Try Converter

lib/core/state_notifiers/hive_state_notifier.dart

@@ -3,21 +3,55 @@ import 'package:hive/hive.dart';
 import 'package:cube_system/core/state_notifiers/open_state_notifier.dart';
 
 class HiveStateNotifier<T> extends OpenStateNotifier<T> {
-  String boxName;
+  final String _boxName;
+  String get boxName => _boxName;
+
   late Box _box;
 
-  HiveStateNotifier(super.state, {required this.boxName}) {
+  final Converter<T, Object?>? _converter;
+
+  HiveStateNotifier(
+    super.state, {
+    required String boxName,
+    Converter<T, Object?>? converter,
+  })  : _boxName = boxName,
+        _converter = converter {
     _init();
   }
 
   void _init() async {
-    _box = await Hive.openBox(boxName);
-    state = _box.get(boxName) ?? state;
+    await _openBox();
+    _getData();
     addListener(_saveData);
   }
 
+  Future<void> _openBox() async {
+    _box = await Hive.openBox(boxName);
+  }
+
+  void _getData() {
+    final data = _box.get(boxName);
+
+    if (data != null) {
+      if (_converter != null) {
+        final newState = _converter!.from(data);
+        state = newState;
+      } else {
+        state = data;
+      }
+    }
+  }
+
   Future<void> _saveData(T data) async {
-    await _box.put(boxName, data);
+    void put(data) {
+      _box.put(boxName, data);
+    }
+
+    if (_converter != null) {
+      put(_converter!.to(data));
+    } else {
+      put(data);
+    }
   }
 
   @override
@@ -27,7 +61,21 @@ class HiveStateNotifier<T> extends OpenStateNotifier<T> {
   }
 }
 
-class SingleHiveStateNotifier<T> extends HiveStateNotifier<T?>
+abstract class SingleHiveStateNotifier<T> extends HiveStateNotifier<T>
     with ChangeStateMixin {
-  SingleHiveStateNotifier(super.state, {required super.boxName});
+  SingleHiveStateNotifier(
+    super.state, {
+    required super.boxName,
+    super.converter,
+  });
+}
+
+class Converter<T, K> {
+  K Function(T data) to;
+  T Function(K data) from;
+
+  Converter({
+    required this.to,
+    required this.from,
+  });
 }

lib/features/timetable_page/managers/timetable_day_event_manager.dart

@@ -2,7 +2,6 @@ import 'dart:collection';
 
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
-import 'package:cube_system/models/lesson/lesson.dart';
 import 'package:cube_system/models/timetable_day/timetable_day_event.dart';
 
 import 'package:cube_system/features/timetable_page/state_holders/timetable_page_events.dart';
@@ -12,13 +11,13 @@ import 'package:cube_system/models/timetable_day/timetable_day_type.dart';
 
 final timetableDayEventManager = Provider<TimetableDayEventManager>((ref) {
   return TimetableDayEventManager(
-    timetable: ref.watch(timetablePageTimetable.notifier),
+    timetable: ref.watch(timetablePageLessons.notifier),
     events: ref.watch(timetablePageLessonEvents.notifier),
   );
 });
 
 class TimetableDayEventManager {
-  final StateController<SplayTreeMap<DateTime, List<Lesson>>> timetable;
+  final TimetablePageLessonsNotifier timetable;
   final StateController<SplayTreeMap<DateTime, TimetableDayEvent>> events;
 
   TimetableDayEventManager({

lib/features/timetable_page/managers/timetable_lessons_manager.dart

@@ -26,7 +26,7 @@ final timetableLessonsManager = Provider<TimetableLessonsManager>((ref) {
     lessonConvertor: ref.watch(lessonConvertor),
     eventManager: ref.watch(timetableDayEventManager),
     selectedTimetable: ref.watch(selectedTimetableStateHolder.notifier),
-    timetable: ref.watch(timetablePageTimetable.notifier),
+    timetable: ref.watch(timetablePageLessons.notifier),
     events: ref.watch(timetablePageLessonEvents.notifier),
     currentDateTime: ref.watch(currentDateTimeQuick.notifier),
     selectedDate: ref.watch(selectedDate.notifier),
@@ -42,7 +42,7 @@ class TimetableLessonsManager {
   final TimetableDayEventManager eventManager;
 
   final SelectedTimetableNotifier selectedTimetable;
-  final StateController<SplayTreeMap<DateTime, List<Lesson>>> timetable;
+  final TimetablePageLessonsNotifier timetable;
   final StateController<SplayTreeMap<DateTime, TimetableDayEvent>> events;
   final StateController<DateTime> currentDateTime;
   final StateController<DateTime> selectedDate;
@@ -65,7 +65,7 @@ class TimetableLessonsManager {
   });
 
   void clear() {
-    timetable.state = SplayTreeMap();
+    timetable.change(SplayTreeMap());
     events.state = SplayTreeMap();
   }
 
@@ -92,8 +92,7 @@ class TimetableLessonsManager {
   }
 
   void _setLessons(List<LessonFullNamesInDb> lessons) {
-    SplayTreeMap<DateTime, List<Lesson>> timetableMap =
-        SplayTreeMap.of(timetable.state.cast());
+    TimetableLessons timetableMap = SplayTreeMap.of(timetable.state.cast());
 
     for (final lesson in lessons) {
       timetableMap[lesson.date] = [];
@@ -113,7 +112,7 @@ class TimetableLessonsManager {
       timetableMap[lesson.date]!.add(l);
     }
 
-    timetable.state = timetableMap;
+    timetable.change(timetableMap);
   }
 
   Future<void> updateCurrentTimetable() async {

lib/features/timetable_page/state_holders/timetable_page_lessons.dart

@@ -1,14 +1,40 @@
 import 'dart:collection';
 
+import 'package:cube_system/models/app_box_names/app_box_names.dart';
 import 'package:cube_system/models/lesson/lesson.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import 'package:cube_system/core/state_notifiers/hive_state_notifier.dart';
+
+typedef TimetableLessons = SplayTreeMap<DateTime, List<Lesson>>;
+
 final timetablePageDayLessons =
     Provider.family<List<Lesson>?, DateTime>((ref, date) {
-  return ref.watch(timetablePageTimetable)[date];
+  return ref.watch(timetablePageLessons)[date];
 });
 
-final timetablePageTimetable =
-    StateProvider<SplayTreeMap<DateTime, List<Lesson>>>((ref) {
-  return SplayTreeMap();
+// final timetablePageTimetable = StateProvider<TimetableLessons>((ref) {
+//   return SplayTreeMap();
+// });
+
+final timetablePageLessons =
+    StateNotifierProvider<TimetablePageLessonsNotifier, TimetableLessons>(
+        (ref) {
+  return TimetablePageLessonsNotifier(
+    SplayTreeMap(),
+    boxName: AppBoxNames.timetablePageLessons,
+    converter: Converter<TimetableLessons, Map<DateTime, List<Lesson>>>(
+      to: (data) => data,
+      from: (data) => SplayTreeMap.from(data),
+    ),
+  );
 });
+
+class TimetablePageLessonsNotifier
+    extends SingleHiveStateNotifier<TimetableLessons> {
+  TimetablePageLessonsNotifier(
+    super.state, {
+    required super.boxName,
+    required super.converter,
+  });
+}

lib/models/app_box_names/app_box_names.dart

@@ -1,4 +1,5 @@
 class AppBoxNames {
   static const appSettings = 'appSettings';
   static const selectedTimetable = 'selectedTimetable';
+  static const timetablePageLessons = 'timetablePageLessons';
 }