module ActionView
  module Helpers
    module UrlHelper
      
    def return_highlight_name
      "ancestor_of_current_page"
    end
      
      # Assumes the presence of @ancestor_urls array.
      def in_ancestors_array? url={}
        if @ancestor_urls and !url.empty?
          link_url=url_for url
          @ancestor_urls.each do |a|
            ancestor_url=url_for a
            if link_url==ancestor_url
              return true
              break
            end
          end
          return false
        else
          return false
        end
      end
      
      def context_sensitive_link_to(name, options = {}, html_options = nil, *parameters_for_method_reference)
        if in_ancestors_array? options
          if !html_options.nil? and !html_options[:class].nil?
            html_options[:class]=html_options[:class]+" "+return_highlight_name
          elsif !html_options.nil? and html_options[:class].nil?
            html_options.merge({:class=>return_highlight_name})
          else
            html_options={:class=>return_highlight_name}
          end
        end
        return(link_to(name, options, html_options, *parameters_for_method_reference))
      end
      
      def return_highlight_class url={}
        if !url.empty? and in_ancestors_array?(url)
          return_highlight_name
        else
          ""
        end
      end
      
    end
  end
end