absolutizer.rb

require 'uri'

module Julik
  module AbsolutizeHelper
    def canonicalize_hyperlinks(htmlcontent, root, host = nil, prot = nil)
      htmlcontent.gsub(/(<(img|a)\b[^>]*(src|href)=)(["'])(.*?)\4/) do
        md = $~

        prefix = (host && prot) ? (prot + host) : ''
        prefix.gsub!(/\/$/, '')
        begin
          url = URI.parse CGI.unescapeHTML(md[5])
          prefix = '' if (md[5].include?(prefix) && prefix.length > 0)
          if url.relative? && url.path !~ /^\//
            absolutized = File.expand_path(File.join(root, md[5], md[4]))
            # Clean the trailing slash but leave the quote
            absolutized.gsub!(/(\/)(["'])$/) { $2 }
            md[1] + md[4] + prefix + absolutized
          else
            md[1] + md[4] + prefix + md[5] + md[4]
          end
        rescue URI::InvalidURIError
          md[0]
        end
      end
    end
    
    def canonicalize_hyperlinks_in_context(html)
      host =  request.host
      proto = request.protocol
      # honor substandard port
      host += ":#{request.port}" unless request.port == '80'
      canonicalize_hyperlinks(html, '/', request.host, request.protocol)
    end
    
    def markdown_with_canonic_links(text)
      canonicalize_hyperlinks_in_context(markdown(text))
    end
    
    def textilize_with_canonic_links(text)
      canonicalize_hyperlinks_in_context(textilize(text))
    end
  end
end