AmiReel/Controls/SourceCropEditor.xaml.cs

using System.Runtime.InteropServices.WindowsRuntime;
using AmiReel.Models;
using AmiReel.Services;
using Microsoft.UI;
using Microsoft.UI.Input;
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Automation;
using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Controls.Primitives;
using Microsoft.UI.Xaml.Input;
using Microsoft.UI.Xaml.Media;
using Microsoft.UI.Xaml.Media.Imaging;
using Windows.Foundation;
using Windows.System;
using Windows.UI.Core;

namespace AmiReel.Controls;

public sealed partial class SourceCropEditor : UserControl
{
    private const double HandleHitSize = 12;
    private const double HandleVisualSize = 10;
    private const double MinZoom = 1;
    private const double MaxZoom = 4;
    private const double ZoomStep = 0.25;
    private const int ThumbnailWidth = 128;

    private readonly List<Button> _frameButtons = [];
    private readonly List<string> _framePaths = [];
    private readonly List<string> _frameLabels = [];
    private readonly List<BitmapImage?> _fullFrames = [];
    private int _selectedFrame;

    private int _pixelWidth;
    private int _pixelHeight;
    private double _zoom = 1;
    private bool _isDragging;
    private CropHit _dragHit = CropHit.None;
    private Point _dragStart;
    private Rect _dragOriginRect;
    private PixelInsets _insets;

    public SourceCropEditor()
    {
        InitializeComponent();
    }

    public PixelInsets Insets => _insets;

    public async Task LoadVideoFrameAsync(
        string inputFile, string start, double durationSeconds, string ffmpegPath, string ffprobePath, CancellationToken token)
    {
        LoadProgress.Visibility = Visibility.Visible;
        StatusText.Text = "Loading preview frames...";
        try
        {
            IReadOnlyList<double> offsets = ShortsPipeline.CropPreviewOffsets(durationSeconds);
            string directory = Path.Combine(Path.GetTempPath(), "AmiReel", "crop-editor", Guid.NewGuid().ToString("N"));
            ShortsPipeline pipeline = new();
            IReadOnlyList<string> paths = await pipeline.ExtractSourceFramesAsync(
                inputFile, start, offsets, ffmpegPath, ffprobePath, directory, _ => { }, token);

            _framePaths.Clear();
            _frameLabels.Clear();
            _fullFrames.Clear();
            _frameButtons.Clear();
            FrameStrip.Children.Clear();

            for (int index = 0; index < paths.Count; index++)
            {
                _framePaths.Add(paths[index]);
                _frameLabels.Add(ShortsPipeline.FormatPreviewOffsetLabel(offsets[index]));
                _fullFrames.Add(null);
                FrameStrip.Children.Add(CreateFrameButton(index, paths[index], _frameLabels[index]));
            }

            await ShowFrameAsync(0);
            StatusText.Text = $"{_pixelWidth} × {_pixelHeight} · pick a still, then drag a region and fine-tune the handles.";
        }
        finally
        {
            LoadProgress.Visibility = Visibility.Collapsed;
        }
    }

    public void SetInsets(PixelInsets insets)
    {
        _insets = insets;
        RefreshSelectionVisual();
        UpdateInsetsText();
    }

    private Button CreateFrameButton(int index, string path, string label)
    {
        Image thumb = new()
        {
            Width = 112,
            Height = 63,
            Stretch = Stretch.Uniform,
            IsHitTestVisible = false,
        };
        _ = LoadThumbnailAsync(thumb, path);

        TextBlock caption = new()
        {
            Text = label,
            FontSize = 11,
            HorizontalAlignment = HorizontalAlignment.Center,
            Style = (Style)Application.Current.Resources["MutedTextStyle"],
        };

        StackPanel content = new() { Spacing = 4 };
        content.Children.Add(thumb);
        content.Children.Add(caption);

        Button button = new()
        {
            Content = content,
            Padding = new Thickness(6),
            Tag = index,
            BorderThickness = new Thickness(2),
        };
        AutomationProperties.SetName(button, $"Preview at {label}");
        AutomationProperties.SetAutomationId(button, $"CropPreviewFrame{index}");
        button.Click += FrameButton_Click;
        _frameButtons.Add(button);
        return button;
    }

    private async void FrameButton_Click(object sender, RoutedEventArgs e)
    {
        if (sender is not Button button || button.Tag is not int index)
            return;

        try
        {
            await ShowFrameAsync(index);
        }
        catch (Exception exception)
        {
            StatusText.Text = exception.Message;
        }
    }

    private async Task ShowFrameAsync(int index)
    {
        if (index < 0 || index >= _framePaths.Count)
            return;

        _selectedFrame = index;
        UpdateFrameButtonStyles();

        if (_fullFrames[index] is null)
            _fullFrames[index] = await LoadBitmapAsync(_framePaths[index], decodePixelWidth: 0);

        BitmapImage bitmap = _fullFrames[index]!;
        SourceImage.Source = bitmap;
        if (bitmap.PixelWidth > 0 && bitmap.PixelHeight > 0)
        {
            _pixelWidth = bitmap.PixelWidth;
            _pixelHeight = bitmap.PixelHeight;
        }

        ApplyViewTransform();
        RefreshSelectionVisual();
        UpdateInsetsText();
        StatusText.Text = $"{_pixelWidth} × {_pixelHeight} · {_frameLabels[index]}  ({index + 1} of {_framePaths.Count})";
    }

    private void UpdateFrameButtonStyles()
    {
        Brush accent = (Brush)Application.Current.Resources["AccentBrush"];
        Brush border = (Brush)Application.Current.Resources["BorderBrush"];
        for (int index = 0; index < _frameButtons.Count; index++)
            _frameButtons[index].BorderBrush = index == _selectedFrame ? accent : border;
    }

    private static async Task LoadThumbnailAsync(Image target, string path)
    {
        target.Source = await LoadBitmapAsync(path, ThumbnailWidth);
    }

    private static async Task<BitmapImage> LoadBitmapAsync(string path, int decodePixelWidth)
    {
        await using FileStream stream = File.OpenRead(path);
        BitmapImage bitmap = new();
        if (decodePixelWidth > 0)
            bitmap.DecodePixelWidth = decodePixelWidth;
        await bitmap.SetSourceAsync(stream.AsRandomAccessStream());
        return bitmap;
    }

    private void ImageSurface_PointerPressed(object sender, PointerRoutedEventArgs e)
    {
        if (_pixelWidth <= 0 || !TryMapToDisplay(e, out double x, out double y, out double displayWidth, out double displayHeight))
            return;

        ImageSurface.Focus(FocusState.Pointer);
        (double rectX, double rectY, double rectW, double rectH) = CurrentDisplayRect(displayWidth, displayHeight);
        CropHit hit = _insets.IsEmpty
            ? CropHit.None
            : SourceCropSelection.HitTest(rectX, rectY, rectW, rectH, x, y, HandleHitSize);

        _isDragging = true;
        _dragHit = hit;
        _dragStart = new Point(x, y);
        _dragOriginRect = new Rect(rectX, rectY, rectW, rectH);
        ImageSurface.CapturePointer(e.Pointer);
        e.Handled = true;
    }

    private void ImageSurface_PointerMoved(object sender, PointerRoutedEventArgs e)
    {
        if (!_isDragging)
        {
            UpdateHoverCursor(e);
            return;
        }

        if (!TryMapToDisplay(e, out double x, out double y, out double displayWidth, out double displayHeight))
            return;

        if (_dragHit == CropHit.None)
            UpdateDraftSelection(x, y);
        else
            UpdateAdjustedSelection(x, y, displayWidth, displayHeight);

        e.Handled = true;
    }

    private void ImageSurface_PointerReleased(object sender, PointerRoutedEventArgs e)
    {
        if (!_isDragging)
            return;

        EndDrag();
        ImageSurface.ReleasePointerCapture(e.Pointer);
        e.Handled = true;
    }

    private void ImageSurface_PointerCaptureLost(object sender, PointerRoutedEventArgs e)
    {
        if (_isDragging)
            EndDrag();
    }

    private void EndDrag()
    {
        _isDragging = false;
        _dragHit = CropHit.None;
        RefreshSelectionVisual();
        UpdateInsetsText();
    }

    private void ImageSurface_KeyDown(object sender, KeyRoutedEventArgs e)
    {
        if (_pixelWidth <= 0)
            return;

        bool shift = InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.Shift).HasFlag(CoreVirtualKeyStates.Down);
        int step = 2;
        PixelInsets next = _insets;
        switch (e.Key)
        {
            case VirtualKey.Left:
                next = shift
                    ? SourceCropSelection.NudgeEdge(_insets, _pixelWidth, _pixelHeight, -step, 0, 0, 0)
                    : SourceCropSelection.Nudge(_insets, _pixelWidth, _pixelHeight, -step, 0);
                break;
            case VirtualKey.Right:
                next = shift
                    ? SourceCropSelection.NudgeEdge(_insets, _pixelWidth, _pixelHeight, 0, 0, -step, 0)
                    : SourceCropSelection.Nudge(_insets, _pixelWidth, _pixelHeight, step, 0);
                break;
            case VirtualKey.Up:
                next = shift
                    ? SourceCropSelection.NudgeEdge(_insets, _pixelWidth, _pixelHeight, 0, -step, 0, 0)
                    : SourceCropSelection.Nudge(_insets, _pixelWidth, _pixelHeight, 0, -step);
                break;
            case VirtualKey.Down:
                next = shift
                    ? SourceCropSelection.NudgeEdge(_insets, _pixelWidth, _pixelHeight, 0, 0, 0, -step)
                    : SourceCropSelection.Nudge(_insets, _pixelWidth, _pixelHeight, 0, step);
                break;
            default:
                return;
        }

        if (_insets.IsEmpty)
            return;

        SetInsets(next);
        e.Handled = true;
    }

    private void CropScroller_SizeChanged(object sender, SizeChangedEventArgs e) => ApplyViewTransform();

    private void CropScroller_PointerWheelChanged(object sender, PointerRoutedEventArgs e)
    {
        if (!e.KeyModifiers.HasFlag(VirtualKeyModifiers.Control))
            return;

        double delta = e.GetCurrentPoint(CropScroller).Properties.MouseWheelDelta > 0 ? ZoomStep : -ZoomStep;
        SetZoom(_zoom + delta);
        e.Handled = true;
    }

    private void ZoomSlider_ValueChanged(object sender, RangeBaseValueChangedEventArgs e)
    {
        if (!IsLoaded)
            return;
        SetZoom(e.NewValue);
    }

    private void BrightnessSlider_ValueChanged(object sender, RangeBaseValueChangedEventArgs e)
    {
        if (!IsLoaded)
            return;
        ApplyBrightness(e.NewValue);
    }

    private void ClearCrop_Click(object sender, RoutedEventArgs e) => SetInsets(default);

    private void SetZoom(double zoom)
    {
        _zoom = Math.Clamp(Math.Round(zoom / ZoomStep) * ZoomStep, MinZoom, MaxZoom);
        if (Math.Abs(ZoomSlider.Value - _zoom) > 0.001)
            ZoomSlider.Value = _zoom;
        ZoomSlider.Header = $"Zoom  {_zoom * 100:0}%";
        ApplyViewTransform();
    }

    private void ApplyBrightness(double value)
    {
        double amount = Math.Clamp(value, -0.7, 0.7);
        BrightnessOverlay.Fill = new SolidColorBrush(amount >= 0 ? Colors.White : Colors.Black);
        BrightnessOverlay.Opacity = Math.Abs(amount);
        BrightnessSlider.Header = amount == 0
            ? "View brightness"
            : $"View brightness  {(amount > 0 ? "+" : "")}{amount:0.00}";
    }

    private void ApplyViewTransform()
    {
        if (_pixelWidth <= 0)
            return;

        double viewportWidth = CropScroller.ActualWidth > 0 ? CropScroller.ActualWidth : 800;
        double viewportHeight = CropScroller.ActualHeight > 0 ? CropScroller.ActualHeight : 420;
        (_, _, double displayWidth, double displayHeight) =
            SourceCropSelection.FitUniform(viewportWidth, viewportHeight, _pixelWidth, _pixelHeight);
        ImageSurface.Width = Math.Max(1, displayWidth * _zoom);
        ImageSurface.Height = Math.Max(1, displayHeight * _zoom);
        RefreshSelectionVisual();
    }

    private bool TryMapToDisplay(
        PointerRoutedEventArgs e, out double x, out double y, out double displayWidth, out double displayHeight)
    {
        displayWidth = ImageSurface.Width;
        displayHeight = ImageSurface.Height;
        x = 0;
        y = 0;
        if (displayWidth <= 0 || displayHeight <= 0)
            return false;

        PointerPoint point = e.GetCurrentPoint(ImageSurface);
        (x, y) = SourceCropSelection.ClampToDisplay(point.Position.X, point.Position.Y, displayWidth, displayHeight);
        return true;
    }

    private void UpdateDraftSelection(double x, double y)
    {
        double displayWidth = ImageSurface.Width;
        double displayHeight = ImageSurface.Height;
        if (displayWidth <= 0)
            return;

        double left = Math.Min(_dragStart.X, x);
        double top = Math.Min(_dragStart.Y, y);
        double width = Math.Abs(x - _dragStart.X);
        double height = Math.Abs(y - _dragStart.Y);
        ShowDisplayRect(left, top, width, height);
        _insets = SourceCropSelection.ToInsets(
            _pixelWidth, _pixelHeight, displayWidth, displayHeight, left, top, width, height);
        UpdateInsetsText();
    }

    private void UpdateAdjustedSelection(double x, double y, double displayWidth, double displayHeight)
    {
        (double nextX, double nextY, double nextW, double nextH) = SourceCropSelection.AdjustRect(
            _dragOriginRect.X,
            _dragOriginRect.Y,
            _dragOriginRect.Width,
            _dragOriginRect.Height,
            _dragHit,
            x - _dragStart.X,
            y - _dragStart.Y,
            displayWidth,
            displayHeight);
        ShowDisplayRect(nextX, nextY, nextW, nextH);
        _insets = SourceCropSelection.ToInsets(_pixelWidth, _pixelHeight, displayWidth, displayHeight, nextX, nextY, nextW, nextH);
        UpdateInsetsText();
    }

    private void RefreshSelectionVisual()
    {
        if (ImageSurface.Width <= 0 || _pixelWidth <= 0 || _insets.IsEmpty)
        {
            SetHandlesVisible(false);
            return;
        }

        (double x, double y, double width, double height) = CurrentDisplayRect(ImageSurface.Width, ImageSurface.Height);
        ShowDisplayRect(x, y, width, height);
    }

    private void ShowDisplayRect(double x, double y, double width, double height)
    {
        Canvas.SetLeft(SelectionRect, x);
        Canvas.SetTop(SelectionRect, y);
        SelectionRect.Width = Math.Max(1, width);
        SelectionRect.Height = Math.Max(1, height);
        SelectionRect.Visibility = Visibility.Visible;
        PlaceHandle(HandleNW, x, y);
        PlaceHandle(HandleN, x + (width / 2), y);
        PlaceHandle(HandleNE, x + width, y);
        PlaceHandle(HandleE, x + width, y + (height / 2));
        PlaceHandle(HandleSE, x + width, y + height);
        PlaceHandle(HandleS, x + (width / 2), y + height);
        PlaceHandle(HandleSW, x, y + height);
        PlaceHandle(HandleW, x, y + (height / 2));
        SetHandlesVisible(true);
    }

    private (double X, double Y, double Width, double Height) CurrentDisplayRect(double displayWidth, double displayHeight) =>
        SourceCropSelection.ToDisplayRect(_pixelWidth, _pixelHeight, displayWidth, displayHeight, _insets);

    private void PlaceHandle(Microsoft.UI.Xaml.Shapes.Rectangle handle, double centerX, double centerY)
    {
        Canvas.SetLeft(handle, centerX - (HandleVisualSize / 2));
        Canvas.SetTop(handle, centerY - (HandleVisualSize / 2));
    }

    private void SetHandlesVisible(bool visible)
    {
        Visibility visibility = visible ? Visibility.Visible : Visibility.Collapsed;
        SelectionRect.Visibility = visibility;
        HandleNW.Visibility = visibility;
        HandleN.Visibility = visibility;
        HandleNE.Visibility = visibility;
        HandleE.Visibility = visibility;
        HandleSE.Visibility = visibility;
        HandleS.Visibility = visibility;
        HandleSW.Visibility = visibility;
        HandleW.Visibility = visibility;
    }

    private void UpdateHoverCursor(PointerRoutedEventArgs e)
    {
        if (_pixelWidth <= 0 || _insets.IsEmpty || !TryMapToDisplay(e, out double x, out double y, out double displayWidth, out double displayHeight))
        {
            ProtectedCursor = InputSystemCursor.Create(InputSystemCursorShape.Cross);
            return;
        }

        (double rectX, double rectY, double rectW, double rectH) = CurrentDisplayRect(displayWidth, displayHeight);
        CropHit hit = SourceCropSelection.HitTest(rectX, rectY, rectW, rectH, x, y, HandleHitSize);
        ProtectedCursor = InputSystemCursor.Create(CursorFor(hit));
    }

    private static InputSystemCursorShape CursorFor(CropHit hit) => hit switch
    {
        CropHit.Move => InputSystemCursorShape.SizeAll,
        CropHit.North or CropHit.South => InputSystemCursorShape.SizeNorthSouth,
        CropHit.East or CropHit.West => InputSystemCursorShape.SizeWestEast,
        CropHit.NorthWest or CropHit.SouthEast => InputSystemCursorShape.SizeNorthwestSoutheast,
        CropHit.NorthEast or CropHit.SouthWest => InputSystemCursorShape.SizeNortheastSouthwest,
        _ => InputSystemCursorShape.Cross,
    };

    private void UpdateInsetsText() =>
        InsetsText.Text = _pixelWidth <= 0
            ? "Crop L0  R0  T0  B0"
            : $"Crop L{_insets.Left}  R{_insets.Right}  T{_insets.Top}  B{_insets.Bottom}  ·  {_pixelWidth - _insets.Left - _insets.Right}×{_pixelHeight - _insets.Top - _insets.Bottom}";
}