Theme Changer (Primitive?)

lib/app_settings.dart

@@ -1,9 +1,16 @@
 import 'package:flutter/material.dart';
-import 'package:witl/theme_manager.dart';
+import 'package:witl/main.dart';
 
-class Settings extends StatelessWidget {
+class Settings extends StatefulWidget {
   const Settings({super.key});
 
+  @override
+  State<Settings> createState() => _Settings();
+}
+
+class _Settings extends State<Settings> {
+  late String selectedTheme = 'Dark';
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -13,7 +20,25 @@ class Settings extends StatelessWidget {
 
       body: ListView(
         children:[
-          
+          ListTile(
+            title: const Text("App Theme"),
+            subtitle: const Text("Sets the theme of the app between: Dark, Light, System Default."),
+            trailing: DropdownButton<String> (
+              value: selectedTheme,
+              items: <String>["Light", "Dark", "System Default"].map((String value) {
+                return DropdownMenuItem<String>(
+                  value: value,
+                  child: Text(value),
+                  );
+              }).toList(),
+              onChanged: (String? updatedTheme) {
+                setState(() {
+                  selectedTheme = updatedTheme ?? selectedTheme;
+                  MyApp.of(context).changeTheme(selectedTheme);
+                });
+              },
+            ),
+          )
         ],
       )
     );

lib/main.dart

@@ -6,9 +6,18 @@ import 'package:witl/input_data.dart';
 
 void main() => runApp(const MyApp());
 
-class MyApp extends StatelessWidget {
+class MyApp extends StatefulWidget {
   const MyApp({super.key});
 
+  @override
+  State<MyApp> createState() => _MyAppState();
+
+  static _MyAppState of(BuildContext context) => context.findAncestorStateOfType<_MyAppState>()!;
+}
+
+class _MyAppState  extends State<MyApp> {
+  ThemeMode _theme = ThemeMode.system;
+  
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
@@ -26,11 +35,11 @@ class MyApp extends StatelessWidget {
         primaryColor: Colors.black,
         brightness: Brightness.dark,
         dividerColor: Colors.black12,
-        scaffoldBackgroundColor: Color(0xFF131313),
+        scaffoldBackgroundColor: const Color(0xFF131313),
 
       ),
 
-      themeMode: ThemeMode.system,
+      themeMode: _theme,
 
       // Navigashun with Routes
       // Base "Home" Route
@@ -52,4 +61,17 @@ class MyApp extends StatelessWidget {
       },
     );
   }
+
+  void changeTheme(String newTheme) {
+    setState(() {
+      switch(newTheme) {
+        case "Light":
+          _theme = ThemeMode.light;
+        case "Dark":
+          _theme = ThemeMode.dark;
+        case "System Default":
+          _theme = ThemeMode.system;
+      }
+    });
+  }
 }

lib/storage_manager.dart

@@ -1,27 +0,0 @@
-import 'package:shared_preferences/shared_preferences.dart';
-
-class StorageManager {
-  static void saveData(String key, dynamic value) async {
-    final prefs = await SharedPreferences.getInstance();
-    if (value is int) {
-      prefs.setInt(key, value);
-    } else if (value is String) {
-      prefs.setString(key, value);
-    } else if (value is bool) {
-      prefs.setBool(key, value);
-    } else {
-      throw("Invalid Type (Shared Preference Error)");
-    }
-  }
-
-  static Future<dynamic> readData(String key) async {
-    final prefs = await SharedPreferences.getInstance();
-    dynamic obj = prefs.get(key);
-    return obj;
-  }
-
-  static Future<bool> deleteData(String key) async {
-    final prefs = await SharedPreferences.getInstance();
-    return prefs.remove(key);
-  }
-}

lib/theme_manager.dart

@@ -1,45 +0,0 @@
-import 'package:flutter/material.dart';
-import 'package:witl/storage_manager.dart';
-
-class ThemeNotifier with ChangeNotifier {
-  final darkTheme = ThemeData(
-    primaryColor: Colors.black,
-    brightness: Brightness.dark,
-    dividerColor: Colors.black12, colorScheme: ColorScheme.fromSwatch(primarySwatch: Colors.grey).copyWith(background: const Color(0xFF212121)),
-  );
-
-  final lightTheme = ThemeData(
-    primaryColor: Colors.white,
-    brightness: Brightness.light,
-    dividerColor: Colors.white54, colorScheme: ColorScheme.fromSwatch(primarySwatch: Colors.grey).copyWith(background: const Color(0xFFE5E5E5)),
-  );
-
-  late ThemeData _themeData;
-  ThemeData getTheme() => _themeData;
-
-  ThemeNotifier() {
-    StorageManager.readData('themeMode').then((value) {
-      'value read from storage: ' + value.toString();
-      var themeMode = value ?? 'light';
-      if (themeMode == 'light') {
-        _themeData = lightTheme;
-      } else {
-        'setting dark theme';
-        _themeData = darkTheme;
-      }
-      notifyListeners();
-    });
-  }
-
-  void setDarkMode() async {
-    _themeData = darkTheme;
-    StorageManager.saveData('themeMode', 'dark');
-    notifyListeners();
-  }
-
-  void setLightMode() async {
-    _themeData = lightTheme;
-    StorageManager.saveData('themeMode', 'light');
-    notifyListeners();
-  }
-}