module FFaker::Code

def ean
  ean = rand(100_000_000_000..999_999_999_999).to_s
  sum = 0
  ean.chars.each_with_index { |c, i| sum += c.to_i * (i.odd? ? 3 : 1) }
  nearest_multiple_of_ten = sum.round(-1)
  nearest_multiple_of_ten += 10 if nearest_multiple_of_ten < sum
  "#{ean}#{nearest_multiple_of_ten - sum}"
end

def npi(legacy: false)
  max = legacy ? 299_999_999 : 999_999_999
  base_npi = rand(100_000_000..max).to_s
  summed_digits = base_npi
                  .chars
                  .each_with_index
                  .map { |n, i| (i.even? ? n.to_i * 2 : n).to_s }
                  .join
                  .chars
                  .inject(0) { |sum, digit| sum + digit.to_i }
  npi_checksum = (10 - (24 + summed_digits) % 10).to_s.chars.last
  base_npi + npi_checksum
end