gistfile1.txt

def assert_equal(expected, actual)
  print expected == actual ? "." : "Expected #{expected}, but got #{actual}\n"
end

class PriceRule
  def initialize(code, price)
    @code = code
    @price = price
  end

  def apply(basket)
    basket.count(@code) * @price
  end
end

Discount = Struct.new(:code, :number, :amount) do
  def apply(basket)
    (basket.count(code) / number) * -amount
  end
end

#class Discount < Struct.new(:code, :number, :amount)
  #def apply(basket)
    #(basket.count(code) / number) * -amount
  #end
#end

class Discount
  def initialize(code, number, amount)
    @code = code
    @number = number
    @amount = amount
  end

  def apply(basket)
    (basket.count(@code) / @number) * -@amount
  end
end

class Checkout
  def initialize
    @basket = []
    @rules = [PriceRule.new("A", 50),
              PriceRule.new("B", 30),
              Discount.new("A", 3, 20),
              Discount.new("B", 2, 15)]
  end

  def total
    @rules.map { |r| r.apply(@basket) }.reduce(0, :+)
  end

  def scan(item)
    @basket.push(item)
  end
end

checkout = Checkout.new
assert_equal(0, checkout.total)
checkout.scan("A")
assert_equal(50, checkout.total)

checkout = Checkout.new
checkout.scan("A")
checkout.scan("A")
checkout.scan("A")
assert_equal(130, checkout.total)

checkout = Checkout.new
checkout.scan("B")
assert_equal(30, checkout.total)

checkout = Checkout.new
checkout.scan("B")
checkout.scan("B")
assert_equal(45, checkout.total)



puts