LearnAI - Subscription-Based Learning App

A comprehensive React Native (Expo) application with subscription-based authentication using Firebase Auth and in-app purchases.

🏗️ Architecture

[Expo App] -> [Express API] -> [Apple/Google APIs]
                         -> [Firebase Admin SDK]

🔧 Tech Stack

• Frontend: Expo (React Native)
• Authentication: Firebase Authentication
• Backend: Express.js (Node.js)
• Database: Firestore
• Payments:
  • iOS: Apple In-App Purchases (StoreKit)
  • Android: Google Play Billing
  • Unified handling: expo-in-app-purchases

📁 Project Structure

LearnAi/
├── Front-end/
│   ├── services/
│   │   ├── firebaseConfig.ts       # Firebase configuration
│   │   ├── authService.ts          # Authentication service
│   │   └── subscriptionService.ts  # In-app purchase service
│   ├── contexts/
│   │   └── AuthContext.tsx         # Authentication context
│   ├── app/components/
│   │   ├── login.tsx               # Login/Signup component
│   │   ├── subscriptionScreen.tsx  # Subscription screen
│   │   └── authGuard.tsx           # Route protection
│   └── .env                        # Environment variables
├── Back-end/
│   ├── config/
│   │   └── firebase.js             # Firebase Admin SDK config
│   ├── routes/
│   │   ├── auth.js                 # Authentication routes
│   │   └── subscriptions.js        # Subscription routes
│   ├── services/
│   │   └── receiptVerification.js  # Receipt verification
│   ├── server.js                   # Main server file
│   └── .env                        # Environment variables

🚀 Setup Instructions

1. Firebase Setup

1. Create a Firebase project at https://firebase.google.com/
2. Enable Authentication with Email/Password
3. Enable Firestore Database
4. Generate a Firebase Admin SDK private key
5. Get your Firebase web app configuration

2. Apple App Store Setup (iOS)

1. Enroll in Apple Developer Program
2. Create your app in App Store Connect
3. Set up in-app purchase products:
   • Monthly subscription: learn_ai_monthly
   • Yearly subscription: learn_ai_yearly
4. Generate App Store Connect API key
5. Get your bundle ID and other credentials

3. Google Play Setup (Android)

1. Create Google Play Developer account
2. Create your app in Google Play Console
3. Set up subscription products:
   • Monthly subscription: learn_ai_monthly_android
   • Yearly subscription: learn_ai_yearly_android
4. Create service account for Google Play API
5. Enable Google Play Developer API

4. Environment Configuration

Frontend (.env)

LOCAL_HTTP_SERVER=http://localhost:3000
EXPO_PUBLIC_FIREBASE_API_KEY=your-firebase-api-key
EXPO_PUBLIC_FIREBASE_AUTH_DOMAIN=your-project.firebaseapp.com
EXPO_PUBLIC_FIREBASE_PROJECT_ID=your-project-id
EXPO_PUBLIC_FIREBASE_STORAGE_BUCKET=your-project.appspot.com
EXPO_PUBLIC_FIREBASE_MESSAGING_SENDER_ID=123456789
EXPO_PUBLIC_FIREBASE_APP_ID=1:123456789:web:abcdef

Backend (.env)

# Server
PORT=3000
NODE_ENV=development

# Firebase Admin
FIREBASE_PROJECT_ID=your-project-id
FIREBASE_PRIVATE_KEY="-----BEGIN PRIVATE KEY-----\n...\n-----END PRIVATE KEY-----\n"
FIREBASE_CLIENT_EMAIL=firebase-adminsdk-xxxxx@your-project.iam.gserviceaccount.com

# Apple App Store
APPLE_ISSUER_ID=your-issuer-id
APPLE_KEY_ID=your-key-id
APPLE_BUNDLE_ID=com.yourcompany.learnai
APPLE_PRIVATE_KEY="-----BEGIN PRIVATE KEY-----\n...\n-----END PRIVATE KEY-----\n"
APPLE_SHARED_SECRET=your-shared-secret

# Google Play
GOOGLE_PLAY_PACKAGE_NAME=com.yourcompany.learnai
GOOGLE_SERVICE_ACCOUNT_KEY={"type":"service_account",...}

# Gemini AI (existing)
GEMINI_API_KEY=your-gemini-api-key

5. Installation

Backend

cd Back-end
npm install
npm start

Frontend

cd Front-end
npm install
npx expo start

🔐 Authentication Flow

Subscription Flow (New Users)

1. User opens app → sees subscription screen
2. User chooses monthly/yearly plan
3. expo-in-app-purchases handles purchase
4. App sends receipt to backend for verification
5. Backend verifies with Apple/Google APIs
6. If valid, user can create account
7. Firebase Auth creates user account
8. User is signed in and can access app

Login Flow (Existing Users)

1. User enters email/password
2. Firebase Auth validates credentials
3. App checks subscription status with backend
4. If subscription valid → user accesses app
5. If subscription expired → redirect to subscription screen

📱 Key Components

SubscriptionScreen

• Displays available subscription plans
• Handles in-app purchases
• Communicates with backend for verification
• Manages purchase restoration

LoginScreen

• Multi-mode component (login/signup/forgot password)
• Integrated with subscription flow
• Form validation and error handling
• Responsive design

AuthGuard

• Protects routes requiring authentication
• Shows loading states
• Redirects to login when needed

AuthContext

• Manages global authentication state
• Provides auth methods to components
• Handles automatic subscription validation

🛡️ Security Features

• Firebase Admin SDK for server-side user management
• Receipt verification with Apple/Google APIs
• JWT token validation for API requests
• Subscription status validation on each app launch
• Automatic logout on subscription expiry

🔧 Backend API Endpoints

Authentication (/api/auth)

• POST /check-subscription - Check user subscription status
• POST /create-profile - Create user profile
• GET /profile - Get user profile
• PUT /profile - Update user profile
• DELETE /account - Delete user account

Subscriptions (/api/subscriptions)

• POST /verify - Verify purchase receipt
• POST /link-to-user - Link subscription to user
• POST /status - Check subscription status
• GET /history/:uid - Get subscription history
• PUT /update-status - Update subscription status

🧪 Testing

1. Use sandbox environments for testing:
   • Apple: TestFlight or Simulator
   • Google: Internal testing track
2. Test subscription flows thoroughly
3. Verify receipt validation works correctly
4. Test edge cases (network failures, invalid receipts)

📚 Additional Resources

• Expo In-App Purchases Documentation
• Firebase Authentication
• Apple App Store Server API
• Google Play Billing

🤝 Support

For issues and questions:

1. Check the documentation
2. Review error logs
3. Test in sandbox environments first
4. Verify all credentials are correctly configured

📝 License

This project is licensed under the MIT License.