module PageModelExtensions

  # this method (and its sub method -- parse_w3_messages) is specific to the
  # w3 validator's SOAP output.  Essentially, this submits the page's content
  # to the validator and parses the response into a more useful structure for
  # the templates and controller to use.
  #
  # the SOAP interface was chosen because the w3 web interface...
  #  * has relative css commands that cause a locally rendered copy to not
  #    display properly.
  #  * contains relative links which break when rendered locally (confusing the
  #    user)
  #  * the web interface inhibits us dealing directly with the results (which 
  #    will be more beneficial in future changes to this extension).
  #
  # A fair number of workarounds can be found here due to the fact that the w3's
  # SOAP interface is not a poor correlation to their web interface (and the way
  # their validator 'thinks'). We have made suggestions to the w3 and they are 
  # looking to improve their SOAP output.  In the meantime, this works ok.
  def validate_html_markup
    rendered_page = self.render

    validator_uri = 'http://validator.w3.org/check'
    validator_params = {'ss' => 0, # don't show rendered_page (irrelevant for SOAP)
                        'fragment' => rendered_page,
                        'output' => 'soap12'}

    response = Net::HTTP.post_form(URI.parse(validator_uri), validator_params)

    # Try again if redirected (only one redirect will be handled)
    response = Net::HTTP.post_form(URI.parse(response['location']), validator_params) if response.is_a?(Net::HTTPRedirection)

    if response.is_a?(Net::HTTPSuccess) then

      # parse w3's XML(SOAP) output into something more useful
      w3_xml_struct = XmlSimple.xml_in(response.body)
      validation_data = {'source' => rendered_page,
                    'doctype' => w3_xml_struct['Body'][0]['markupvalidationresponse'][0]['doctype'][0].to_s,
                    'charset' => w3_xml_struct['Body'][0]['markupvalidationresponse'][0]['charset'][0].to_s,
                    'checked_by' => w3_xml_struct['Body'][0]['markupvalidationresponse'][0]['checkedby'][0].to_s,
                    'valid' => w3_xml_struct['Body'][0]['markupvalidationresponse'][0]['validity'][0].downcase == 'true' ? true : false,
                    'errorcount' => w3_xml_struct['Body'][0]['markupvalidationresponse'][0]['errors'][0]['errorcount'][0].to_i,
                    'warningcount' => w3_xml_struct['Body'][0]['markupvalidationresponse'][0]['warnings'][0]['warningcount'][0].to_i,
                    'prevalidation_messages' => []}

      # trim leading '-//W3C//DTD ' and trailing '//EN' from doctype
      validation_data['doctype'].slice!(/^-\/\/W3C\/\/DTD/i)
      validation_data['doctype'].slice!(/\/\/[A-Z]{2}$/i)
      validation_data['doctype'].strip!

      # parse errors and warnings as stored in w3's SOAP struct into messages
      validation_data['messages'] = parse_w3_messages(w3_xml_struct['Body'][0]['markupvalidationresponse'][0]['warnings'][0], 'warning', 0)
      validation_data['messages'] += parse_w3_messages(w3_xml_struct['Body'][0]['markupvalidationresponse'][0]['errors'][0], 'error', 1)

      # sort messages by line number then column, then type (error, msg, etc).
      validation_data['messages'] =  validation_data['messages'].sort_by { |message| 
         [ message['sortable_line'],
           message['sortable_col'],
           message['sortable_type'] ] 
      }

      # iterate over messages and slice out those that are pre-validation msgs
      i = 0; while i < validation_data['messages'].length
        if validation_data['messages'][i]['mid'] =~ /^[Ww][0-9]+/ then
          validation_data['prevalidation_messages'] << validation_data['messages'].slice!(i)
          i -= 1
        end
        i += 1
      end

      # mark validation process as completed
      validation_data['completed'] = true

    else
      # some sort of http problem getting the response, validation not complete
      validation_data = {'completed' => false,
                         'error_code' => response.code,
                         'error_code_description' => response.message,
                         'source' => rendered_page}
      # add redirection location if applicable
      validation_data['error_code_description'] += " (redirect: " + response['location'] + ")" if (response.is_a?(Net::HTTPRedirection) && !response['location'].blank?)
    end

    return validation_data
  end


private


  def parse_w3_messages(w3_messages, message_type, sortable_type)
    messages = []
    if w3_messages[message_type + 'count'][0].to_i > 0 then
      w3_messages[message_type + 'list'][0][message_type].each {|curr_message|
        messages << {'type' => message_type,
                     'sortable_type' => sortable_type, #way to force 'warning' to sort before 'error'
                     'line' => (curr_message['line'][0] unless curr_message['line'].nil?),
                     'sortable_line' => (curr_message['line'].nil? ? -1 : curr_message['line'][0].to_i),
                     'col' => (curr_message['col'][0] unless curr_message['col'].nil?),
                     'sortable_col' => (curr_message['col'].nil? ? -1 : curr_message['col'][0].to_i),
                     'summary' => (curr_message['message'][0] unless curr_message['message'].nil?),
                     'mid' => (curr_message['messageid'][0] unless curr_message['messageid'].nil?),
                     'source' => (curr_message['source'][0].sub('<![CDATA[','').sub(']]','') unless curr_message['source'].nil?),
                     'explanation' => (curr_message['explanation'][0].sub('<![CDATA[','').sub(']]','') unless curr_message['explanation'].nil?) }
      }
    end
    return messages
  end

end