module TrackChanges
  module ActionController #:nodoc:
    def self.included(base)
      base.send :extend, ClassMethods
    end

    module ClassMethods

      # Sets up an around filter to assign the controller's <tt>current_user</tt>
      # to the given model names that are already set as instance variables in a
      # prior <tt>before_filter</tt>.
      #
      # Example:
      #
      #  track_changes :post
      #  track_changes :post, :post_attribute
      #
      # Currently does not work if the instance variable is anything except
      # an model that has <tt>current_user</tt> accessors.
      def track_changes models
        models_to_track = [models].flatten
        define_method(:__track_changes_to_models) { models_to_track }

        self.class_eval do
          helper :audits
          before_filter TrackChanges::CurrentUserFilter
        end
      end
    end
  end
end

ActionController::Base.send :include, TrackChanges::ActionController