module Models
  module Likable
    extend ActiveSupport::Concern

    def liked?(record)
      $redis.sismember redis_key, record.id
    end

    def likes_count
      $redis.scard redis_key
    end

    def like(record)
      $redis.sadd record.redis_key, id
    end

  protected

    def redis_key
      "likes:#{id}:#{self.class.model_name}"
    end
  end
end