Add remaining providers

lib/screens/cart/cart_screen.dart

@@ -1,22 +1,16 @@
 import 'package:flutter/material.dart';
-import 'package:thesis_shop/models/cart_item.dart';
-import 'package:thesis_shop/models/product.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:thesis_shop/screens/cart/total_price_text.dart';
+import 'package:thesis_shop/stores/cart_store.dart';
 import 'package:thesis_shop/widgets/user_switch.dart';
 
 import 'cart_item_list.dart';
 
-const _placeHolderItems = [
-  CartItem(product: Product(title: 'Äpfel', price: 3), amount: 3),
-  CartItem(product: Product(title: 'Äpfel', price: 3), amount: 3),
-  CartItem(product: Product(title: 'Äpfel', price: 3), amount: 3),
-];
-
-class CartScreen extends StatelessWidget {
+class CartScreen extends ConsumerWidget {
   const CartScreen({Key? key}) : super(key: key);
 
   @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, ref) {
     return Scaffold(
       appBar: AppBar(
         title: const Text('Warenkorb'),
@@ -24,9 +18,9 @@ class CartScreen extends StatelessWidget {
       ),
       body: Column(
         mainAxisSize: MainAxisSize.max,
-        children: const [
-          Expanded(child: CartItemList(items: _placeHolderItems)),
-          TotalPriceText(),
+        children: [
+          Expanded(child: CartItemList(items: ref.watch(cartItemListProvider))),
+          const TotalPriceText(),
         ],
       ),
     );

lib/screens/cart/total_price_text.dart

@@ -1,15 +1,18 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:thesis_shop/stores/cart_store.dart';
 
-class TotalPriceText extends StatelessWidget {
+class TotalPriceText extends ConsumerWidget {
   const TotalPriceText({Key? key}) : super(key: key);
 
   @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, ref) {
+    final totalPrice = ref.watch(totalPriceProvider).toStringAsFixed(2);
     return SafeArea(
       child: Padding(
         padding: const EdgeInsets.all(8.0),
         child: Text(
-          'Gesamtpreis: 27€',
+          'Gesamtpreis: $totalPrice€',
           style: Theme.of(context).textTheme.labelLarge?.copyWith(fontSize: 24),
         ),
       ),

lib/screens/product_list/cart_button.dart

@@ -1,17 +1,20 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:thesis_shop/benchmark_counter.dart';
 import 'package:thesis_shop/route_key.dart';
+import 'package:thesis_shop/stores/cart_store.dart';
 
-class CartButton extends StatelessWidget {
+class CartButton extends ConsumerWidget {
   const CartButton() : super(key: const Key('cart_button'));
 
   @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, ref) {
+    final count = ref.watch(totalProductInCartCountProvider);
     BenchmarkCounters.cartButton++;
     return ElevatedButton.icon(
       onPressed: () => Navigator.of(context).pushRouteKey(RouteKey.cart),
       icon: const Icon(Icons.shopping_basket),
-      label: const Text('Warenkorb (3 Produkte)'),
+      label: Text('Warenkorb ($count Produkte)'),
     );
   }
 }

lib/screens/product_list/product_item.dart

@@ -1,16 +1,27 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:thesis_shop/models/product.dart';
+import 'package:thesis_shop/stores/cart_store.dart';
 import 'package:thesis_shop/widgets/number_picker.dart';
 
-class ProductItem extends StatelessWidget {
+class ProductItem extends ConsumerWidget {
   final Product product;
   const ProductItem({Key? key, required this.product}) : super(key: key);
 
   @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, ref) {
+    final count = ref.watch(cartStoreProvider)[product.title] ?? 0;
     return ListTile(
       title: Text('${product.title} (${product.priceAsString}€/Stück)'),
-      trailing: NumberPicker(value: 5, onUp: () {}, onDown: () {}),
+      trailing: NumberPicker(
+        value: count,
+        onUp: () => ref
+            .read(cartStoreProvider.notifier)
+            .increaseAmountOfProduct(product),
+        onDown: () => ref
+            .read(cartStoreProvider.notifier)
+            .decreaseAmountOfProduct(product),
+      ),
     );
   }
 }

lib/stores/cart_store.dart

@@ -0,0 +1,53 @@
+import 'package:riverpod/riverpod.dart';
+import 'package:thesis_shop/models/cart_item.dart';
+import 'package:thesis_shop/models/product.dart';
+import 'package:thesis_shop/stores/product_list_provider.dart';
+
+class CartStore extends StateNotifier<Map<String, int>> {
+  CartStore() : super({});
+
+  void _addAmountOfProduct(Product product, int amount) {
+    final value = state[product.title] ?? 0;
+    if (value + amount < 0) {
+      return;
+    } else if (value + amount == 0) {
+      state.remove(product.title);
+      state = {...state};
+      return;
+    }
+    state = {...state, product.title: value + amount};
+  }
+
+  void increaseAmountOfProduct(Product product) =>
+      _addAmountOfProduct(product, 1);
+  void decreaseAmountOfProduct(Product product) =>
+      _addAmountOfProduct(product, -1);
+}
+
+final totalProductInCartCountProvider = Provider(
+  (ref) => ref.watch(cartItemListProvider).length,
+  dependencies: [cartItemListProvider],
+);
+
+final totalPriceProvider = Provider(
+    (ref) => ref.watch(cartItemListProvider).fold<double>(
+        0.0,
+        (previousValue, element) =>
+            previousValue + element.amount * element.product.price),
+    dependencies: [cartItemListProvider]);
+
+final cartStoreProvider =
+    StateNotifierProvider<CartStore, Map<String, int>>((ref) => CartStore());
+
+final cartItemListProvider = Provider((ref) {
+  final cart = ref.watch(cartStoreProvider);
+  final productsByTitle = ref.watch(productListProvider).whenOrNull(
+      data: (products) =>
+          {for (final product in products) product.title: product});
+  if (productsByTitle == null) return <CartItem>[];
+  return cart.entries
+      .where((entry) => productsByTitle.containsKey(entry.key))
+      .map((entry) =>
+          CartItem(product: productsByTitle[entry.key]!, amount: entry.value))
+      .toList();
+}, dependencies: [cartStoreProvider, productListProvider]);

lib/stores/product_list_provider.dart

@@ -10,4 +10,4 @@ final productListProvider = Provider<AsyncValue<List<Product>>>((ref) {
   }
   return ref.watch(productLoadingProvider).whenData(
       (products) => products.map((pro) => pro.copyWithDiscount()).toList());
-});
+}, dependencies: [productLoadingProvider, userStoreProvider]);