCondition(() => driver.OnDataChangeSubscriberCount == 0, TimeSpan.FromSeconds(2));
        driver.FireDataChange("tag-1", value: 99, statusCode: 0u);
        parent.ExpectNoMsg(TimeSpan.FromMilliseconds(300));
    }

    /// <summary>
    ///     Archreview <b>03/S15 (T11)</b> — a child that is <b>stopped</b> announces comms loss on its way
    ///     out, so the host latches its value nodes <c>BadNoCommunication</c>.
    ///     <para>Every other route into <c>Reconnecting</c> announces it (watchdog trip, failed initial
    ///     connect, Force Reconnect all run the <c>Reconnecting</c> entry). Stopping did not: an operator's
    ///     Restart and a supervision respawn tore the child down silently, so its nodes kept serving their
    ///     last value at Good across the gap. The fresh child's re-subscribe + initial push (03/S16) is what
    ///     clears them again.</para>
    /// </summary>
    [Fact]
    public void Stopping_a_connected_child_announces_comms_loss_to_its_parent()
    {
        var parent = CreateTestProbe();
        var driver = new StubDriver();
        var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver));

        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
        parent.ExpectMsg<DriverInstanceActor.ConnectivityChanged>(PresenceBudget).Connected.ShouldBeTrue();

        parent.Watch(actor);
        parent.Send(actor, PoisonPill.Instance);

        parent.ExpectMsg<DriverInstanceActor.ConnectivityChanged>(PresenceBudget).Connected.ShouldBeFalse();
        parent.ExpectTerminated(actor, PresenceBudget);
    }

    /// <summary>
    ///     <b>Control.</b> A child that never reached <c>Connected</c> announces nothing when stopped — its
    ///     nodes are still <c>BadWaitingForInitialData</c>, which is a more precise statement than
    ///     "communication lost", and overwriting it would claim an outage that never happened.
    /// </summary>
    [Fact]
    public void Stopping_a_never_connected_child_announces_nothing()
    {
        var parent = CreateTestProbe();
        var driver = new StubDriver { InitializeShouldThrow = true };
        var actor = parent.ChildActorOf(DriverInstanceActor.Props(
            driver, reconnectInterval: TimeSpan.FromSeconds(30)));

        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
        // The failed initial connect announces Connected=false from the Reconnecting entry; consume it, so
        // what follows is only what STOPPING produced.
        parent.ExpectMsg<DriverInstanceActor.ConnectivityChanged>(PresenceBudget).Connected.ShouldBeFalse();

        parent.Watch(actor);
        parent.Send(actor, PoisonPill.Instance);

        parent.ExpectTerminated(actor, PresenceBudget);
        parent.ExpectNoMsg(TimeSpan.FromMilliseconds(300));
    }
}