Validace rodného čísla v Ruby on Rails 3

birthday_number_validator.rb

# encoding: utf-8
require 'date'

# Validation of Czech (Slovak) birth number
class BirthNumberValidator < ActiveModel::EachValidator
  attr_reader :record, :attribute, :value
  RC_FORMAT = Regexp.compile /^\s*(\d\d)(\d\d)(\d\d)[ -\/]*(\d\d\d)(\d?)\s*$/

  def validate_each(record, attribute, value)
    @record, @attribute, @value = record, attribute, value

    add_error unless valid?
  end

  def valid?
    # "be liberal in what you receive"
    m = value.match RC_FORMAT
    if m == nil || m.size != 6
      return false
    end
    year, month, day, ext, c = m[1], m[2], m[3], m[4], m[5]
   
    # do roku 1954 pridelovana devitimistna RC nelze overit
    if c.empty?
      return year.to_i < 54
    end
    #zbytek po deleni 11
    #nemuzeme prevest na integer, protoze bychom prisli o nuly v cislech!
    mod = "#{year}#{month}#{day}#{ext}".to_i % 11
    mod = 0 if mod == 10
    if mod != c.to_i
      return false
    end
    #kontrola roku
    year = year.to_i
    month = month.to_i
    day = day.to_i
    year += year < 54 ? 2000 : 1900

    #k mesici muze byt pripocteno 20, 50, 70
    if month > 70 && year > 2003
      month -= 70
    elsif month > 50
      month -= 50
    elsif month > 20 && year > 2003
      month -= 20
    end
    if Date.valid_date?(year, month, day)
      return true
    end
    false
  end

  def add_error
    if message = options[:message]
      record.errors[attribute] << message
    else
      record.errors.add(attribute, :invalid)
    end
  end
end


#usage:
class Person < ActiveRecord::Base
  # @see +BirthNumberValidator+
  validates :birth_number, :allow_blank => true, birth_number: true
end