using Omika.Core.Observability.Diagnostic;

namespace Omika.Tests.Observability.Diagnostic;

public class TraceContextTests
{
    [Fact]
    public void BeginTrace_SetsCurrentTraceId_AndDisposeRestores()
    {
        var context = new TraceContext();
        Assert.Null(context.CurrentTraceId);

        using (context.BeginTrace())
        {
            Assert.NotNull(context.CurrentTraceId);
            Assert.NotEqual(Guid.Empty, context.CurrentTraceId!.Value);
        }

        Assert.Null(context.CurrentTraceId);
    }

    [Fact]
    public void NestedScope_RestoresPreviousTrace()
    {
        var context = new TraceContext();
        Guid outer = Guid.Parse("11111111-1111-1111-1111-111111111111");
        Guid inner = Guid.Parse("22222222-2222-2222-2222-222222222222");

        using (context.BeginTrace(outer))
        {
            using (context.BeginTrace(inner))
            {
                Assert.Equal(inner, context.CurrentTraceId);
            }

            Assert.Equal(outer, context.CurrentTraceId);
        }

        Assert.Null(context.CurrentTraceId);
    }

    [Fact]
    public async Task AsyncFlow_PreservesTraceAcrossAwait()
    {
        var context = new TraceContext();
        Guid trace = Guid.NewGuid();

        using (context.BeginTrace(trace))
        {
            await Task.Delay(20);
            Assert.Equal(trace, context.CurrentTraceId);
        }

        Assert.Null(context.CurrentTraceId);
    }

    [Fact]
    public async Task AsyncParallel_NoTraceIdLeak()
    {
        var context = new TraceContext();
        Guid first = Guid.NewGuid();
        Guid second = Guid.NewGuid();

        async Task RunAsync(Guid traceId)
        {
            using (context.BeginTrace(traceId))
            {
                await Task.Delay(30);
                Assert.Equal(traceId, context.CurrentTraceId);
            }
        }

        await Task.WhenAll(RunAsync(first), RunAsync(second));

        Assert.Null(context.CurrentTraceId);
    }
}