# -*- encoding: utf-8 -*-

module CiteProc
  # A CiteProc Variable used for numeric values.
  class Number < Variable

    MAX_ROMAN = 5000

    FACTORS = [
      ['m', 1000], ['cm', 900], ['d', 500], ['cd', 400],
      ['c',  100], ['xc',  90], ['l',  50], ['xl',  40],
      ['x',   10], ['ix',   9], ['v',   5], ['iv',   4],
      ['i',    1]
    ].freeze

    class << self
      def pluralize?(string)
        /\S[\s,&–-]\S|\df/ === string
      end

      # @param number [#to_i] the number to convert
      # @return [String] roman equivalent of the passed-in number
      def romanize(number)
        number, roman = number.to_i, ''

        return number unless number > 0 || number < MAX_ROMAN

        FACTORS.each do |code, factor|
          count, number = number.divmod(factor)
          roman << (code * count)
        end

        roman
      end
    end

    def <=>(other)
      case
      when other.nil?
        1
      when numeric?
        if other.respond_to?(:to_i)
          to_i <=> other.to_i
        else
          nil
        end
      when other.is_a?(Variable) || other.is_a?(String)
        to_s <=> other.to_s
      else
        nil
      end
    end
  end

end