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

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

/// <summary>
///     Exercises the factory that creates per-script Serilog loggers with the
///     <c>ScriptName</c> structured property pre-bound. The property is what lets
///     Admin UI filter the scripts-*.log sink by which tag/alarm emitted each event.
/// </summary>
[Trait("Category", "Unit")]
public sealed class ScriptLoggerFactoryTests
{
    /// <summary>Capturing sink that collects every emitted LogEvent for assertion.</summary>
    private sealed class CapturingSink : ILogEventSink
    {
        public List<LogEvent> Events { get; } = [];
        public void Emit(LogEvent logEvent) => Events.Add(logEvent);
    }

    [Fact]
    public void Create_sets_ScriptName_structured_property()
    {
        var sink = new CapturingSink();
        var root = new LoggerConfiguration().MinimumLevel.Verbose().WriteTo.Sink(sink).CreateLogger();
        var factory = new ScriptLoggerFactory(root);

        var logger = factory.Create("LineRate");
        logger.Information("hello");

        sink.Events.Count.ShouldBe(1);
        var ev = sink.Events[0];
        ev.Properties.ShouldContainKey(ScriptLoggerFactory.ScriptNameProperty);
        ((ScalarValue)ev.Properties[ScriptLoggerFactory.ScriptNameProperty]).Value.ShouldBe("LineRate");
    }

    [Fact]
    public void Each_script_gets_its_own_property_value()
    {
        var sink = new CapturingSink();
        var root = new LoggerConfiguration().MinimumLevel.Verbose().WriteTo.Sink(sink).CreateLogger();
        var factory = new ScriptLoggerFactory(root);

        factory.Create("Alarm_A").Information("event A");
        factory.Create("Tag_B").Warning("event B");
        factory.Create("Alarm_A").Error("event A again");

        sink.Events.Count.ShouldBe(3);
        ((ScalarValue)sink.Events[0].Properties[ScriptLoggerFactory.ScriptNameProperty]).Value.ShouldBe("Alarm_A");
        ((ScalarValue)sink.Events[1].Properties[ScriptLoggerFactory.ScriptNameProperty]).Value.ShouldBe("Tag_B");
        ((ScalarValue)sink.Events[2].Properties[ScriptLoggerFactory.ScriptNameProperty]).Value.ShouldBe("Alarm_A");
    }

    [Fact]
    public void Error_level_event_preserves_level_and_exception()
    {
        var sink = new CapturingSink();
        var root = new LoggerConfiguration().MinimumLevel.Verbose().WriteTo.Sink(sink).CreateLogger();
        var factory = new ScriptLoggerFactory(root);

        factory.Create("Test").Error(new InvalidOperationException("boom"), "script failed");

        sink.Events[0].Level.ShouldBe(LogEventLevel.Error);
        sink.Events[0].Exception.ShouldBeOfType<InvalidOperationException>();
    }

    [Fact]
    public void Null_root_rejected()
    {
        Should.Throw<ArgumentNullException>(() => new ScriptLoggerFactory(null!));
    }

    [Fact]
    public void Empty_script_name_rejected()
    {
        var root = new LoggerConfiguration().CreateLogger();
        var factory = new ScriptLoggerFactory(root);
        Should.Throw<ArgumentException>(() => factory.Create(""));
        Should.Throw<ArgumentException>(() => factory.Create("   "));
        Should.Throw<ArgumentException>(() => factory.Create(null!));
    }

    [Fact]
    public void ScriptNameProperty_constant_is_stable()
    {
        // Stability is an external contract — the Admin UI's log filter references
        // this exact string. If it changes, the filter breaks silently.
        ScriptLoggerFactory.ScriptNameProperty.ShouldBe("ScriptName");
    }
}