Add user store

lib/app.dart

@@ -3,6 +3,7 @@ import 'package:thesis_shop/route_key.dart';
 import 'package:thesis_shop/screens/cart/cart_screen.dart';
 import 'package:thesis_shop/screens/product_list/product_list_screen.dart';
 import 'package:thesis_shop/service/product_service.dart';
+import 'package:thesis_shop/stores/user_store.dart';
 import 'package:thesis_shop/utils/map_keys_extension.dart';
 
 class ThesisShopApp extends StatelessWidget {
@@ -10,20 +11,27 @@ class ThesisShopApp extends StatelessWidget {
   const ThesisShopApp({Key? key, required this.productService})
       : super(key: key);
 
+  Widget injectStores(BuildContext context, {required Widget child}) {
+    return UserStoreImplementation(child: child);
+  }
+
   @override
   Widget build(BuildContext context) {
-    return MaterialApp(
-      title: 'Thesis Shop',
-      theme: ThemeData(primarySwatch: Colors.red),
-      darkTheme: ThemeData(
-        primarySwatch: Colors.red,
-        brightness: Brightness.dark,
+    return injectStores(
+      context,
+      child: MaterialApp(
+        title: 'Thesis Shop',
+        theme: ThemeData(primarySwatch: Colors.red),
+        darkTheme: ThemeData(
+          primarySwatch: Colors.red,
+          brightness: Brightness.dark,
+        ),
+        routes: {
+          RouteKey.products: (context) => const ProductListScreen(),
+          RouteKey.cart: (context) => const CartScreen(),
+        }.mapKeys((key) => key.name),
+        initialRoute: 'products',
       ),
-      routes: {
-        RouteKey.products: (context) => const ProductListScreen(),
-        RouteKey.cart: (context) => const CartScreen(),
-      }.mapKeys((key) => key.name),
-      initialRoute: 'products',
     );
   }
 }

lib/screens/cart/cart_screen.dart

@@ -12,7 +12,7 @@ class CartScreen extends StatelessWidget {
     return Scaffold(
       appBar: AppBar(
         title: const Text('Warenkorb'),
-        actions: [UserSwitch(isOn: true, onChanged: (_) {})],
+        actions: const [UserSwitch()],
       ),
       body: Column(
         mainAxisSize: MainAxisSize.max,

lib/screens/product_list/product_list_screen.dart

@@ -21,7 +21,7 @@ class ProductListScreen extends StatelessWidget {
     return Scaffold(
       appBar: AppBar(
         title: const Text('Thesis Shop'),
-        actions: [UserSwitch(isOn: true, onChanged: (_) {})],
+        actions: const [UserSwitch()],
       ),
       body: const CartButtonOverlay(
         child: ProductList(products: products),

lib/stores/user_store.dart

@@ -0,0 +1,56 @@
+import 'package:flutter/material.dart';
+
+typedef BoolSetter = Function(bool isSignedIn);
+
+class UserStoreImplementation extends StatefulWidget {
+  final Widget child;
+  const UserStoreImplementation({Key? key, required this.child})
+      : super(key: key);
+
+  @override
+  _UserStoreImplementationState createState() =>
+      _UserStoreImplementationState();
+}
+
+class _UserStoreImplementationState extends State<UserStoreImplementation> {
+  bool _isSignedIn = false;
+
+  void _updateSignedIn(bool newValue) => setState(
+        () {
+          _isSignedIn = newValue;
+        },
+      );
+
+  @override
+  Widget build(BuildContext context) {
+    return UserStore(
+      isSignedIn: _isSignedIn,
+      setIsSignedIn: _updateSignedIn,
+      child: widget.child,
+    );
+  }
+}
+
+class UserStore extends InheritedWidget {
+  const UserStore({
+    Key? key,
+    required this.isSignedIn,
+    required this.setIsSignedIn,
+    required Widget child,
+  }) : super(key: key, child: child);
+
+  final bool isSignedIn;
+  final BoolSetter setIsSignedIn;
+
+  static UserStore of(BuildContext context) {
+    final UserStore? result =
+        context.dependOnInheritedWidgetOfExactType<UserStore>();
+    assert(result != null, 'No UserStore found in context');
+    return result!;
+  }
+
+  @override
+  bool updateShouldNotify(UserStore oldWidget) {
+    return oldWidget.isSignedIn != isSignedIn;
+  }
+}

lib/widgets/user_switch.dart

@@ -1,24 +1,21 @@
 import 'package:flutter/material.dart';
 import 'package:thesis_shop/benchmark_counter.dart';
+import 'package:thesis_shop/stores/user_store.dart';
 
 class UserSwitch extends StatelessWidget {
-  final bool isOn;
-  final ValueChanged<bool> onChanged;
-  const UserSwitch({
-    required this.isOn,
-    required this.onChanged,
-  }) : super(key: const Key('user_switch'));
+  const UserSwitch() : super(key: const Key('user_switch'));
 
   @override
   Widget build(BuildContext context) {
+    final userStore = UserStore.of(context);
     BenchmarkCounters.userSwitch++;
     return Row(
       mainAxisSize: MainAxisSize.min,
       children: [
         const Icon(Icons.account_circle),
         Switch(
-          value: isOn,
-          onChanged: onChanged,
+          value: userStore.isSignedIn,
+          onChanged: userStore.setIsSignedIn,
           activeColor: Colors.green,
         )
       ],