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

namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests;

/// <summary>
///     lmxopcua#779 — an engine built without an explicit <c>scriptTimeout</c> (which is how the host built every
///     production engine) ran its predicates on the 250 ms Phase-7 default instead of the 2 s budget virtual tags
///     and Calculation tags get. The default is now <see cref="ScriptingOptions.RunTimeout"/>.
/// </summary>
[Trait("Category", "Unit")]
public sealed class ScriptedAlarmEngineBudgetTests
{
    /// <summary>A predicate that busy-waits ~600 ms and then fires: over the old 250 ms budget, well inside 2 s.</summary>
    private const string SixHundredMsPredicate =
        """var t = ctx.GetTag("Temp"); var end = System.DateTime.UtcNow.AddMilliseconds(600); while (System.DateTime.UtcNow < end) { } return true;""";

    private static ScriptedAlarmEngine Build(FakeUpstream up, ScriptingOptions? scripting = null)
    {
        var logger = new LoggerConfiguration().CreateLogger();
        return new ScriptedAlarmEngine(up, new InMemoryAlarmStateStore(), new ScriptLoggerFactory(logger), logger,
            scripting: scripting);
    }

    [Fact]
    public void Without_an_explicit_timeout_the_budget_is_the_Scripting_RunTimeout_default_not_250ms()
    {
        using var eng = Build(new FakeUpstream());
        eng.ScriptTimeout.ShouldBe(ScriptingOptions.DefaultRunTimeout);
        eng.ScriptTimeout.ShouldBe(TimeSpan.FromSeconds(2));
    }

    [Fact]
    public void A_configured_RunTimeout_is_the_budget()
    {
        using var eng = Build(new FakeUpstream(), new ScriptingOptions { RunTimeout = TimeSpan.FromSeconds(7) });
        eng.ScriptTimeout.ShouldBe(TimeSpan.FromSeconds(7));
    }

    [Fact]
    public async Task A_predicate_slower_than_250ms_but_inside_the_budget_completes_and_activates()
    {
        var up = new FakeUpstream();
        up.Set("Temp", 50);
        using var eng = Build(up);

        await eng.LoadAsync(
            [new ScriptedAlarmDefinition(AlarmId: "slow", EquipmentPath: "Plant/Line1/Reactor", AlarmName: "slow",
                Kind: AlarmKind.AlarmCondition, Severity: AlarmSeverity.High, MessageTemplate: "m",
                PredicateScriptSource: SixHundredMsPredicate)],
            TestContext.Current.CancellationToken);

        // LoadAsync evaluates once (startup recovery). Under the old 250 ms default that run timed out and the
        // condition stayed Inactive with a Bad annotation.
        eng.RunGuard.StartedRunCount.ShouldBe(1);
        eng.GetState("slow")!.Active.ShouldBe(AlarmActiveState.Active);
    }
}