class Page < ActiveRecord::Base
  belongs_to :book

  has_many :versions, :order => "created_at", :dependent => :destroy
  has_one  :current_version, :class_name => "Version", :order => "created_at DESC"
  
  def find_or_build_version(number = nil)
    number ? versions[number.to_i - 1] : versions.build(:body => body)
  end
  
  def body
    current_version ? current_version.body : nil
  end
  
  def to_param
    title
  end
end