Simple retail shop interface

gem 'mercadona'

require 'mercadona'

# Define discount rules
bogo_discount = Mercadona::Entity::DiscountRule.new(type: Mercadona::Discount::Bogo, condition: '>=', quantity: 2)
quantity_discount = Mercadona::Entity::DiscountRule.new(type: Mercadona::Discount::Quantity, condition: '>=', quantity: 3, discount: 0.5)
bulk_discount = Mercadona::Entity::DiscountRule.new(type: Mercadona::Discount::Bulk, condition: '>=', quantity: 3, discount: 1/3r)

# Define checkout with discount rules specified through product codes
checkout = Mercadona::Checkout.new(
  'GR1' => bogo_discount,
  'SR1' => quantity_discount,
  'CF1' => bulk_discount
)

# Define order items
green_tea = Mercadona::Entity::OrderItem.new(product_code: 'GR1', name: 'Green Tea', price: 3.11)
strawberries = Mercadona::Entity::OrderItem.new(product_code: 'SR1', name: 'Strawberries', price: 5.0)
coffee = Mercadona::Entity::OrderItem.new(product_code: 'CF1', name: 'Coffee', price: 11.23)

# Add order items to checkout
[green_tea, strawberries, coffee].each { |order_item| checkout.scan(order_item) }

# Calculate total amount using current discount rules
checkout.total # => "£19.34"

require 'mercadona'

class YourCustomDiscount < Mercadona::Discount::Base
  def call
    return amount_without_discount unless discount_case?

    # Your logic here...
  end
end