Revision for 'fast forward the calendar widget' code

fast-forward-mini-cal.php

<?php
/**
 * 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_admin() ) return;
		$this->target_date = $target_date;
		add_action( 'wp_loaded', array( $this, 'set_target_date' ) );
		add_filter( 'widget_display_callback', array( $this, 'advance_minical' ), 20, 2 );
	}

	/**
	 * Basic check to help filter out spurious date formats or automatically determine
	 * the next most appropriate date to use.
	 */
	public function set_target_date() {
		if ( ! is_string($this->target_date) || 1 !== preg_match( '#^\d{4}-\d{2}(-\d{2})?$# ', $this->target_date ) )
			$this->target_date = $this->next_upcoming_date();
	}

	public function advance_minical( $instance, $widget ) {
		if ( 'tribe-mini-calendar' !== $widget->id_base || isset( $instance['eventDate'] ) ) return $instance;
		if ( date( 'Y-m' ) === $this->target_date) return;
		add_action('pre_get_posts', 'include_categories',100,1);
		add_action( 'tribe_before_get_template_part', array( $this, 'modify_list_query' ), 5 );
		$instance['eventDate'] = $this->target_date;
		return $instance;
	}

	public function include_categories() {
		//Categories to include
		$include_cats = array('featured');

		//Join current tax query if it's set
		if(is_array($wp_query->tax_query))
			$tax_query = $wp_query->tax_query;
		else
			$tax_query = array();

		//Setup an include from the tribe_events_cat taxonomy
		$tax_query = array(
			'taxonomy' => 'tribe_events_cat',
			'field' => 'slug',
			'terms' => $include_cats,
			'operator' => 'IN'
		);

		if(tribe_is_event_query()){
			$wp_query->set('tax_query',$tax_query);
		}

		return $wp_query;
	}

	public function modify_list_query( $template ) {
		if ( false === strpos( $template, 'mini-calendar/list.php' ) ) return;
		add_action( 'parse_query', array( $this, 'amend_list_query' ) );
	}

	public function amend_list_query( $query ) {
		remove_action( 'parse_query', array( $this, 'amend_list_query' ) ); // Run this once only
		$the_query = $query->query_vars;

		$the_query['start_date'] = $this->target_date . '-01';
		$last_day = TribeDateUtils::getLastDayOfMonth( strtotime( $the_query['start_date'] ) );
		$the_query['end_date'] = substr_replace( $the_query['start_date'], $last_day, -2 );
		$the_query['end_date'] = TribeDateUtils::endOfDay( $the_query['end_date'] );
		$query->query_vars = $the_query;
	}

	protected function next_upcoming_date() {
		$next_event = tribe_get_events( array(
			'eventDisplay' => 'list',
			'posts_per_page' => 1,
			'start_date' => date( 'Y-m-d' )
		));

		$start_date = date( 'Y-m' );

		if ( !empty( $next_event ) || isset( $next_event[0] ) ) {
			$next_event_date = tribe_get_start_date( $next_event[0]->ID, false, 'Y-m' );

			// Prevent calendar from rewinding to the start of a currently ongoing event
			$start_date = ( $next_event_date > $start_date ) ? $next_event_date : $start_date;
		}

		return $start_date;
	}


}

/**
 * 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();