# frozen_string_literal: true

class CNPJ
  class VerifierDigit
    def self.generate(numbers)
      index = 2

      sum = numbers.reverse.reduce(0) do |buffer, number|
        (buffer + (number * index)).tap do
          index = index == 9 ? 2 : index + 1
        end
      end

      mod = sum % 11
      mod < 2 ? 0 : 11 - mod
    end
  end
end