rsvpmaker-mailpoet.php

<?php

add_filter('mailpoet_newsletter_shortcode', 'mailpoet_rsvpmaker_shortcode', 10, 5);

function mailpoet_rsvpmaker_shortcode($shortcode, $newsletter, $subscriber, $queue, $newsletter_body) {
  // always return the shortcode if it doesn't match your own!
  if (!strpos($shortcode,'rsvpmaker') && !strpos($shortcode,'event_listing') ) return $shortcode;
  global $email_context;
  $email_context = true;
  $shortcode = str_replace('custom:','',$shortcode);
  return do_shortcode($shortcode);
}

//this function is called whenever a submitted RSVP form includes the "Add me to your email list" checkbox
function mailpoet_email_list_okay($rsvp) {
	if (class_exists(\MailPoet\API\API::class)) {
		$mailpoet_api = \MailPoet\API\API::MP('v1');
		$list = get_option('rsvpmaker_mailpoet_list');
		if(!$list)
			return;
		$list_ids = array($list);
		$mailpoet_api = \MailPoet\API\API::MP('v1');
		$first = (empty($rsvp['first'])) ? '' : $rsvp['first'];
		$last = (empty($rsvp['last'])) ? '' : $rsvp['last'];
		$subscriber = array('email' => $rsvp['email'], 'first_name' => $first,'last_name' => $last);
			try {
				$get_subscriber = $mailpoet_api->getSubscriber($subscriber['email']);
			  } catch (\Exception $e) {}			
			  try {
				if (!$get_subscriber) {
				  // Subscriber doesn't exist let's create one
				  $mailpoet_api->addSubscriber($subscriber, $list_ids);
				} else {
				  // In case subscriber exists just add him to new lists
				  $mailpoet_api->subscribeToLists($subscriber['email'], $list_ids);
				}
			  } catch (\Exception $e) {
				$error_message = $e->getMessage();
			  }
	}
}