This codebase provides a boilerplate code utilizing the following three technologies:

1. Flutter 3.0 - For UX and uses Dart languange. See [https://flutter.dev/]
2. GetX - State management for Flutter. See [https://github.com/jonataslaw/getx/tree/4.6.1]
3. Firebase - For Backend as a Service. See [https://firebase.google.com/]
   1. Easy Authentication flow
   2. Server side functions
   3. Remote Configurations which can be used for A/B testing

This was created as part of my own learning process and you will find that git commits were made according to the Steps listed below. You can use the git version history to check each commit and learn step by step, as I did.

I am also using this codebase as an experiment towards hiring people (freshers especially but not limited to them) for my development team. If you are in Mumbai and are interested to join my team, you can use this codebase in the following manner:

• Fork the codebase
• Add your own firebase_options.dart (follow steps and see firebase_options.template)
• Build your own application using this as a base (integrating any existing project of yours also works), or complete a TODO or fix a bug (only if you have no other ideas)
• Send me a Pull Request. Mention a way of connecting with you in the commit message along with details of commit. Also modify ReadMe to say what you have changed in detail.
• I will go through the request and then connect with you if I find the entry to be interesting and take an interview round.

Step 1: Use Get CLI [https://pub.dev/packages/get_cli]

get create project

Step 2: Copy code from [https://github.com/jonataslaw/getx/tree/4.6.1/example_nav2/lib]

Step 3: Integrate FlutterFire Authentication

• Tutorials [https://firebase.google.com/codelabs/firebase-auth-in-flutter-apps#0] for inspiration

• Firebase Documentation [https://firebase.google.com/docs/auth/flutter/start]

• Blog [www.medium.com/TBD]

• To compile the code ensure that you generate your own firebase_options.dart by running

  flutterfire configure

Step 4: Add Google OAuth [https://firebase.google.com/codelabs/firebase-auth-in-flutter-apps#6]. Note ensure you do the steps for Android and iOS as the code for it is not in Github

Step 5: Add Guest User/Anonymous login with a Cart and Checkout use case [https://firebase.google.com/docs/auth/flutter/anonymous-auth]

• delete unlinked anonymous user post logout

Step 6: Add ImagePicker and Firebase Storage for profile image

• Create PopupMenu button for web [https://api.flutter.dev/flutter/material/PopupMenuButton-class.html]

• BottomSheet for phones and single file button for desktops

• GetX and Image Picker [https://stackoverflow.com/questions/66559553/flutter-imagepicker-with-getx]

• Add FilePicker [https://medium.com/@onuaugustine07/pick-any-file-file-picker-flutter-f82c0144e27c]

• Firebase Storage [https://mercyjemosop.medium.com/select-and-upload-images-to-firebase-storage-flutter-6fac855970a9] and [https://firebase.google.com/docs/storage/flutter/start]

  Modify the Firebase Rules service firebase.storage { match /b/{bucket}/o { match /{allPaths=**} { allow write: if request.auth.uid != null; allow read: if true; } } }

  Fix CORS [https://stackoverflow.com/questions/37760695/firebase-storage-and-access-control-allow-origin]

• PList additions [https://medium.com/unitechie/flutter-tutorial-image-picker-from-camera-gallery-c27af5490b74]

Step 7: Additional Auth flow items

1. Add a Change Password Screen. The Flutter Fire package does not have this screen.
2. TODO: Add ReCaptcha to login flow for password authentication for Web only
   • Phone Auth on Web has a ReCaptcha already [https://firebase.flutter.dev/docs/auth/phone/]. Tried to use that library but it is very cryptic.
   • Use the following instead [https://stackoverflow.com/questions/60675575/how-to-implement-recaptcha-into-a-flutter-app] or [https://medium.com/cloudcraftz/securing-your-flutter-web-app-with-google-recaptcha-b556c567f409] or [https://pub.dev/packages/g_recaptcha_v3]
3. TODO: Ensure Reset Password has Email verification
4. TODO: Add Phone verification [https://firebase.google.com/docs/auth/flutter/phone-auth]
   • See [firebase/flutterfire#4189].
5. TODO: Add 2FA with SMS Pin. This screen is available in the Flutter Fire package

Step 8: Add Firebase Emulator to test on laptop instead of server so that we can use Functions without upgrading the plan to Blaze. See [https://firebase.google.com/docs/emulator-suite/install_and_configure]

Step 9: Add User Roles using Custom Claims. This requires upgrade of plan as we need to use Firebase Functions. Instead using Emulator.

1. In Emulator we can add user via http://127.0.0.1:4000/auth and add custom claim via UI as {"role":"admin"}. The effect is shown via Product page in Nav instead of Cart page for admin user.

2. Add Function to add the custom claim to make the first user the admin using the Admin SDK

3. Registeration form to collect some data post signUp and enforce email verification from Client side.

   • Note! for Emulator check the console to verify using the link provided as email is not sent.

4. Enforcing verify email using a button which appears when SignIn fails due to non verification.

   • Fixed the error handling message during login.
   • Coverted server side to Typescript
   • Enabled Resend verification mail button
     • Approach 1 - Use Email Link Authentication and signIn, assuming it marks email as verified also. We cannot send the verification mail as is, since that can be sent only if signed in (which was allowed only for first login post signup)
       • Refer https://firebase.google.com/docs/auth/flutter/email-link-auth
       • TODO Enable Deep Linking: According to https://firebase.google.com/docs/dynamic-links/flutter/receive, the Flutter feature is being deprecated and we should use the AppLinks (Android), UniversalLinks(iOS) instead. Leaving this for future as adding complexity.
       • We could use the server side handling instead of deep linking. See [https://firebase.google.com/docs/auth/custom-email-handler?hl=en&authuser=0#web]. However, this requires changing the email template for the URL which is not possible in Emulator. Using the continueURL instead does not work as oobCode is already expired. This handling also uses the web client sdk. Thus it is better to go with the below method instead.
     • Approach 2 - (Hack) send a create request with suffix ".verify" added in email when button clicked. Use the server side beforeCreate to catch this and send verification mail
       • Note that the Server side beforeCreate function can also bypass user creation till verification but the user record (esp password) needs to be stored anyways, so bypassing user creation is not a good idea. Instead, we should use the verified tag in subsequent processing
       • Sending emails from server side is possible but by using the web client SDK.

5. TODO: Other Items

   • TODO: Using autocomplete for emails is throwing error log in terminal. No impact but need to fix when all is done.
   • TODO: Add a job that removes all unverified users after a while automatically. This could be useful if you were victim of bot attacks, but adding the Recaptcha is better precaution. See [https://stackoverflow.com/questions/67148672/how-to-delete-unverified-e-mail-addresses-in-firebase-authentication-flutter/67150606#67150606]

6. Added Roles of Buyer and Seller.

   1. Added Access level in increasing order of role order => Buyer then Seller then Admin
   2. Created Navigation for each of Admin, Buyer, Seller screens
   3. Allowed switch from lower role Navigation to Navigation view till the given role of the user

Step 10: Firebase Remote Config for A/B testing. See [https://firebase.google.com/docs/remote-config]

1. Complete the Screen enum based Navigation framework
2. Config useBottomSheetForProfileOptions for Navigation element to be one of the following
   • False: Drawer for Account, Settings, Sign Out
   • True: Hamburger that opens BottomSheet (Context Menu in larger screen) for the same options
3. TODO: Config for adding Search Bar at the Top vs a Bottom Navigation button

Step 11: TODO: CRUD

• Users request role upgrade
• Add this request data to Firebase Datastore
• Create ListView with slidable tiles for approvals
• Admin SDK used by admin user via workflow on this request data and is approved from app
  • Allow a Plan attribute via Custome Claims (e.g. Premium user flag) for Buyer and Seller, to add features which are not Navigation linked. Add a button Upgrade to Plan in Drawer that leads to Payment screen. Also certain aspects of premium plan can be visible that leads to upgrade plan screen via middleware
• Nested Category, Sub-Category tree creation

Step 12: TODO: Theming and Custom Settings

• Add Persona (like that in Netflix) and create a Persona selection only for Buyer Role
• Add Minimal (Three Color Gradient Pallette) Material Theme. Align it with Persona Templates (like Kids Template in Netflix)
• Dark theme toggle setting based on each Persona of the logged in User

Step 13: TODO: Large vs Small screen responsiveness

• Drawer: Triggered by Top Left Icon (App Logo). For iOS this icon changes to back button when required. Contains allowed Role List, Screens specified as Drawer. Becomes Left Side Navigation for Horizontal Screens. Can have additional extreme left vertical Navigation Strip. Bottom Navigation Bar also folds into this strip in Horizontal Screens.
• Top Right Icon: used for Login and post Login triggers BottomSheet/Context Menu for Persona Change, Profile, Settings, Change Password, Logout
• Search Bar (Toggle Button for phones) on Top Center with Title
• Status Bottom Bar for desktops only instead of SnackBars
• FAB vs Main Menu

Step 14: TODO: Make own login flow screens. Remove firebase library reference from all but auth_service