/**
 * Implements hook_mail().
 */
function ipnotification_mail($key, &$message, $params) {
  $options = array(
    'langcode' => $message['langcode'],
  );
  switch ($key) {
    case 'entity_create':
      $message['from'] = Drupal::config('system.site')->get('mail');
      $message['subject'] = $this->t('%entity created', ['%entity' => $params['title']], $options);
      $message['body'][] = Html::escape($params['message']);
      break;
    case 'entity_delete':
      $message['from'] = Drupal::config('system.site')->get('mail');
      $message['subject'] = $this->t('%entity deleted', ['%entity' => $params['title']], $options);
      $message['body'][] = $params['message'];
      break;
    case 'entity_update':
      $message['from'] = Drupal::config('system.site')->get('mail');
      $message['subject'] = $this->t('%entity updated', ['%entity' => $params['title']], $options);
      $message['body'][] = $params['message'];
      break;
    case 'user_login':
      $message['from'] = Drupal::config('system.site')->get('mail');
      $message['subject'] = $this->t('User has logged in', $options);
      $message['body'][] = $params['message'];
      break;
    case 'user_logout':
      $message['from'] = Drupal::config('system.site')->get('mail');
      $message['subject'] = $this->t('User has logged out', $options);
      $message['body'][] = $params['message'];
      break;
  }
}

/**
   * Send email to site admin.
   *
   * @param string $key
   *    The mail key to check on 5 available entity_create, entity_delete, entity_update, user_login, user_logout.
   * @param string $entity_label
   *    The label of the current entity.
   * @param string $link
   *    The link where stuff happened.
   */
  public function sendMail($key, $entity_label, $link) {
    $module = 'ipnotfiication';
    $to = Drupal::config('system.site')->get('mail');
    $params['title'] = $entity_label;
    $params['user'] = $this->user->getAccountName();
    $params['date'] = date('Y-m-d H:i:s');
    $params['mail'] = $this->user->getEmail();
    $params['link'] = $link;
    if (strpos('entity', $key)) {
      if (strpos('create', $key)) {
        $params['message'] = $this->t('User %user created Entity %link: %title',
          array('%title' => $params['title'], '%link' => $params['link']));
      }
      if (strpos('delete', $key)) {
        $params['message'] = $this->t('User %user deleted Entity %link: %title',
          array('%title' => $params['title'], '%link' => $params['link']));
      }
      if (strpos('update', $key)) {
        $params['message'] = $this->t('User %user updated Entity %link: %title',
          array('%title' => $params['title'], '%link' => $params['link']));
      }
    }
    else {
      if (strpos('login', $key)) {
        $params['message'] = $this->t('User %user has logged in on %date ',
          array(
            '%user' => $params['user'],
            '%date' => $params['date'],
          ));
      }
      else {
        $params['message'] = $this->t('User %user has logged out on %date ',
          array(
            '%user' => $params['user'],
            '%date' => $params['date'],
          ));
      }
    }
    $langcode = $this->user->getPreferredLangcode();
    $send = true;
    $result = $this->mailManager->mail($module, $key, $to, $langcode, $params, NULL, $send);

    if ($result['result'] !== true) {
      drupal_set_message(t('There was a problem sending your message and it was not sent.'), 'error');
    }
    else {
     drupal_set_message(t('Your message has been sent.'));
    }
  }