Flutter - Designing Email Authentication System using Firebase

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import '../libmodels/user_model.dart';

class AuthenticationService {
  final FirebaseAuth _firebaseAuth;
  UserModel userModel = UserModel(
    email: '',
    uid: '',
    username: '',
    timestamp: DateTime.now(),
  );
  final userRef = FirebaseFirestore.instance.collection("users");

  AuthenticationService(this._firebaseAuth);

  // managing the user state via stream.
  // stream provides an immediate event of
  // the user's current authentication state,
  // and then provides subsequent events whenever
  // the authentication state changes.
  Stream<User?> get authStateChanges => _firebaseAuth.authStateChanges();

  //1
  Future<String> signIn({
    required String email,
    required String password,
  }) async {
    try {
      await _firebaseAuth.signInWithEmailAndPassword(
        email: email,
        password: password,
      );

      return "Signed In";
    } on FirebaseAuthException catch (e) {
      if (e.code == 'user-not-found') {
        return "No user found for that email.";
      } else if (e.code == 'wrong-password') {
        return "Wrong password provided for that user.";
      } else {
        return "Something Went Wrong.";
      }
    }
  }

  //2
  Future<String> signUp({
    required String email,
    required String password,
  }) async {
    try {
      await _firebaseAuth.createUserWithEmailAndPassword(
        email: email,
        password: password,
      );
      return "Signed Up";
    } on FirebaseAuthException catch (e) {
      if (e.code == 'weak-password') {
        return "The password provided is too weak.";
      } else if (e.code == 'email-already-in-use') {
        return "The account already exists for that email.";
      } else {
        return "Something Went Wrong.";
      }
    } catch (e) {
      print(e);
      return "An unexpected error occurred.";
    }
  }

  Future<void> addUserToDB({
    required String uid,
    required String username,
    required String email,
    required DateTime timestamp,
  }) async {
    try {
      // Creating the userModel object
      final userModel = UserModel(
        uid: uid,
        username: username,
        email: email,
        timestamp: timestamp,
      );

      // Storing user data in Firestore
      await userRef.doc(uid).set(userModel.toMap());
      print("successfully added user to DB");
    } catch (e) {
      // Log the error or show a user-friendly message
      print('Error adding user to DB: $e');
      rethrow;
    }
  }

  //4
  Future<UserModel> getUserFromDB({required String uid}) async {
    final DocumentSnapshot doc = await userRef.doc(uid).get();

    //print(doc.data());

    return UserModel.fromMap(doc.data() as Map<String, dynamic>);
  }

  //5
  Future<void> signOut() async {
    await _firebaseAuth.signOut();
  }
}

class UserModel {
  final String uid;
  final String username;
  final String email;
  final DateTime timestamp;

  UserModel({
    required this.uid,
    required this.username,
    required this.email,
    required this.timestamp,
  });

  // Convert UserModel instance to Map
  Map<String, dynamic> toMap() {
    return {
      'uid': uid,
      'username': username,
      'email': email,
      'timestamp':
          timestamp.toIso8601String(), // Convert DateTime to string if needed
    };
  }

  // Convert Map to UserModel instance
  factory UserModel.fromMap(Map<String, dynamic> map) {
    return UserModel(
      uid: map['uid'],
      username: map['username'],
      email: map['email'],
      timestamp: DateTime.parse(map['timestamp']),
    );
  }
}

import 'package:firebase_auth/firebase_auth.dart'; 
import 'package:firebase_core/firebase_core.dart'; 
import 'package:flutter/material.dart';
import 'package:flutter_geeks/libservices/authentication_service.dart';
import 'package:flutter_geeks/pages/home_page.dart'; 
import 'package:flutter_geeks/pages/login_page.dart';  // Assuming you have a LoginPage.
import 'package:flutter_geeks/pages/register_page.dart';
import 'package:provider/provider.dart'; 

Future<void> main() async { 
  WidgetsFlutterBinding.ensureInitialized(); 
  await Firebase.initializeApp(); 
  runApp(MyApp()); 
} 

class MyApp extends StatelessWidget { 
  @override 
  Widget build(BuildContext context) { 
    return MultiProvider( 
      
      providers: [ 
        Provider<AuthenticationService>( 
          create: (_) => AuthenticationService(FirebaseAuth.instance), 
        ), 
        StreamProvider<User?>(
          create: (context) => 
            context.read<AuthenticationService>().authStateChanges, 
          initialData: null,
        ),
      ], 
      child: MaterialApp( 
        debugShowCheckedModeBanner: false,
        theme: ThemeData( 
          brightness: Brightness.dark, 
          primaryColor: Colors.green[400], 
          hintColor: Colors.deepOrange[200],
        ), 
        home: AuthenticationWrapper(), 
      ), 
    ); 
  } 
} 

class AuthenticationWrapper extends StatelessWidget { 
  @override 
  Widget build(BuildContext context) { 
    final user = context.watch<User?>();  // Watch User?

    if (user != null) {
      // If user is logged in, navigate to HomePage
      return HomePage(); 
    } else {
      // If user is not logged in, navigate to LoginPage
      return RegisterPage();  // Assuming you have a LoginPage widget
    }
  } 
}

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_geeks/pages/login_page.dart';
import 'package:flutter_geeks/pages/register_page.dart';
import 'package:font_awesome_flutter/font_awesome_flutter.dart';

class AuthScreenView extends StatefulWidget {
  @override
  _AuthScreenViewState createState() => _AuthScreenViewState();
}

class _AuthScreenViewState extends State<AuthScreenView> {
  late PageController pageController;
  int pageIndex = 0;

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    pageController = PageController();
  }

  @override
  void dispose() {
    // TODO: implement dispose
    super.dispose();
    pageController.dispose();
  }

  onPageChanged(int pageIndex) {
    setState(() {
      this.pageIndex = pageIndex;
    });
  }

  onTap(int pageIndex) {
    //pageController.jumpToPage(pageIndex);
    pageController.animateToPage(
      pageIndex,
      duration: Duration(milliseconds: 300),
      curve: Curves.easeInOut,
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: PageView(
        children: [
          //when pageIndex == 0
          LoginPage(),

          //when pageIndex == 1
          RegisterPage(),
        ],
        controller: pageController,
        onPageChanged: onPageChanged,
      ),
      bottomNavigationBar: CupertinoTabBar(
        currentIndex: pageIndex,
        onTap: onTap,
        activeColor: Theme.of(context).primaryColor,
        items: [
          BottomNavigationBarItem(
            label: "Log-In",
            icon: Icon(FontAwesomeIcons.signInAlt),
          ),
          BottomNavigationBarItem(
            label: "Register",
            icon: Icon(FontAwesomeIcons.userPlus),
          ),
        ],
      ),
    );
  }
}

import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';

import 'package:flutter_geeks/libservices/authentication_service.dart';
import 'package:flutter_geeks/pages/login_page.dart';
import 'package:provider/provider.dart';

class RegisterPage extends StatefulWidget {
  @override
  _RegisterPageState createState() => _RegisterPageState();
}

class _RegisterPageState extends State<RegisterPage> {
  //To Toggle Password Text Visibility.
  bool _obscureText = true;
  late String _username, _email, _password;

  //For the loading state.
  bool _isSubmitting = false;

  final _formKey = GlobalKey<FormState>();
  final _scaffoldKey = GlobalKey<ScaffoldState>();

  FirebaseAuth auth = FirebaseAuth.instance;
  final DateTime timestamp = DateTime.now();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(title: Text("GeeksForGeeks"), centerTitle: true),
      body: Container(
        padding: EdgeInsets.symmetric(horizontal: 20),
        child: Center(
          child: SingleChildScrollView(
            child: Form(
              key: _formKey,
              child: Column(
                children: [
                  _showTitle(),
                  _showUsernameInput(),
                  _showEmailInput(),
                  _showPasswordInput(),
                  Row(
                    mainAxisAlignment: MainAxisAlignment.end,
                    children: [
                      Text("Already have an account?"),
                      TextButton(
                        child: Text("Login"),
                        style: TextButton.styleFrom(
                          foregroundColor: Colors.orange,
                          textStyle: TextStyle(fontSize: 20),
                        ),
                        onPressed: () {
                          Navigator.pushReplacement(
                            context,
                            MaterialPageRoute(
                              builder: (context) => LoginPage(),
                            ),
                          );
                        },
                      ),
                    ],
                  ),
                  _showFormActions(),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }

  //1
  _showTitle() {
    return Text(
      "Register",
      style: TextStyle(fontSize: 72, fontWeight: FontWeight.bold),
    );
  }

  //2
  _showUsernameInput() {
    return Padding(
      padding: EdgeInsets.only(top: 20),
      child: TextFormField(
        onSaved: (val) => _username = val!,
        validator: (val) => val!.length < 6 ? "Username is too short." : null,
        decoration: InputDecoration(
          border: OutlineInputBorder(),
          labelText: "Username",
          hintText: "Enter Valid Username",
          icon: Icon(Icons.face, color: Colors.grey),
        ),
      ),
    );
  }

  //3
  _showEmailInput() {
    return Padding(
      padding: EdgeInsets.only(top: 20),
      child: TextFormField(
        onSaved: (val) => _email = val!,
        validator: (val) => !val!.contains("@") ? "Invalid Email" : null,
        decoration: InputDecoration(
          border: OutlineInputBorder(),
          labelText: "Email",
          hintText: "Enter Valid Email",
          icon: Icon(Icons.mail, color: Colors.grey),
        ),
      ),
    );
  }

  //4
  _showPasswordInput() {
    return Padding(
      padding: EdgeInsets.only(top: 20),
      child: TextFormField(
        onSaved: (val) => _password = val!,
        validator: (val) => val!.length < 6 ? "Password Is Too Short" : null,
        obscureText: _obscureText,
        decoration: InputDecoration(
          suffixIcon: GestureDetector(
            onTap: () {
              setState(() {
                _obscureText = !_obscureText;
              });
            },
            child: Icon(_obscureText ? Icons.visibility_off : Icons.visibility),
          ),
          border: OutlineInputBorder(),
          labelText: "Password",
          hintText: "Enter Valid Password",
          icon: Icon(Icons.lock, color: Colors.grey),
        ),
      ),
    );
  }

  //5
  _showFormActions() {
    return Padding(
      padding: EdgeInsets.only(top: 20),
      child: Column(
        children: [
          _isSubmitting == true
              ? CircularProgressIndicator(
                valueColor: AlwaysStoppedAnimation(
                  Theme.of(context).primaryColor,
                ),
              )
              : ElevatedButton(
                child: Text(
                  "Submit",
                  style: TextStyle(color: Colors.black, fontSize: 18),
                ),
                style: ElevatedButton.styleFrom(
                  backgroundColor: Colors.orange,
                  foregroundColor: Colors.white,
                  elevation: 8.0,
                  shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.all(Radius.circular(10)),
                  ),
                ),
                onPressed: _submit,
              ),
        ],
      ),
    );
  }

  //6
  _submit() {
    final _form = _formKey.currentState;
    if (_form!.validate()) {
      _form.save();
      //print("Email $_email, Password $_password, Username $_username");
      _registerUser();
    } else {
      print("Form is Invalid");
    }
  }

  //7
  _registerUser() async {
    setState(() {
      _isSubmitting = true;
    });

    final logMessage = await context.read<AuthenticationService>().signUp(
      email: _email,
      password: _password,
    );

    logMessage == "Signed Up"
        ? _showSuccessSnack(logMessage)
        : _showErrorSnack(logMessage);

    print("logMessage:$logMessage");

    if (logMessage == "Signed Up") {
      createUserInFirestore();
    } else {
      setState(() {
        _isSubmitting = false;
      });
    }
  }

  //When User "Signed Up", success snack will display.
  _showSuccessSnack(String message) {
    final snackbar = SnackBar(
      backgroundColor: Colors.black,
      content: Text("$message", style: TextStyle(color: Colors.green)),
    );
    ScaffoldMessenger.of(context).showSnackBar(snackbar);
    _formKey.currentState!.reset();
  }

  //When FirebaseAuth Catches error, error snack will display.
  _showErrorSnack(String message) {
    final snackbar = SnackBar(
      backgroundColor: Colors.black,
      content: Text("$message", style: TextStyle(color: Colors.red)),
    );
    ScaffoldMessenger.of(context).showSnackBar(snackbar);
  }

  createUserInFirestore() async {
    context.read<AuthenticationService>().addUserToDB(
      uid: auth.currentUser!.uid,
      username: _username,
      email: auth.currentUser!.email ?? '',
      timestamp: timestamp,
    );
  }
}

import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:flutter_geeks/libservices/authentication_service.dart';
import 'package:flutter_geeks/pages/home_page.dart';
import 'package:flutter_geeks/pages/register_page.dart';
import 'package:provider/provider.dart';

class LoginPage extends StatefulWidget {
  @override
  _LoginPageState createState() => _LoginPageState();
}

class _LoginPageState extends State<LoginPage> {
  bool _obscureText = true;
  late String _email, _password;
  bool _isSubmitting = false;

  final _formKey = GlobalKey<FormState>();
  final _scaffoldKey = GlobalKey<ScaffoldState>();

  FirebaseAuth auth = FirebaseAuth.instance;
  final DateTime timestamp = DateTime.now();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(centerTitle: true, title: Text("GeeksForGeeks")),
      body: Container(
        padding: EdgeInsets.symmetric(horizontal: 20),
        child: Center(
          child: SingleChildScrollView(
            child: Form(
              key: _formKey,
              child: Column(
                children: [
                  _showTitle(),
                  _showEmailInput(),
                  _showPasswordInput(),
                  Row(
                    mainAxisAlignment: MainAxisAlignment.end,
                    children: [
                      Text("Don't have an account?"),
                      TextButton(
                        child: Text("Register"),
                        style: TextButton.styleFrom(
                          foregroundColor: Colors.orange,
                          textStyle: TextStyle(fontSize: 20),
                        ),
                        onPressed: () {
                          Navigator.pushReplacement(
                            context,
                            MaterialPageRoute(
                              builder: (context) => RegisterPage(),
                            ),
                          );
                        },
                      ),
                    ],
                  ),
                  _showFormActions(),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }

  _showTitle() {
    return Text(
      "Login",
      style: TextStyle(fontSize: 72, fontWeight: FontWeight.bold),
    );
  }

  _showEmailInput() {
    return Padding(
      padding: EdgeInsets.only(top: 20),
      child: TextFormField(
        onSaved: (val) => _email = val!,
        validator: (val) => !val!.contains("@") ? "Invalid Email" : null,
        decoration: InputDecoration(
          border: OutlineInputBorder(),
          labelText: "Email",
          hintText: "Enter Valid Email",
          icon: Icon(Icons.mail, color: Colors.grey),
        ),
      ),
    );
  }

  _showPasswordInput() {
    return Padding(
      padding: EdgeInsets.only(top: 20),
      child: TextFormField(
        onSaved: (val) => _password = val!,
        validator: (val) => val!.length < 6 ? "Password Is Too Short" : null,
        obscureText: _obscureText,
        decoration: InputDecoration(
          suffixIcon: GestureDetector(
            onTap: () {
              setState(() {
                _obscureText = !_obscureText;
              });
            },
            child: Icon(_obscureText ? Icons.visibility_off : Icons.visibility),
          ),
          border: OutlineInputBorder(),
          labelText: "Password",
          hintText: "Enter Valid Password",
          icon: Icon(Icons.lock, color: Colors.grey),
        ),
      ),
    );
  }

  _showFormActions() {
    return Padding(
      padding: EdgeInsets.only(top: 20),
      child: Column(
        children: [
          _isSubmitting == true
              ? CircularProgressIndicator(
                valueColor: AlwaysStoppedAnimation(
                  Theme.of(context).primaryColor,
                ),
              )
              : ElevatedButton(
                child: Text(
                  "Submit",
                  style: TextStyle(color: Colors.black, fontSize: 18),
                ),
                style: ElevatedButton.styleFrom(
                  backgroundColor: Colors.orange,
                  foregroundColor: Colors.black,
                  elevation: 8.0,
                  shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.all(Radius.circular(10)),
                  ),
                ),
                onPressed: _submit,
              ),
        ],
      ),
    );
  }

  _submit() {
    final _form = _formKey.currentState;
    if (_form!.validate()) {
      _form.save();
      //print("Email $_email, Password $_password");
      _LoginUser();
    } else {
      print("Form is Invalid");
    }
  }

  _LoginUser() async {
    setState(() {
      _isSubmitting = true;
    });

    final logMessage = await context.read<AuthenticationService>().signIn(
      email: _email,
      password: _password,
    );

    logMessage == "Signed In"
        ? _showSuccessSnack(logMessage)
        : _showErrorSnack(logMessage);

    //print("I am logMessage $logMessage");

    if (logMessage == "Signed In") {
      // Navigate to HomePage after successful login
      Navigator.pushReplacement(
        context,
        MaterialPageRoute(
          builder:
              (context) => HomePage(), // Assuming you have a HomePage widget
        ),
      );
    } else {
      setState(() {
        _isSubmitting = false;
      });
    }
  }

  _showSuccessSnack(String message) async {
    final snackbar = SnackBar(
      backgroundColor: Colors.black,
      content: Text("$message", style: TextStyle(color: Colors.green)),
    );
    ScaffoldMessenger.of(context).showSnackBar(snackbar);
    _formKey.currentState!.reset();
  }

  _showErrorSnack(String message) {
    final snackbar = SnackBar(
      backgroundColor: Colors.black,
      content: Text("$message", style: TextStyle(color: Colors.red)),
    );
    ScaffoldMessenger.of(context).showSnackBar(snackbar);
    setState(() {
      _isSubmitting = false;
    });
  }
}

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:flutter_geeks/libmodels/user_model.dart';
import 'package:flutter_geeks/libservices/authentication_service.dart';
import 'package:provider/provider.dart';

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  FirebaseAuth auth = FirebaseAuth.instance;
  final userRef = FirebaseFirestore.instance.collection("users");
  late UserModel _currentUser;

  String _uid = "";
  String _username = "";
  String _email = "";

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    getCurrentUser();
  }

  getCurrentUser() async {
    UserModel currentUser = await context
        .read<AuthenticationService>()
        .getUserFromDB(uid: auth.currentUser!.uid);

    _currentUser = currentUser;

    print("${_currentUser.username}");

    setState(() {
      _uid = _currentUser.uid ?? "";
      _username = _currentUser.username ?? "";
      _email = _currentUser.email ?? "";
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("HomePage"), centerTitle: true),
      body:
          _uid.isEmpty || _username.isEmpty || _email.isEmpty
              ? Center(child: CircularProgressIndicator())
              : Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Text(
                    "uid is ${_uid} , email is ${_email}, name is ${_username}",
                    textAlign: TextAlign.center,
                  ),
                  Center(
                    child: ElevatedButton(
                      child: Text(
                        "Logout",
                        style: TextStyle(color: Colors.black, fontSize: 18),
                      ),
                      style: ElevatedButton.styleFrom(
                        backgroundColor: Colors.orange,
                        foregroundColor: Colors.white,
                        elevation: 8.0,
                        shape: RoundedRectangleBorder(
                          borderRadius: BorderRadius.all(Radius.circular(10)),
                        ),
                      ),
                      onPressed: () {
                        context.read<AuthenticationService>().signOut();
                      },
                    ),
                  ),
                ],
              ),
    );
  }
}