# Example:
#   B40 = HighBase.new(40, ([*"0".."9"]+[*"a".."z"]+[*"A".."Z"]).first(40))
#   a = B40.new 100  # => #<B40:0x1724b 2k (100 in base 40)>
#   b = B40.new '2k' # => #<B40:0x1728b 2k (100 in base 40)>
#   a.digits         # => [2,20]
#   a.to_s           # => "2k"
class HighBase
  def self.new(base, characters)
    Class.new(Base) do
      eigenclass = class <<self; self; end

      eigenclass.instance_eval do
        define_method :base do
          base
        end

        define_method :characters do
          characters
        end
      end

      define_method :base do
        base
      end

      define_method :characters do
        characters
      end

      yield if block_given?
    end
  end

  class Base
    include Comparable

    attr_reader :number

    def self.from_string(string)
      number = string.split("").map { |c|
        characters.index(c)
      }.inject(0) { |num,digit|
        num*base+digit
      }

      new(number)
    end

    def self.new(number)
      String === number ? from_string(number) : super
    end

    def initialize(number)
      @number = number
    end

    %w[+ - * ** / % div quo].each { |name|
      sym_name = name.to_sym
      define_method(name) { |other|
        #printf "%p %s %p (%p)\n", self, name, other, (self.class === other ? other.instance_variable_get(:@number) : other)
        self.class.new(@number.__send__(sym_name, self.class === other ? other.instance_variable_get(:@number) : other))
      }
    }

    def coerce(other)
      self.class === other ? [other, self] : [self.class.new(other), self]
    end

    def <=>(other)
      @number <=> (self.class === other ? other.instance_variable_get(:@number) : other)
    end

    def digits
      rv   = []
      rest = @number
      until rest < base
        rest, num = *rest.divmod(base)
        rv << num
      end
      rv << rest
      rv.reverse
    end

    def to_s
      digits.map { |digit| characters[digit,1] }.join("")
    end

    def inspect
      sprintf "#<%s:0x%x %s (%d in base %d)>",
        self.class,
        object_id >> 1,
        self,
        @number,
        base
    end
  end
end