stackoverflow & reddit

gistfile1.txt

module Order
  module Ranking
    def self.included(base)
      base.extend(ClassMethods)
    end

    def update_r_ranking
      t = self
      t.r_ranking = Topic.calculate_ranking(t.pushes_count, t.created_at)
      t.save(:validate => false)
    end

    def update_s_ranking
      t = self
      factor = Math.log10(t.visits_count+1)*4 + (t.comments_count * t.pushes_count )/5 + t.comment_pushes_count.to_i
      #http://meta.stackoverflow.com/questions/11602/what-formula-should-be-used-to-determine-hot-questions
      t.s_ranking = Topic.calculate_ranking(factor, t.created_at)
      t.save(:validate => false)
    end

    module ClassMethods
      def calculate_ranking(score, created_at)
        order = Math.log10(([score.abs,1].max))

        if score > 0
          sign = 1
        elsif score < 0
          sign = -1
        else
          sign = 0
        end

        seconds = created_at - DateTime.new(1970,1,1)
        long_num = order + sign * seconds / 45000
        (long_num * 10**7).round.to_f / (10**7)
      end
    end
  end
end