module Billing
  class ReferenceNo
    REGEXP = /\A\d{2,20}\z/.freeze
    MULTI_REGEXP = /(\d{2,20})/.freeze

    def self.generate
      base = Base.generate
      "#{base}#{base.check_digit}"
    end

    def self.valid?(ref)
      base = Base.new(ref.to_s[0...-1])
      ref.to_s == "#{base}#{base.check_digit}"
    end
  end
end