# This is what every "RTML Helper" ends up instantiating -- eventually.
#
# The process of loading an RTML helper actually begins in +Rtml::Controller::RtmlHelpers+, which loads the relevant
# helpers after being included into a descendant of +ActionController::Base+. After finding the helpers and loading
# them, the helpers themselves invoke +Rtml::actions_for+, which analyzes the methods they define and adds them to
# an instance of Rtml::Controller::DocumentGenerator. It is at this time that default actions are created in the
# controller, where they haven't already been defined, which proxy the actions into a call to
#
#    "render :rtml_helpers => {method_name}"
#
# - where {method_name} is the name of a given RTML Helper method (also called an RTML Action).
#
module Rtml::Controller::DocumentGenerator
  def generate_rtml_helpers(base)
    base.instance_eval do
      def hidden_action?(*names)
        !names.select { |name| hidden_actions.include?(name) }.empty?
      end

      def hidden_actions
        @hidden_actions ||= []
      end

      def hide_action(*names)
        hidden_actions.concat names.flatten
      end
    end

    base.class_eval do
      attr_reader :controller
      delegate :rtml_document, :params, :url_for, :expires_at, :to => :controller
      delegate :rtml_actions, :to => 'self.class'

      def initialize(controller)
        @controller = controller
      end

      def respond_to?(name, *args, &block)
        return super || rtml_document.respond_to?(name, *args, &block)
      end

      def method_missing(name, *args, &block)
        rtml_document.copy_ivars_from(self)
        rtml_document.send(name, *args, &block)
      rescue
        raise $!, $!.message, caller
      end

      def fire_action(action_name)
        copy_ivars_from(controller)
        # Give rtml actions access to the controller's view helpers
        (class << self; self; end).send(:include, controller.response.template.helpers)
        __send__(action_name)
      end

      def copy_ivars_from(source)
        ivars = source.instance_variables
        ivars -= source.protected_instance_variables if source.respond_to?(:protected_instance_variables)
        ivars -= source.rtml_protected_instance_variables if source.respond_to?(:rtml_protected_instance_variables)
        ivars.each { |ivar| instance_variable_set(ivar, source.instance_variable_get(ivar)) }
        rtml_document.copy_ivars_from(self)
      end

      hide_action :initialize, :method_missing, :respond_to?, :copy_ivars_from
    end
    
    base
  end
end