feat: Enhance CLI and GUI to support configurable game data directory persistence

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_flutter/lib/wolf_3d_flutter.dart

@@ -7,13 +7,17 @@ import 'package:wolf_3d_dart/wolf_3d_data.dart';
 import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
 import 'package:wolf_3d_dart/wolf_3d_engine.dart';
 import 'package:wolf_3d_flutter/audio/wolf3d_platform_audio.dart';
+import 'package:wolf_3d_flutter/managers/desktop_windowing_support.dart'
+    as desktop_windowing_support;
+import 'package:wolf_3d_flutter/managers/game_data_directory_persistence.dart';
 import 'package:wolf_3d_flutter/wolf_3d_input_flutter.dart';
 
 export 'package:wolf_3d_dart/wolf_3d_audio.dart' show DebugMusicPlayer;
 
 export 'audio/wolf3d_platform_audio.dart' show Wolf3dPlatformAudio;
-export 'managers/desktop_windowing_support.dart' show supportsDesktopWindowing;
 export 'managers/game_app_lifecycle_manager.dart' show GameAppLifecycleManager;
+export 'managers/game_data_directory_persistence.dart'
+    show DefaultGameDataDirectoryPersistence;
 export 'managers/game_display_manager.dart' show GameDisplayManager;
 export 'managers/game_persistence_manager.dart' show GamePersistenceManager;
 export 'managers/game_renderer_mode_manager.dart'
@@ -44,12 +48,26 @@ export 'widgets/wolf_menu_shell.dart' show WolfMenuShell;
 class Wolf3dFlutterEngine extends Wolf3dEngine {
   /// Creates an empty facade that must be initialized with [init].
   Wolf3dFlutterEngine({
+    bool debug = false,
     EngineAudio? audioBackend,
     Wolf3dFlutterInput? inputBackend,
-  }) : super(
+    DefaultGameDataDirectoryPersistence? dataDirectoryPersistence,
+  }) : dataDirectoryPersistence =
+           dataDirectoryPersistence ?? DefaultGameDataDirectoryPersistence(),
+       super(
          audio: audioBackend ?? Wolf3dPlatformAudio(),
          input: inputBackend ?? Wolf3dFlutterInput(),
-       );
+       ) {
+    if (debug) {
+      enableDebug();
+    }
+  }
+
+  /// Persists and restores the preferred external game-data directory.
+  final DefaultGameDataDirectoryPersistence dataDirectoryPersistence;
+
+  /// Last configured/loaded external game-data directory path.
+  String? configuredDataDirectory;
 
   /// Shared Flutter input adapter reused by gameplay screens.
   @override
@@ -63,18 +81,24 @@ class Wolf3dFlutterEngine extends Wolf3dEngine {
   }
 
   /// Initializes the engine by loading available game data.
-  ///
-  /// Set [debug] to `true` to explicitly enable host-level debug affordances.
   Future<Wolf3dFlutterEngine> init({
     String? directory,
-    bool debug = false,
   }) async {
-    if (debug) {
-      enableDebug();
-    }
+    await desktop_windowing_support.ensureDesktopWindowingInitialized();
     await audio.init();
     availableGames.clear();
 
+    final String? requestedDirectory = directory?.trim();
+    final String? resolvedDirectory =
+        requestedDirectory != null && requestedDirectory.isNotEmpty
+        ? requestedDirectory
+        : await dataDirectoryPersistence.loadDataDirectory();
+    configuredDataDirectory = resolvedDirectory;
+
+    if (requestedDirectory != null && requestedDirectory.isNotEmpty) {
+      await dataDirectoryPersistence.saveDataDirectory(requestedDirectory);
+    }
+
     // Bundled assets let the GUI work out of the box on supported platforms.
     final versionsToTry = [
       (version: GameVersion.retail, path: 'retail'),
@@ -106,10 +130,10 @@ class Wolf3dFlutterEngine extends Wolf3dEngine {
 
     // On non-web platforms, also scan the local filesystem for user-supplied
     // data folders so the host can pick up extra versions automatically.
-    if (!kIsWeb) {
+    if (!kIsWeb && resolvedDirectory != null) {
       try {
         final externalGames = await WolfensteinLoader.discover(
-          directoryPath: directory,
+          directoryPath: resolvedDirectory,
           recursive: true,
         );
         for (var entry in externalGames.entries) {
@@ -135,9 +159,3 @@ class Wolf3dFlutterEngine extends Wolf3dEngine {
     }
   }
 }
-
-/// Backward-compatible alias for the previous Flutter host facade name.
-typedef Wolf3dFlutter = Wolf3dFlutterEngine;
-
-/// Backward-compatible alias for the legacy Flutter host facade name.
-typedef Wolf3d = Wolf3dFlutterEngine;