Implement Google and Email-Based Authentication using Firebase

[MasterAffan]

Description:
Add Firebase Authentication to the Flutter app, enabling users to sign up and log in using Google or email/password. This will serve as the primary authentication system for OptiFit.

Tasks:

• Set up Firebase Authentication in the Firebase console for the project.

• Add firebase_core, firebase_auth, and google_sign_in packages to the Flutter project.

• Initialize Firebase in the app (main.dart).

• Implement email/password registration and login:

  • Create UI for sign-up and login screens.
  • Add validation for email format, password strength, and confirm password field.
  • Display helpful error messages (invalid email, weak password, wrong credentials, etc.).

• Implement Google Sign-In:

  • Add “Continue with Google” button on login screen.
  • Configure OAuth consent screen and SHA-1/SHA-256 fingerprints in Firebase console.
  • Retrieve and store user profile data (name, email, photo URL).

• Store basic user info (UID, email, display name, auth provider) in Firestore for later use.

• Add loading indicators for all network calls.

• Implement sign-out and handle proper state cleanup.

• Redirect authenticated users to the main app screen; unauthenticated users to the login screen.

• Ensure persistence across app restarts using Firebase’s built-in session management.

• Update README with Firebase setup instructions for developers.

Acceptance Criteria:

• Users can log in or register via Google or email/password.

• Invalid credentials and network issues show proper error messages.

• Auth state persists after restarting the app.

• Logging out returns the user to the login screen and clears session data.

• Firebase integration is stable and verified on both Android and iOS.

• Screenshots included showing:

  • Login and sign-up screens
  • Successful login via Google
  • User data visible in Firebase console

[uddeshyagautam]

i would like to work on this..

[MasterAffan]

@uddeshyagautam assigned

[uddeshyagautam]

@MasterAffan great i will check your code