feat: Refactor project structure and integrate Clean Architecture

1. lib/app/:
   - Reviewed and optimized global configurations and routes.
   - Updated `app.dart` with improved root widget setup.

2. config/:
   - Added and refined application theme and settings.
   - Simplified configurations for better scalability.

3. navigation/:
   - Integrated `go_router` for route management.
   - Created `app_router.dart` and `routes.dart` for centralized navigation.

4. lib/core/:
   - Restructured common providers, helper classes, and constants.
   - Enhanced modularity and readability.

5. lib/features/:
   - Improved feature-based module structure by separating into:
     - **presentation/**: Widgets, Pages, and UI components.
     - **application/**: State Notifiers, Providers, and business logic.
     - **domain/**: Entities, Use Cases, and core business rules.
     - **infrastructure/**: Repository implementations, data sources, and external integrations.
   - Added new Entity and Use Case definitions in the domain layer.
   - Enhanced state management with StateNotifier in the application layer.

6. lib/main.dart:
   - Refactored entry point for better alignment with Clean Architecture.
   - Optimized Firebase initialization as a separate function.

Additionally:
- Fully integrated Clean Architecture principles.
- Removed unnecessary files and legacy code.
- Improved Riverpod integration and configured ProviderScope.

These changes aim to enhance project maintainability and simplify the addition of new features.

lib/app/app.dart

@@ -0,0 +1,16 @@
+import 'package:flutter/material.dart';
+import 'config/app_config.dart';
+import 'navigation/app_router.dart';
+
+class StructureApp extends StatelessWidget {
+  const StructureApp({Key? key}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp.router(
+      title: AppConfig.appName,
+      theme: AppConfig.themeData,
+      routerConfig: appRouter,
+    );
+  }
+}

lib/app/config/app_config.dart

@@ -0,0 +1,10 @@
+import 'package:flutter/material.dart';
+
+class AppConfig {
+  static const String appName = 'Structure App';
+
+  static ThemeData themeData = ThemeData(
+    colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
+    useMaterial3: true,
+  );
+}

lib/app/navigation/app_router.dart

@@ -0,0 +1,8 @@
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+import 'routes.dart';
+final GoRouter appRouter = GoRouter(
+  initialLocation: '/',
+  routes: appRoutes,
+);

lib/app/navigation/routes.dart

@@ -0,0 +1,13 @@
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+import '../../features/counter/presentation/pages/counter_page.dart';
+
+List<GoRoute> appRoutes = [
+  GoRoute(
+    path: '/',
+    name: 'counter',
+    builder: (BuildContext context, GoRouterState state) => const CounterPage(),
+  ),
+  // The other routes will come here.
+];

lib/core/providers/firebase_provider.dart

@@ -0,0 +1,5 @@
+import 'package:firebase_core/firebase_core.dart';
+
+Future<void> initializeFirebase() async {
+  await Firebase.initializeApp();
+}

lib/features/counter/application/counter_notifier.dart

@@ -0,0 +1,18 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../domain/entities/counter.dart';
+
+class CounterNotifier extends StateNotifier<Counter> {
+  CounterNotifier() : super(Counter(value: 0, incrementValue: 0));
+
+  void increment() {
+    state = state.copyWith(
+      value: state.value + 1,
+      incrementValue: 1,
+    );
+    print(state.value);
+  }
+}
+
+final counterProvider = StateNotifierProvider<CounterNotifier, Counter>(
+      (ref) => CounterNotifier(),
+);

lib/features/counter/domain/entities/counter.dart

@@ -0,0 +1,13 @@
+class Counter {
+  final int value;
+  final int incrementValue;
+
+  Counter({required this.value, required this.incrementValue});
+
+  Counter copyWith({int? value, int? incrementValue}) {
+    return Counter(
+      value: value ?? this.value,
+      incrementValue: incrementValue ?? this.incrementValue,
+    );
+  }
+}

lib/features/counter/presentation/pages/counter_page.dart

@@ -0,0 +1,30 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../../application/counter_notifier.dart';
+
+class CounterPage extends ConsumerWidget {
+  const CounterPage({Key? key}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final counter = ref.watch(counterProvider);
+
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text('Structure App counter'),
+      ),
+      body: Center(
+        child: Text(
+          'Counter: ${counter.value}',
+          style: Theme.of(context).textTheme.headlineMedium,
+        ),
+      ),
+      floatingActionButton: FloatingActionButton(
+        onPressed: () => ref.read(counterProvider.notifier).increment(),
+        tooltip: 'Increment',
+        child: const Icon(Icons.add),
+      ),
+    );
+  }
+}

lib/main.dart

@@ -1,6 +1,9 @@
 import 'package:flutter/material.dart';
 import 'package:firebase_core/firebase_core.dart';
 import 'package:firebase_messaging/firebase_messaging.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import 'app/app.dart';
 
 void main () async {
   WidgetsFlutterBinding.ensureInitialized();
@@ -14,125 +17,9 @@ void main () async {
     badge: true,
     sound: true,
   );
-  runApp(const MyApp());
-}
-
-class MyApp extends StatelessWidget {
-  const MyApp({super.key});
-
-  // This widget is the root of your application.
-  @override
-  Widget build(BuildContext context) {
-    return MaterialApp(
-      title: 'Flutter Demo',
-      theme: ThemeData(
-        // This is the theme of your application.
-        //
-        // TRY THIS: Try running your application with "flutter run". You'll see
-        // the application has a purple toolbar. Then, without quitting the app,
-        // try changing the seedColor in the colorScheme below to Colors.green
-        // and then invoke "hot reload" (save your changes or press the "hot
-        // reload" button in a Flutter-supported IDE, or press "r" if you used
-        // the command line to start the app).
-        //
-        // Notice that the counter didn't reset back to zero; the application
-        // state is not lost during the reload. To reset the state, use hot
-        // restart instead.
-        //
-        // This works for code too, not just values: Most code changes can be
-        // tested with just a hot reload.
-        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
-        useMaterial3: true,
-      ),
-      home: const MyHomePage(title: 'Flutter Demo Home Page'),
-    );
-  }
-}
-
-class MyHomePage extends StatefulWidget {
-  const MyHomePage({super.key, required this.title});
-
-  // This widget is the home page of your application. It is stateful, meaning
-  // that it has a State object (defined below) that contains fields that affect
-  // how it looks.
-
-  // This class is the configuration for the state. It holds the values (in this
-  // case the title) provided by the parent (in this case the App widget) and
-  // used by the build method of the State. Fields in a Widget subclass are
-  // always marked "final".
-
-  final String title;
-
-  @override
-  State<MyHomePage> createState() => _MyHomePageState();
-}
-
-class _MyHomePageState extends State<MyHomePage> {
-  int _counter = 0;
-
-  void _incrementCounter() {
-    setState(() {
-      // This call to setState tells the Flutter framework that something has
-      // changed in this State, which causes it to rerun the build method below
-      // so that the display can reflect the updated values. If we changed
-      // _counter without calling setState(), then the build method would not be
-      // called again, and so nothing would appear to happen.
-      _counter++;
-    });
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    // This method is rerun every time setState is called, for instance as done
-    // by the _incrementCounter method above.
-    //
-    // The Flutter framework has been optimized to make rerunning build methods
-    // fast, so that you can just rebuild anything that needs updating rather
-    // than having to individually change instances of widgets.
-    return Scaffold(
-      appBar: AppBar(
-        // TRY THIS: Try changing the color here to a specific color (to
-        // Colors.amber, perhaps?) and trigger a hot reload to see the AppBar
-        // change color while the other colors stay the same.
-        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
-        // Here we take the value from the MyHomePage object that was created by
-        // the App.build method, and use it to set our appbar title.
-        title: Text(widget.title),
-      ),
-      body: Center(
-        // Center is a layout widget. It takes a single child and positions it
-        // in the middle of the parent.
-        child: Column(
-          // Column is also a layout widget. It takes a list of children and
-          // arranges them vertically. By default, it sizes itself to fit its
-          // children horizontally, and tries to be as tall as its parent.
-          //
-          // Column has various properties to control how it sizes itself and
-          // how it positions its children. Here we use mainAxisAlignment to
-          // center the children vertically; the main axis here is the vertical
-          // axis because Columns are vertical (the cross axis would be
-          // horizontal).
-          //
-          // TRY THIS: Invoke "debug painting" (choose the "Toggle Debug Paint"
-          // action in the IDE, or press "p" in the console), to see the
-          // wireframe for each widget.
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[
-            const Text(
-              'You have pushed the button this many times:',
-            ),
-            Text(
-              '$_counter',
-              style: Theme.of(context).textTheme.headlineMedium,
-            ),
-          ],
-        ),
-      ),
-      floatingActionButton: FloatingActionButton(
-        onPressed: _incrementCounter,
-        tooltip: 'Increment',
-        child: const Icon(Icons.add),
-      ), // This trailing comma makes auto-formatting nicer for build methods.
-    );
-  }
+  runApp(
+      const ProviderScope(
+        child: StructureApp(),
+  ),
+  );
 }

pubspec.yaml

@@ -31,9 +31,13 @@ dependencies:
   flutter:
     sdk: flutter
   async: '>=2.11.0 <3.0.0'
+
   firebase_core: '>=2.32.0 <4.0.0'
   firebase_messaging: ^14.3.0
 
+  go_router: ^14.3.0
+  flutter_riverpod: ^2.6.1
+
 
   # The following adds the Cupertino Icons font to your application.
   # Use with the CupertinoIcons class for iOS style icons.

test/widget_test.dart

@@ -6,14 +6,15 @@
 // tree, read text, and verify that the values of widget properties are correct.
 
 import 'package:flutter/material.dart';
+import 'package:flutter_high_level_project_structure/app/app.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 import 'package:flutter_high_level_project_structure/main.dart';
 
 void main() {
   testWidgets('Counter increments smoke test', (WidgetTester tester) async {
     // Build our app and trigger a frame.
-    await tester.pumpWidget(const MyApp());
+    await tester.pumpWidget(const StructureApp());
 
     // Verify that our counter starts at 0.
     expect(find.text('0'), findsOneWidget);