using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Driver.AbCip.Tests;

/// <summary>
///     Task #177 — tests covering ALMD projection detection, feature-flag gate,
///     subscribe/unsubscribe lifecycle, state-transition event emission, and acknowledge.
/// </summary>
[Trait("Category", "Unit")]
public sealed class AbCipAlarmProjectionTests
{
    private const string Device = "ab://10.0.0.5/1,0";

    private static AbCipTagDefinition AlmdTag(string name) => new(
        name, Device, name, AbCipDataType.Structure, Members:
        [
            new AbCipStructureMember("InFaulted", AbCipDataType.DInt), // Logix stores ALMD bools as DINT
            new AbCipStructureMember("Acked", AbCipDataType.DInt),
            new AbCipStructureMember("Severity", AbCipDataType.DInt),
            new AbCipStructureMember("In", AbCipDataType.DInt),
        ]);

    /// <summary>Verifies that ALMD structure signature is correctly detected as an alarm.</summary>
    [Fact]
    public void AbCipAlarmDetector_Flags_AlmdSignature_As_Alarm()
    {
        var almd = AlmdTag("HighTemp");
        AbCipAlarmDetector.IsAlmd(almd).ShouldBeTrue();

        var plainUdt = new AbCipTagDefinition("Plain", Device, "Plain", AbCipDataType.Structure, Members:
            [new AbCipStructureMember("X", AbCipDataType.DInt)]);
        AbCipAlarmDetector.IsAlmd(plainUdt).ShouldBeFalse();

        var atomic = new AbCipTagDefinition("Plain", Device, "Plain", AbCipDataType.DInt);
        AbCipAlarmDetector.IsAlmd(atomic).ShouldBeFalse();
    }

    /// <summary>Verifies that severity values map correctly to OPC UA alarm severity levels.</summary>
    [Fact]
    public void Severity_Mapping_Matches_OPC_UA_Convention()
    {
        // Logix severity 1–1000 — mirror the OpcUaClient ACAndC bucketing.
        AbCipAlarmProjection.MapSeverity(100).ShouldBe(AlarmSeverity.Low);
        AbCipAlarmProjection.MapSeverity(400).ShouldBe(AlarmSeverity.Medium);
        AbCipAlarmProjection.MapSeverity(600).ShouldBe(AlarmSeverity.High);
        AbCipAlarmProjection.MapSeverity(900).ShouldBe(AlarmSeverity.Critical);
    }

    private static AbCipDriverOptions Options(bool enabled) => new()
    {
        Devices = [new AbCipDeviceOptions(Device)],
        RawTags = AbCipRawTags.From(AlmdTag("HighTemp")),
        EnableAlarmProjection = enabled,
        AlarmPollInterval = TimeSpan.FromMilliseconds(20),
        // The ALMD projection here drives the parent-UDT runtime via offset-keyed values,
        // so it needs the declaration-only whole-UDT grouping fast path (Driver.AbCip-003).
        EnableDeclarationOnlyUdtGrouping = true,
    };

    /// <summary>Verifies that disabled alarm projection returns a valid handle but does not poll.</summary>
    [Fact]
    public async Task FeatureFlag_Off_SubscribeAlarms_Returns_Handle_But_Never_Polls()
    {
        var factory = new FakeAbCipTagFactory();
        var drv = new AbCipDriver(Options(enabled: false), "drv-1", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        var handle = await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
        handle.ShouldNotBeNull();
        handle.DiagnosticId.ShouldContain("abcip-alarm-sub-");

        // Positive control (#583): the same options with the flag ON poll three times — so a loop this
        // subscription had started would have read (and so created) the ALMD runtime by now.
        await PolledThreeTimesWithTheFlagOnAsync();
        factory.Tags.ShouldNotContainKey("HighTemp");
        factory.Tags.ShouldNotContainKey("HighTemp.InFaulted");
        factory.Tags.ShouldNotContainKey("HighTemp.Severity");

        await drv.UnsubscribeAlarmsAsync(handle, CancellationToken.None);
        await drv.ShutdownAsync(CancellationToken.None);
    }

    /// <summary>Verifies that enabled alarm projection starts polling and fires raise event on 0-to-1 transition.</summary>
    [Fact]
    public async Task FeatureFlag_On_Subscribe_Starts_Polling_And_Fires_Raise_On_0_to_1()
    {
        var factory = new FakeAbCipTagFactory();
        var drv = new AbCipDriver(Options(enabled: true), "drv-1", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        var events = new List<AlarmEventArgs>();
        drv.OnAlarmEvent += (_, e) => { lock (events) events.Add(e); };

        var handle = await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);

        // The ALMD UDT is declared so whole-UDT grouping kicks in; the parent HighTemp runtime
        // gets created + polled. Set InFaulted offset-value to 0 first (clear), let polls seed the
        // "last-seen false" state, then flip to 1 (fault) + wait for the raise event.
        await WaitForTagCreation(factory, "HighTemp");
        factory.Tags["HighTemp"].ValuesByOffset[0] = 0;  // InFaulted=false at offset 0
        factory.Tags["HighTemp"].ValuesByOffset[8] = 500; // Severity at offset 8 (after InFaulted+Acked)
        await WaitForMoreReadsAsync(factory, "HighTemp", 2);

        factory.Tags["HighTemp"].ValuesByOffset[0] = 1; // flip to faulted
        await WaitForEventAsync(events, e => e.SourceNodeId == "HighTemp" && e.AlarmType == "ALMD"
            && e.Message.Contains("raised"));

        await drv.UnsubscribeAlarmsAsync(handle, CancellationToken.None);
        await drv.ShutdownAsync(CancellationToken.None);
    }

    /// <summary>
    ///     Regression for the reconnect poll-loop leak (#399 sibling): the owning
    ///     DriverInstanceActor re-subscribes alarms on every Connected entry without first calling
    ///     Unsubscribe, and the driver object (and its projection) survives the in-place reconnect.
    ///     Each SubscribeAsync used to start a fresh, never-cancelled poll loop — so after N
    ///     reconnects there were N live loops all polling the device and all firing the same
    ///     raise/clear transition, producing DUPLICATE alarm events.
    ///
    ///     This simulates two re-subscribes (one reconnect) against the same source, then drives
    ///     ONE 0->1 device transition. After the collapse-to-single-loop fix exactly one loop is
    ///     alive so the raise fires exactly once; before the fix both loops fire it ⇒ two events.
    /// </summary>
    [Fact]
    public async Task Resubscribe_Collapses_To_Single_Loop_No_Duplicate_Raise()
    {
        var factory = new FakeAbCipTagFactory();
        var drv = new AbCipDriver(Options(enabled: true), "drv-1", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        var raises = new List<AlarmEventArgs>();
        drv.OnAlarmEvent += (_, e) =>
        {
            if (e.Message.Contains("raised")) lock (raises) raises.Add(e);
        };

        // First subscribe creates + starts polling the HighTemp runtime. Seed InFaulted=false +
        // a severity so the loop's baseline settles on "not faulted".
        var sub1 = await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
        await WaitForTagCreation(factory, "HighTemp");
        factory.Tags["HighTemp"].ValuesByOffset[0] = 0;   // InFaulted=false at offset 0
        factory.Tags["HighTemp"].ValuesByOffset[8] = 500; // Severity at offset 8
        await WaitForMoreReadsAsync(factory, "HighTemp", 2); // sub1's loop has seeded its baseline

        // Second subscribe = the actor re-subscribing across a reconnect. Its loop reads the same
        // shared HighTemp runtime; let it poll (and so seed its own "last-seen false" baseline) too.
        var sub2 = await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
        await WaitForMoreReadsAsync(factory, "HighTemp", 3);

        factory.Tags["HighTemp"].ValuesByOffset[0] = 1; // one 0->1 transition
        await WaitForEventAsync(raises, _ => true);
        // Processed-count wait (#583), not a fixed delay: six more reads of the shared runtime after the raise,
        // so a leaked second loop — which reads it too — has had polls in which to fire its duplicate.
        await WaitForMoreReadsAsync(factory, "HighTemp", 6);

        await drv.UnsubscribeAlarmsAsync(sub1, CancellationToken.None);
        await drv.UnsubscribeAlarmsAsync(sub2, CancellationToken.None);
        await drv.ShutdownAsync(CancellationToken.None);

        lock (raises)
        {
            raises.Count.ShouldBe(1,
                "exactly one poll loop must survive a re-subscribe; a leaked loop fires a duplicate raise");
        }
    }

    /// <summary>Verifies that alarm clear event fires on 1-to-0 transition.</summary>
    [Fact]
    public async Task Clear_Event_Fires_On_1_to_0_Transition()
    {
        var factory = new FakeAbCipTagFactory();
        var drv = new AbCipDriver(Options(enabled: true), "drv-1", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        var events = new List<AlarmEventArgs>();
        drv.OnAlarmEvent += (_, e) => { lock (events) events.Add(e); };

        var handle = await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
        await WaitForTagCreation(factory, "HighTemp");

        factory.Tags["HighTemp"].ValuesByOffset[0] = 1;
        factory.Tags["HighTemp"].ValuesByOffset[8] = 500;
        await WaitForEventAsync(events, e => e.Message.Contains("raised"));

        factory.Tags["HighTemp"].ValuesByOffset[0] = 0;
        await WaitForEventAsync(events, e => e.Message.Contains("cleared"));

        await drv.UnsubscribeAlarmsAsync(handle, CancellationToken.None);
        await drv.ShutdownAsync(CancellationToken.None);

        // Gitea #641 (item 4): the host routes a native transition on ConditionId == the subscribed RawPath and
        // projects it from Kind. The projection used to emit "{ref}#active" with an Unspecified kind, so every
        // ALMD transition was dropped as "no alarm condition" — and would have projected no state change even if
        // it had routed.
        AlarmEventArgs raised, cleared;
        lock (events)
        {
            raised = events.First(e => e.Message.Contains("raised"));
            cleared = events.First(e => e.Message.Contains("cleared"));
        }
        raised.ConditionId.ShouldBe("HighTemp");
        raised.Kind.ShouldBe(AlarmTransitionKind.Raise);
        cleared.ConditionId.ShouldBe("HighTemp");
        cleared.Kind.ShouldBe(AlarmTransitionKind.Clear);
    }

    /// <summary>
    ///     Gitea #641 review — the server carries every surviving native condition's state (a client's
    ///     acknowledgement included) across an address-space rebuild, and the host re-subscribes alarms on every
    ///     reconnect and every alarm-set change. A re-subscribe used to start from an empty "last seen" record, so
    ///     a still-faulted ALMD was re-RAISED, which the host projects as Active+UNacked — un-acknowledging an alarm
    ///     an operator had already acknowledged. The record is the driver's, kept for refs that stay in the set.
    /// </summary>
    [Fact]
    public async Task A_resubscribe_does_not_re_raise_a_still_faulted_alarm()
    {
        var factory = new FakeAbCipTagFactory();
        var drv = new AbCipDriver(Options(enabled: true), "drv-1", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        var raises = new List<AlarmEventArgs>();
        drv.OnAlarmEvent += (_, e) => { if (e.Kind == AlarmTransitionKind.Raise) lock (raises) raises.Add(e); };

        var sub1 = await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
        await WaitForTagCreation(factory, "HighTemp");
        factory.Tags["HighTemp"].ValuesByOffset[8] = 500;
        factory.Tags["HighTemp"].ValuesByOffset[0] = 1;
        await WaitForEventAsync(raises, _ => true);

        // A reconnect / alarm-set change: the same ref, still faulted.
        var sub2 = await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
        await WaitForMoreReadsAsync(factory, "HighTemp", 6);

        lock (raises) raises.Count.ShouldBe(1, "a re-subscribe must not re-raise (and so un-acknowledge) a still-faulted alarm");

        await drv.UnsubscribeAlarmsAsync(sub1, CancellationToken.None);
        await drv.UnsubscribeAlarmsAsync(sub2, CancellationToken.None);
        await drv.ShutdownAsync(CancellationToken.None);
    }

    /// <summary>Gitea #641 review — positive control: a ref that LEFT the subscribed set was materialised fresh
    /// (inactive) when it came back, so it is raised again.</summary>
    [Fact]
    public async Task A_ref_that_left_the_set_and_came_back_is_raised_again()
    {
        var factory = new FakeAbCipTagFactory();
        var drv = new AbCipDriver(Options(enabled: true), "drv-1", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        var raises = new List<AlarmEventArgs>();
        drv.OnAlarmEvent += (_, e) => { if (e.Kind == AlarmTransitionKind.Raise) lock (raises) raises.Add(e); };

        await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
        await WaitForTagCreation(factory, "HighTemp");
        factory.Tags["HighTemp"].ValuesByOffset[8] = 500;
        factory.Tags["HighTemp"].ValuesByOffset[0] = 1;
        await WaitForEventAsync(raises, _ => true);

        await drv.SubscribeAlarmsAsync([], CancellationToken.None);
        await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
        await WaitForEventAsync(raises, _ => raises.Count >= 2);

        await drv.ShutdownAsync(CancellationToken.None);
    }

    /// <summary>Verifies that unsubscribing stops the alarm poll loop.</summary>
    [Fact]
    public async Task Unsubscribe_Stops_The_Poll_Loop()
    {
        var factory = new FakeAbCipTagFactory();
        var drv = new AbCipDriver(Options(enabled: true), "drv-1", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);

        var handle = await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
        await WaitForTagCreation(factory, "HighTemp");
        await WaitForMoreReadsAsync(factory, "HighTemp", 1);   // the loop is running

        // Unsubscribe awaits the loop's exit, so no read can land after it returns.
        await drv.UnsubscribeAlarmsAsync(handle, CancellationToken.None);
        var postUnsubReadCount = factory.Tags["HighTemp"].ReadCount;

        // Positive control (#583): an identical, still-subscribed driver polls three more times on the same
        // interval — so the unsubscribed loop, had it survived, would have read again by now.
        await PolledThreeTimesWithTheFlagOnAsync();
        factory.Tags["HighTemp"].ReadCount.ShouldBe(postUnsubReadCount);

        await drv.ShutdownAsync(CancellationToken.None);
    }

    /// <summary>A control driver with the projection ON polls its ALMD runtime three times.</summary>
    private static async Task PolledThreeTimesWithTheFlagOnAsync()
    {
        var factory = new FakeAbCipTagFactory();
        var control = new AbCipDriver(Options(enabled: true), "drv-control", factory);
        await control.InitializeAsync("{}", CancellationToken.None);
        var handle = await control.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
        await WaitForTagCreation(factory, "HighTemp");
        await WaitForMoreReadsAsync(factory, "HighTemp", 3);
        await control.UnsubscribeAlarmsAsync(handle, CancellationToken.None);
        await control.ShutdownAsync(CancellationToken.None);
    }

    /// <summary>Waits for <paramref name="more"/> further reads of the fake runtime (a processed-count wait).</summary>
    /// <summary>
    ///     #630 — a re-Initialize on a live driver must dispose the alarm projection's poll loop rather
    ///     than leave it running (it would keep raising duplicate alarm events through this driver).
    /// </summary>
    [Fact]
    public async Task Reinitialize_Stops_The_Previous_Projection_Poll_Loop()
    {
        var factory = new FakeAbCipTagFactory();
        var drv = new AbCipDriver(Options(enabled: true), "drv-1", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);
        await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);

        await WaitForTagCreation(factory, "HighTemp");
        var tag = factory.Tags["HighTemp"];
        // Positive control: the loop is demonstrably polling before the re-init.
        await WaitForMoreReadsAsync(factory, "HighTemp", 3);

        await drv.InitializeAsync("{}", CancellationToken.None);

        int Reads() => factory.Tags.Values.Sum(t => t.ReadCount); // the loop may re-create its runtime on the new device state
        var frozen = Reads();
        await Task.Delay(300); // ~15 poll intervals; a live loop would advance the count
        Reads().ShouldBe(frozen);

        await drv.ShutdownAsync(CancellationToken.None);
    }

    private static async Task WaitForMoreReadsAsync(FakeAbCipTagFactory factory, string tagName, int more)
    {
        var tag = factory.Tags[tagName];
        var target = tag.ReadCount + more;
        var deadline = DateTime.UtcNow.AddSeconds(5);
        while (tag.ReadCount < target && DateTime.UtcNow < deadline) await Task.Delay(5);
        tag.ReadCount.ShouldBeGreaterThanOrEqualTo(target, $"'{tagName}' should have been read {more} more times");
    }

    private static async Task WaitForEventAsync(List<AlarmEventArgs> events, Func<AlarmEventArgs, bool> match)
    {
        var deadline = DateTime.UtcNow.AddSeconds(5);
        while (DateTime.UtcNow < deadline)
        {
            lock (events) if (events.Any(match)) return;
            await Task.Delay(5);
        }
        throw new TimeoutException("The expected alarm event was never raised.");
    }

    private static async Task WaitForTagCreation(FakeAbCipTagFactory factory, string tagName)
    {
        var deadline = DateTime.UtcNow.AddSeconds(2);
        while (DateTime.UtcNow < deadline)
        {
            if (factory.Tags.ContainsKey(tagName)) return;
            await Task.Delay(10);
        }
        throw new TimeoutException($"Tag {tagName} was never created by the fake factory.");
    }
}