helper that truncates html and removes coderay syntax

truncate_html

require "rubygems"
require "nokogiri"

module TextHelper

  def truncate_html(text, max_length = 10, ellipsis = "...")    
    doc = Nokogiri::HTML::DocumentFragment.parse text
    # remove syntax highlighting
    doc.css("div.CodeRay").each do |node|
      node.remove
    end
    content_length = doc.inner_text.length
    if content_length > max_length
      doc = doc.truncate(max_length)
      more = Nokogiri::HTML::DocumentFragment.parse ellipsis
      doc.children.last.add_child(more.children)
      doc.to_html.html_safe
    else
      text.to_s
    end   
  end

end

module NokogiriTruncator
  module NodeWithChildren
    def truncate(max_length)
      return self if inner_text.length <= max_length
      truncated_node = self.dup
      truncated_node.children.remove

      self.children.each do |node|
        remaining_length = max_length - truncated_node.inner_text.length
        break if remaining_length <= 0
        truncated_node.add_child node.truncate(remaining_length)
      end
      truncated_node      
    end
  end

  module TextNode
    def truncate(max_length)
      Nokogiri::XML::Text.new(content[0..(max_length - 1)], parent)
    end
  end

end

Nokogiri::HTML::DocumentFragment.send(:include, NokogiriTruncator::NodeWithChildren)
Nokogiri::XML::Element.send(:include, NokogiriTruncator::NodeWithChildren)
Nokogiri::XML::Text.send(:include, NokogiriTruncator::TextNode)