class Memento::Session < ActiveRecord::Base
  set_table_name "memento_sessions"
  
  has_many :states, :class_name => "Memento::State", :dependent => :delete_all
  belongs_to :user
  validates_presence_of :user
  
  def add_state(action_type, record)
    states.store(action_type, record)
  end
  
  def undo
    states.map(&:undo).inject(Memento::ResultArray.new) do |results, result|
      result.state.destroy if result.success?
      results << result
    end
  ensure
    destroy if states.count.zero?
  end
  
  def undo!
    transaction do
      returning(undo) do |results|
        raise Memento::ErrorOnRewind if results.failed?
      end
    end
  end
  
end