using System.Diagnostics;
using System.Diagnostics.Metrics;
using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using OpenTelemetry.Metrics;
using OpenTelemetry.Trace;
using Shouldly;
using Xunit;
using ZB.MOM.WW.LocalDb.Replication;
using ZB.MOM.WW.OtOpcUa.Commons.Observability;
using ZB.MOM.WW.OtOpcUa.Driver.Galaxy;
using ZB.MOM.WW.OtOpcUa.Host.Observability;

namespace ZB.MOM.WW.OtOpcUa.Host.IntegrationTests;

/// <summary>
///     scadaproj#13 — <c>ZbTelemetryOptions.Meters</c> / <c>.ActivitySources</c> are strict allowlists,
///     so a meter or activity source the host forgets to name is silently never exported (the Galaxy
///     driver's <c>galaxy.*</c> spans and <c>galaxy.events.*</c> counters were). These tests build the
///     real <see cref="ObservabilityExtensions.AddOtOpcUaObservability"/> container, start its
///     providers, and assert on the listener side: a span from a named source is sampled, and an
///     instrument on a named meter is enabled. An unregistered name is the negative control proving
///     the assertion can fail.
/// </summary>
public sealed class ObservabilityAllowlistTests : IAsyncDisposable
{
    private readonly WebApplication _app;

    public ObservabilityAllowlistTests()
    {
        var builder = WebApplication.CreateBuilder(new WebApplicationOptions { Args = [] });
        builder.Services.AddOtOpcUaObservability(builder.Configuration);
        _app = builder.Build();
        // Resolving the providers is what attaches their ActivityListener / MeterListener.
        _app.Services.GetRequiredService<TracerProvider>();
        _app.Services.GetRequiredService<MeterProvider>();
    }

    [Fact]
    public void ObservedLists_NameTheGalaxyDriverMeterAndSource()
    {
        ObservabilityExtensions.ObservedMeters.ShouldBe(
            [OtOpcUaTelemetry.MeterName, LocalDbMetrics.MeterName, GalaxyDriverTelemetryNames.MeterName],
            ignoreOrder: true);
        ObservabilityExtensions.ObservedActivitySources.ShouldBe(
            [OtOpcUaTelemetry.ActivitySourceName, GalaxyDriverTelemetryNames.ActivitySourceName],
            ignoreOrder: true);
    }

    [Theory]
    [InlineData(OtOpcUaTelemetry.ActivitySourceName)]
    [InlineData(GalaxyDriverTelemetryNames.ActivitySourceName)]
    public void SpanFromAnObservedSource_IsRecorded(string sourceName)
    {
        using var source = new ActivitySource(sourceName);
        using var activity = source.StartActivity("allowlist-probe");
        activity.ShouldNotBeNull();
        activity.IsAllDataRequested.ShouldBeTrue();
    }

    [Fact]
    public void SpanFromAnUnregisteredSource_IsDropped_NegativeControl()
    {
        using var source = new ActivitySource("ZB.MOM.WW.OtOpcUa.Unregistered." + Guid.NewGuid().ToString("N"));
        source.StartActivity("allowlist-probe").ShouldBeNull();
    }

    [Theory]
    [InlineData(OtOpcUaTelemetry.MeterName)]
    [InlineData(LocalDbMetrics.MeterName)]
    [InlineData(GalaxyDriverTelemetryNames.MeterName)]
    public void InstrumentOnAnObservedMeter_IsEnabled(string meterName)
    {
        using var meter = new Meter(meterName);
        var counter = meter.CreateCounter<long>("allowlist.probe." + Guid.NewGuid().ToString("N"));
        counter.Enabled.ShouldBeTrue();
    }

    [Fact]
    public void InstrumentOnAnUnregisteredMeter_IsNotEnabled_NegativeControl()
    {
        using var meter = new Meter("ZB.MOM.WW.OtOpcUa.Unregistered." + Guid.NewGuid().ToString("N"));
        meter.CreateCounter<long>("allowlist.probe").Enabled.ShouldBeFalse();
    }

    public async ValueTask DisposeAsync() => await _app.DisposeAsync();
}