using Omika.App.Diagnostics;
using Omika.App.Navigation;
using Omika.Core.Observability;
using Omika.Core.Observability.Diagnostic;

namespace Omika.Tests.Observability;

/// <summary>
/// T18 (§73/§74/§75/§77) : une navigation logique génère EXACTEMENT un ScreenView ;
/// le retour = nouvelle vue ; le refresh/même page ne multiplie pas les événements ;
/// l'écran initial est émis une fois. L'émission est centralisée dans
/// <see cref="ScreenUsageTelemetry"/> (jamais par ViewModel).
/// </summary>
public class ScreenUsageTelemetryTests
{
    [Fact]
    public void TrackInitialScreen_EmitsSingleScreenView_ForCurrentPage()
    {
        var navigation = new NavigationService();
        var capturing = new CapturingTelemetry();
        var tracker = new ScreenUsageTelemetry(navigation, capturing, null);

        tracker.TrackInitialScreen();

        OmikaEvent evt = Assert.Single(capturing.Events);
        Assert.Equal(TelemetryEventCodes.MobileScreenView, evt.EventCode);
        Assert.Equal(DiagnosticScreenCodes.Agenda, evt.ScreenCode);
        Assert.Null(evt.FeatureCode);
    }

    [Fact]
    public void Navigate_EmitsExactlyOneScreenView_ForTarget()
    {
        var navigation = new NavigationService();
        var capturing = new CapturingTelemetry();
        var tracker = new ScreenUsageTelemetry(navigation, capturing, null);
        tracker.TrackInitialScreen();
        capturing.Clear();

        navigation.NavigateTo(AppPage.SiteDetail);

        OmikaEvent evt = Assert.Single(capturing.Events);
        Assert.Equal(TelemetryEventCodes.MobileScreenView, evt.EventCode);
        Assert.Equal(DiagnosticScreenCodes.SiteDetail, evt.ScreenCode);
    }

    [Fact]
    public void Return_IsANewScreenView()
    {
        var navigation = new NavigationService();
        var capturing = new CapturingTelemetry();
        var tracker = new ScreenUsageTelemetry(navigation, capturing, null);
        tracker.TrackInitialScreen(); // AGENDA (1)
        navigation.NavigateTo(AppPage.SiteDetail); // SITE_DETAIL (2)
        navigation.GoBack(); // AGENDA (3)

        Assert.Equal(3, capturing.Events.Count);
        Assert.Equal(DiagnosticScreenCodes.Agenda, capturing.Events[0].ScreenCode);
        Assert.Equal(DiagnosticScreenCodes.SiteDetail, capturing.Events[1].ScreenCode);
        Assert.Equal(DiagnosticScreenCodes.Agenda, capturing.Events[2].ScreenCode);
    }

    [Fact]
    public void Refresh_OrSamePage_DoesNotEmitAnotherScreenView()
    {
        var navigation = new NavigationService();
        var capturing = new CapturingTelemetry();
        var tracker = new ScreenUsageTelemetry(navigation, capturing, null);
        tracker.TrackInitialScreen(); // AGENDA (1)
        navigation.NavigateTo(AppPage.SiteDetail); // SITE_DETAIL (2)

        // Même page (paramètre identique ou différent) : NavigationService ne lève
        // pas PageChanged (seulement ParameterChanged) → aucun ScreenView.
        navigation.NavigateTo(AppPage.SiteDetail);
        navigation.NavigateTo(AppPage.SiteDetail, new object());

        Assert.Equal(2, capturing.Events.Count);
    }

    [Fact]
    public void Navigate_SetsCurrentScreenOnDiagnosticContext()
    {
        var navigation = new NavigationService();
        var capturing = new CapturingTelemetry();
        var context = new DiagnosticContext(new DiagnosticSession(), new DeviceInfoSnapshot());
        var tracker = new ScreenUsageTelemetry(navigation, capturing, context);
        tracker.TrackInitialScreen();

        navigation.NavigateTo(AppPage.InterventionDetail);

        Assert.Equal(DiagnosticScreenCodes.InterventionDetail, context.ScreenCode);
    }

    [Fact]
    public void UnknownPage_DoesNotEmit()
    {
        var navigation = new NavigationService();
        var capturing = new CapturingTelemetry();
        var tracker = new ScreenUsageTelemetry(navigation, capturing, null);

        // Aucune page inconnue n'est navigable, mais le tracker reste fail-open :
        // la navigation vers une page non résolue n'émet rien.
        tracker.TrackInitialScreen();
        capturing.Clear();

        navigation.NavigateTo(AppPage.Parametres);
        Assert.Single(capturing.Events);
        Assert.Equal(DiagnosticScreenCodes.Settings, capturing.Events[0].ScreenCode);
    }

    private sealed class CapturingTelemetry : IOmikaTelemetry
    {
        public List<OmikaEvent> Events { get; } = [];

        public void Track(TelemetryEvent telemetryEvent) => Events.Add(telemetryEvent);

        public void Log(DiagnosticEvent diagnosticEvent) => Events.Add(diagnosticEvent);

        public void Clear() => Events.Clear();
    }
}