CheckoutSystem

Used for calculating total cart value, based on a list of items (their discount rules and prices)

Running the code

*assuming elixir and erlang is installed with the versions from .tool-versions

1. Fetch the dependecies with mix deps.get
2. Run iex using iex -S mix
3. define inside iex the discount rules:

discount_rules = %{
    "GR1" => %{
      product_code: "GR1",
      min_items_for_discount: 2,
      discount_strategy: %{
        type: :get_some_free,
        free_items_received: 1
      }
    },
    "SR1" => %{
      product_code: "SR1",
      min_items_for_discount: 3,
      discount_strategy: %{
        type: :price_drop,
        price_drop: 4.5
      }
    },
    "CF1" => %{
      product_code: "CF1",
      min_items_for_discount: 3,
      discount_strategy: %{
        type: :percentage_discount,
        percentage_discount: 33.33
      }
    }
  }

4. also define the prices prices = %{ "GR1" => 3.11, "SR1" => 5.00, "CF1" => 11.23 }
5. Update in iex the prices CheckoutSystem.Checkout.Cart.update_prices(prices) and the discounts CheckoutSystem.Checkout.Cart.update_discounts(discount_rules)
6. Run in iex the examples from the Technical evaluation

CheckoutSystem.Checkout.Cart.calculate_total(["GR1", "SR1", "GR1", "GR1", "CF1"])

22.45

CheckoutSystem.Checkout.Cart.calculate_total(["GR1", "GR1"])

3.11

CheckoutSystem.Checkout.Cart.calculate_total(["SR1", "SR1", "GR1", "SR1"])

16.61

CheckoutSystem.Checkout.Cart.calculate_total(["GR1", "CF1", "SR1", "CF1", "CF1"])

30.57