SimplePhotosApp/Photos/Views/MainWindow.axaml.cs

using System.Threading.Tasks;
using Avalonia.Controls;
using Avalonia.Input;
using Avalonia.Xaml.Interactions.DragAndDrop;
using Photos.Models;
using Photos.ViewModels;

namespace Photos.Views;

public partial class MainWindow : Window
{
    private IFolderPickerService _folderPickerService;
    private int _currentImageIndex = 0;

    public MainWindow()
    {
        InitializeComponent();
        _folderPickerService = new FolderPickerService(this);
        DataContext = new MainWindowViewModel(_folderPickerService);
    }

    public void DropHandler(object sender, DragEventArgs e)
    {
        (DataContext as MainWindowViewModel)?.WindowDropHandler(e);
    }

    private void OnKeyDownHandler(object sender, KeyEventArgs e)
    {
        if (DataContext is not MainWindowViewModel vm) return;

        async Task HandleEnter()
        {
            if (vm.IsPhotoFocused()) vm.UnfocusPhoto();
            else await vm.TryFocusImage(_currentImageIndex);
        }

        void HandleEscape()
        {
            vm.UnfocusPhoto();
        }

        async Task HandleArrowKey()
        {
            if(vm.IsPhotoFocused()) await vm.TryFocusImage(_currentImageIndex);
            // TODO: move basic selection
        }

        switch (e.Key)
        {
            case Key.Enter:
                HandleEnter().GetAwaiter();
                break;
            case Key.Escape:
                HandleEscape();
                break;
            case Key.Down:
                break;
            case Key.Left:
                if (_currentImageIndex > 0)
                {
                    _currentImageIndex--;
                    HandleArrowKey().GetAwaiter();
                }
                break;
            case Key.Right:
                if (_currentImageIndex < vm.Photos.Count - 1)
                {
                    _currentImageIndex++;
                    HandleArrowKey().GetAwaiter();
                }
                break;
        }
    }

    private void PointerEnteredPhotoHandler(object sender, PointerEventArgs e)
    {
        if (sender is not Image i || DataContext is not MainWindowViewModel vm) return;
        var idx = vm.GetImageIndex(i);
        if (idx == -1) return;
        _currentImageIndex = idx;
    }
}