Couldn't find any credit card verification code written in ruby so I wrote up my own. This code turns out a lot smaller than the perl version I have been using. I thought it was an interesting exercise, here is how its done, if anybody can improve on what I've done I'd be impressed.
Heres a howto guide on it
http://www.beachnet.com/~hstiles/cardtype.html
Feel free to use the code.
class CreditCard < ActiveRecord::Base
def before_save
if number_is_valid && number_matches_type
...
end
end
def number_is_valid
total = 0
number.gsub(/[^0-9]/, '').reverse.scan(/(\d)(\d){0,1}/) do |ud,ad|
(ad.to_i*2).to_s.each {|d| total = total + d.to_i} if ad
total = total + ud.to_i
end
total % 10 == 0 ? false : true
end
def number_matches_type
digit_length = number.length
if card_type == 'visa'
if (digit_length == 16) || (digit_length == 13)
return true if number[/^\d/].to_i == 4
end
elsif card_type == 'mastercard'
if digit_length == 16
return true if (51..55).to_a.include?(number[0..1].to_i)
end
elsif card_type == 'amex'
if digit_length == 15
return true if [34,37].include?(number[0..1].to_i)
end
elsif card_type == 'discover'
if digit_length == 16
return true if number[0..3].to_i == 6011
end
end
end
end
