Recap - Coupon Codes

Part of the Object Oriented Programming section of Coddy's Ruby journey. Lesson 16 of 57.

Challenge

Medium

Complete the class Coupon. The factory Coupon.parse(code) accepts SAVE followed by a percentage (SAVE10) or OFF followed by an amount (OFF5) and returns nil for any other code. Percentages above the constant MAX_PERCENT (50) are reduced to 50. Every coupon the factory creates is counted in a class instance variable, readable as Coupon.issued; make new private. apply(total) returns the discounted total, never below 0, and to_s returns SAVE10 (10% off) or OFF5 (5.00 off).

The supplied code reads the order total from the first line and one code per following line. It prints SAVE10 (10% off): 90.00 or invalid code HELLO, and finally issued: 2.

Your code goes in coupon.rb. main.rb holds the supplied input/output code and cannot be edited.

Try it yourself

require_relative 'coupon'

# Supplied input/output code: keep it as it is
input = []
while (line = gets)
  input << line.chomp
end
total = input[0].to_f
input.drop(1).each do |code|
  coupon = Coupon.parse(code)
  if coupon
    puts format("%s: %.2f", coupon, coupon.apply(total))
  else
    puts "invalid code #{code}"
  end
end
puts "issued: #{Coupon.issued}"