class CardRedactor

Constants

CARD_PATTERN: Matches Visa, Mastercard, AMEX, Discover Read more: www.richardsramblings.com/regex/credit-card-numbers/

Public Class Methods

card_matches(string) click to toggle source

# File lib/card_redactor.rb, line 16
def card_matches(string)
  # Scan to get all cards in the string, but get the Matchdata instead
  # Read more: http://stackoverflow.com/a/13817639/881691
  [].tap { |matches| string.scan(CARD_PATTERN) { matches << $~ } }
end

contains_card?(string) click to toggle source

# File lib/card_redactor.rb, line 12
def contains_card?(string)
  card_matches(string).any?
end

redact(string) click to toggle source

# File lib/card_redactor.rb, line 22
def redact(string)
  matches = card_matches(string)

  return string if matches.none?

  matches.each do |match|
    card = match[0]

    parts = []

    # In Ruby 1.9, there's no reliable way to deal with chars in strings
    # individually apart from splitting them into an array. In 2.x, we can
    # use array access notation to get at individual characters in a byte-safe manner.
    card.split("").reverse.each_with_index do |char, index|
      if index < 4 || char !~ /\d/
        parts << char
      else
        # If we've gone past the last 4 digits, redact numbers
        parts << "X"
      end
    end

    # Turn the numbers around the right way and implode them into a string
    redacted_card = parts.reverse.join("")

    # Replace the plaintext card with the redacted card in the original string
    string = string.sub(card, redacted_card)
  end

  string
end