From: Bartosz Blimke <bartosz.blimke@...>
Date: 2007-05-01T06:42:28+09:00
Subject: Re: [SOLUTION] Checking Credit Cards (#122)

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class CreditCardNumberValidator

    CARD_TYPE =  {
        :amex => 'AMEX',
        :discover => 'DISCOVER',
        :master_card => 'MASTER CARD',
        :visa => 'VISA',
        :unknown =>  'UNKNOWN'
    }

    CARD_NUMBER_PATTERN = {
        :amex => /^3[4|7][0-9]{13}$/,
        :discover => /^6011[0-9]{12}$/,
        :master_card => /^5[1-5][0-9]{14}$/,
        :visa => /^4[0-9]{12}$|^4[0-9]{15}$/
    }


    def self.card_type(card_num)
        CARD_NUMBER_PATTERN.each do |t, p|
            return CARD_TYPE[t] if card_num =~ p
        end
        CARD_TYPE[:unknown]
    end

    def self.valid?(card_num)
        sum = 0
        card_num.to_s.reverse.scan(/./).each_with_index do |digit, index|
          digit = digit.to_i * (1 + (index % 2))
          sum+=digit/10 + digit%10;
        end
        sum % 10 == 0
    end
end

abort "Usage: #{$0} number" unless  ARGV.length > 0
card_num = ARGV.join.to_i
puts "Number: #{card_num}"
puts 'Type: ' + CreditCardNumberValidator.card_type(card_num)
puts 'Validation: ' + (CreditCardNumberValidator.valid
?(card_num)?'Valid':'Invalid')

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