Advance the minical to the month of next event (TEC3)

/**
 * Tries to force the minicalendar widget to show the month of the next upcoming event by default, rather
 * than simply showing the current month (which might be empty).
 */
class Tribe_Advance_Minical
{
    protected $target_date = false;


    /**
     * Sets up auto advance for minicalendar widgets. If an optional target date is provided that will be used to
     * set the month.
     *
     * @param bool $target_date
     */
    public function __construct($target_date = false) {
        if (is_string($target_date)) $this->set_target_date($target_date);
        add_filter('widget_display_callback', array($this, 'advance_minical'), 20, 2);
    }

    /**
     * Basic check to help filter out spurious date formats.
     *
     * @param $date
     */
    protected function set_target_date($date) {
        if (1 === preg_match('#^\d{4}-\d{2}(-\d{2})?$#', $date))
            $this->target_date = $date;
    }

    public function advance_minical($instance, $widget) {
        if ('tribe-mini-calendar' !== $widget->id_base) return $instance;
        if (isset($instance['eventDate'])) return $instance;
        $instance['eventDate'] = $this->determine_date();
        return $instance;
    }

    protected function determine_date() {
        return (false !== $this->target_date) ? $this->target_date : $this->next_upcoming_date();
    }

    protected function next_upcoming_date() {
        $next_event = tribe_get_events(array(
            'eventDisplay' => 'upcoming',
            'posts_per_page' => 1
        ));

        if (empty($next_event) || ! isset($next_event[0]->EventStartDate)) return date('Y-m');
        return substr($next_event[0]->EventStartDate, 0, 7); // Pull out the yyyy-dd portion
    }
}


/**
 * If we don't pass a parameter it will try to advance the calendar to the same month as the next upcoming event.
 * However, we can also pass in a specific month:
 *
 *     new Tribe_Advance_Minical('2014-12'); // Set it to December 2014
 */
new Tribe_Advance_Minical();