Auto update countdown widget: move it to the next available event if it's target has already started

dynamically-update-countdown-widget__ecp.4.4.php

<?php
/**
 * Updates instances of the Countdown Widget so that they always
 * point to an event which has not yet started.
 *
 * This works by intercepting events before the widget is rendered:
 * if it looks like the event the widget is targeting has already
 * started, the object will select the next upcoming event (if one
 * is available) and set the widget to use that instead.
 *
 * Tested with Events Calendar PRO 4.4 (in development)
 */
class Perpetual_Countdown_Widget {
	protected $instance;
	protected $widget;
	protected $next_event;

	public function __construct() {
		add_filter( 'widget_display_callback', array( $this, 'listen' ), 10, 2 );
	}

	public function listen( $instance, $widget ) {
		$this->instance = $instance;
		$this->widget = $widget;

		if (
			$widget->id_base !== 'tribe-events-countdown-widget'
			|| ! $this->current_event_has_started()
			|| ! $this->get_next_event()
		) {
			return $instance;
		}

		$this->update_instance();
		return $this->instance;
	}

	/**
	 * Checks if the current target event has started or not.
	 *
	 * @return bool
	 */
	protected function current_event_has_started() {
		// Load the widget's current target event
		$target_event = current( tribe_get_events( array( 'p' => $this->instance['event'] ) ) );

		// Check if it's a valid event that has already started
		if (
			$target_event
			&& date( 'Y-m-d H:i:s' ) >= $target_event->_EventStartDateUTC
		) {
			return true;
		}

		return false;
	}

	/**
	 * Fetches the next suitable event for the countdown widget,
	 * if one is available and returns true (else returns false).
	 *
	 * Be nice to use WP_Query or tribe_get_events() here, but a
	 * straight select will be used instead to avoid unwanted side
	 * effects.
	 *
	 * @returns bool
	 */
	protected function get_next_event() {
		global $wpdb;

		$query = "
			SELECT DISTINCT( ID )
			FROM   $wpdb->posts
			JOIN   $wpdb->postmeta ON post_id = ID
			
			WHERE  post_type  = 'tribe_events'
			  AND  meta_key   = '_EventStartDateUTC'
			  AND  meta_value > %s
			  
			ORDER BY meta_value ASC
			
			LIMIT  1
		";

		$next_id = $wpdb->get_var( $wpdb->prepare(
			$query, date( 'Y-m-d H:i:s', strtotime( '+1 second' ) )
		) );

		$next_event = get_post( $next_id );

		if ( ! $next_id || $next_event->ID != $next_id ) {
			return false;
		}

		$this->next_event = $next_event;
		return true;
	}

	protected function update_instance() {
		$this->instance['event'] = $this->instance['event_id'] = $this->next_event->ID;
		$this->widget->save_settings( array( $this->widget->number => $this->instance ) );
	}
}

new Perpetual_Countdown_Widget;