Custom conditional placeholder {waitlist_open}

<?php


function em_event_output_show_condition( $show, $condition, $full_match, $EM_Event ){

  switch ($condition) {

	  case 'waitlist_open' :

		$is_fully_booked    = $EM_Event->get_bookings()->get_available_spaces() <= 0;
		$is_waitlists_limit = get_option('dbem_waitlists_limit');

		if( !empty($EM_Event->event_attributes['waitlist_limit']) ){
		  $is_waitlists_limit= $EM_Event->event_attributes['waitlist_limit'];
		}

		$is_waitlist_enable = get_option('dbem_waitlists');
		if( !empty($EM_Event->event_attributes['waitlist']) ){
			$is_waitlist_enable = $EM_Event->event_attributes['waitlist'];
		}

		$show = $is_waitlist_enable && $is_fully_booked && $is_waitlists_limit;

		break;

  }

  return $show;
}
add_filter('em_event_output_show_condition', 'em_event_output_show_condition', 100, 4);