using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Effects;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Windows.Threading;
using ytLive.Helpers;
using ytLive.Models;
using ytLive.ViewModels;

namespace ytLive.Controls;

public partial class PreviewPane : UserControl
{
    private bool _isDraggingOverlay;
    private bool _isResizing;
    private bool _isZoomDragging;
    private Point _grabOffset;
    private double _resizeAspect;

    private readonly System.Collections.Generic.Dictionary<string, Storyboard> _activeBorderAnimations =
        new();

    private DispatcherTimer? _socialGlowTimer;
    private double _socialGlowAngle;

    public PreviewPane()
    {
        InitializeComponent();
        DataContextChanged += PreviewPane_DataContextChanged;
        OverlayElements.ItemContainerGenerator.StatusChanged += (_, _) => UpdateSelectedLayerZOrder();
    }

    private void PreviewPane_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        if (e.OldValue is MainViewModel oldVm)
        {
            oldVm.PropertyChanged -= ViewModel_PropertyChanged;
            oldVm.PreviewTransition -= PlayPreviewTransition;
        }
        if (e.NewValue is MainViewModel newVm)
        {
            newVm.PropertyChanged += ViewModel_PropertyChanged;
            newVm.PreviewTransition += PlayPreviewTransition;
            UpdateZoomBox();
            UpdateSelectedLayerZOrder();
        }
    }

    /// <summary>Animates the outgoing picture away over the new scene: a fade for Fade and Move,
    /// a right-to-left shrink for Wipe. Cut plays nothing.</summary>
    private void PlayPreviewTransition(ytLive.Services.TransitionType type, double milliseconds)
    {
        TransitionOverlay.BeginAnimation(System.Windows.UIElement.OpacityProperty, null);
        TransitionOverlay.Clip = null;
        if (type == ytLive.Services.TransitionType.Cut || milliseconds <= 0)
        {
            TransitionOverlay.Visibility = Visibility.Collapsed;
            return;
        }

        var snapshot = new System.Windows.Media.Imaging.RenderTargetBitmap(1920, 1080, 96, 96,
            System.Windows.Media.PixelFormats.Pbgra32);
        snapshot.Render(PreviewCanvas);
        TransitionOverlay.Source = snapshot;
        TransitionOverlay.Opacity = 1;
        TransitionOverlay.Visibility = Visibility.Visible;
        var duration = TimeSpan.FromMilliseconds(milliseconds);

        if (type == ytLive.Services.TransitionType.Wipe)
        {
            var clip = new System.Windows.Media.RectangleGeometry(new Rect(0, 0, 1920, 1080));
            TransitionOverlay.Clip = clip;
            var reveal = new System.Windows.Media.Animation.RectAnimation(new Rect(0, 0, 0, 1080), duration)
            {
                FillBehavior = System.Windows.Media.Animation.FillBehavior.Stop,
            };
            reveal.Completed += (_, _) => TransitionOverlay.Visibility = Visibility.Collapsed;
            clip.BeginAnimation(System.Windows.Media.RectangleGeometry.RectProperty, reveal);
        }
        else
        {
            var fade = new System.Windows.Media.Animation.DoubleAnimation(1, 0, duration)
            {
                FillBehavior = System.Windows.Media.Animation.FillBehavior.Stop,
            };
            fade.Completed += (_, _) => TransitionOverlay.Visibility = Visibility.Collapsed;
            TransitionOverlay.BeginAnimation(System.Windows.UIElement.OpacityProperty, fade);
        }
    }

    private void ViewModel_PropertyChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e)
    {
        if (e.PropertyName == nameof(MainViewModel.SelectedElement))
            UpdateSelectedLayerZOrder();
        if (e.PropertyName == nameof(MainViewModel.IsZoomActive) || e.PropertyName == nameof(MainViewModel.ZoomState) || e.PropertyName == nameof(MainViewModel.ZoomShape))
        {
            UpdateZoomBox();
        }
    }

    private void UpdateSelectedLayerZOrder()
    {
        var selected = (DataContext as MainViewModel)?.SelectedElement;
        if (selected != null && !IsDraggableElement(selected))
            selected = null;

        for (var i = 0; i < OverlayElements.Items.Count; i++)
        {
            if (OverlayElements.ItemContainerGenerator.ContainerFromIndex(i) is UIElement container)
                Panel.SetZIndex(container, ReferenceEquals(OverlayElements.Items[i], selected) ? 1 : 0);
        }
    }



    // Static images and the webcam share the move/resize/selection behavior.
    public static bool IsDraggableElement(SceneElement element)
        => element.IsDraggable;

    public void UpdateSelectionOverlay(bool selected)
    {
        SelectionOverlay.Visibility = selected ? Visibility.Visible : Visibility.Collapsed;
    }

    // ─── Clicking inside the preview / pull-out drawer (used by the window's
    //     Window_PreviewMouseLeftButtonDown deselection logic) ───
    public bool IsClickInsidePreview(DependencyObject original)
        => IsDescendantOf(original, PreviewGrid);

    public bool IsClickInsideDrawer(DependencyObject original)
        => IsDescendantOf(original, TextPullOutHost);

    private static bool IsDescendantOf(DependencyObject? child, DependencyObject ancestor)
    {
        while (child != null && !ReferenceEquals(child, ancestor))
        {
            child = child is Visual or System.Windows.Media.Media3D.Visual3D
                ? VisualTreeHelper.GetParent(child)
                : LogicalTreeHelper.GetParent(child);
        }
        return child != null;
    }

    // ─── Audio meters + TRAX + socials (ROW 2 of the preview pane) ───
    private void VolumeSlider_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        if (sender is Slider slider)
            SetSliderValueFromClick(slider, e);
        if (sender is FrameworkElement { DataContext: MainViewModel vm })
            vm.SetVolumeAdjusting(true);
    }

    private void VolumeSlider_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    {
        if (sender is FrameworkElement { DataContext: MainViewModel vm })
            vm.SetVolumeAdjusting(false);
    }

    private void VolumeSlider_LostMouseCapture(object sender, MouseEventArgs e)
    {
        if (sender is FrameworkElement { DataContext: MainViewModel vm })
            vm.SetVolumeAdjusting(false);
    }

    private void GameVolumeSlider_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        if (sender is Slider slider)
            SetSliderValueFromClick(slider, e);
        if (sender is FrameworkElement { DataContext: MainViewModel vm })
            vm.SetGameVolumeAdjusting(true);
    }

    private void GameVolumeSlider_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    {
        if (sender is FrameworkElement { DataContext: MainViewModel vm })
            vm.SetGameVolumeAdjusting(false);
    }

    private void GameVolumeSlider_LostMouseCapture(object sender, MouseEventArgs e)
    {
        if (sender is FrameworkElement { DataContext: MainViewModel vm })
            vm.SetGameVolumeAdjusting(false);
    }

    private static void SetSliderValueFromClick(Slider slider, MouseButtonEventArgs e)
    {
        if (FindParent<System.Windows.Controls.Primitives.Thumb>(e.OriginalSource as Visual) != null)
            return;
        var track = slider.Template.FindName("PART_Track", slider) as System.Windows.Controls.Primitives.Track;
        if (track == null) return;
        var pos = e.GetPosition(track);
        var fraction = Math.Clamp(pos.X / track.RenderSize.Width, 0, 1);
        slider.Value = slider.Minimum + fraction * (slider.Maximum - slider.Minimum);
        e.Handled = true;
    }

    private static T? FindParent<T>(Visual? visual) where T : Visual
    {
        while (visual != null)
        {
            if (visual is T match) return match;
            visual = VisualTreeHelper.GetParent(visual) as Visual;
        }
        return null;
    }


    private void GameSpeaker_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    {
        if (sender is FrameworkElement { DataContext: MainViewModel vm })
        {
            vm.ToggleGameMuteCommand.Execute(null);
        }
    }

    // TRAX (TASK 9): left-click toggles play/pause (picks a track when none is
    // loaded); right-click always opens the picker. The picker is the OS file
    // dialog — the "never the OS viewer" rule covers the preview, not pickers.


    // ─── Webcam / background context menus (right-click on overlay elements) ───
    private void WebcamMenu_ChangeWebcam(object sender, RoutedEventArgs e)
        => (DataContext as MainViewModel)?.ChangeWebcamCommand.Execute(null);

    private void WebcamMenu_SetBorderAnimation(object sender, RoutedEventArgs e)
    {
        if (sender is not MenuItem { DataContext: SceneElement element, Tag: string tag }
            || !Enum.TryParse<BorderAnimation>(tag, out var animation))
            return;

        element.BorderAnimation = animation;

        StopBorderAnimation(element.Id);

        if (animation == BorderAnimation.None) return;

        var shape = FindBorderShape(sender as DependencyObject);
        if (shape == null) return;

        var sb = CreateBorderAnimation(animation, shape);
        if (sb == null) return;

        sb.Freeze();
        _activeBorderAnimations[element.Id] = sb;
        shape.BeginAnimation(Shape.OpacityProperty, null);
        Storyboard.SetTarget(sb, shape);
        sb.Begin();
    }

    private void StopBorderAnimation(string elementId)
    {
        if (_activeBorderAnimations.TryGetValue(elementId, out var old))
        {
            old.Stop();
            _activeBorderAnimations.Remove(elementId);
        }
    }

    private static Shape? FindBorderShape(DependencyObject? start)
    {
        var current = start;
        while (current != null)
        {
            if (current is ContextMenu cm && cm.PlacementTarget is FrameworkElement target)
            {
                for (var i = 0; i < VisualTreeHelper.GetChildrenCount(target); i++)
                {
                    var child = VisualTreeHelper.GetChild(target, i);
                    if (child is Shape s && (s is Rectangle or Ellipse) && !s.IsHitTestVisible)
                        return s;
                }
                return null;
            }
            current = VisualTreeHelper.GetParent(current);
        }
        return null;
    }

    private static Storyboard? CreateBorderAnimation(BorderAnimation animation, Shape shape)
    {
        var sb = new Storyboard();
        switch (animation)
        {
            case BorderAnimation.Pulse:
                AddDoubleAnimation(sb, Shape.OpacityProperty, 1.0, 0.3, TimeSpan.FromSeconds(0.8), true);
                break;
            case BorderAnimation.Glow:
                AddDoubleAnimation(sb, Shape.OpacityProperty, 1.0, 0.5, TimeSpan.FromSeconds(1.2), true);
                break;
            case BorderAnimation.Shimmer:
                AddDoubleAnimation(sb, Shape.OpacityProperty, 1.0, 0.15, TimeSpan.FromSeconds(0.5), true);
                break;
            case BorderAnimation.Electricity:
                AddDoubleAnimation(sb, Shape.OpacityProperty, 1.0, 0.2, TimeSpan.FromSeconds(0.1), true);
                break;
            case BorderAnimation.Sparkles:
                AddDoubleAnimation(sb, Shape.OpacityProperty, 1.0, 0.4, TimeSpan.FromSeconds(0.3), true);
                break;
            case BorderAnimation.MarchingAnts:
                shape.StrokeDashArray = new DoubleCollection { 4, 2 };
                AddDoubleAnimation(sb, Shape.StrokeDashOffsetProperty, 0, -20, TimeSpan.FromSeconds(0.8), false);
                break;
            case BorderAnimation.Chase:
                shape.StrokeDashArray = new DoubleCollection { 8, 4 };
                AddDoubleAnimation(sb, Shape.StrokeDashOffsetProperty, 0, -30, TimeSpan.FromSeconds(1.5), false);
                break;
            case BorderAnimation.Rainbow:
                if (shape.Stroke is SolidColorBrush brush)
                {
                    var frozen = brush.IsFrozen;
                    if (frozen) brush = brush.Clone();
                    shape.Stroke = brush;
                    var colorAnim = new ColorAnimationUsingKeyFrames
                    {
                        Duration = new Duration(TimeSpan.FromSeconds(3)),
                        RepeatBehavior = RepeatBehavior.Forever
                    };
                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.Red, KeyTime.FromTimeSpan(TimeSpan.Zero)));
                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.Yellow, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(0.5))));
                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.Green, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(1))));
                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.DodgerBlue, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(1.5))));
                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.MediumPurple, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(2))));
                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.Red, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(2.5))));
                    Storyboard.SetTargetProperty(colorAnim, new PropertyPath("(Shape.Stroke).(SolidColorBrush.Color)"));
                    sb.Children.Add(colorAnim);
                }
                break;
            default:
                return null;
        }
        return sb.Children.Count > 0 ? sb : null;
    }

    private static void AddDoubleAnimation(Storyboard sb, DependencyProperty prop,
        double from, double to, Duration duration, bool autoReverse)
    {
        var anim = new DoubleAnimation(from, to, duration)
        {
            AutoReverse = autoReverse,
            RepeatBehavior = RepeatBehavior.Forever
        };
        Storyboard.SetTargetProperty(anim, new PropertyPath(prop));
        sb.Children.Add(anim);
    }

    /// <summary>The border-colour submenu is BUILT from the palette on open: the list of
    /// offered colours lives once, in <see cref="BorderColorPalette"/> (TASK 63's rule —
    /// a picker never carries its own copy). The generated rows inherit this menu's
    /// DataContext (the <see cref="SceneElement"/>), so the click handler is unchanged.</summary>
    private void WebcamBorderColorMenu_SubmenuOpened(object sender, RoutedEventArgs e)
    {
        if (sender is not MenuItem { DataContext: SceneElement element } menu) return;

        menu.Items.Clear();
        var none = new MenuItem { Header = "None", Tag = string.Empty, IsCheckable = true,
                                  IsChecked = string.IsNullOrEmpty(element.BorderColor) };
        none.Click += WebcamMenu_SetBorderColor;
        menu.Items.Add(none);

        foreach (var colour in BorderColorPalette.All)
        {
            var row = new MenuItem
            {
                Header = colour.ToString(),
                Tag = colour.Hex,
                IsCheckable = true,
                IsChecked = string.Equals(element.BorderColor, colour.Hex, StringComparison.OrdinalIgnoreCase),
            };
            row.Click += WebcamMenu_SetBorderColor;
            menu.Items.Add(row);
        }
    }

    private void WebcamMenu_SetBorderColor(object sender, RoutedEventArgs e)
    {
        if (sender is MenuItem { DataContext: SceneElement element, Tag: string color })
            element.BorderColor = color;
    }

    private void WebcamMenu_HideInScene(object sender, RoutedEventArgs e)
    {
        if (sender is MenuItem { DataContext: SceneElement element })
            element.IsVisible = false;
    }

    private void WebcamMenu_Remove(object sender, RoutedEventArgs e)
    {
        if (sender is MenuItem { DataContext: SceneElement element })
            (DataContext as MainViewModel)?.RemoveSourceCommand.Execute(element);
    }

    // ─── Social bar: click toggles top ⇄ bottom. KISS — the drag variant was
    // unusable for shaky hands (jitter around the direction deadzone), so the bar
    // rides on {Binding SocialBarTop} alone and a click flips it. ───
    private void SocialBar_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        (DataContext as MainViewModel)?.ToggleSocialBarPosition();
        e.Handled = true;
    }

    /// <summary>Is this canvas point inside the social bar? It is a full-width strip at the top or
    /// bottom of the frame and it consumes its own click, so the preview's tunnelling handler has
    /// to step aside (see <c>Preview_MouseLeftButtonDown</c>).</summary>
    private bool IsOverSocialBar(Point canvasPoint)
    {
        if (DataContext is not MainViewModel { SocialBarVisible: true }) return false;
        if (SocialBarElement.ActualHeight <= 0) return false;

        var topLeft = SocialBarElement.TranslatePoint(new Point(0, 0), CanvasGrid);
        return new Rect(topLeft, SocialBarElement.RenderSize).Contains(canvasPoint);
    }

    private void SocialsButton_MouseEnter(object sender, MouseEventArgs e)
    {
        if (SocialBarElement == null) return;

        // Kick the social bar to full brightness so it's immediately visible
        var effect = SocialBarElement.Effect as DropShadowEffect;
        if (effect != null)
        {
            effect.BlurRadius = 40;
            effect.Opacity = 1.0;
        }

        // Pulse the glow so it catches the eye
        _socialGlowAngle = 0;
        _socialGlowTimer?.Stop();
        _socialGlowTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(30) };
        _socialGlowTimer.Tick += SocialGlowTick;
        _socialGlowTimer.Start();
    }

    private void SocialsButton_MouseLeave(object sender, MouseEventArgs e)
    {
        _socialGlowTimer?.Stop();
        _socialGlowTimer = null;

        if (SocialBarElement?.Effect is DropShadowEffect effect)
        {
            effect.BlurRadius = 18;
            effect.Opacity = 0.9;
        }
    }

    private void SocialGlowTick(object? sender, EventArgs e)
    {
        if (SocialBarElement?.Effect is not DropShadowEffect effect) return;

        _socialGlowAngle += 0.18;
        if (_socialGlowAngle > Math.PI * 2) _socialGlowAngle -= Math.PI * 2;

        // Smooth sine pulse: BlurRadius 24→48, Opacity 0.7→1.0
        double t = (Math.Sin(_socialGlowAngle) + 1.0) / 2.0; // 0..1
        effect.BlurRadius = 24 + t * 24;
        effect.Opacity = 0.7 + t * 0.3;
    }

    // ─── Preview: element selection / move / resize / hit-testing ───
    private void Preview_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        var vm = DataContext as MainViewModel;
        if (vm is null) return;

        var grid = (Grid)sender;
        var toCanvas = CanvasGrid.TransformToVisual(grid).Inverse;
        var p = toCanvas.Transform(e.GetPosition(grid));

        // The social bar owns its own left-click (toggle top ⇄ bottom). This handler is the
        // TUNNELLING preview event, so it fires before the bar's bubbling handler: without this
        // guard the bar would be unclickable in preview mode (zoom would win) and, in edit mode,
        // it would drag whatever layer sat underneath it.
        if (IsOverSocialBar(p)) return;

        // Preview mode (EDIT off): the left button drives the zoom box — the common gesture in
        // the mode where nothing is editable. Dragging it afterwards is handled by MouseMove.
        if (!vm.IsEditMode)
        {
            vm.ToggleZoom();
            e.Handled = true;
            return;
        }
        var selected = vm.SelectedElement;

        if (selected is { } sel && IsDraggableElement(sel) && HitHandle(e.GetPosition(grid), sel))
        {
            vm.PushPreviewUndo();
            _isResizing = true;
            _resizeAspect = sel.ClipShape == ClipShape.Round ? 1 : sel.Width / Math.Max(1, sel.Height);
            grid.CaptureMouse();
            e.Handled = true;
            return;
        }

        var hit = HitElementAt(vm, p);
        if (hit != null)
        {
            vm.SelectedElement = hit;
            // One snapshot per gesture: pushing inside the move loop would fill the stack with
            // a hundred one-pixel steps.
            vm.PushPreviewUndo();
            _isDraggingOverlay = true;
            _grabOffset = new Point(p.X - hit.X, p.Y - hit.Y);
            grid.CaptureMouse();
            e.Handled = true;
            return;
        }

        vm.SelectedElement = null;
    }

    private void Preview_MouseMove(object sender, MouseEventArgs e)
    {
        var vm = DataContext as MainViewModel;
        if (vm is null) return;
        var grid = (Grid)sender;
        var toCanvas = CanvasGrid.TransformToVisual(grid).Inverse;
        var p = toCanvas.Transform(e.GetPosition(grid));

        if (e.LeftButton == MouseButtonState.Pressed && vm.IsZoomActive)
        {
            if (!_isZoomDragging)
            {
                vm.StartZoomMove(p.X, p.Y);
                _isZoomDragging = true;
                grid.CaptureMouse();
            }
            else
            {
                vm.UpdateZoomMove(p.X, p.Y);
            }
            return;
        }

        if (!vm.IsEditMode) return;
        if (!_isDraggingOverlay && !_isResizing) return;

        var selected = vm.SelectedElement;
        if (selected == null)
        {
            EndPreviewDrag(grid);
            return;
        }

        if (_isDraggingOverlay)
        {
            // TASK 57: under the vertical tier the camera snaps into the
            // cropped band (one of six spots) instead of free-floating over
            // the master — outside the band it is not in the stream at all.
            if (vm.IsVerticalTier && selected is WebcamSceneConfig verticalCam)
            {
                vm.MoveWebcamInVerticalTier(verticalCam, p.X - _grabOffset.X, p.Y - _grabOffset.Y);
            }
            else
            {
                var minX = -(selected.Width - 20);
                var maxX = 1920 - 20;
                var minY = -(selected.Height - 20);
                var maxY = 1080 - 20;
                selected.X = Math.Clamp(p.X - _grabOffset.X, Math.Min(minX, maxX), Math.Max(minX, maxX));
                selected.Y = Math.Clamp(p.Y - _grabOffset.Y, Math.Min(minY, maxY), Math.Max(minY, maxY));
            }
        }
        else if (_isResizing)
        {
            var isWebcam = selected is WebcamSceneConfig;
            var isRound = selected.ClipShape == ClipShape.Round;
            var proportional = isRound || Keyboard.Modifiers.HasFlag(ModifierKeys.Shift);
            var maxW = isWebcam ? MainViewModel.MaxWebcamWidthFor(vm.StagedScene?.Name) : 1920;
            var maxH = isWebcam ? MainViewModel.MaxWebcamHeightFor(vm.StagedScene?.Name) : 1080;
            var newW = Math.Clamp(p.X - selected.X, 32, maxW);
            var newH = proportional ? newW / _resizeAspect : Math.Clamp(p.Y - selected.Y, 32, maxH);
            if (proportional && newH > maxH)
            {
                newH = maxH;
                newW = newH * _resizeAspect;
            }
            selected.Width = newW;
            selected.Height = newH;

            // TASK 57: inside the vertical band the size snaps (the Chat
            // camera has two sizes: the small tile or one whole area) and the
            // camera ends up on its spot.
            if (vm.IsVerticalTier && selected is WebcamSceneConfig verticalCam)
                vm.ResizeWebcamInVerticalTier(verticalCam, newW, newH);
        }
    }

    private void Preview_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    {
        if (_isZoomDragging && DataContext is MainViewModel vm)
        {
            vm.EndZoomMove();
            _isZoomDragging = false;
            ((Grid)sender).ReleaseMouseCapture();
            e.Handled = true;
            return;
        }
        EndPreviewDrag((Grid)sender);
    }

    private void Preview_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
    {
        // Right-click = the context menu, in both modes (creator ruling 2026-11-01).
        // Ctrl+right-click = the zoom box, EDIT MODE ONLY: the creator asked for no two-handed
        // chords while live or recording, so the preview swallows Ctrl+right-click instead of
        // letting it fall through to the menu. Returning without Handled is what lets WPF's
        // ContextMenuService open the menu under the cursor.
        var vm = DataContext as MainViewModel;
        if (vm is null) return;
        if ((Keyboard.Modifiers & ModifierKeys.Control) == 0) return;

        if (!vm.IsEditMode)
        {
            e.Handled = true;
            return;
        }

        vm.ToggleZoom();
        e.Handled = true;
    }

    private void Preview_MouseRightButtonUp(object sender, MouseButtonEventArgs e)
    {
        if (_isZoomDragging)
        {
            var grid = (Grid)sender;
            grid.ReleaseMouseCapture();
            _isZoomDragging = false;
            if (DataContext is MainViewModel vm) vm.EndZoomMove();
            e.Handled = true;
            return;
        }

        // WPF's PopupControlService opens a context menu on right-button-UP, not down — so
        // handling the Down event alone still let a menu appear under a Ctrl+right-click (found
        // by the creator in edit mode, 2026-11-01). Swallow the Up event too, in both modes:
        // Down decides the action, Up must not undo that decision.
        if ((Keyboard.Modifiers & ModifierKeys.Control) != 0)
            e.Handled = true;
    }

    private void EndPreviewDrag(Grid grid)
    {
        if (_isDraggingOverlay || _isResizing || _isZoomDragging)
            grid.ReleaseMouseCapture();
        _isDraggingOverlay = false;
        _isResizing = false;
        _isZoomDragging = false;
        if (DataContext is MainViewModel vm) vm.EndZoomMove();
    }

    private bool HitHandle(Point mouseScreen, SceneElement element)
    {
        var corner = CanvasGrid.TransformToVisual(PreviewGrid).Transform(new Point(element.X + element.Width, element.Y + element.Height));
        return Math.Abs(mouseScreen.X - corner.X) <= 20 && Math.Abs(mouseScreen.Y - corner.Y) <= 20;
    }

    internal SceneElement? HitElementAt(MainViewModel vm, Point p)
    {
        var scene = vm.StagedScene;
        if (scene == null) return null;

        // A layer selected from the list temporarily wins both preview stacking and hit-testing;
        // the scene's persistent element order remains unchanged.
        if (vm.SelectedElement is { } selected && IsHitTestable(selected) && Contains(selected, p))
            return selected;

        for (var i = scene.Elements.Count - 1; i >= 0; i--)
        {
            var element = scene.Elements[i];
            if (IsHitTestable(element) && Contains(element, p))
                return element;
        }
        return null;
    }

    private static bool IsHitTestable(SceneElement element)
        => IsDraggableElement(element)
           && element is not Source { IsEnabled: false }
           && element is not WebcamSceneConfig { IsVisible: false };

    private static bool Contains(SceneElement element, Point point)
        => point.X >= element.X && point.X <= element.X + element.Width
           && point.Y >= element.Y && point.Y <= element.Y + element.Height;

    private void UpdateZoomBox()
    {
        if (DataContext is not MainViewModel vm) return;
        if (vm.IsZoomActive && ZoomVisualBrush != null)
        {
            // The preview mirrors the output zoom layer: sample the WHOLE composed
            // preview (CanvasGrid = backdrop + every element layer — the same all-layer
            // source the output compositor magnifies) at the FIXED capture window (the
            // box/2 region centred on the click) → 2x via Stretch=Fill. Moving the box
            // only moves the ZoomBox element; the Viewbox stays glued to the capture.
            ZoomVisualBrush.Visual = CanvasGrid;
            ZoomVisualBrush.Viewbox = new Rect(
                vm.ZoomState.CaptureX,
                vm.ZoomState.CaptureY,
                vm.ZoomState.Width / 2,
                vm.ZoomState.Height / 2);
            ZoomVisualBrush.ViewboxUnits = BrushMappingMode.Absolute;
            if (vm.ZoomShape == Models.ZoomShape.Circle)
            {
                ZoomCircleOutline.Visibility = Visibility.Visible;
                ZoomRectOutline.Visibility = Visibility.Collapsed;
                ZoomBox.Clip = new EllipseGeometry(new Rect(0, 0, vm.ZoomState.Width, vm.ZoomState.Height));
            }
            else
            {
                ZoomCircleOutline.Visibility = Visibility.Collapsed;
                ZoomRectOutline.Visibility = Visibility.Visible;
                ZoomBox.Clip = null;
            }
        }
        else if (!vm.IsZoomActive && ZoomVisualBrush != null && ReferenceEquals(ZoomVisualBrush.Visual, CanvasGrid))
        {
            ZoomVisualBrush.Visual = null;
        }
    }

    /// <summary>Rail settings tab (creator ruling 2026-11-01): left-click opens the same app menu
    /// the top-bar gear used to own, so Bug / Feature / About keep their only entry point.</summary>
    private void SettingsTab_Click(object sender, MouseButtonEventArgs e)
    {
        if (sender is not FrameworkElement { ContextMenu: { } menu } anchor) return;
        menu.PlacementTarget = anchor;
        menu.Placement = System.Windows.Controls.Primitives.PlacementMode.Left;
        menu.IsOpen = true;
        e.Handled = true;
    }

    /// <summary>Right-click goes straight to App Settings — the same shortcut the old gear had.</summary>
    private void SettingsTab_PreviewMouseRightButtonDown(object sender, MouseButtonEventArgs e)
    {
        e.Handled = true;
        if (DataContext is MainViewModel { OpenSettingsCommand: { } open } && open.CanExecute(null))
            open.Execute(null);
    }
}