I’m facing an issue with my Flutter app that uses Firebase Authentication. The problem occurs when a user’s account is deleted from Firebase and then they re-register using the same phone number. After re-registering, the app is incorrectly routing them back to the registration page instead of the home page.

Details
Platform: Flutter
State Management: Riverpod
Authentication: Firebase Authentication (Phone Authentication)

Problem Description
Initial Setup: The app works perfectly for new users. They can register and are routed to the correct page based on their authentication state.
Issue Encountered: When a user’s account is deleted from Firebase and they re-register, the app routes them back to the registration page instead of the home page.
Observation: The issue seems to be specific to re-registered users, as the app works fine for new users and other users whose haven’t got their account deleted from firebase and re-registered their accounts.

Debugging Steps Taken
Cleared Local Data: Cleared app data and cache, and reinstalled the app.
Checked Auth State Changes: Added logs to trace authentication state changes.
Verified User Data: Checked that all necessary user data is correctly initialized and saved in Firebase.
Routing Logic: Verified that the routing logic correctly redirects the user based on their authentication state.

Auth Repository

abstract class AuthRepository {
  AppUser? get currentUser;
  Stream<AppUser?> authStateChanges();
  Future<void> signInWithPhone({
    required String phoneNumber,
    required Function(PhoneAuthCredential) onVerificationComplete,
  });
  Future<void> verifyOtp({ required String otp });
  Future<String?> getToken();
  Future<void> signOut();
}

firebase_auth_repository.dart

class FireBaseAuthRepository implements AuthRepository {
  final FirebaseAuth _firebaseAuth;
  FireBaseAuthRepository(this._firebaseAuth);
  String _verificationId = '';

  Future<void> initialize() async {
    await _firebaseAuth.setPersistence(Persistence.LOCAL);
  }

  Future<void> clearLocalData() async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.clear();
    print('Local data cleared');
  }

  AppUser? _userFromFirebase(User? user) {
    if (user == null) {
      return null;
    }
    return AppUser(
      uid: user.uid,
      phone: user.phoneNumber!,
    );
  }

  @override
  AppUser? get currentUser {
    final user = _firebaseAuth.currentUser;
    print('Current user: ${user?.uid}');
    return _userFromFirebase(user);
  }

  @override
  Stream<AppUser?> authStateChanges() {
    return _firebaseAuth.authStateChanges().map((user) {
      print('Auth state changed: ${user?.uid}');
      return _userFromFirebase(user);
    });
  }

  @override
  Future<String?> getToken() async {
    try {
      final token = await _firebaseAuth.currentUser?.getIdToken();
      print('Token retrieved: $token');
      return token;
    } catch (e) {
      print('Error getting token: $e');
      throw Exception(e);
    }
  }

  @override
  Future<void> signInWithPhone({
    required String phoneNumber,
    required Function(PhoneAuthCredential) onVerificationComplete,
  }) async {
    String phoneNumberWithCountryCode = '+91$phoneNumber';
    await _firebaseAuth.verifyPhoneNumber(
      phoneNumber: phoneNumberWithCountryCode,
      verificationCompleted: (PhoneAuthCredential credential) async {
        print('Verification completed');
        final user = await AsyncValue.guard(() => _firebaseAuth.signInWithCredential(credential));
        user.when(data: (data) async {
          if (data.user?.uid != "" || data.user != null) {
            print('User signed in: ${data.user?.uid}');
            await onVerificationComplete(credential);
          }
        }, error: (error, stackTrace) {
          print('Verification error: $error');
        }, loading: () {
          print('Verification loading');
        });
      },
      verificationFailed: (FirebaseAuthException e) {
        print('Verification failed: ${e.message}');
        throw Exception(e.message);
      },
      codeSent: (String verificationId, int? resendToken) async {
        print('Code sent: $verificationId');
        _verificationId = verificationId;
      },
      codeAutoRetrievalTimeout: (verificationId) {
        print('Code auto retrieval timeout: $verificationId');
      },
    );
  }