Checkout Kata https://www.slideshare.net/chrismdp/lean-code

checkout-kata

#!/usr/bin/env ruby

@products = {
  "apples"   => 100,
  "mele"     => 100,
  "pommes"   => 100,
  "bananas"  => 150,
  "cherries" => 75,
}

@cart = []

def total_price
  @cart.reduce(0) { |total, cart_product| total += @products[cart_product] }
end

def count_in_cart(product)
  @cart.reduce(0) do |total, cart_product|
    total += cart_product == product ? 1 : 0
  end
end

def total_discount
  discount = @cart.size / 5
  discount * 200
end

def discount(product, number_of_items_for_discount, price_discounted)
  number_of_product_in_cart = count_in_cart(product)
  discounts = number_of_product_in_cart / number_of_items_for_discount
  discounts * price_discounted
end

def cherries_discount
  discount("cherries", 2, 20)
end

def bananas_discount
  discount("bananas", 2, 150)
end

def pommes_discount
  discount("pommes", 3, 100)
end

def mele_discount
  discount("mele", 2, 50)
end

def apples_discount
  kind_of_apple = count_in_cart("apples") + count_in_cart("pommes") + count_in_cart("mele")
  discounts = kind_of_apple / 4
  discounts * 100
end

def read_input
  STDIN.gets.chomp.split(",")
end

while true
  @cart << read_input
  @cart.flatten!
  puts total_price - total_discount - cherries_discount - bananas_discount - pommes_discount - mele_discount - apples_discount
end