using System.Reflection;
using Omika.Core.Observability;

namespace Omika.Tests.Observability;

/// <summary>
/// Contrat structurel de la façade d'observabilité : les méthodes exposées au
/// métier sont strictement <c>void</c> (never-throw, non bloquantes, sans await).
/// Aucune méthode <c>Task ...Async</c> ne doit apparaître.
/// </summary>
public class ObservabilityContractTests
{
    [Fact]
    public void AllTelemetryInterfaces_ExposeOnlyVoidMethods()
    {
        Type[] interfaces = [typeof(IOmikaTelemetry), typeof(IEventTracker), typeof(IDiagnosticLogger)];

        foreach (Type type in interfaces)
        {
            foreach (MethodInfo method in type.GetMethods())
            {
                Assert.True(
                    method.ReturnType == typeof(void),
                    $"{type.Name}.{method.Name} doit retourner void (jamais Task).");
            }
        }
    }

    [Fact]
    public void NoAsyncTrackOrLogMethod_IsExposed()
    {
        MethodInfo[] methods = typeof(IEventTracker).GetMethods()
            .Concat(typeof(IDiagnosticLogger).GetMethods())
            .Concat(typeof(IOmikaTelemetry).GetMethods())
            .ToArray();

        Assert.DoesNotContain(methods, m => m.Name.EndsWith("Async", StringComparison.Ordinal));
    }

    [Fact]
    public void EventTracker_ExposesTrack_ReturningVoid()
    {
        MethodInfo track = typeof(IEventTracker).GetMethod(nameof(IEventTracker.Track))!;

        Assert.NotNull(track);
        Assert.Equal(typeof(void), track.ReturnType);
        Assert.Equal(typeof(TelemetryEvent), track.GetParameters().Single().ParameterType);
    }

    [Fact]
    public void DiagnosticLogger_ExposesLog_ReturningVoid()
    {
        MethodInfo log = typeof(IDiagnosticLogger).GetMethod(nameof(IDiagnosticLogger.Log))!;

        Assert.NotNull(log);
        Assert.Equal(typeof(void), log.ReturnType);
        Assert.Equal(typeof(DiagnosticEvent), log.GetParameters().Single().ParameterType);
    }
}