nofollowlist.module in Nofollow List 6

File

nofollowlist.module

<?php

/**
 * Implementation of hook_menu()
 */
function nofollowlist_menu() {
  $items['admin/settings/nofollowlist'] = array(
    'title' => 'Nofollowlist',
    'description' => 'Add sites to the nofollowlist and determine whether links to those sites are followable or not.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array(
      'nofollowlist_settings_form',
    ),
    'access callback' => 'user_access',
    'access arguments' => array(
      'administer nofollowlist',
    ),
  );
  return $items;
}

/**
 * Implementation of hook_perm().
 */
function nofollowlist_perm() {
  return array(
    'administer nofollowlist',
  );
}

/**
 * Builds the form for administrators to add sites to the black/white lists.
 */
function nofollowlist_settings_form() {
  $form['nofollowlist_option'] = array(
    '#type' => 'radios',
    '#title' => t('Hosts list option'),
    '#description' => t('If you choose the whitelist option, be sure to add your own site to the list!'),
    '#options' => array(
      'black' => t('Blacklist: Add rel="nofollow" to links leading to the listed hosts.'),
      'white' => t('Whitelist: Add rel="nofollow" to all links <b>except</b> the listed hosts.'),
    ),
    '#default_value' => variable_get('nofollowlist_option', 'black'),
  );
  $form['nofollowlist_hosts'] = array(
    '#type' => 'textarea',
    '#title' => t('Nofollowlist hosts'),
    '#description' => t('Add one host per line. Ex: en.wikipedia.org'),
    '#default_value' => variable_get('nofollowlist_hosts', 'en.wikipedia.org'),
  );
  return system_settings_form($form);
}

/**
 * Enter description here...
 *
 * @param string $section
 *   A Drupal path
 * @return string
 *   The help text
 */
function nofollowlist_help($path, $arg) {
  switch ($path) {
    case 'admin/help#nofollowlist':
      $output = '<p>' . t('This module implements a simple filter to add the nofollow tag to sites that are on your blacklist or to all sites except those on your whitelist.') . '</p>';
      return $output;
  }
}

/**
 * Implementation of hook_filter_tips()
 *
 * @param int $delta
 *   Used when a module defines more than one filter
 * @param unknown_type $format
 * @param boolean $long
 *   Determines whether the long or the short tip version is displayed
 * @return string
 *   The tip to be displayed
 */
function nofollowlist_filter_tips($delta, $format, $long = false) {
  $output .= '<p>' . t('Links to specified hosts will have a rel="nofollow" added to them.') . "</p>\n";
  return $output;
}

/**
 * Implementation of hook_filter. Defines a filter, "Nofollow list filter",
 * that can be used in conjunction with the built in HTML filter to 
 * automatically add the rel="nofollow" to links to certain sites 
 *
 * @param string $op
 * @param int $delta
 * @param int $format
 * @param string $text
 *   The text to be filtered
 * @return string
 */
function nofollowlist_filter($op, $delta = 0, $format = -1, $text = '') {
  switch ($op) {
    case 'list':
      return array(
        0 => t('Nofollow list filter'),
      );
    case 'description':
      return t('Links to specified hosts will have a rel="nofollow" added to them.');
    case "process":
      $text = preg_replace_callback('!<a.*?href="([^"]+)".*?>!', 'nofollowlist_replace', $text);
      return $text;
    default:
      return $text;
  }
}

/**
 * Inserts a nofollow class if the domain passed in is in the blacklist.
 *
 * @param string $input
 * @return boolean
 *   true if all the hosts are on the whitelist, false if any host is not.
 */
function nofollowlist_replace($match) {
  $url = parse_url($match[1]);
  $list = preg_split('/\\s+/', variable_get('nofollowlist_hosts', 'en.wikipedia.org'));

  // Default in case it doesn't get changed.
  $link = $match[0];

  // Handle relative links by adding base_url to the host
  if (empty($url['host'])) {
    $url['host'] = parse_url($GLOBALS['base_url'], PHP_URL_HOST);
  }

  // Matches if the list is set as a blacklist and the host is in the list or if
  // the list is set as a whitelist and the host is not found in the list.
  if (variable_get('nofollowlist_option', 'black') == 'black' && in_array($url['host'], $list) || variable_get('nofollowlist_option', 'black') == 'white' && !in_array($url['host'], $list)) {
    if (strpos($match[0], 'nofollow') === FALSE) {

      // Only add the nofollow if it doesn't already exist.
      if (strpos($match[0], 'rel="') === FALSE) {

        // It is faster to use PHP's string functions then complex regexes
        // In this case we strip off the last > in the <a> and then append our class and close the tag
        $link = substr($match[0], 0, -1);
        $link .= ' rel="nofollow">';
      }
      else {

        // Append outgoing class if this <a> already has a class.
        $link = preg_replace('!rel="([^"]+)"!', 'rel="${1} nofollow"', $match[0]);
      }
    }
  }
  return $link;
}

Functions

Name	Description
nofollowlist_filter	Implementation of hook_filter. Defines a filter, "Nofollow list filter", that can be used in conjunction with the built in HTML filter to automatically add the rel="nofollow" to links to certain sites
nofollowlist_filter_tips	Implementation of hook_filter_tips()
nofollowlist_help	Enter description here...
nofollowlist_menu	Implementation of hook_menu()
nofollowlist_perm	Implementation of hook_perm().
nofollowlist_replace	Inserts a nofollow class if the domain passed in is in the blacklist.
nofollowlist_settings_form	Builds the form for administrators to add sites to the black/white lists.