prototype-sorted-set.rb

COMMENTS_SCORE = 1
BOOKMARK_SCORE = 2
COOKS_SCORE = 3

task :build_top_fans do |_, args|
  user_id = args[:user_id]
  
  redis_client = Redis.new(configurations)
  top_fan_ids_with_scores = group_by_id_and_sum_scopres( bookmarker_fan_ids_with_score(user_id) + 
                                                         commenters_fan_ids_with_scope(user_id) + 
                                                         cooker_fan_ids_with_score(user_id)
                                                       )
    
  top_fan_ids_with_scores.each do |id, score|
    redis_client.zadd("top-fans:#{user_id}", score, id)
  end
end


class User
  def top_fan_ids
    # top-fans:user_1: [17, 15, 11, 8, 14, 12, 2, 16, 5, 13]
    redis_client.zrangebyscore(top_fan_key, "+inf", "-inf")
  end

  def top_fans
    User.where(id: top_fan_ids)
  end
  
  def is_fan?(other_id)
    !!redis_client.zrank(top_fan_key, other_id)
  end
  
  private
    
    def top_fan_key
      "top-fans:#{id}"
    end  
end