Validera personnummer

gistfile1.txt

# encoding: utf-8
class SocialSecurityNumber
  
  def initialize str
     if str =~ /(\d{2})(\d{2})(\d{2})(\d{4})/
       @str = str
       @year,@month,@day,@last_four = $1,$2,$3,$4
       current_year = Time.now.year % 100
       century = @year.to_i > current_year ? "19" : "20"
       @full_year = "#{century}#{@year}"
     else
       raise ArgumentError, "formatet är är felaktigt"
     end
  end
  
  def valid_date?
    begin
      date = Time.new(@full_year.to_i,@month.to_i,@day.to_i,0,0)
    rescue ArgumentError => e
      return false
    end
  end
  
  def valid_checksum?
    checksum = Luhn.new(@str)
    checksum.valid?
  end
  
  def valid?
    valid_date? && valid_checksum?
  end
  
  class Luhn
    def initialize str
      @arr = str.split(//).map(&:to_i)
      @sums = @arr.enum_for(:each_with_index).map do |x,index| 
        value = (index %2 == 0) ? x * 2 : x
        ((value < 10) ? value : value - 9)
      end
    end
    
    def sum
      @sums.inject { |a,b| a + b }
    end
    
    def valid?
      sum % 10 == 0
    end
  
  end
  
end

if __FILE__ == $0
  pnum=ARGV[0]
  if pnum==nil then
    print "Ange personnummer som yyMMddcccc.\n"
    exit
  end
  
  ssn = SocialSecurityNumber.new pnum
  
  puts ssn.valid? ? "Korrekt personnummer" : "Inkorrekt personnummer"
  
end