Build an E-Commerce Cart & Checkout Engine

What you'll build

=== MentorNxt Tech Store ===

1. View Catalog
2. Add to Cart
3. View Cart
4. Apply Coupon
5. Checkout & Exit
Select option (1-5): 1

[CATALOG]
- KB01: Mechanical Keyboard ($89.99, Stock: 5)
- MO02: Wireless Mouse ($29.99, Stock: 10)
- HP03: USB-C Headset ($49.99, Stock: 4)

1. View Catalog
2. Add to Cart
3. View Cart
4. Apply Coupon
5. Checkout & Exit
Select option (1-5): 2
Enter Product ID: KB01
Enter Quantity: 1
Added 1x Mechanical Keyboard to cart.

1. View Catalog
2. Add to Cart
3. View Cart
4. Apply Coupon
5. Checkout & Exit
Select option (1-5): 4
Enter Coupon Code: SAVE10
Coupon applied: 10% discount on cart subtotal.

1. View Catalog
2. Add to Cart
3. View Cart
4. Apply Coupon
5. Checkout & Exit
Select option (1-5): 5

========================================
           FINAL INVOICE
========================================
Item                 Qty     Unit       Total
----------------------------------------
Mechanical Keyboard    1  $ 89.99    $ 89.99
----------------------------------------
Subtotal:                      $ 89.99
Discount (10%):               -$  9.00
Tax (8%):                      $  6.48
----------------------------------------
Grand Total:                   $ 87.47
========================================
Thank you for shopping with us!

Requirements

• 1Display a recurring main menu with 5 choices until the user selects Checkout & Exit.
• 2Maintain a catalog dictionary containing SKU, title, unit price, and available inventory stock.
• 3Validate product ID existence and ensure requested quantity does not exceed available stock.
• 4Support coupon code SAVE10 (10% discount) and reject invalid codes with an informative alert.
• 5Calculate subtotal, discount reduction, 8% sales tax, and final payable total with 2 decimal places.
• 6Render an itemized receipt using aligned f-string table formatting.

1. 1

   Initialize catalog and cart state

   Define the catalog data structure and an empty shopping cart list.

   Mark as done
2. 2

   Build the interactive menu loop

   Run a menu loop reading user choices and handling invalid inputs.

   Mark as done
3. 3

   Implement item selection with stock validation

   Safely add items to cart and deduct stock.

   Mark as done
4. 4

   Calculate totals and render invoice

   Produce an aligned final invoice with subtotal, discount, tax, and grand total.

   Mark as done

Build it in your own GitHub repository and push after each milestone. When everything works, mark the project as complete.

1. 1

   Add free shipping badge and waive a $5.00 shipping fee when subtotal before discounts exceeds $50.00.· easy

   Mark as done
2. 2

   Implement a loyalty points calculator where customers earn 1 reward point per $10 spent, redeemable on subsequent purchases.· medium

   Mark as done
3. 3

   Export the finalized order receipt to a formatted text file named receipt.txt upon checkout completion.· hard

   Mark as done

Solution

Opens when you add your repository link.