Besides providing exceptional financial services, Lana also runs a physical store which sells (only) 3 products

The current prices of the products are the following:

Code         | Name                |  Price
-------------------------------------------------
CAP          | Lana Cap          |   5.00€
TSHIRT       | Lana T-Shirt      |  20.00€
MUG          | Lana Coffee Mug   |   7.50€

And we are offering users these discounts:

• 2-for-1 promotions: buy two of the same product, get one free, applied to CAP items.
• bulk discounts: buying 3 or more of TSHIRT product, the price of that product is reduced 5%. E.g., if you buy 3 or more TSHIRT items, the price per unit should be 19.00€.

Our top UI engineer has already made an initial implementation of the store with vanilla html and css, but it lacks the implementation.

Using the framework/library of your choice you have to:

• Implement the cart logic with the following requisites:

  • Have a Checkout class, that can be instantiated with products and discounts available.
  • Allow adding products to the checkout with the scan method, passing the product ID as string in his first argument.
  • Allow calculating the total price with the total method, which won't accept any arguments and will return the total price (discount already applied) as number. Example of how it would work:

      const co = new Checkout(pricingRules);
      co.scan("TSHIRT").scan("CAP").scan("TSHIRT");
      const totalPrice = co.total();

  • Add any extra method you may need to fulfill UI requirements

• Properly decompose the markup in components or whatever it suits you better to make it a production ready App.

• Add the presentation logic to update "Order summary" subsection whenever a product is added or removed. You should use the Checkout class to get the total and discounts

Take into account the following aspects:

• Have notes attached, explaining the solution and why certain things are included and others are left out.
• Deliver production ready code.
• Provide a solution that could be easy to grow and easy to add new functionality.
• You can add any UX / UI improvements you consider, but we are going to focus on the requested features. We value succinctness.
• When in doubt, act as a product owner
• [BONUS]: our UI engineer hadn't time either to work on the product details modal which you can see in the /bonus folder. It would be a plus if you could implement it.