TCKN Verifier - Turkish Citizenship Number Checker - TCKN Kimlik No Doğrulama

tckn_verifier.rb

###
# Author : Turhan Coskun
# Name   : TCKN Number Verification - TCKN Dogrulama
# Usage  : ruby tckn_verifier.rb <turkish citizenship number>
###

raw_id_number = ARGV[0] # Assign the first argument of the program to the variable

# Extensions of the String class
class String
  def numeric? # Check if the given string is numeric
    Float(self) != nil rescue false
  end

  def to_a # Convert the string into a char array
    arr = []
    self.each_char do |c| arr << c end
    return arr
  end
end

def tckn_verifier(tckn)
  tckn_id_number = tckn.to_s # Function arg converted to a string for manupulation

  if tckn_id_number.length != 11 # TCKN must be 11 digits
    return false
  end

  if not tckn_id_number.numeric? # TCKN must be numerical
    return false
  end

  if tckn_id_number[0] == 0 # TCKN cannot start with "0"
    return false
  end

  digits = tckn_id_number.to_a.collect do |n| n.to_i end # String array converted to an integer array

  # Implementation of the TCKN algorythm
  sum = 0
  digits[0..9].each do |i|
    sum += i # Get sum of the first 10 digits
  end

  if sum % 10 != digits[10]
    return false # Modulus 10 of the first 10 digits must point to the last digit
  end

  sum_odd=0
  sum_even=0
  order=0
  digits[0..9].each do |i|
    order += 1
    if order.even?
      sum_even += i
    else
      sum_odd += i
    end
  end

  if(sum_odd*7 - sum_even) % 10 == digits[9]
    return true
  end

  return true # If we got so far, we did all good
end

if tckn_verifier(raw_id_number)
  puts("This is a VALID TCKN")
else
  puts("INVALID TCKN")
end