module Alnum

# File lib/alnum.rb, line 7
def self.cypher(number)
  raise TypeError, "Only integers allowed" unless number.is_a? Integer   

  numbers = []

  until number < BASE do
    remainder = number % BASE
    numbers << SYMBOLS[remainder]
    number = (number - remainder) / BASE
  end

  numbers << SYMBOLS[number]
  numbers.reverse.join
end

# File lib/alnum.rb, line 22
def self.decipher(alphanumeric)
  number, count = 0, 0

  alphanumeric.to_s.reverse.each_char() do |c|
    raise RangeError, "Code contains characters out of range: '#{c}'" if SYMBOLS.index(c).nil?
    number += SYMBOLS.index(c) * BASE**count
    count += 1
  end

  number    
end