restructure

- move list_item_divider into lib/shared
- move lib/engine into lib/services/engine

unify Import style

- I've unified the way files are imported. We now use absolute imports everywhere.

This is not a must but I find it more usefull.

cleanup imports

- prefer using part files where needed

src/ui/flutter_app/lib/l10n/resources.dart

@@ -19,10 +19,10 @@
 import 'dart:io';
 
 import 'package:flutter/material.dart';
-import 'package:sanmill/generated/l10n.dart';
-import 'package:sanmill/screens/list_item_divider.dart';
 import 'package:sanmill/shared/common/config.dart';
 import 'package:sanmill/shared/common/constants.dart';
+import 'package:sanmill/generated/l10n.dart';
+import 'package:sanmill/shared/list_item_divider.dart';
 import 'package:sanmill/shared/theme/app_theme.dart';
 
 Map<String, Strings> languageCodeToStrings = {
@@ -520,9 +520,7 @@ class Resources {
 }
 
 Future<void> setLanguage(
-  BuildContext context,
-  Function(String?)? callback,
-) async {
+    BuildContext context, Function(String?)? callback) async {
   final languageColumn = Column(
     mainAxisSize: MainAxisSize.min,
     children: <Widget>[
@@ -572,7 +570,7 @@ Bidirectionality getBidirectionality(BuildContext context) {
       currentLocale.languageCode == "he" ||
       currentLocale.languageCode == "ps" ||
       currentLocale.languageCode == "ur") {
-    debugPrint("bidirectionality: RTL");
+    print("bidirectionality: RTL");
     return Bidirectionality.rightToLeft;
   } else {
     return Bidirectionality.leftToRight;
@@ -593,5 +591,5 @@ void setSpecialCountryAndRegion(BuildContext context) {
       break;
   }
 
-  debugPrint("Set Special Country and Region to $specialCountryAndRegion.");
+  print("Set Special Country and Region to $specialCountryAndRegion.");
 }

src/ui/flutter_app/lib/main.dart

@@ -16,7 +16,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'dart:async';
 import 'dart:io';
 import 'dart:ui';
 
@@ -34,8 +33,6 @@ import 'package:sanmill/services/audios.dart';
 import 'package:sanmill/shared/common/constants.dart';
 import 'package:sanmill/shared/theme/app_theme.dart';
 
-import 'services/audios.dart';
-
 Future<void> main() async {
   final catcher = Catcher(
     rootWidget: BetterFeedback(

src/ui/flutter_app/lib/mill/game.dart

@@ -17,12 +17,11 @@
 */
 
 import 'package:flutter/foundation.dart';
-import 'package:sanmill/engine/engine.dart';
+import 'package:sanmill/mill/position.dart';
+import 'package:sanmill/mill/types.dart';
+import 'package:sanmill/services/engine/engine.dart';
 import 'package:sanmill/shared/common/config.dart';
 
-import 'position.dart';
-import 'types.dart';
-
 enum PlayerType { human, AI }
 Map<String, bool> isAi = {PieceColor.white: false, PieceColor.black: true};
 

src/ui/flutter_app/lib/mill/mills.dart

@@ -16,8 +16,8 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'position.dart';
-import 'rule.dart';
+import 'package:sanmill/mill/position.dart';
+import 'package:sanmill/mill/rule.dart';
 
 class Mills {
   const Mills._();

src/ui/flutter_app/lib/mill/position.dart

@@ -17,16 +17,14 @@
 */
 
 import 'package:flutter/foundation.dart';
-import 'package:sanmill/engine/engine.dart';
 import 'package:sanmill/mill/game.dart';
+import 'package:sanmill/mill/mills.dart';
 import 'package:sanmill/mill/recorder.dart';
 import 'package:sanmill/mill/rule.dart';
 import 'package:sanmill/mill/types.dart';
+import 'package:sanmill/mill/zobrist.dart';
 import 'package:sanmill/services/audios.dart';
-
-import 'mills.dart';
-import 'types.dart';
-import 'zobrist.dart';
+import 'package:sanmill/services/engine/engine.dart';
 
 List<int> posKeyHistory = [];
 

src/ui/flutter_app/lib/mill/recorder.dart

@@ -17,11 +17,10 @@
 */
 
 import 'package:flutter/foundation.dart';
+import 'package:sanmill/mill/position.dart';
+import 'package:sanmill/mill/types.dart';
 import 'package:sanmill/shared/common/config.dart';
 
-import 'position.dart';
-import 'types.dart';
-
 // TODO
 class GameRecorder {
   int cur = -1;

src/ui/flutter_app/lib/screens/about_page.dart

@@ -24,15 +24,14 @@ import 'package:flutter/material.dart';
 import 'package:package_info_plus/package_info_plus.dart';
 import 'package:sanmill/generated/flutter_version.dart';
 import 'package:sanmill/generated/l10n.dart';
-import 'package:sanmill/screens/settings/settings_list_tile.dart';
+import 'package:sanmill/screens/license_page.dart';
+import 'package:sanmill/screens/oss_license_page.dart';
 import 'package:sanmill/shared/common/constants.dart';
+import 'package:sanmill/shared/list_item_divider.dart';
+import 'package:sanmill/shared/settings/settings_list_tile.dart';
 import 'package:sanmill/shared/theme/app_theme.dart';
 import 'package:url_launcher/url_launcher.dart';
 
-import 'license_page.dart';
-import 'list_item_divider.dart';
-import 'oss_license_page.dart';
-
 class AboutPage extends StatelessWidget {
   final String tag = "[about] ";
 

src/ui/flutter_app/lib/screens/game_page/board.dart

@@ -16,15 +16,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'package:flutter/material.dart';
-import 'package:sanmill/generated/l10n.dart';
-import 'package:sanmill/l10n/resources.dart';
-import 'package:sanmill/mill/game.dart';
-import 'package:sanmill/mill/types.dart';
-import 'package:sanmill/shared/common/config.dart';
-import 'package:sanmill/shared/painters/board_painter.dart';
-import 'package:sanmill/shared/painters/pieces_painter.dart';
-import 'package:sanmill/shared/theme/app_theme.dart';
+part of 'package:sanmill/screens/game_page/game_page.dart';
 
 typedef BoardTapCallback = dynamic Function(int index);
 

src/ui/flutter_app/lib/screens/game_page/game_page.dart

@@ -16,15 +16,13 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'dart:async';
-
 //import 'dart:typed_data';
 
+import 'dart:async';
+
 import 'package:fluentui_system_icons/fluentui_system_icons.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
-import 'package:sanmill/engine/engine.dart';
-import 'package:sanmill/engine/native_engine.dart';
 import 'package:sanmill/generated/l10n.dart';
 import 'package:sanmill/l10n/resources.dart';
 import 'package:sanmill/main.dart';
@@ -32,9 +30,10 @@ import 'package:sanmill/mill/game.dart';
 import 'package:sanmill/mill/position.dart';
 import 'package:sanmill/mill/rule.dart';
 import 'package:sanmill/mill/types.dart';
-import 'package:sanmill/screens/board.dart';
 import 'package:sanmill/screens/game_settings_page.dart';
 import 'package:sanmill/services/audios.dart';
+import 'package:sanmill/services/engine/engine.dart';
+import 'package:sanmill/services/engine/native_engine.dart';
 import 'package:sanmill/shared/common/config.dart';
 import 'package:sanmill/shared/common/constants.dart';
 import 'package:sanmill/shared/dialog.dart';
@@ -45,6 +44,10 @@ import 'package:sanmill/shared/theme/app_theme.dart';
 import 'package:stack_trace/stack_trace.dart';
 
 part 'package:sanmill/screens/game_page/game_page_tool_bar.dart';
+part 'package:sanmill/screens/game_page/board.dart';
+part 'package:sanmill/shared/painters/board_painter.dart';
+part 'package:sanmill/shared/painters/pieces_painter.dart';
+part 'package:sanmill/shared/painters/painter_base.dart';
 
 double boardWidth = 0.0;
 

src/ui/flutter_app/lib/screens/game_settings_page.dart

@@ -21,16 +21,15 @@ import 'dart:io';
 
 import 'package:flutter/material.dart';
 import 'package:sanmill/generated/l10n.dart';
-import 'package:sanmill/screens/settings/settings_card.dart';
-import 'package:sanmill/screens/settings/settings_list_tile.dart';
-import 'package:sanmill/screens/settings/settings_switch_list_tile.dart';
+import 'package:sanmill/screens/env_page.dart';
 import 'package:sanmill/shared/common/config.dart';
 import 'package:sanmill/shared/common/settings.dart';
+import 'package:sanmill/shared/dialog.dart';
+import 'package:sanmill/shared/settings/settings_card.dart';
+import 'package:sanmill/shared/settings/settings_list_tile.dart';
+import 'package:sanmill/shared/settings/settings_switch_list_tile.dart';
 import 'package:sanmill/shared/theme/app_theme.dart';
 
-import '../shared/dialog.dart';
-import 'env_page.dart';
-
 class Developer {
   const Developer._();
   static bool developerModeEnabled = false;

src/ui/flutter_app/lib/screens/home_drawer.dart

@@ -16,16 +16,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'dart:async';
-
-import 'package:animated_text_kit/animated_text_kit.dart';
-import 'package:flutter/material.dart';
-import 'package:sanmill/generated/l10n.dart';
-import 'package:sanmill/l10n/resources.dart';
-import 'package:sanmill/screens/game_settings_page.dart';
-import 'package:sanmill/shared/common/config.dart';
-import 'package:sanmill/shared/common/constants.dart';
-import 'package:sanmill/shared/theme/app_theme.dart';
+part of 'package:sanmill/screens/navigation_home_screen.dart';
 
 enum DrawerIndex {
   humanVsAi,

src/ui/flutter_app/lib/screens/navigation_home_screen.dart

@@ -19,19 +19,20 @@
 import 'dart:io';
 import 'dart:typed_data';
 
+import 'package:animated_text_kit/animated_text_kit.dart';
 import 'package:feedback/feedback.dart';
+import 'package:fluentui_system_icons/fluentui_system_icons.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_email_sender/flutter_email_sender.dart';
 import 'package:package_info_plus/package_info_plus.dart';
 import 'package:path_provider/path_provider.dart';
-import 'package:sanmill/engine/engine.dart';
+import 'package:sanmill/generated/l10n.dart';
+import 'package:sanmill/l10n/resources.dart';
 import 'package:sanmill/mill/game.dart';
 import 'package:sanmill/screens/about_page.dart';
-import 'package:sanmill/screens/drawer_user_controller.dart';
 import 'package:sanmill/screens/game_page/game_page.dart';
 import 'package:sanmill/screens/game_settings_page.dart';
 import 'package:sanmill/screens/help_screen.dart';
-import 'package:sanmill/screens/home_drawer.dart';
 import 'package:sanmill/screens/personalization_settings_page.dart';
 import 'package:sanmill/screens/rule_settings_page.dart';
 import 'package:sanmill/services/engine/engine.dart';
@@ -39,6 +40,9 @@ import 'package:sanmill/shared/common/config.dart';
 import 'package:sanmill/shared/common/constants.dart';
 import 'package:sanmill/shared/theme/app_theme.dart';
 
+part 'package:sanmill/screens/home_drawer.dart';
+part 'package:sanmill/shared/drawer_controller.dart';
+
 class NavigationHomeScreen extends StatefulWidget {
   @override
   _NavigationHomeScreenState createState() => _NavigationHomeScreenState();
@@ -59,7 +63,7 @@ class _NavigationHomeScreenState extends State<NavigationHomeScreen> {
   Widget build(BuildContext context) {
     return Material(
       color: AppTheme.navigationHomeScreenBackgroundColor,
-      child: DrawerUserController(
+      child: DrawerController(
         screenIndex: drawerIndex,
         drawerWidth: MediaQuery.of(context).size.width * 0.75,
         onDrawerCall: changeIndex,

src/ui/flutter_app/lib/screens/personalization_settings_page.dart

@@ -20,11 +20,11 @@ import 'package:flutter/material.dart';
 import 'package:flutter_colorpicker/flutter_colorpicker.dart';
 import 'package:sanmill/generated/l10n.dart';
 import 'package:sanmill/l10n/resources.dart';
-import 'package:sanmill/screens/settings/settings_card.dart';
-import 'package:sanmill/screens/settings/settings_list_tile.dart';
-import 'package:sanmill/screens/settings/settings_switch_list_tile.dart';
 import 'package:sanmill/shared/common/config.dart';
 import 'package:sanmill/shared/common/constants.dart';
+import 'package:sanmill/shared/settings/settings_card.dart';
+import 'package:sanmill/shared/settings/settings_list_tile.dart';
+import 'package:sanmill/shared/settings/settings_switch_list_tile.dart';
 import 'package:sanmill/shared/theme/app_theme.dart';
 
 class PersonalizationSettingsPage extends StatefulWidget {

src/ui/flutter_app/lib/screens/rule_settings_page.dart

@@ -20,14 +20,13 @@ import 'package:flutter/material.dart';
 import 'package:sanmill/generated/l10n.dart';
 import 'package:sanmill/l10n/resources.dart';
 import 'package:sanmill/mill/rule.dart';
-import 'package:sanmill/screens/settings/settings_card.dart';
-import 'package:sanmill/screens/settings/settings_list_tile.dart';
-import 'package:sanmill/screens/settings/settings_switch_list_tile.dart';
 import 'package:sanmill/shared/common/config.dart';
+import 'package:sanmill/shared/settings/settings_card.dart';
+import 'package:sanmill/shared/settings/settings_list_tile.dart';
+import 'package:sanmill/shared/settings/settings_switch_list_tile.dart';
+import 'package:sanmill/shared/snack_bar.dart';
 import 'package:sanmill/shared/theme/app_theme.dart';
 
-import '../shared/snack_bar.dart';
-
 class RuleSettingsPage extends StatefulWidget {
   @override
   _RuleSettingsPageState createState() => _RuleSettingsPageState();

src/ui/flutter_app/lib/services/engine/native_engine.dart

@@ -22,10 +22,9 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:sanmill/mill/position.dart';
 import 'package:sanmill/mill/types.dart';
+import 'package:sanmill/services/engine/engine.dart';
 import 'package:sanmill/shared/common/config.dart';
 
-import 'engine.dart';
-
 class NativeEngine extends Engine {
   static const platform = MethodChannel('com.calcitem.sanmill/engine');
   bool isActive = false;
@@ -55,8 +54,13 @@ class NativeEngine extends Engine {
     return platform.invokeMethod('isReady');
   }
 
-  Future<bool> isThinking() async {
-    return platform.invokeMethod<bool>('isThinking') as Future<bool>;
+  FutureOr<bool> isThinking() async {
+    final _isThinking = await platform.invokeMethod<bool>('isThinking');
+    if (_isThinking is bool) {
+      return _isThinking;
+    } else {
+      throw 'Invalid platform response. Expected a value of type bool';
+    }
   }
 
   @override

src/ui/flutter_app/lib/shared/drawer_controller.dart

@@ -16,16 +16,10 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'package:fluentui_system_icons/fluentui_system_icons.dart';
-import 'package:flutter/material.dart';
-import 'package:sanmill/generated/l10n.dart';
-import 'package:sanmill/l10n/resources.dart';
-import 'package:sanmill/screens/home_drawer.dart';
-import 'package:sanmill/shared/common/config.dart';
-import 'package:sanmill/shared/theme/app_theme.dart';
+part of 'package:sanmill/screens/navigation_home_screen.dart';
 
-class DrawerUserController extends StatefulWidget {
-  const DrawerUserController({
+class DrawerController extends StatefulWidget {
+  const DrawerController({
     Key? key,
     this.drawerWidth = AppTheme.drawerWidth,
     required this.onDrawerCall,
@@ -45,10 +39,10 @@ class DrawerUserController extends StatefulWidget {
   final DrawerIndex screenIndex;
 
   @override
-  _DrawerUserControllerState createState() => _DrawerUserControllerState();
+  _DrawerControllerState createState() => _DrawerControllerState();
 }
 
-class _DrawerUserControllerState extends State<DrawerUserController>
+class _DrawerControllerState extends State<DrawerController>
     with TickerProviderStateMixin {
   late final ScrollController scrollController;
   late final AnimationController iconAnimationController;

src/ui/flutter_app/lib/shared/painters/board_painter.dart

@@ -16,14 +16,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'package:flutter/material.dart';
-import 'package:sanmill/mill/game.dart';
-import 'package:sanmill/mill/types.dart';
-import 'package:sanmill/screens/game_page/game_page.dart';
-import 'package:sanmill/shared/common/config.dart';
-import 'package:sanmill/shared/theme/app_theme.dart';
-
-import 'painter_base.dart';
+part of 'package:sanmill/screens/game_page/game_page.dart';
 
 class BoardPainter extends PiecesBasePainter {
   BoardPainter({required double width}) : super(width: width);

src/ui/flutter_app/lib/shared/painters/painter_base.dart

@@ -16,8 +16,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'package:flutter/material.dart';
-import 'package:sanmill/shared/theme/app_theme.dart';
+part of 'package:sanmill/screens/game_page/game_page.dart';
 
 abstract class PiecesBasePainter extends CustomPainter {
   final double width;

src/ui/flutter_app/lib/shared/painters/pieces_painter.dart

@@ -16,13 +16,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'package:flutter/material.dart';
-import 'package:sanmill/mill/position.dart';
-import 'package:sanmill/mill/types.dart';
-import 'package:sanmill/shared/common/config.dart';
-import 'package:sanmill/shared/theme/app_theme.dart';
-
-import 'painter_base.dart';
+part of 'package:sanmill/screens/game_page/game_page.dart';
 
 class PiecePaintParam {
   final String piece;

src/ui/flutter_app/lib/shared/settings/settings_card.dart

@@ -17,7 +17,7 @@
 */
 
 import 'package:flutter/material.dart';
-import 'package:sanmill/screens/list_item_divider.dart';
+import 'package:sanmill/shared/list_item_divider.dart';
 import 'package:sanmill/shared/theme/app_theme.dart';
 
 class SettingsCard extends StatelessWidget {