metatag-8.x-1.x-dev/metatag_mobile/metatag_mobile.module

<?php

/**
 * @file
 * Contains metatag_mobile.module..
 */

use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;

/**
 * Implements hook_help().
 */
function metatag_mobile_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    // Main module help for the metatag_mobile module.
    case 'help.page.metatag_mobile':
      $output = '';
      $output .= '<h3>' . (string) new TranslatableMarkup('About') . '</h3>';
      $output .= '<p>' . (string) new TranslatableMarkup('Provides support for meta tags used to control the mobile browser experience.') . '</p>';
      return $output;

    default:
  }
}

/**
 * Implements hook_page_attachments_alter().
 */
function metatag_mobile_page_attachments_alter(array &$attachments) {
  // @todo This does not seem to still work, see HandheldFriendly.
  if (isset($attachments['#attached']['html_head'])) {
    // A list of core tags that will be replaced, in the format:
    // core tag => Metatag-supplied tag(s)
    // This assumes that the module's meta tags are output *before* the core
    // tags, if this changes then We're Going To Have A Bad Time. Also, the
    // Metatag output can have a "_0" suffix, which is why they need to be in
    // an array.
    $dupes = [
      'MobileOptimized' => ['mobileoptimized', 'mobileoptimized_0'],
      'HandheldFriendly' => ['handheldfriendly', 'handheldfriendly_0'],
      'viewport' => ['viewport'],
    ];

    // Keep track of when the Metatag-supplied meta tags are found, so if the
    // core tag is also found it can be removed.
    $found = [];

    foreach ($dupes as $core_tag => $meta_tags) {
      foreach ($attachments['#attached']['html_head'] as $key => $item) {
        if (isset($item[1])) {
          // The Metatag values are output before core's, so skip the first item
          // found so it can be picked up as the dupe; this is important for the
          // "viewport" meta tag where both core and Metatag use the same name.
          if (in_array($item[1], $meta_tags) && !isset($found[$core_tag])) {
            $found[$core_tag] = $key;
          }
          elseif ($item[1] == $core_tag && isset($found[$core_tag])) {
            // @todo This ought to work, but doesn't?
            // @code
            // $attachments['#attached']['html_head'][$key]['#access'] = FALSE;
            // @endcode
            unset($attachments['#attached']['html_head'][$key]);
          }
        }
      }
    }
  }
}