Made Settings persistent with autosave

lib/storage/settings/settings.dart

@@ -0,0 +1,22 @@
+import 'package:flutter/material.dart';
+import 'package:json_annotation/json_annotation.dart';
+
+part 'settings.g.dart';
+
+@JsonSerializable(explicitToJson: true)
+class Settings {
+  @JsonKey(
+    toJson: _themeToJson,
+    fromJson: _themeFromJson,
+  )
+  ThemeMode appTheme;
+  bool devToolsEnabled;
+
+  Settings(this.appTheme, this.devToolsEnabled);
+
+  static String _themeToJson(ThemeMode m) => m.name;
+  static ThemeMode _themeFromJson(String m) => ThemeMode.values.firstWhere((element) => element.name == m);
+
+  factory Settings.fromJson(Map<String, dynamic> json) => _$SettingsFromJson(json);
+  Map<String, dynamic> toJson() => _$SettingsToJson(this);
+}

lib/storage/settings/settings.g.dart

@@ -0,0 +1,17 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'settings.dart';
+
+// **************************************************************************
+// JsonSerializableGenerator
+// **************************************************************************
+
+Settings _$SettingsFromJson(Map<String, dynamic> json) => Settings(
+      Settings._themeFromJson(json['appTheme'] as String),
+      json['devToolsEnabled'] as bool,
+    );
+
+Map<String, dynamic> _$SettingsToJson(Settings instance) => <String, dynamic>{
+      'appTheme': Settings._themeToJson(instance.appTheme),
+      'devToolsEnabled': instance.devToolsEnabled,
+    };

lib/storage/settings/settingsProvider.dart

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+import 'dart:convert';
+import 'dart:developer';
+import 'package:flutter/material.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'settings.dart';
+
+class SettingsProvider extends ChangeNotifier {
+  static const String _fieldName = "settings";
+
+  late SharedPreferences _storage;
+  late Settings _settings = _defaults();
+
+  Settings val({bool write = false}) {
+    if(write) {
+      notifyListeners();
+      Future.delayed(const Duration(milliseconds: 300)).then((_) => update());
+    }
+    return _settings;
+  }
+
+  SettingsProvider() {
+    init();
+  }
+
+  void init() async {
+    _storage = await SharedPreferences.getInstance();
+
+    if(_storage.containsKey(_fieldName)) {
+      log("Settings from disk: ${_storage.getString(_fieldName)}");
+      _settings = Settings.fromJson(jsonDecode(_storage.getString(_fieldName)!));
+    } else {
+      _settings = _defaults();
+    }
+
+    notifyListeners();
+  }
+
+  void update() async {
+    await _storage.setString(_fieldName, jsonEncode(_settings.toJson()));
+  }
+
+  Settings _defaults() {
+    return Settings(
+      ThemeMode.system,
+      false,
+    );
+  }
+}