<?php

/**
 * @file
 * Contains facebook_pixel.module..
 */

use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Entity\Display\EntityViewDisplayInterface;
use Drupal\Component\Utility\Xss;
use Drupal\Core\Config\ImmutableConfig;

/**
 * Implements hook_help().
 */
function facebook_pixel_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    // Main module help for the facebook_pixel module.
    case 'help.page.facebook_pixel':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Facebook Pixel') . '</p>';
      return $output;

    default:
  }
}

/**
 * Implements hook_page_attachments().
 */
function facebook_pixel_page_attachments(array &$page) {
  $config = \Drupal::config('facebook_pixel.settings');

  if (!_facebook_pixel_request_should_be_tracked($config)) {
    return;
  }

  $id = $config->get('facebook_id');
  $jsIdString = Xss::filter($id);

  // Add registered events to the script execution.
  /** @var \Drupal\facebook_pixel\FacebookEvent $facebook_event */
  $facebook_event = \Drupal::service('facebook_pixel.facebook_event');

  $events = [];
  foreach ($facebook_event->getEvents() as $event) {
    $events[] = [
      'event' => Xss::filter($event['event']),
      'data' => Xss::filter(json_encode($event['data'])),
    ];
  }

  $page['#attached']['library'][] = "facebook_pixel/facebook_pixel";
  $page['#attached']['drupalSettings']['facebook_pixel'] = [
    'facebook_id' => $jsIdString,
    'events' => $events,
    'fb_disable_advanced' => $config->get('privacy.fb_disable_advanced'),
    'eu_cookie_compliance' => $config->get('privacy.eu_cookie_compliance'),
    'donottrack' => $config->get('privacy.donottrack'),
  ];
}

/**
 * Implements hook_page_top().
 */
function facebook_pixel_page_top(array &$page_bottom) {
  $config = \Drupal::config('facebook_pixel.settings');
  $id = $config->get('facebook_id');
  if (empty($id) || $config->get('privacy.disable_noscript_img')) {
    // Skip the noscript img fallback if there's no id or it is disabled due to
    // privacy settings.
    return;
  }
  $urlParameter = Xss::filter(urlencode($id));
  // Empty alt attribute is expected here:
  // @see https://www.w3.org/WAI/tutorials/images/decorative/
  $noscript = '<img src="https://www.facebook.com/tr?id=' . $urlParameter . '&ev=PageView&noscript=1" alt="" height="1" width="1" style="display:none" />';
  $page_bottom[] = [
    '#markup' => '<noscript>' . $noscript . '</noscript>',
    '#allowed_tags' => ['noscript', 'img'],
  ];
}

/**
 * Implements hook_entity_insert().
 */
function facebook_pixel_entity_insert(EntityInterface $entity) {
  $facebook_event = \Drupal::service('facebook_pixel.facebook_event');
  // Register new user event.
  if ($entity->getEntityType()->id() == 'user') {
    /** @var \Drupal\facebook_pixel\FacebookEvent $facebook_event */
    $facebook_event->addEvent('CompleteRegistration', $entity->id());
  }
}

/**
 * Implements hook_entity_view().
 */
function facebook_pixel_entity_view(array &$build, EntityInterface $entity, EntityViewDisplayInterface $display, $view_mode) {
  $facebook_event = \Drupal::service('facebook_pixel.facebook_event');

  if ($entity->getEntityType()->id() == 'node' && in_array($view_mode, [
    'default',
    'full',
  ])) {
    /** @var \Drupal\node\NodeInterface $entity */
    $data = [
      'content_name' => $entity->getTitle(),
      'content_type' => $entity->getType(),
      'content_ids' => [$entity->id()],
    ];
    $facebook_event->addEvent('ViewContent', $data);
  }
}

/**
 * Validate the facebook id configuration.
 *
 * @param \Drupal\Core\Config\ImmutableConfig $config
 *   The config object.
 *
 * @return bool
 *   Whether or not the facebook id is empty.
 */
function _facebook_pixel_facebook_id_configured(ImmutableConfig $config) {
  $facebook_id = $config->get('facebook_id');
  if (empty($facebook_id)) {
    return FALSE;
  }
  else {
    return TRUE;
  }
}

/**
 * Tracking visibility check for user roles.
 *
 * Based on visibility setting this function returns TRUE if JS code should
 * be added for the current role and otherwise FALSE.
 *
 * @param object $account
 *   A user object containing an array of roles to check.
 *
 * @return bool
 *   TRUE if JS code should be added for the current role and otherwise FALSE.
 */
function _facebook_pixel_visibility_roles($account) {
  $config = \Drupal::config('facebook_pixel.settings');

  $role_should_be_tracked = &drupal_static(__FUNCTION__);
  if (!isset($role_should_be_tracked)) {
    // First we get the user's roles and the ones configured for facebook_pixel.
    $account_roles = $account->getRoles();
    $configured_roles = $config->get('visibility.user_role_roles');

    // Now we can get the roles present in both lists
    // and check if there are any.
    $matching_roles = array_intersect($account_roles, $configured_roles);
    $user_has_any_role = count($matching_roles) > 0;
    $track_all_roles = $config->get('visibility.user_role_mode') === 'all_roles';

    // Either the user has a tracked role or no untracked role.
    $role_should_be_tracked = ($user_has_any_role xor $track_all_roles);
  }
  return $role_should_be_tracked;
}

/**
 * Tracking visibility check for pages.
 *
 * Based on visibility setting this function returns TRUE if JS code should
 * be added to the current page and otherwise FALSE.
 */
function _facebook_pixel_visibility_pages() {
  static $page_match;

  // Cache visibility result if function is called more than once.
  if (!isset($page_match)) {
    $path_should_be_tracked = &drupal_static(__FUNCTION__);

    // Cache tracking result if function is called more than once.
    if (!isset($path_should_be_tracked)) {
      $config = \Drupal::config('facebook_pixel.settings');

      $visible_path_mode = $config->get('visibility.request_path_mode');
      $visible_path_pages = $config->get('visibility.request_path_pages');

      // Match path if necessary.
      if (!empty($visible_path_pages)) {
        // Convert path to lowercase. This allows comparison of the same path
        // with different case. Ex: /Page, /page, /PAGE.
        $pages = mb_strtolower($visible_path_pages);

        $path = Drupal::service('path.current')->getPath();
        $path_alias = \Drupal::service('path_alias.manager')->getAliasByPath($path);
        if (empty($path_alias)) {
          $path_alias = mb_strtolower($path);
        }
        else {
          $path_alias = mb_strtolower($path_alias);
        }
        $page_match = \Drupal::service('path.matcher')->matchPath($path_alias, $pages) || (($path != $path_alias) && \Drupal::service('path.matcher')->matchPath($path, $pages));
        // When $visible_path_mode has a value of 'all_pages', the tracking
        // code is displayed on all pages except those listed in $pages. When
        // set to 'all_listed', it is displayed only on those pages listed in
        // $pages.
        $track_all_paths = ($visible_path_mode == 'all_pages');
        $path_should_be_tracked = ($track_all_paths xor $page_match);
      }
      else {
        $path_should_be_tracked = TRUE;
      }
    }
    return $path_should_be_tracked;
  }
}

/**
 * Checks the config, if the current request should be tracked.
 *
 * @param \Drupal\Core\Config\ImmutableConfig $config
 *   A config object.
 *
 * @return array|bool
 *   Whether or not the request should be tracked.
 */
function _facebook_pixel_request_should_be_tracked(ImmutableConfig $config) {
  $request_should_be_tracked = &drupal_static(__FUNCTION__);
  if (!isset($request_should_be_tracked)) {
    $request_should_be_tracked = _facebook_pixel_facebook_id_configured($config) && _facebook_pixel_visibility_pages() && _facebook_pixel_visibility_roles(\Drupal::currentUser());
  }
  return $request_should_be_tracked;
}