require 'active_record'
require 'active_support/core_ext/numeric/time'
require 'active_support/core_ext/date/calculations'

module Tjcrawler
  class Page < ActiveRecord::Base
    @@semaphore = Mutex.new
    class << self
      def enqueue url
        @@semaphore.synchronize{Page.find_or_create_by url: url}
      end

      def dequeue
        Page.where('crawled_at IS NULL OR crawled_at < ?', 1.day.ago).order('crawled_at IS NOT NULL, crawled_at').first
      end
    end
  end
end