using System.Diagnostics;
using System.Linq;
using FluentAssertions;
using StellaOps.TestKit.Observability;
using Xunit;

namespace StellaOps.TestKit.Tests;

public sealed partial class ObservabilityContractTests
{
    [Fact]
    public void HasRequiredSpans_AllPresent_NoException()
    {
        using var source = new ActivitySource("TestSource");
        using var capture = new OtelCapture("TestSource");

        using (source.StartActivity("Span1")) { }
        using (source.StartActivity("Span2")) { }

        var act = () => OTelContractAssert.HasRequiredSpans(capture, "Span1", "Span2");

        act.Should().NotThrow();
    }

    [Fact]
    public void HasRequiredSpans_Missing_ThrowsContractViolation()
    {
        using var source = new ActivitySource("TestSource2");
        using var capture = new OtelCapture("TestSource2");

        using (source.StartActivity("Span1")) { }

        var act = () => OTelContractAssert.HasRequiredSpans(capture, "Span1", "MissingSpan");

        act.Should().Throw<ContractViolationException>()
            .WithMessage("*MissingSpan*");
    }

    [Fact]
    public void SpanHasAttributes_AllPresent_NoException()
    {
        using var source = new ActivitySource("TestSource3");
        using var capture = new OtelCapture("TestSource3");

        using (var activity = source.StartActivity("TestSpan"))
        {
            activity?.SetTag("user_id", "123");
            activity?.SetTag("tenant_id", "acme");
        }

        var span = capture.CapturedActivities.First();
        var act = () => OTelContractAssert.SpanHasAttributes(span, "user_id", "tenant_id");

        act.Should().NotThrow();
    }

    [Fact]
    public void SpanHasAttributes_Missing_ThrowsContractViolation()
    {
        using var source = new ActivitySource("TestSource4");
        using var capture = new OtelCapture("TestSource4");

        using (var activity = source.StartActivity("TestSpan"))
        {
            activity?.SetTag("user_id", "123");
        }

        var span = capture.CapturedActivities.First();
        var act = () => OTelContractAssert.SpanHasAttributes(span, "user_id", "missing_attr");

        act.Should().Throw<ContractViolationException>()
            .WithMessage("*missing_attr*");
    }

    [Fact]
    public void AttributeCardinality_WithinThreshold_NoException()
    {
        using var source = new ActivitySource("TestSource5");
        using var capture = new OtelCapture("TestSource5");

        for (int i = 0; i < 5; i++)
        {
            using (var activity = source.StartActivity($"Span{i}"))
            {
                activity?.SetTag("status", i % 3 == 0 ? "ok" : "error");
            }
        }

        var act = () => OTelContractAssert.AttributeCardinality(capture, "status", maxCardinality: 10);

        act.Should().NotThrow();
    }
}