A checkout system with pricing rules and special offers, built with React (Frontend) and Java Spring Boot (Backend).

• ✅ Dual Calculation Modes: Switch between JavaScript (frontend) and Java (backend) calculations
• ✅ Special Offers: Automatic discount calculation (e.g., "3 for £1.30")
• ✅ Real-time Updates: Live total calculation as items are added/removed
• ✅ Responsive Design: Works on desktop, tablet, and mobile
• ✅ Error Handling: Graceful fallback if backend is unavailable
• ✅ RESTful API: Clean Spring Boot backend with proper validation

git clone <your-repository-url>
cd checkout-system

# Navigate to backend directory
cd backend

# Install dependencies and start the server
./mvnw spring-boot:run

Expected Output:

Started CheckoutSystemApplication in 2.5 seconds
Tomcat started on port(s): 8080

✅ Backend is now running on: http://localhost:8080

Open a new terminal window/tab and run:

# Navigate to frontend directory
cd front-end

# Install dependencies
npm install

# Start the development server
npm run dev

Expected Output:

Local:   http://localhost:3000

1. Open your browser and go to http://localhost:3000

2. Test Frontend Calculation:

   • Add some items to your cart (try 3 × Item A, 2 × Item B)
   • Ensure the dropdown shows "Javascript"
   • Verify calculations are working

3. Test Backend Integration:

   • Switch the dropdown to "Java"
   • The indicator should show "Java Spring Boot" with a green dot
   • Calculations should remain the same
   • If you see any red error messages, check that your backend is running

4. Health Check:

   • Visit http://localhost:8080/api/checkout/health
   • Should return: "Calculation service is running!"

cd backend

# Run tests
./mvnw test

# Build JAR file
./mvnw clean package

# Run with different profile
./mvnw spring-boot:run -Dspring-boot.run.profiles=production

cd fron