google_tag.module

<?php

/**
 * @file
 * Provides primary Drupal hook implementations.
 *
 * Adds a JavaScript snippet to selected page responses to trigger analytics and
 * other tracking items configured using the Google Tag Manager.
 *
 * @author Jim Berry ("solotandem", http://drupal.org/user/240748)
 */

use Drupal\Component\Utility\Unicode;
use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Default for matching all items except listed.
 */
const GOOGLE_TAG_EXCLUDE_LISTED = 'exclude listed';

/**
 * Default for matching only listed items.
 */
const GOOGLE_TAG_INCLUDE_LISTED = 'include listed';

/**
 * Directory to output scripts.
 */
const GOOGLE_TAG_DIR = 'public://google_tag/js';

/**
 * Implements hook_help().
 */
function google_tag_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    case 'help.page.google_tag':
    case 'google_tag.settings_form':
      return t('<a href=":url">Google Tag Manager</a> is a free service (registration required) to manage the insertion of tags for capturing website analytics.', [':url' => 'https://tagmanager.google.com/']);
  }
}

/**
 * Implements hook_page_attachments().
 */
function google_tag_page_attachments(&$attachments) {
  if (!google_tag_insert_snippet()) {
    return;
  }

  $config = \Drupal::config('google_tag.settings');
  $include_script_as_file = $config->get('include_file');

  // Add data_layer and script snippets to head (no longer by default).
  $weight = 9;
  if ($include_script_as_file) {
    foreach (['data_layer', 'script'] as $type) {
      // @todo Will it matter if file is empty?
      // @todo Check config for the whitelist and blacklist classes before adding.
      $attachments['#attached']['html_head'][] = _google_tag_file_tag($type, $weight++);
    }
  }
  else {
    foreach (['data_layer', 'script'] as $type) {
      // @see drupal_get_js() in 7.x core.
      // For inline JavaScript to validate as XHTML, all JavaScript containing
      // XHTML needs to be wrapped in CDATA.
      $attachment = _google_tag_inline_tag($type, $weight++);
      if (!empty($attachment)) {
        $attachments['#attached']['html_head'][] = $attachment;
      }
    }
  }
}

/**
 * Returns tag array for the snippet type.
 *
 * @param string $type
 *   The snippet type.
 * @param int $weight
 *   The weight of the item.
 *
 * @return array
 *   The tag array.
 */
function _google_tag_file_tag($type, $weight) {
  $uri = _google_tag_get_js_dir() . "/google_tag.$type.js";
  $url = file_url_transform_relative(file_create_url($uri));
  $query_string = \Drupal::state()->get('system.css_js_query_string') ?: '0';
  $attachment = [
    [
      '#type' => 'html_tag',
      '#tag' => 'script',
      '#attributes' => ['src' => $url . '?' . $query_string],
      '#weight' => $weight,
    ],
    "google_tag_{$type}_tag",
  ];
  return $attachment;
}

/**
 * Returns tag array for the snippet type.
 *
 * @param string $type
 *   The snippet type.
 * @param int $weight
 *   The weight of the item.
 *
 * @return array
 *   The tag array.
 */
function _google_tag_inline_tag($type, $weight) {
  $uri = _google_tag_get_js_dir() . "/google_tag.$type.js";
  $url = \Drupal::service('file_system')->realpath($uri);
  $contents = @file_get_contents($url);
  $attachment = $contents ? [
    [
      '#type' => 'html_tag',
      '#tag' => 'script',
      '#value' => $contents,
      '#weight' => $weight,
    ],
    "google_tag_{$type}_tag",
  ] : [];
  return $attachment;
}

/**
 * Implements hook_page_top().
 */
function google_tag_page_top(&$page) {
  if (!google_tag_insert_snippet()) {
    return;
  }

  // Add noscript snippet to page_top region.
  $uri = _google_tag_get_js_dir() . '/google_tag.noscript.js';
  $url = \Drupal::service('file_system')->realpath($uri);
  $contents = @file_get_contents($url);

  // Note: depending on the theme, this may not place the snippet immediately
  // after the body tag but should be close and it can be altered.

  // @see https://api.drupal.org/api/drupal/core!lib!Drupal!Core!Render!theme.api.php/group/theme_render/8.2.x
  // The markup is passed through \Drupal\Component\Utility\Xss::filterAdmin()
  // which strips known vectors while allowing a permissive list of HTML tags
  // that are not XSS vectors. (e.g., <script> and <style> are not allowed.)
  // @todo Core is removing the 'style' attribute from the noscript snippet.
  if ($contents) {
    $page['google_tag_noscript_tag'] = [
      '#markup' => $contents,
      '#allowed_tags' => ['noscript', 'iframe'],
      '#weight' => -10,
    ];
  }
}

/**
 * Determines whether to insert the snippet on the response.
 *
 * @return bool
 *   TRUE if the conditions are met; FALSE otherwise.
 */
function google_tag_insert_snippet() {
  static $satisfied;

  if (!isset($satisfied)) {
    $config = \Drupal::config('google_tag.settings');
    $id = $config->get('container_id');

    if (empty($id)) {
      // No container ID.
      return FALSE;
    }

    $satisfied = TRUE;
    if (!_google_tag_status_check() || !_google_tag_path_check() || !_google_tag_role_check()) {
      // Omit snippet if any condition is not met.
      $satisfied = FALSE;
    }

    // Allow other modules to alter the insertion criteria.
    \Drupal::moduleHandler()->alter('google_tag_insert', $satisfied);
  }
  return $satisfied;
}

/**
 * Determines whether to insert the snippet based on status code settings.
 *
 * @return bool
 *   TRUE if the status conditions are met; FALSE otherwise.
 */
function _google_tag_status_check() {
  static $satisfied;

  if (!isset($satisfied)) {
    $config = \Drupal::config('google_tag.settings');
    $toggle = $config->get('status_toggle');
    $statuses = $config->get('status_list');

    if (empty($statuses)) {
      $satisfied = ($toggle == GOOGLE_TAG_EXCLUDE_LISTED);
    }
    else {
      // Get the HTTP response status.
      $request = \Drupal::request();
      $status = '200';
      if ($exception = $request->attributes->get('exception')) {
        $status = $exception->getStatusCode();
      }
      $satisfied = strpos($statuses, (string) $status) !== FALSE;
      $satisfied = ($toggle == GOOGLE_TAG_EXCLUDE_LISTED) ? !$satisfied : $satisfied;
    }
  }
  return $satisfied;
}

/**
 * Determines whether to insert the snippet based on the path settings.
 *
 * @return bool
 *   TRUE if the path conditions are met; FALSE otherwise.
 */
function _google_tag_path_check() {
  static $satisfied;

  if (!isset($satisfied)) {
    $config = \Drupal::config('google_tag.settings');
    $toggle = $config->get('path_toggle');
    $paths = Unicode::strtolower($config->get('path_list'));

    if (empty($paths)) {
      $satisfied = ($toggle == GOOGLE_TAG_EXCLUDE_LISTED);
    }
    else {
      $request = \Drupal::request();
      $current_path = \Drupal::service('path.current');
      $alias_manager = \Drupal::service('path.alias_manager');
      $path_matcher = \Drupal::service('path.matcher');
      // @todo Are not some paths case sensitive???
      // Compare the lowercase path alias (if any) and internal path.
      $path = rtrim($current_path->getPath($request), '/');
      $path_alias = Unicode::strtolower($alias_manager->getAliasByPath($path));
      $satisfied = $path_matcher->matchPath($path_alias, $paths) || (($path != $path_alias) && $path_matcher->matchPath($path, $paths));
      $satisfied = ($toggle == GOOGLE_TAG_EXCLUDE_LISTED) ? !$satisfied : $satisfied;
    }
  }
  return $satisfied;
}

/**
 * Determines whether to insert the snippet based on the user role settings.
 *
 * @return bool
 *   TRUE if the role conditions are met; FALSE otherwise.
 */
function _google_tag_role_check() {
  static $satisfied;

  if (!isset($satisfied)) {
    $config = \Drupal::config('google_tag.settings');
    $toggle = $config->get('role_toggle');
    $roles = $config->get('role_list');
    $roles = array_filter($roles);

    if (empty($roles)) {
      $satisfied = ($toggle == GOOGLE_TAG_EXCLUDE_LISTED);
    }
    else {
      $satisfied = FALSE;
      // Check user roles against listed roles.
      $satisfied = (bool) array_intersect($roles, \Drupal::currentUser()->getRoles());
      $satisfied = ($toggle == GOOGLE_TAG_EXCLUDE_LISTED) ? !$satisfied : $satisfied;
    }
  }
  return $satisfied;
}

/**
 * Saves JS snippet files based on current settings.
 *
 * @return bool
 *   TRUE if at least some of the files were saved.
 *   This doesn't mean they were all saved.
 */
function google_tag_save_snippets() {
  // Save the altered snippets after hook_google_tag_snippets_alter().
  module_load_include('inc', 'google_tag', 'includes/snippet');

  // If there is more than one snippet some may be saved and some may fail.
  $saved = FALSE; $unsaved = FALSE;
  $dir = _google_tag_get_js_dir();
  $snippets = google_tag_snippets();
  foreach ($snippets as $type => $snippet) {
    if ($dir_exists = file_prepare_directory($dir, FILE_CREATE_DIRECTORY)) {
      $path = file_unmanaged_save_data($snippet, "{$dir}/google_tag.{$type}.js", FILE_EXISTS_REPLACE);
    }
    if ($dir_exists === TRUE && $path !== FALSE) {
      $saved = TRUE;
    }
    else {
      $unsaved = TRUE;
    }

  }
  if ($unsaved) {
    drupal_set_message(t('An error occurred saving one or more snippet files. Please try again or contact the site administrator if it persists.'));
  }
  if ($saved) {
    \Drupal::service('asset.js.collection_optimizer')->deleteAll();
    _drupal_flush_css_js();
    return TRUE;
  }
  return FALSE;
}

/**
 * Implements hook_rebuild().
 */
function google_tag_rebuild() {
  google_tag_save_snippets();
}

/**
 * Get's the public directory for storing google_tag files
 */
function _google_tag_get_js_dir() {
  $dir = GOOGLE_TAG_DIR;
  // Allow other modules to alter the directory.
  \Drupal::moduleHandler()->alter('google_tag_dir', $dir);
  return $dir;
}