using System;
using System.Threading;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Shapes;
using System.Windows.Threading;
using Xunit;
using ytLive.Models;
using ytLive.ViewModels;

namespace ytLive.Tests;

/// <summary>
/// Reproduces the real MainWindow preview to check the round-clip corner
/// handle: whether a click at the corner actually stays inside the preview
/// (doesn't fall through and deselect the source) and whether the round clip
/// renders as a circle rather than an oval.
/// </summary>
public sealed class RoundClipInteractionTests
{
    [Fact]
    public void Round_Clip_Corner_Is_Grabbable_And_Shape_Is_Circle()
    {
        Exception? failure = null;
        var thread = new Thread(() =>
        {
            try
            {
                Run();
            }
            catch (Exception ex)
            {
                failure = ex;
            }
        });
        thread.SetApartmentState(ApartmentState.STA);
        thread.Start();
        thread.Join();

        if (failure != null)
            throw new Xunit.Sdk.XunitException("Round-clip interaction failed: " + failure);
    }

    private void Run()
    {
        var app = new App();
        app.InitializeComponent();

        var window = new MainWindow();
        var vm = (MainViewModel)window.DataContext;
        try
        {
            window.Show();
            window.UpdateLayout();

            var scene = vm.ActiveScene!;
            var source = new Source
            {
                Name = "Webcam",
                Type = SourceType.Webcam,
                DeviceId = "test-camera",
                X = 1408,
                Y = 778,
                Width = 480,
                Height = 270,
            };
            scene.Sources.Add(source);
            vm.SelectedSource = source;
            window.UpdateLayout();

            var previewGrid = (Grid)window.FindName("PreviewGrid")!;
            var canvasGrid = (Grid)window.FindName("CanvasGrid")!;
            var toWindow = canvasGrid.TransformToVisual(window);

            var corner = new Point(source.X + source.Width, source.Y + source.Height);

            foreach (var shape in new[] { ClipShape.Traditional, ClipShape.Round })
            {
                source.ClipShape = shape;
                window.UpdateLayout();

                var cornerInWindow = toWindow.Transform(corner);

                // A click on the corner must land inside the preview (descendant
                // of PreviewGrid); otherwise Window_PreviewMouseLeftButtonDown
                // deselects the source and the handle can never be grabbed.
                var hit = VisualTreeHelper.HitTest(window, cornerInWindow);
                var grabbable = hit != null && IsDescendantOf(hit.VisualHit, previewGrid);

                Assert.True(grabbable,
                    $"{shape}: corner click fell through to '{hit?.VisualHit.GetType().Name ?? "null"}' " +
                    "so the source gets deselected before the resize handler runs");
            }

            // The round clip must render as a circle (square bounding box), not an oval.
            source.ClipShape = ClipShape.Round;
            window.UpdateLayout();
            var ellipse = FindRoundEllipse(window);
            Assert.NotNull(ellipse);
            Assert.Equal(ellipse!.RenderSize.Width, ellipse.RenderSize.Height, 1.0);
        }
        finally
        {
            window.Close();
        }
    }

    private static Ellipse? FindRoundEllipse(Window window)
    {
        return Walk(window, element => element is Ellipse e && e.IsVisible) as Ellipse;
    }

    private static DependencyObject? Walk(DependencyObject parent, Func<DependencyObject, bool> predicate)
    {
        for (var i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
        {
            var child = VisualTreeHelper.GetChild(parent, i);
            if (predicate(child)) return child;
            var found = Walk(child, predicate);
            if (found != null) return found;
        }
        return null;
    }

    private static bool IsDescendantOf(DependencyObject? child, DependencyObject ancestor)
    {
        while (child != null && !ReferenceEquals(child, ancestor))
            child = VisualTreeHelper.GetParent(child);
        return child != null;
    }
}