ruby alphadecimal SHA MD5 human-readable hash

require 'rubygems'
# options available by superclassing. See defs/examples below.

class MDS
  class << self    
    def shalphadecimal(number) 
      case number
        when String
          require 'digest'
          shalphadecimal( Digest::MD5.new << number ).rjust(20,"0")
        when (0..(base - 1))
          options[:alphabet][number,1]      
        when Integer
            [ number/base, remainder = number%base ].inject("") do |string, i|
                string += shalphadecimal(i).to_s
            end
        else; raise TypeError
      end
    rescue TypeError => e
      raise e, 'number must be a positive integer'
    end
    alias shal shalphadecimal
    
    def deconstruct_simple(shal)
      digits = shal.to_s.split('').map {|d| upcase(d) }
      padding = digits.length
      decomposition = []
      
      strings = []
        digits.each_with_index do |digit,index|
          spacing = 12 + digits.length - (padding -= 1)
          base10 = options[:alphabet].index(digit.to_s) || (puts("skipping #{digit}") || next)
          power = digits.length-index-1
          last = (decomposition << base10*(base**power))[-1]
          strings << digit.to_s + "(#{base10}* #{base}^#{power})" + " => " + (last).to_s.rjust(spacing, " ")
        end
      puts strings
      sum = decomposition.inject(0) {|i,d|i+=d}
    end
    alias to_i deconstruct_simple

    protected
    # OPTIONS (override in Thor?)
    def options; {:alphabet=>'0123456789ACDEFGHJKMNPQRTUVWXYZ'}  end
    def base;  options[:alphabet].length  end
    def upcase(character); character.upcase end
  end      
end

=begin
require 'test/unit'
class MDSTest < Test::Unit::TestCase
 def test_single_digit  assert_equal "G",      MDS.shal(15)                  end
 def test_double_digit  assert_equal "1G",     MDS.shal( 31 + 15)            end
 def test_triple_digit; assert_equal "12G",    MDS.shal( 31*31 + 2*31 + 15)  end
 def test_binary;       assert_equal "HAXOR",  MDS.shal(652190)              end
 def test_negative_i;   assert_raise TypeError,MDS.shal(-100)                end
 
end
=end