using Serilog;
using Serilog.Core;
using Serilog.Events;
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>Review R05:6 — a throwing <see cref="ScriptedAlarmSource.OnAlarmEvent"/> subscriber used to be
/// swallowed with no diagnostic: a lost alarm event with no trace. It is now logged at Warning.</summary>
[Trait("Category", "Unit")]
public sealed class ScriptedAlarmSourceLoggingTests
{
    private sealed class CapturingSink : ILogEventSink
    {
        public List<LogEvent> Events { get; } = [];
        public void Emit(LogEvent logEvent) { lock (Events) Events.Add(logEvent); }
    }

    [Fact]
    public async Task A_throwing_subscriber_is_logged_at_Warning_and_does_not_crash_the_adapter()
    {
        var sinkCapture = new CapturingSink();
        var logger = new LoggerConfiguration().MinimumLevel.Verbose().WriteTo.Sink(sinkCapture).CreateLogger();
        var up = new FakeUpstream();
        up.Set("Temp", 50);
        var engine = new ScriptedAlarmEngine(up, new InMemoryAlarmStateStore(), new ScriptLoggerFactory(logger), logger);
        await engine.LoadAsync(
            [new ScriptedAlarmDefinition("Plant/Line1::HighTemp", "Plant/Line1", "HighTemp", AlarmKind.LimitAlarm,
                AlarmSeverity.High, "Temp {Temp}C", """return (int)ctx.GetTag("Temp").Value > 100;""")],
            TestContext.Current.CancellationToken);
        using var _e = engine;
        using var source = new ScriptedAlarmSource(engine, logger);
        await source.SubscribeAlarmsAsync(Array.Empty<string>(), TestContext.Current.CancellationToken);
        source.OnAlarmEvent += (_, _) => throw new InvalidOperationException("subscriber broke");

        up.Push("Temp", 150);

        var deadline = DateTime.UtcNow.AddSeconds(10);
        while (DateTime.UtcNow < deadline)
        {
            lock (sinkCapture.Events)
            {
                if (sinkCapture.Events.Any(e => e.Level == LogEventLevel.Warning && e.Exception?.Message == "subscriber broke"))
                    break;
            }
            await Task.Delay(25);
        }

        LogEvent warning;
        lock (sinkCapture.Events)
            warning = sinkCapture.Events.Single(e => e.Level == LogEventLevel.Warning && e.Exception?.Message == "subscriber broke");
        warning.RenderMessage().ShouldContain("Plant/Line1::HighTemp");
        // The adapter survived: the engine's state still moved.
        engine.GetState("Plant/Line1::HighTemp")!.Active.ShouldBe(AlarmActiveState.Active);
    }
}