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

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

[Trait("Category", "Unit")]
public sealed class FocasAlarmProjectionTests
{
    private const string Host = "focas://10.0.0.5:8193";

    private static (FocasDriver drv, FakeFocasClientFactory factory) NewDriver(bool alarmsEnabled)
    {
        var factory = new FakeFocasClientFactory();
        var drv = new FocasDriver(new FocasDriverOptions
        {
            Devices = [new FocasDeviceOptions(Host)],
            Tags = [],
            Probe = new FocasProbeOptions { Enabled = false },
            AlarmProjection = new FocasAlarmProjectionOptions
            {
                Enabled = alarmsEnabled,
                PollInterval = TimeSpan.FromMilliseconds(30),
            },
        }, "drv-1", factory);
        return (drv, factory);
    }

    /// <summary>Verifies that subscribe without enable throws NotSupported.</summary>
    [Fact]
    public async Task Subscribe_without_Enable_throws_NotSupported()
    {
        var (drv, _) = NewDriver(alarmsEnabled: false);
        await drv.InitializeAsync("{}", CancellationToken.None);

        await Should.ThrowAsync<NotSupportedException>(() =>
            drv.SubscribeAlarmsAsync([], CancellationToken.None));
    }

    /// <summary>Verifies that raise then clear emits both events.</summary>
    [Fact]
    public async Task Raise_then_clear_emits_both_events()
    {
        var (drv, factory) = NewDriver(alarmsEnabled: true);
        factory.Customise = () => new FakeFocasClient();
        await drv.InitializeAsync("{}", CancellationToken.None);

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

        var sub = await drv.SubscribeAlarmsAsync([], CancellationToken.None);

        // First tick creates the client via EnsureConnectedAsync — wait for it before we
        // poke the alarm list so we don't race the poll loop.
        await WaitFor(() => factory.Clients.Count > 0, TimeSpan.FromSeconds(3));
        var client = factory.Clients[0];
        client.Alarms.Add(new FocasActiveAlarm(500, FocasAlarmType.Overtravel, 1, "Axis 1 overtravel"));
        await WaitFor(() => events.Any(e => e.Message.Contains("overtravel")), TimeSpan.FromSeconds(3));

        // Clear — the clear event wraps the original message with "(cleared)".
        client.Alarms.Clear();
        await WaitFor(() => events.Any(e => e.Message.Contains("cleared")), TimeSpan.FromSeconds(3));

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

        events.ShouldContain(e => e.AlarmType == "Overtravel" && e.Severity == AlarmSeverity.Critical);
        events.ShouldContain(e => e.Message.Contains("cleared"));
        events[0].SourceNodeId.ShouldBe(Host);
    }

    /// <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 SubscribeAlarmsAsync 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 test simulates two re-subscribes (one reconnect) against the same source, then
    ///     drives ONE device raise. After the collapse-to-single-loop fix exactly one loop is alive
    ///     so the raise must fire 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 (drv, factory) = NewDriver(alarmsEnabled: true);
        factory.Customise = () => new FakeFocasClient();
        await drv.InitializeAsync("{}", CancellationToken.None);

        var raises = new List<AlarmEventArgs>();
        drv.OnAlarmEvent += (_, e) =>
        {
            // Count only the raise (the initial 0->1) — clears wrap the message in "(cleared)".
            if (!e.Message.Contains("cleared")) lock (raises) raises.Add(e);
        };

        // First subscribe creates + connects the per-device client and starts polling. Wait for
        // it + a couple empty-list ticks so the loop's LastByDevice baseline is seeded empty.
        var sub1 = await drv.SubscribeAlarmsAsync([], CancellationToken.None);
        await WaitFor(() => factory.Clients.Count > 0, TimeSpan.FromSeconds(3));
        await Task.Delay(120);

        // Second subscribe = the actor re-subscribing across a reconnect. Its loop reuses the same
        // connected DeviceState.Client (EnsureConnectedAsync), so it polls the same alarm list.
        var sub2 = await drv.SubscribeAlarmsAsync([], CancellationToken.None);
        await Task.Delay(120); // let sub2's loop seed its own empty LastByDevice baseline

        // One device raise transition. Add to every created client so that whichever instance the
        // live loop(s) poll, the raise is observed (EnsureConnectedAsync may have churned clients).
        foreach (var c in factory.Clients)
            c.Alarms.Add(new FocasActiveAlarm(500, FocasAlarmType.Overtravel, 1, "Axis 1 overtravel"));

        // Wait until at least one raise is observed, then give any leaked second loop ample time
        // (well past several 30ms poll intervals) to ALSO fire its duplicate before we assert.
        await WaitFor(() => { lock (raises) return raises.Count > 0; }, TimeSpan.FromSeconds(3));
        await Task.Delay(200);

        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 tick diffs raises and clears without polling loop.</summary>
    [Fact]
    public async Task Tick_diffs_raises_and_clears_without_polling_loop()
    {
        // Drive Tick directly so the test isn't timing-dependent. The projection's
        // Tick() is internal so we reach it through the driver using a handcrafted
        // subscription — simpler than standing up the full loop.
        var (drv, factory) = NewDriver(alarmsEnabled: true);
        factory.Customise = () => new FakeFocasClient();
        await drv.InitializeAsync("{}", CancellationToken.None);

        var projection = new FocasAlarmProjection(drv, TimeSpan.FromMinutes(1));
        var sub = new FocasAlarmProjection.Subscription(
            new FocasAlarmSubscriptionHandle(1), deviceFilter: null,
            new CancellationTokenSource());

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

        // Tick 1 — raise two alarms.
        projection.Tick(sub, Host, [
            new FocasActiveAlarm(100, FocasAlarmType.Parameter, 0, "Param 100"),
            new FocasActiveAlarm(200, FocasAlarmType.Servo, 1, "Servo 200"),
        ]);
        events.Count.ShouldBe(2);
        events[0].Severity.ShouldBe(AlarmSeverity.Medium);
        events[1].Severity.ShouldBe(AlarmSeverity.Critical);

        // Tick 2 — same alarms stay active → no new events.
        events.Clear();
        projection.Tick(sub, Host, [
            new FocasActiveAlarm(100, FocasAlarmType.Parameter, 0, "Param 100"),
            new FocasActiveAlarm(200, FocasAlarmType.Servo, 1, "Servo 200"),
        ]);
        events.ShouldBeEmpty();

        // Tick 3 — one clears, one stays → one "cleared" event only.
        projection.Tick(sub, Host, [
            new FocasActiveAlarm(200, FocasAlarmType.Servo, 1, "Servo 200"),
        ]);
        events.Count.ShouldBe(1);
        events[0].Message.ShouldEndWith("(cleared)");
        events[0].AlarmType.ShouldBe("Parameter");
    }

    /// <summary>Verifies that severity mapping matches docs.</summary>
    [Fact]
    public void Severity_mapping_matches_docs()
    {
        FocasAlarmProjection.MapSeverity(FocasAlarmType.Overtravel).ShouldBe(AlarmSeverity.Critical);
        FocasAlarmProjection.MapSeverity(FocasAlarmType.Servo).ShouldBe(AlarmSeverity.Critical);
        FocasAlarmProjection.MapSeverity(FocasAlarmType.PulseCode).ShouldBe(AlarmSeverity.Critical);
        FocasAlarmProjection.MapSeverity(FocasAlarmType.Parameter).ShouldBe(AlarmSeverity.Medium);
        FocasAlarmProjection.MapSeverity(FocasAlarmType.MacroAlarm).ShouldBe(AlarmSeverity.Medium);
        FocasAlarmProjection.MapSeverity(FocasAlarmType.Overheat).ShouldBe(AlarmSeverity.High);
    }

    private static async Task WaitFor(Func<bool> pred, TimeSpan timeout)
    {
        var deadline = DateTime.UtcNow + timeout;
        while (DateTime.UtcNow < deadline)
        {
            if (pred()) return;
            await Task.Delay(30);
        }
    }
}