Architectural Patterns

MVVM Pattern

FolderRewind uses CommunityToolkit.Mvvm to implement the MVVM pattern.

• All ViewModels inherit from ViewModelBase (which extends ObservableObject)
• ViewModelBase provides an EnqueueOnUiThread() method that dispatches operations to the UI thread via UiDispatcherService
• The [ObservableProperty] source-generator attribute is used to auto-generate properties and change-notification code
• XAML.cs code-behind is limited to UI event bridging; business logic lives in Services or ViewModels

Static Service Architecture

The application uses static services instead of dependency injection (DI):

• Nearly all services are static classes with static methods (e.g. ConfigService.Load(), BackupService.RunBackup())
• Services are manually initialized in App.OnLaunched()
• UiDispatcherService acts as the central dispatch point for non-UI services to post operations to the UI thread

Rationale: WinUI 3 applications have a short lifecycle and inter-service dependencies are simple, so static calls are more straightforward.

Shell Navigation Pattern

graph LR
    ShellPage["ShellPage<br/>(INavigationHost)"] --> ContentFrame["ContentFrame"]
    NavigationService["NavigationService<br/>(static)"] --> ShellPage
    Pages["HomePage / FolderManagerPage<br/>/ HistoryPage / SettingsPage / ..."] --> ContentFrame

• ShellPage is the navigation host, containing a NavigationView and a ContentFrame
• NavigationService is a static service that holds the current INavigationHost reference
• Pages are identified by string tags ("Home", "Manager", "Tasks", "History", "Logs", "Settings")
• Navigation requests are initiated via NavigationService.NavigateTo(tag)

Configuration-Driven Design

All application state is persisted in a single config.json file:

• ConfigService is the single source of truth for configuration
• The top-level AppConfig contains GlobalSettings, BackupConfig[], and ConfigTemplate[]
• Legacy configuration formats are automatically migrated
• Import/export functionality is provided

Partial Class Organization

Complex services are split across multiple files using C# partial classes, with BackupService as the canonical example:

File	Responsibility
BackupService.cs	Main orchestration (backup/restore entry points)
BackupService.Archive.cs	7-Zip archive creation
BackupService.Filtering.cs	File inclusion/exclusion logic
BackupService.Helpers.cs	Utility methods
BackupService.Metadata.cs	Incremental backup metadata management
BackupService.Pruning.cs	Old archive cleanup
BackupService.Restore.cs	Restore logic

Serialization Strategy

• All models are serialized to JSON using System.Text.Json
• AOT-compatible serialization is achieved via AppJsonContext (source-generator context)
• All serializable types are registered in AppJsonContext
• Configuration migration logic handles conversion from legacy JSON formats to the current version