some cleanup and some fixes

lib/main.dart

@@ -5,12 +5,12 @@ import 'package:provider/provider.dart';
 import 'package:flutter_dotenv/flutter_dotenv.dart';
 import 'src/services/deck_repository.dart';
 import 'src/screens/start_screen.dart';
+import 'src/services/tts_service.dart';
 
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
   try {
     await dotenv.load(fileName: ".env");
-    // No need to catch because the file is only needed for dev
   } catch (_) {}
 
   runApp(
@@ -19,6 +19,14 @@ void main() async {
         Provider<DeckRepository>(create: (_) => DeckRepository()),
         Provider<VocabDeckRepository>(create: (_) => VocabDeckRepository()),
         ChangeNotifierProvider<ThemeModel>(create: (_) => ThemeModel()),
+        Provider<TtsService>(
+          create: (_) {
+            final ttsService = TtsService();
+            ttsService.initTts();
+            return ttsService;
+          },
+          dispose: (_, ttsService) => ttsService.dispose(),
+        ),
       ],
       child: const WkApp(),
     ),

lib/src/screens/add_card_screen.dart

@@ -18,11 +18,14 @@ class _AddCardScreenState extends State<AddCardScreen> {
   final _kanaKit = const KanaKit();
   final _deckRepository = CustomDeckRepository();
   bool _useInterval = false;
+  late FocusNode _japaneseFocusNode;
 
   @override
   void initState() {
     super.initState();
     _japaneseController.addListener(_convertToKana);
+    _japaneseFocusNode = FocusNode();
+    _japaneseFocusNode.addListener(_onJapaneseFocusChange);
   }
 
   @override
@@ -31,13 +34,24 @@ class _AddCardScreenState extends State<AddCardScreen> {
     _japaneseController.dispose();
     _englishController.dispose();
     _kanjiController.dispose();
+    _japaneseFocusNode.removeListener(_onJapaneseFocusChange);
+    _japaneseFocusNode.dispose();
     super.dispose();
   }
 
   void _convertToKana() {
     final text = _japaneseController.text;
+    final selection = _japaneseController.selection;
+    final offset = selection.baseOffset;
+
+    if ((offset > 1 && text[offset - 1] == 'n' && text[offset - 2] != 'n') ||
+        (offset == 1 && text[offset - 1] == 'n')) {
+      return;
+    }
+
     final converted = _kanaKit.toKana(text);
-    if (text != converted) {
+
+    if (converted != text) {
       _japaneseController.value = _japaneseController.value.copyWith(
         text: converted,
         selection: TextSelection.fromPosition(
@@ -47,6 +61,21 @@ class _AddCardScreenState extends State<AddCardScreen> {
     }
   }
 
+  void _onJapaneseFocusChange() {
+    if (!_japaneseFocusNode.hasFocus) {
+      _forceNConversion();
+    }
+  }
+
+  void _forceNConversion() {
+    final text = _japaneseController.text;
+    if (text.isNotEmpty &&
+        text.endsWith('n') &&
+        _kanaKit.toKana(text) != text) {
+      _japaneseController.text = _kanaKit.toKana(text);
+    }
+  }
+
   void _saveCard() {
     if (_formKey.currentState!.validate()) {
       final srsData = _useInterval
@@ -83,6 +112,7 @@ class _AddCardScreenState extends State<AddCardScreen> {
             children: [
               TextFormField(
                 controller: _japaneseController,
+                focusNode: _japaneseFocusNode,
                 decoration: const InputDecoration(
                   labelText: 'Japanese (Kana)',
                   hintText: 'Enter Japanese vocabulary or kanji',

lib/src/screens/browse_screen.dart

@@ -200,14 +200,13 @@ class _BrowseScreenState extends State<BrowseScreen>
       padding: const EdgeInsets.symmetric(vertical: 8.0),
       color: Theme.of(context).colorScheme.surfaceContainer,
       height: 60,
-      child: SingleChildScrollView(
+      child: Row(
-        scrollDirection: Axis.horizontal,
+        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
-        child: Row(
+        children: List.generate(levels.length, (index) {
-          mainAxisAlignment: MainAxisAlignment.center,
+          final level = levels[index];
-          children: List.generate(levels.length, (index) {
+          final isSelected = index == currentPage;
-            final level = levels[index];
+          return Expanded(
-            final isSelected = index == currentPage;
+            child: Padding(
-            return Padding(
               padding: const EdgeInsets.symmetric(horizontal: 4.0),
               child: ElevatedButton(
                 onPressed: () {
@@ -222,14 +221,14 @@ class _BrowseScreenState extends State<BrowseScreen>
                       ? Theme.of(context).colorScheme.primary
                       : Theme.of(context).colorScheme.surfaceContainerHighest,
                   foregroundColor: Theme.of(context).colorScheme.onPrimary,
-                  shape: const CircleBorder(),
+                  shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8)),
                   padding: const EdgeInsets.all(12),
                 ),
                 child: Text(level.toString()),
               ),
-            );
+            ),
-          }),
+          );
-        ),
+        }),
       ),
     );
   }
@@ -882,11 +881,10 @@ class _VocabDetailsDialogState extends State<_VocabDetailsDialog> {
   @override
   void initState() {
     super.initState();
-    _fetchExampleSentences();
+    _fetchExampleSentences(context);
   }
 
-  Future<void> _fetchExampleSentences() async {
+  Future<void> _fetchExampleSentences(BuildContext context) async {
-    final theme = Theme.of(context);
     try {
       final uri = Uri.parse(
         'https://jisho.org/api/v1/search/words?keyword=${Uri.encodeComponent(widget.vocab.characters)}',
@@ -913,11 +911,11 @@ class _VocabDetailsDialogState extends State<_VocabDetailsDialog> {
                     children: [
                       Text(
                         japaneseWord,
-                        style: TextStyle(color: theme.colorScheme.onSurface),
+                        style: TextStyle(color: Theme.of(context).colorScheme.onSurface),
                       ),
                       Text(
                         englishDefinition,
-                        style: TextStyle(color: theme.colorScheme.onSurfaceVariant),
+                        style: TextStyle(color: Theme.of(context).colorScheme.onSurfaceVariant),
                       ),
                       const SizedBox(height: 8),
                     ],
@@ -931,7 +929,7 @@ class _VocabDetailsDialogState extends State<_VocabDetailsDialog> {
           sentences.add(
             Text(
               'No example sentences found.',
-              style: TextStyle(color: theme.colorScheme.onSurface),
+              style: TextStyle(color: Theme.of(context).colorScheme.onSurface),
             ),
           );
         }
@@ -946,7 +944,7 @@ class _VocabDetailsDialogState extends State<_VocabDetailsDialog> {
             _exampleSentences = [
               Text(
                 'Failed to load example sentences.',
-                style: TextStyle(color: theme.colorScheme.error),
+                style: TextStyle(color: Theme.of(context).colorScheme.error),
               ),
             ];
           });
@@ -958,7 +956,7 @@ class _VocabDetailsDialogState extends State<_VocabDetailsDialog> {
           _exampleSentences = [
             Text(
               'Error loading example sentences.',
-              style: TextStyle(color: theme.colorScheme.error),
+              style: TextStyle(color: Theme.of(context).colorScheme.error),
             ),
           ];
         });

lib/src/screens/custom_quiz_screen.dart

@@ -1,9 +1,10 @@
 import 'package:flutter/material.dart';
 import 'dart:math';
-import 'package:flutter_tts/flutter_tts.dart';
 import '../models/custom_kanji_item.dart';
 import '../widgets/options_grid.dart';
 import '../widgets/kanji_card.dart';
+import 'package:provider/provider.dart';
+import '../services/tts_service.dart';
 
 enum CustomQuizMode {
   japaneseToEnglish,
@@ -38,7 +39,6 @@ class CustomQuizScreenState extends State<CustomQuizScreen>
   List<String> _options = [];
   bool _answered = false;
   bool? _correct;
-  late FlutterTts _flutterTts;
   late AnimationController _shakeController;
   late Animation<double> _shakeAnimation;
   final List<String> _incorrectlyAnsweredItems = [];
@@ -47,7 +47,6 @@ class CustomQuizScreenState extends State<CustomQuizScreen>
   void initState() {
     super.initState();
     _shuffledDeck = widget.deck.toList()..shuffle();
-    _initTts();
     if (_shuffledDeck.isNotEmpty) {
       _generateOptions();
     }
@@ -61,6 +60,11 @@ class CustomQuizScreenState extends State<CustomQuizScreen>
     );
   }
 
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+  }
+
   @override
   void didUpdateWidget(CustomQuizScreen oldWidget) {
     super.didUpdateWidget(oldWidget);
@@ -82,21 +86,18 @@ class CustomQuizScreenState extends State<CustomQuizScreen>
     }
   }
 
-  void playAudio() {
+  void playAudio() async {
     if (widget.quizMode == CustomQuizMode.listeningComprehension &&
         _currentIndex < _shuffledDeck.length) {
-      _speak(_shuffledDeck[_currentIndex].characters);
+      final ttsService = Provider.of<TtsService>(context, listen: false);
+      await ttsService.speak(_shuffledDeck[_currentIndex].characters);
     }
   }
 
-  void _initTts() async {
+
-    _flutterTts = FlutterTts();
-    await _flutterTts.setLanguage("ja-JP");
-  }
 
   @override
   void dispose() {
-    _flutterTts.stop();
     _shakeController.dispose();
     super.dispose();
   }
@@ -106,7 +107,8 @@ class CustomQuizScreenState extends State<CustomQuizScreen>
     if (widget.quizMode == CustomQuizMode.listeningComprehension ||
         widget.quizMode == CustomQuizMode.japaneseToEnglish) {
       _options = [currentItem.meaning];
-    } else {
+    }
+    else {
       _options = [
         widget.useKanji && currentItem.kanji != null
             ? currentItem.kanji!
@@ -232,7 +234,8 @@ class CustomQuizScreenState extends State<CustomQuizScreen>
     }
 
     if (isCorrect) {
-      if (widget.quizMode == CustomQuizMode.japaneseToEnglish) {
+      if (widget.quizMode == CustomQuizMode.japaneseToEnglish ||
+          widget.quizMode == CustomQuizMode.englishToJapanese) {
         await _speak(currentItem.characters);
       }
       await Future.delayed(const Duration(milliseconds: 500));
@@ -244,22 +247,24 @@ class CustomQuizScreenState extends State<CustomQuizScreen>
     _nextQuestion();
   }
 
-  void _nextQuestion() {
+  Future<void> _nextQuestion() async {
     setState(() {
       _currentIndex++;
       _answered = false;
       _correct = null;
       if (_currentIndex < _shuffledDeck.length) {
         _generateOptions();
-        if (widget.quizMode == CustomQuizMode.listeningComprehension) {
-          _speak(_shuffledDeck[_currentIndex].characters);
-        }
       }
     });
+    if (_currentIndex < _shuffledDeck.length &&
+        widget.quizMode == CustomQuizMode.listeningComprehension) {
+      await _speak(_shuffledDeck[_currentIndex].characters);
+    }
   }
 
   Future<void> _speak(String text) async {
-    await _flutterTts.speak(text);
+    final ttsService = Provider.of<TtsService>(context, listen: false);
+    await ttsService.speak(text);
   }
 
   void _onOptionSelected(String option) {
@@ -287,6 +292,12 @@ class CustomQuizScreenState extends State<CustomQuizScreen>
         icon: const Icon(Icons.volume_up, size: 64),
         onPressed: () => _speak(currentItem.characters),
       );
+    } else if (widget.quizMode == CustomQuizMode.englishToJapanese) {
+      promptWidget = Text(
+        question,
+        style: TextStyle(fontSize: 48, color: Theme.of(context).colorScheme.onSurface),
+        textAlign: TextAlign.center,
+      );
     } else {
       promptWidget = GestureDetector(
         onTap: () => _speak(question),

lib/src/screens/home_screen.dart

@@ -265,8 +265,6 @@ class _HomeScreenState extends State<HomeScreen>
         ])..shuffle();
         break;
       default:
-        // Handle other QuizMode cases if necessary, or throw an error
-        // if these modes are not expected in this context.
         break;
     }
 
@@ -435,8 +433,6 @@ class _HomeScreenState extends State<HomeScreen>
           subtitle = quizState.readingHint;
           break;
         default:
-          // Handle other QuizMode cases if necessary, or throw an error
-          // if these modes are not expected in this context.
           break;
       }
     }

lib/src/screens/vocab_screen.dart

@@ -54,6 +54,9 @@ class _VocabScreenState extends State<VocabScreen>
     super.initState();
     _tabController = TabController(length: 3, vsync: this);
     _tabController.addListener(() {
+      if (_tabController.index == 2 && !_tabController.indexIsChanging) {
+        _playCurrentAudio();
+      }
       setState(() {});
     });
     _loadSettings();

lib/src/services/database_helper.dart

@@ -50,43 +50,6 @@ class DatabaseHelper {
           '''CREATE TABLE ${DbConstants.srsVocabItemsTable} (${DbConstants.vocabIdColumn} INTEGER, ${DbConstants.quizModeColumn} TEXT, ${DbConstants.srsStageColumn} INTEGER, ${DbConstants.lastAskedColumn} TEXT, PRIMARY KEY (${DbConstants.vocabIdColumn}, ${DbConstants.quizModeColumn}))''',
         );
       },
-      onUpgrade: (db, oldVersion, newVersion) async {
-        if (oldVersion < 2) {
-          await db.execute(
-            '''CREATE TABLE IF NOT EXISTS ${DbConstants.settingsTable} (${DbConstants.keyColumn} TEXT PRIMARY KEY, ${DbConstants.valueColumn} TEXT)''',
-          );
-        }
-        if (oldVersion < 4) {
-          await db.execute(
-            '''CREATE TABLE IF NOT EXISTS ${DbConstants.srsItemsTable} (${DbConstants.kanjiIdColumn} INTEGER, ${DbConstants.quizModeColumn} TEXT, ${DbConstants.readingTypeColumn} TEXT, ${DbConstants.srsStageColumn} INTEGER, ${DbConstants.lastAskedColumn} TEXT, PRIMARY KEY (${DbConstants.kanjiIdColumn}, ${DbConstants.quizModeColumn}, ${DbConstants.readingTypeColumn}))''',
-          );
-        }
-        if (oldVersion < 5) {
-          await db.execute(
-            '''CREATE TABLE IF NOT EXISTS ${DbConstants.vocabularyTable} (${DbConstants.idColumn} INTEGER PRIMARY KEY, ${DbConstants.charactersColumn} TEXT, ${DbConstants.meaningsColumn} TEXT, ${DbConstants.readingsColumn} TEXT)''',
-          );
-          await db.execute(
-            '''CREATE TABLE IF NOT EXISTS ${DbConstants.srsVocabItemsTable} (${DbConstants.vocabIdColumn} INTEGER, ${DbConstants.quizModeColumn} TEXT, ${DbConstants.srsStageColumn} INTEGER, ${DbConstants.lastAskedColumn} TEXT, PRIMARY KEY (${DbConstants.vocabIdColumn}, ${DbConstants.quizModeColumn}))''',
-          );
-        }
-        if (oldVersion < 6) {
-          try {
-            await db.execute(
-              'ALTER TABLE ${DbConstants.vocabularyTable} ADD COLUMN ${DbConstants.pronunciationAudiosColumn} TEXT',
-            );
-          } catch (_) {
-            // Ignore error, column might already exist
-          }
-        }
-        if (oldVersion < 7) {
-          try {
-            await db.execute('ALTER TABLE ${DbConstants.kanjiTable} ADD COLUMN ${DbConstants.levelColumn} INTEGER');
-            await db.execute('ALTER TABLE ${DbConstants.vocabularyTable} ADD COLUMN ${DbConstants.levelColumn} INTEGER');
-          } catch (_) {
-            // Ignore error, column might already exist
-          }
-        }
-      },
     );
   }
 }

lib/src/services/deck_repository.dart

@@ -46,9 +46,7 @@ class DeckRepository {
         _apiKey = envApiKey;
         return _apiKey;
       }
-    } catch (e) {
+    } catch (_) {}
-      // dotenv is not initialized
-    }
 
     return null;
   }
@@ -128,7 +126,8 @@ class DeckRepository {
         DbConstants.srsStageColumn: item.srsStage,
         DbConstants.lastAskedColumn: item.lastAsked.toIso8601String(),
       },
-      where: '${DbConstants.kanjiIdColumn} = ? AND ${DbConstants.quizModeColumn} = ? AND ${DbConstants.readingTypeColumn} = ?',
+      where:
+          '${DbConstants.kanjiIdColumn} = ? AND ${DbConstants.quizModeColumn} = ? AND ${DbConstants.readingTypeColumn} = ?',
       whereArgs: [item.subjectId, item.quizMode.toString(), item.readingType],
     );
   }

lib/src/services/tts_service.dart

@@ -0,0 +1,56 @@
+import 'package:flutter_tts/flutter_tts.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+
+class TtsService {
+  FlutterTts? _flutterTts;
+  bool _isInitialized = false;
+
+  Future<void> initTts() async {
+    if (_isInitialized) return;
+
+    _flutterTts = FlutterTts();
+    if (_flutterTts != null) {
+      final isAvailable = await _flutterTts!.isLanguageAvailable("ja-JP");
+      if (isAvailable == true) {
+        await _flutterTts?.setLanguage("ja-JP");
+      } else {
+        debugPrint('Japanese (ja-JP) TTS language not available.');
+      }
+    }
+    _isInitialized = true;
+  }
+
+  Future<bool> isLanguageAvailable(String language) async {
+    if (_flutterTts == null) {
+      await initTts();
+    }
+    return await _flutterTts?.isLanguageAvailable(language) ?? false;
+  }
+
+  Future<void> speak(String text) async {
+    const int maxRetries = 3;
+    for (int i = 0; i < maxRetries; i++) {
+      try {
+        if (_flutterTts == null || !_isInitialized) {
+          await initTts();
+        }
+        await _flutterTts?.speak(text);
+        return;
+      } on PlatformException catch (_) {
+        debugPrint('TTS speak failed, retrying...');
+        await _flutterTts?.stop();
+        _flutterTts = null;
+        _isInitialized = false;
+        await Future.delayed(const Duration(milliseconds: 500));
+      }
+    }
+    debugPrint('Failed to speak after $maxRetries retries.');
+  }
+
+  void dispose() {
+    _flutterTts?.stop();
+    _flutterTts = null;
+    _isInitialized = false;
+  }
+}