Class: TwValidation::Id

Inherits:
Object
  • Object
show all
Defined in:
lib/tw_validation.rb

Overview

Id validator

Class Method Summary collapse

Class Method Details

.check(id) ⇒ Object 



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# File 'lib/tw_validation.rb', line 10

def self.check(id)
  id = id.chars

  # ID should be 10 characters
  return false if id.length != 10

  # First letter should be English letter
  return false if id[0] !~ /[A-Z]/

  # Second letter should be 1 or 2
  return false if id[1] !~ /[12]/

  # 3-10 should be numbers
  return false if id[2..].any? { |v| v !~ /\d/ }

  # Checksum
  # rule: https://zh.wikipedia.org/zh-tw/%E4%B8%AD%E8%8F%AF%E6%B0%91%E5%9C%8B%E5%9C%8B%E6%B0%91%E8%BA%AB%E5%88%86%E8%AD%89#cite_note-51

  # Calculate checksum
  equal_value_map = ["A".."Z"].zip([1, 0, 9, 8, 7, 6, 5, 4, 9, 3, 2, 2, 1, 0, 8, 9, 8, 7, 6, 5, 4, 3, 1, 3, 2,
                                    0]).to_h
  id[0] = equal_value_map[id[0]]
  id = id.map(&:to_i)

  # (first letter + second letter * 8 + 3rd letter * 7 + ... + 9th letter * 1 + 10th letter * 1) % 10 == 0
  (id.each_with_index.sum { |v, i| v * (9 - i) } % 10).zero?
end