module ActionController::Caching
  class Sweeper < ActiveRecord::Observer #:nodoc:
    attr_accessor :controller
    attr_accessor :controller_stack
    # ActiveRecord::Observer will mark this class as reloadable even though it should not be.
    # However, subclasses of ActionController::Caching::Sweeper should be Reloadable
    include Reloadable::Deprecated
    
    def initialize
      self.controller_stack = []
      super
    end
  
    def before(c)
      self.controller_stack << c
      self.controller = c
      callback(:before)
    end

    def after(c)
      callback(:after)
      # Clean up, so that the controller can be collected after this request
      self.controller_stack.pop
      self.controller = self.controller_stack.last
    end

    private
      def callback(timing)
        controller_callback_method_name = "#{timing}_#{controller.controller_name.underscore}"
        action_callback_method_name     = "#{controller_callback_method_name}_#{controller.action_name}"
        send(controller_callback_method_name) if respond_to?(controller_callback_method_name)
        send(action_callback_method_name)     if respond_to?(action_callback_method_name)
      end

      def method_missing(method, *arguments)
        return if @controller.nil?
        @controller.send(method, *arguments)
      end
  end
end