class Tins::Token

def initialize(bits: 128, length: nil, alphabet: DEFAULT_ALPHABET, random: SecureRandom)
  alphabet.size > 1 or raise ArgumentError, 'need at least 2 symbols in alphabet'
  if length
    length > 0 or raise ArgumentError, 'length has to be positive'
  else
    bits > 0 or raise ArgumentError, 'bits has to be positive'
    length = (Math.log(1 << bits) / Math.log(alphabet.size)).ceil
  end
  self.bits = (Math.log(alphabet.size ** length) / Math.log(2)).floor
  token = ''
  length.times { token << alphabet[random.random_number(alphabet.size)] }
  super token
end