Adding authentication for users

lib/main.dart

@@ -1,12 +1,14 @@
 import 'package:flutter/material.dart';
+import 'package:myshop_app/providers/auth.dart';
 import 'package:myshop_app/providers/orders.dart';
+import 'package:myshop_app/screens/auth_screen.dart';
+import 'package:myshop_app/screens/products_overview_screen.dart';
 import 'package:provider/provider.dart';
 
 import './models/custom_colors.dart';
 import './models/router.dart';
 import './providers/cart.dart';
 import './providers/products_provider.dart';
-import './screens/products_overview_screen.dart';
 
 void main() => runApp(MyApp());
 
@@ -15,23 +17,46 @@ class MyApp extends StatelessWidget {
   Widget build(BuildContext context) {
     return MultiProvider(
       providers: [
-        ChangeNotifierProvider(create: (ctx) => ProductsProvider()),
+        ChangeNotifierProvider(create: (ctx) => Auth()),
+        ChangeNotifierProxyProvider<Auth, ProductsProvider>(
+          update: (ctx, auth, previousProducts) {
+            return ProductsProvider(auth.token, auth.userId, previousProducts == null ? [] : previousProducts.items);
+          },
+          // ProductsProvider(auth.token ),
+          create: (_) => ProductsProvider(
+            null,
+            null,
+            [],
+          ),
+        ),
         ChangeNotifierProvider(create: (ctx) => Cart()),
-        ChangeNotifierProvider(create: (ctx) => Orders()),
+        ChangeNotifierProxyProvider<Auth, Orders>(
+            create: (_) => Orders(
+                  null,
+                  null,
+                  [],
+                ),
+            update: (ctx, auth, previousOrder) =>
+                Orders(auth.token, auth.userId, previousOrder == null ? [] : previousOrder.orders)),
+        // ChangeNotifierProvider(create: (ctx) => Orders()),
       ],
-      child: MaterialApp(
-        title: 'MyShop',
-        theme: ThemeData(
-          primarySwatch: primaryTheme,
-          accentColor: accentTheme,
-          canvasColor: canvasTheme,
-          fontFamily: 'Lato',
-        ),
+      child: Consumer<Auth>(
+        builder: (context, auth, _) => MaterialApp(
+          title: 'MyShop',
+          theme: ThemeData(
+            primarySwatch: primaryTheme,
+            accentColor: accentTheme,
+            canvasColor: canvasTheme,
+            fontFamily: 'Lato',
+          ),
 
-        ///First screen to show
-        initialRoute: ProductsOverviewScreen.routeName,
-        onGenerateRoute: Routers.generateRoute,
+          ///First screen to show
+          initialRoute: firstScreen(auth),
+          onGenerateRoute: Routers.generateRoute,
+        ),
       ),
     );
   }
+
+  String firstScreen(Auth auth) => auth.isAuth ? ProductsOverviewScreen.routeName : AuthScreen.routeName;
 }

lib/models/constants.dart

@@ -1,3 +1,7 @@
 class Constants {
+
   static const url = 'https://shop-app-4ed38-default-rtdb.firebaseio.com';
+  // String authUrl =
+  //     'https://identitytoolkit.googleapis.com/v1/accounts:$urlSegment?key=AIzaSyDDS9QGht-1JD8bUjcqP-0BQ0cgibbacAQ';
+  // static const signInUrl = 'https://identitytoolkit.googleapis.com/v1/accounts:signInWithPassword?key=AIzaSyDDS9QGht-1JD8bUjcqP-0BQ0cgibbacAQ';
 }

lib/models/router.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:myshop_app/screens/auth_screen.dart';
 
 import '../screens/cart_screen.dart';
 import '../screens/edit_product_screen.dart';
@@ -16,10 +17,12 @@ Arguments are used to pass the information to that route
 class Routers {
   static Route<dynamic> generateRoute(RouteSettings setting) {
     switch (setting.name) {
+      case AuthScreen.routeName:
+        return MaterialPageRoute<dynamic>(builder: (BuildContext context) => AuthScreen());
       case ProductsOverviewScreen.routeName:
         return MaterialPageRoute<dynamic>(builder: (BuildContext context) => ProductsOverviewScreen());
       case ProductDetailScreen.routeName:
-        final argument = setting.arguments as String;
+        final argument = setting.arguments as String?;
         return MaterialPageRoute<dynamic>(
             builder: (BuildContext context) => ProductDetailScreen(productDetailArgs: argument));
       case CartScreen.routeName:
@@ -29,7 +32,7 @@ class Routers {
       case UserProductsScreen.routeName:
         return MaterialPageRoute<dynamic>(builder: (BuildContext context) => UserProductsScreen());
       case EditProductScreen.routeName:
-        final args = setting.arguments as EditProductArguments;
+        final args = setting.arguments as EditProductArguments?;
         return MaterialPageRoute<dynamic>(
             builder: (BuildContext context) => EditProductScreen(editProductarguments: args));
       default:

lib/providers/auth.dart

@@ -0,0 +1,82 @@
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:flutter/widgets.dart';
+import 'package:http/http.dart' as http;
+import 'package:myshop_app/models/http_exception.dart';
+
+class Auth with ChangeNotifier {
+  String? _token;
+  DateTime? _expiryDate;
+  String? _userId;
+  Timer? _authTimer;
+
+  bool get isAuth {
+    return token != null;
+  }
+
+  String? get token {
+    if (_expiryDate != null && _expiryDate!.isAfter(DateTime.now()) && _token != null) {
+      return _token;
+    }
+    return null;
+  }
+
+  String? get userId {
+    return _userId;
+  }
+
+  Future<void> _authenticate(String? email, String? password, String urlSegment) async {
+    final url = Uri.parse(
+        'https://identitytoolkit.googleapis.com/v1/accounts:$urlSegment?key=AIzaSyDDS9QGht-1JD8bUjcqP-0BQ0cgibbacAQ');
+
+    try {
+      final response = await http.post(
+        url,
+        body: json.encode(
+          {
+            'email': email,
+            'password': password,
+            'returnSecureToken': true,
+          },
+        ),
+      );
+      final dynamic responseData = json.decode(response.body);
+      if (responseData['error'] != null) {
+        throw HttpException((responseData['error']['message']).toString());
+      }
+      _token = responseData['idToken'].toString();
+      _userId = responseData['localId'].toString();
+      _expiryDate = DateTime.now().add(
+        Duration(
+          seconds: int.parse(
+            responseData['expiresIn'].toString(),
+          ),
+        ),
+      );
+
+      notifyListeners();
+    } catch (error) {
+      rethrow;
+    }
+  }
+
+  Future<void> signUp(String? email, String? password) async {
+    return _authenticate(email, password, 'signUp');
+  }
+
+  Future<void> login(String? email, String? password) async {
+    return _authenticate(email, password, 'signInWithPassword');
+  }
+
+  void logout() {
+    _token = null;
+    _userId = null;
+    _expiryDate = null;
+    if (_authTimer != null) {
+      _authTimer?.cancel();
+      _authTimer = null;
+    }
+    notifyListeners();
+  }
+}

lib/providers/cart.dart

@@ -3,23 +3,23 @@ import 'package:flutter/foundation.dart';
 class CartItem {
   final String id;
   final String title;
-  final int quantity;
-  final double price;
+  final int? quantity;
+  final double? price;
 
   CartItem({
-    @required this.id,
-    @required this.title,
-    @required this.quantity,
-    @required this.price,
+    required this.id,
+    required this.title,
+    required this.quantity,
+    required this.price,
   });
 }
 
 class Cart with ChangeNotifier {
   ///Map for cart items
-  Map<String, CartItem> _items = {};
+  Map<String?, CartItem> _items = {};
 
   ///getter of _items
-  Map<String, CartItem> get items => {..._items};
+  Map<String?, CartItem> get items => {..._items};
 
   ///Counts the number of _items in the cart
   int get itemCount => _items.length;
@@ -28,15 +28,15 @@ class Cart with ChangeNotifier {
   double get totalAmount {
     var total = 0.0;
     _items.forEach((key, cartItem) {
-      total += cartItem.price * cartItem.quantity;
+      total += cartItem.price! * cartItem.quantity!;
     });
     return total;
   }
 
   ///Function for adding items in the cart
   void addItem(
-    String productId,
-    double price,
+    String? productId,
+    double? price,
     String title,
   ) {
     if (_items.containsKey(productId)) {
@@ -48,7 +48,7 @@ class Cart with ChangeNotifier {
                 id: existingCartItem.id,
                 title: existingCartItem.title,
                 price: existingCartItem.price,
-                quantity: existingCartItem.quantity + 1,
+                quantity: existingCartItem.quantity! + 1,
               ));
     } else {
       ///if there is no existing productId, a new item will be added
@@ -68,25 +68,25 @@ class Cart with ChangeNotifier {
   }
 
   ///Removes an item in the cart
-  void removeItem(String productId) {
+  void removeItem(String? productId) {
     _items.remove(productId);
     notifyListeners();
   }
 
   ///This function is used by the snackbar when the UNDO button is pressed
-  void removeSingleItem(String productId) {
+  void removeSingleItem(String? productId) {
     if (!_items.containsKey(productId)) {
       ///If the productId is not present in the cart items, it will return nothing
       return;
     }
-    if (_items[productId].quantity > 1) {
+    if (_items[productId]!.quantity! > 1) {
       ///If the productId is present in the cart items, when the UNDO button is pressed, it will deduct the recently added item
       _items.update(productId, (existingCartItem) {
         return CartItem(
           id: existingCartItem.id,
           title: existingCartItem.title,
           price: existingCartItem.price,
-          quantity: existingCartItem.quantity - 1,
+          quantity: existingCartItem.quantity! - 1,
         );
       });
     } else {

lib/providers/orders.dart

@@ -8,49 +8,53 @@ import './cart.dart';
 
 class OrderItem {
   final String id;
-  final double amount;
+  final double? amount;
   final List<CartItem> products;
   final DateTime dateTime;
 
   OrderItem({
-    @required this.id,
-    @required this.amount,
-    @required this.products,
-    @required this.dateTime,
+    required this.id,
+    required this.amount,
+    required this.products,
+    required this.dateTime,
   });
 }
 
 ///List of _orders
 class Orders with ChangeNotifier {
   List<OrderItem> _orders = [];
+  final String? authToken;
+  final String? userId;
+
+  Orders(this.authToken, this.userId, this._orders);
 
   ///getter of _orders
   List<OrderItem> get orders {
     return [..._orders];
   }
 
   Future<void> fetchAndSetOrders() async {
-    const url = '${Constants.url}/orders.json';
+    final url = Uri.parse('${Constants.url}/orders/$userId.json?auth=$authToken');
 
     final List<OrderItem> loadedOrders = [];
     final response = await http.get(url);
-    final extractedData = json.decode(response.body) as Map<String, dynamic>;
+    final extractedData = json.decode(response.body) as Map<String, dynamic>?;
     if (extractedData == null) {
       return;
     }
     extractedData.forEach((String orderId, dynamic orderData) {
       loadedOrders.add(
         OrderItem(
           id: orderId,
-          amount: orderData['amount'] as double,
+          amount: orderData['amount'] as double?,
           dateTime: DateTime.parse(orderData['dateTime'].toString()),
           products: (orderData['products'] as List<dynamic>)
               .map(
                 (dynamic item) => CartItem(
                   id: item['id'].toString(),
                   title: item['title'].toString(),
-                  quantity: item['quantity'] as int,
-                  price: item['price'] as double,
+                  quantity: item['quantity'] as int?,
+                  price: item['price'] as double?,
                 ),
               )
               .toList(),
@@ -63,7 +67,7 @@ class Orders with ChangeNotifier {
 
   ///Function for adding an order
   Future<void> addOrder(List<CartItem> cartProducts, double total) async {
-    const url = '${Constants.url}/orders.json';
+    final url = Uri.parse('${Constants.url}/orders/$userId.json?auth=$authToken');
     final timestamp = DateTime.now();
     try {
       final response = await http.post(url,