class Page < ActiveRecord::Base
  before_create :page_number
  after_destroy :shift_pages

  def page_number
    max = find_by_sql(['SELECT MAX(page) AS page FROM pages WHERE type = ?', self.class.name]).first.page
    self.page = max + 1
  end

  def shift_pages
    find(:all, :conditions=> ['page > ?', self.page]).each do |entry|
      entry.decrement!('page')
    end
  end
end