App.xaml.cs

using System.IO;

namespace OneColumnEncoder;

/// <summary>
/// Application entry point: loads persisted app settings and data, wires up
/// unhandled-exception and startup-language handling, and hosts the main
/// window with its top-level ViewModel.
/// </summary>
public partial class App : Application
{
    // Pass navigation, app settings and tools imported to MainVM
    internal readonly ModalNavS _modalNavM;
    private readonly AppConfM _appConfM;
    private readonly AppDataM _appDataM;
    private readonly ForkSnapshot? _forkSnapshot;
    private readonly string? _forkSnapshotLoadError;
    public App()
    {
        string? forkSnapshotLoadError;
        _forkSnapshot = ForkSnapshot.LoadFromCommandLine(out forkSnapshotLoadError);
        _forkSnapshotLoadError = forkSnapshotLoadError;
        if (_forkSnapshot != null && !string.IsNullOrWhiteSpace(_forkSnapshot.ConfigSubFolder))
            PersistencePaths.ConfigSubFolder = _forkSnapshot.ConfigSubFolder;

        _modalNavM = new ModalNavS();
        _appConfM = AppConfM.Load();
        _appDataM = AppDataM.Load();

        // Fresh installs need one startup language probe; existing configs keep their saved state.
        if (!File.Exists(Path.Combine(AppConfM.GetConfigDirectory(), "appconfig.json")))
            _appConfM.InitLang = true;

        _forkSnapshot?.ApplyTo(_appDataM, _appConfM);
    }

    protected override void OnStartup(StartupEventArgs e)
    {
        try
        {
            DispatcherUnhandledException += (_, ex) =>
            {
                new OpenErrModalCmd(_modalNavM, "Unhandled UI Exception", ex.Exception.ToString()).Execute(null);
                ex.Handled = true;
            };

            ApplyStartupLanguageOnce();
            _ = new UILangProvider(_appConfM.Lang.LanguageCode);

            if (_forkSnapshotLoadError != null)
            {
                new OpenErrModalCmd(
                    _modalNavM,
                    UICaptionProvider.Errors.ForkSnapshotLoadTitle,
                    string.Format(
                        UICaptionProvider.Errors.ForkSnapshotLoadMessage,
                        _forkSnapshotLoadError)).Execute(null);
                Shutdown(-1);
                return;
            }

            AppFontProvider.Refresh();
            AppFontProvider.ApplyFrom(_appConfM);
            OpenAppConfCmd openAppConf = new(_modalNavM, _appConfM);
            OpenUsagesCmd openUsages = new(_modalNavM, _appConfM);

            MainVM mainVM = new(openAppConf, openUsages, _appDataM, _appConfM, _modalNavM);
            if (_forkSnapshot != null)
                mainVM.ApplyForkSnapshot(_forkSnapshot);
            MainWindow = new MainWindow { DataContext = mainVM };
            MainWindow.Show();
            base.OnStartup(e);
        }
        catch (Exception ex)
        {
            new OpenErrModalCmd(_modalNavM, "Startup Exception", ex.ToString()).Execute(null);
            Shutdown(-1);
        }
    }

    private void ApplyStartupLanguageOnce()
    {
        if (!_appConfM.InitLang) return;

        _appConfM.Lang.LanguageCode = ResolveSupportedLanguageCode(CultureInfo.CurrentUICulture);
        _appConfM.InitLang = false;
        _appConfM.Save();
    }

    private static string ResolveSupportedLanguageCode(CultureInfo culture)
    {
        string name = culture.Name.ToLowerInvariant();
        string twoLetterName = culture.TwoLetterISOLanguageName.ToLowerInvariant();

        return name switch
        {
            "zh-cn" or "zh-sg" or "zh-hans" => "zh-cn",
            "zh-tw" or "zh-hk" or "zh-mo" or "zh-hant" => "zh-tw",
            _ when UICaptionProvider.AppConf.LanguageOptions.Codes.Contains(twoLetterName) => twoLetterName,
            _ => "en"
        };
    }
}