FilterHtml.php

<?php

/**
 * @file
 * Contains \Drupal\filter\Plugin\Filter\FilterHtml.
 */
namespace Drupal\filter\Plugin\Filter;

use Drupal\filter\Annotation\Filter;
use Drupal\Core\Annotation\Translation;
use Drupal\filter\Plugin\FilterBase;

/**
 * Provides a filter to limit allowed HTML tags.
 *
 * @Filter(
 *   id = "filter_html",
 *   module = "filter",
 *   title = @Translation("Limit allowed HTML tags"),
 *   type = FILTER_TYPE_HTML_RESTRICTOR,
 *   settings = {
 *     "allowed_html" = "<a> <em> <strong> <cite> <blockquote> <code> <ul> <ol> <li> <dl> <dt> <dd> <h4> <h5> <h6>",
 *     "filter_html_help" = 1,
 *     "filter_html_nofollow" = 0
 *   },
 *   weight = -10
 * )
 */
class FilterHtml extends FilterBase {

  /**
   * {@inheritdoc}
   */
  public function settingsForm(array $form, array &$form_state) {
    $form['allowed_html'] = array(
      '#type' => 'textfield',
      '#title' => t('Allowed HTML tags'),
      '#default_value' => $this->settings['allowed_html'],
      '#maxlength' => 1024,
      '#description' => t('A list of HTML tags that can be used. JavaScript event attributes, JavaScript URLs, and CSS are always stripped.'),
    );
    $form['filter_html_help'] = array(
      '#type' => 'checkbox',
      '#title' => t('Display basic HTML help in long filter tips'),
      '#default_value' => $this->settings['filter_html_help'],
    );
    $form['filter_html_nofollow'] = array(
      '#type' => 'checkbox',
      '#title' => t('Add rel="nofollow" to all links'),
      '#default_value' => $this->settings['filter_html_nofollow'],
    );
    return $form;
  }

  /**
   * {@inheritdoc}
   */
  public function process($text, $langcode, $cache, $cache_id) {
    return _filter_html($text, $this);
  }

  /**
   * {@inheritdoc}
   */
  public function tips($long = FALSE) {
    global $base_url;
    if (!($allowed_html = $this->settings['allowed_html'])) {
      return;
    }
    $output = t('Allowed HTML tags: @tags', array(
      '@tags' => $allowed_html,
    ));
    if (!$long) {
      return $output;
    }
    $output = '<p>' . $output . '</p>';
    if (!$this->settings['filter_html_help']) {
      return $output;
    }
    $output .= '<p>' . t('This site allows HTML content. While learning all of HTML may feel intimidating, learning how to use a very small number of the most basic HTML "tags" is very easy. This table provides examples for each tag that is enabled on this site.') . '</p>';
    $output .= '<p>' . t('For more information see W3C\'s <a href="@html-specifications">HTML Specifications</a> or use your favorite search engine to find other sites that explain HTML.', array(
      '@html-specifications' => 'http://www.w3.org/TR/html/',
    )) . '</p>';
    $tips = array(
      'a' => array(
        t('Anchors are used to make links to other pages.'),
        '<a href="' . $base_url . '">' . check_plain(config('system.site')
          ->get('name')) . '</a>',
      ),
      'br' => array(
        t('By default line break tags are automatically added, so use this tag to add additional ones. Use of this tag is different because it is not used with an open/close pair like all the others. Use the extra " /" inside the tag to maintain XHTML 1.0 compatibility'),
        t('Text with <br />line break'),
      ),
      'p' => array(
        t('By default paragraph tags are automatically added, so use this tag to add additional ones.'),
        '<p>' . t('Paragraph one.') . '</p> <p>' . t('Paragraph two.') . '</p>',
      ),
      'strong' => array(
        t('Strong', array(), array(
          'context' => 'Font weight',
        )),
        '<strong>' . t('Strong', array(), array(
          'context' => 'Font weight',
        )) . '</strong>',
      ),
      'em' => array(
        t('Emphasized'),
        '<em>' . t('Emphasized') . '</em>',
      ),
      'cite' => array(
        t('Cited'),
        '<cite>' . t('Cited') . '</cite>',
      ),
      'code' => array(
        t('Coded text used to show programming source code'),
        '<code>' . t('Coded') . '</code>',
      ),
      'b' => array(
        t('Bolded'),
        '<b>' . t('Bolded') . '</b>',
      ),
      'u' => array(
        t('Underlined'),
        '<u>' . t('Underlined') . '</u>',
      ),
      'i' => array(
        t('Italicized'),
        '<i>' . t('Italicized') . '</i>',
      ),
      'sup' => array(
        t('Superscripted'),
        t('<sup>Super</sup>scripted'),
      ),
      'sub' => array(
        t('Subscripted'),
        t('<sub>Sub</sub>scripted'),
      ),
      'pre' => array(
        t('Preformatted'),
        '<pre>' . t('Preformatted') . '</pre>',
      ),
      'abbr' => array(
        t('Abbreviation'),
        t('<abbr title="Abbreviation">Abbrev.</abbr>'),
      ),
      'acronym' => array(
        t('Acronym'),
        t('<acronym title="Three-Letter Acronym">TLA</acronym>'),
      ),
      'blockquote' => array(
        t('Block quoted'),
        '<blockquote>' . t('Block quoted') . '</blockquote>',
      ),
      'q' => array(
        t('Quoted inline'),
        '<q>' . t('Quoted inline') . '</q>',
      ),
      // Assumes and describes tr, td, th.
      'table' => array(
        t('Table'),
        '<table> <tr><th>' . t('Table header') . '</th></tr> <tr><td>' . t('Table cell') . '</td></tr> </table>',
      ),
      'tr' => NULL,
      'td' => NULL,
      'th' => NULL,
      'del' => array(
        t('Deleted'),
        '<del>' . t('Deleted') . '</del>',
      ),
      'ins' => array(
        t('Inserted'),
        '<ins>' . t('Inserted') . '</ins>',
      ),
      // Assumes and describes li.
      'ol' => array(
        t('Ordered list - use the &lt;li&gt; to begin each list item'),
        '<ol> <li>' . t('First item') . '</li> <li>' . t('Second item') . '</li> </ol>',
      ),
      'ul' => array(
        t('Unordered list - use the &lt;li&gt; to begin each list item'),
        '<ul> <li>' . t('First item') . '</li> <li>' . t('Second item') . '</li> </ul>',
      ),
      'li' => NULL,
      // Assumes and describes dt and dd.
      'dl' => array(
        t('Definition lists are similar to other HTML lists. &lt;dl&gt; begins the definition list, &lt;dt&gt; begins the definition term and &lt;dd&gt; begins the definition description.'),
        '<dl> <dt>' . t('First term') . '</dt> <dd>' . t('First definition') . '</dd> <dt>' . t('Second term') . '</dt> <dd>' . t('Second definition') . '</dd> </dl>',
      ),
      'dt' => NULL,
      'dd' => NULL,
      'h1' => array(
        t('Heading'),
        '<h1>' . t('Title') . '</h1>',
      ),
      'h2' => array(
        t('Heading'),
        '<h2>' . t('Subtitle') . '</h2>',
      ),
      'h3' => array(
        t('Heading'),
        '<h3>' . t('Subtitle three') . '</h3>',
      ),
      'h4' => array(
        t('Heading'),
        '<h4>' . t('Subtitle four') . '</h4>',
      ),
      'h5' => array(
        t('Heading'),
        '<h5>' . t('Subtitle five') . '</h5>',
      ),
      'h6' => array(
        t('Heading'),
        '<h6>' . t('Subtitle six') . '</h6>',
      ),
    );
    $header = array(
      t('Tag Description'),
      t('You Type'),
      t('You Get'),
    );
    preg_match_all('/<([a-z0-9]+)[^a-z0-9]/i', $allowed_html, $out);
    foreach ($out[1] as $tag) {
      if (!empty($tips[$tag])) {
        $rows[] = array(
          array(
            'data' => $tips[$tag][0],
            'class' => array(
              'description',
            ),
          ),
          array(
            'data' => '<code>' . check_plain($tips[$tag][1]) . '</code>',
            'class' => array(
              'type',
            ),
          ),
          array(
            'data' => $tips[$tag][1],
            'class' => array(
              'get',
            ),
          ),
        );
      }
      else {
        $rows[] = array(
          array(
            'data' => t('No help provided for tag %tag.', array(
              '%tag' => $tag,
            )),
            'class' => array(
              'description',
            ),
            'colspan' => 3,
          ),
        );
      }
    }
    $output .= theme('table', array(
      'header' => $header,
      'rows' => $rows,
    ));
    $output .= '<p>' . t('Most unusual characters can be directly entered without any problems.') . '</p>';
    $output .= '<p>' . t('If you do encounter problems, try using HTML character entities. A common example looks like &amp;amp; for an ampersand &amp; character. For a full list of entities see HTML\'s <a href="@html-entities">entities</a> page. Some of the available characters include:', array(
      '@html-entities' => 'http://www.w3.org/TR/html4/sgml/entities.html',
    )) . '</p>';
    $entities = array(
      array(
        t('Ampersand'),
        '&amp;',
      ),
      array(
        t('Greater than'),
        '&gt;',
      ),
      array(
        t('Less than'),
        '&lt;',
      ),
      array(
        t('Quotation mark'),
        '&quot;',
      ),
    );
    $header = array(
      t('Character Description'),
      t('You Type'),
      t('You Get'),
    );
    unset($rows);
    foreach ($entities as $entity) {
      $rows[] = array(
        array(
          'data' => $entity[0],
          'class' => array(
            'description',
          ),
        ),
        array(
          'data' => '<code>' . check_plain($entity[1]) . '</code>',
          'class' => array(
            'type',
          ),
        ),
        array(
          'data' => $entity[1],
          'class' => array(
            'get',
          ),
        ),
      );
    }
    $output .= theme('table', array(
      'header' => $header,
      'rows' => $rows,
    ));
    return $output;
  }

}