gregExtractor/GUI/MainWindow.axaml.cs

using Avalonia.Controls;
using Avalonia.Interactivity;
using Avalonia.Platform.Storage;
using gregExtractor.GUI.ViewModels;

namespace gregExtractor.GUI;

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        DataContextChanged += OnDataContextChanged;
        WireDataContext();
    }

    private void OnDataContextChanged(object? sender, EventArgs eventArgs)
    {
        WireDataContext();
    }

    private void WireDataContext()
    {
        if (DataContext is MainViewModel viewModel)
            viewModel.WireBrowseHandler(BrowseFolderAsync);
    }

    private async Task<string?> BrowseFolderAsync(string? target)
    {
        IReadOnlyList<IStorageFolder> folders = await StorageProvider.OpenFolderPickerAsync(new FolderPickerOpenOptions
        {
            AllowMultiple = false,
            Title = string.IsNullOrWhiteSpace(target) ? "Select folder" : $"Select folder for {target}",
        });

        if (folders.Count == 0)
            return null;

        return folders[0].Path.LocalPath;
    }

    private void OnMinimizeClicked(object? sender, RoutedEventArgs e)
    {
        WindowState = WindowState.Minimized;
    }

    private void OnCloseClicked(object? sender, RoutedEventArgs e)
    {
        Close();
    }
}