Italian fiscal code generator for Ruby on Rails

fake_cfs.rb

module Italian
  # Generates a random fiscal code
  class << self
    @@generated_cfs = []

    def cf
      res = []

      # ^[A-Z]{6}
      res << _A_Z(6)
      # [0-9]{2}
      res << _0_9(2)
      # [ABCDEHLMPRST]
      res << Array.new(1).map { ['ABCDEHLMPRST'].split.shuffle.first }
      #[0-9]{2}
      res << _0_9(2)
      # [A-Z]
      res << _A_Z(1)
      # [0-9]{3}
      res << _0_9(3)
      # [A-Z]$
      res << _A_Z(1)

      res.join
    end

    # Generates a random unique fiscal code
    def cf_uniq
        random_cf = cf
        while(@@generated_cfs.include?(random_cf))
          random_cf = cf
        end
        @@generated_cfs << random_cf

        random_cf
    end

    private
    def _A_Z(length)
      Array.new(length).map { ('A'..'Z').to_a[rand(26)] }
    end

    def _0_9(length)
      Array.new(length).map { rand(10)}
    end

  end
end