emby-toolbox/EmbyToolbox/Behaviors/TrackExtractionDropTargetBehavior.cs

using System.IO;
using System.Windows;
using EmbyToolbox.Services;
using EmbyToolbox.ViewModels;

namespace EmbyToolbox.Behaviors;

public static class TrackExtractionDropTargetBehavior
{
    public static readonly DependencyProperty IsEnabledProperty = DependencyProperty.RegisterAttached(
        "IsEnabled",
        typeof(bool),
        typeof(TrackExtractionDropTargetBehavior),
        new PropertyMetadata(false, OnIsEnabledChanged));

    public static void SetIsEnabled(DependencyObject d, bool value) => d.SetValue(IsEnabledProperty, value);
    public static bool GetIsEnabled(DependencyObject d) => (bool)d.GetValue(IsEnabledProperty);

    private static void OnIsEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is not FrameworkElement fe)
        {
            return;
        }

        fe.AllowDrop = false;
        fe.PreviewDragOver -= OnPreviewDragOver;
        fe.PreviewDragLeave -= OnPreviewDragLeave;
        fe.PreviewDrop -= OnPreviewDrop;

        if (e.NewValue is true)
        {
            fe.AllowDrop = true;
            fe.PreviewDragOver += OnPreviewDragOver;
            fe.PreviewDragLeave += OnPreviewDragLeave;
            fe.PreviewDrop += OnPreviewDrop;
        }
    }

    private static void OnPreviewDragOver(object sender, DragEventArgs e)
    {
        if (sender is not FrameworkElement fe || fe.DataContext is not TrackExtractionViewModel vm)
        {
            return;
        }

        if (vm.IsBusy)
        {
            e.Effects = DragDropEffects.None;
            vm.IsDropHighlight = false;
            return;
        }

        if (!e.Data.GetDataPresent(DataFormats.FileDrop))
        {
            e.Effects = DragDropEffects.None;
            vm.IsDropHighlight = false;
            return;
        }

        var paths = (string[])e.Data.GetData(DataFormats.FileDrop);
        if (!HasSupportedDrop(paths))
        {
            e.Effects = DragDropEffects.None;
            vm.IsDropHighlight = false;
            return;
        }

        e.Effects = DragDropEffects.Copy;
        e.Handled = true;
        vm.IsDropHighlight = true;
    }

    private static bool HasSupportedDrop(string[] paths)
    {
        if (paths is null || paths.Length == 0)
        {
            return false;
        }

        foreach (var raw in paths)
        {
            try
            {
                var full = Path.GetFullPath(raw);
                if (File.Exists(full) && TrackExtractionFormats.IsSupportedPath(full))
                {
                    return true;
                }

                if (Directory.Exists(full))
                {
                    return true;
                }
            }
            catch
            {
                return false;
            }
        }

        return false;
    }

    private static void OnPreviewDragLeave(object sender, DragEventArgs e)
    {
        if (sender is not FrameworkElement fe || fe.DataContext is not TrackExtractionViewModel vm)
        {
            return;
        }

        vm.IsDropHighlight = false;
    }

    private static void OnPreviewDrop(object sender, DragEventArgs e)
    {
        if (sender is not FrameworkElement fe || fe.DataContext is not TrackExtractionViewModel vm)
        {
            return;
        }

        vm.IsDropHighlight = false;
        if (vm.IsBusy || e.Data.GetData(DataFormats.FileDrop) is not string[] paths || paths.Length == 0)
        {
            e.Handled = true;
            return;
        }

        vm.ApplyDroppedPaths(paths);
        e.Handled = true;
    }
}