pojo-schedule-zoninator.php

<?php

/*
Plugin Name: Pojo Schedule post into Zoninator zone
Depends: Zone Manager (Zoninator)
Description: Inserts scheduled posts into the Zoninator zones on publication
Author: Vladimir Smotesko, Boyle Software, Pojo Team
Version: 1.0.0
Author URI: http://pojo.me/
Text Domain: schedule-zoninator
Domain Path: /languages/
License: GPLv2 or later

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

final class Pojo_Schedule_Zoninator {

	const nonce_field = 'schedule_zoninator_nonce';

	const zone_id_key = 'schedule_zone_zone_id';

	const position_key = 'schedule_zone_position';

	/**
	 * @var Zoninator instance of Zoninator plugin
	 */
	private $zoninator;
	private $zone_posts = array(); // local cache variable

	private static $_instance;

	private function __construct() {
		add_action( 'init', array( $this, 'check_zoninator' ) );
	}

	/**
	 * Throw error on object clone
	 *
	 * The whole idea of the singleton design pattern is that there is a single
	 * object therefore, we don't want the object to be cloned.
	 *
	 * @since 1.0.1
	 * @return void
	 */
	public function __clone() {
		// Cloning instances of the class is forbidden
		_doing_it_wrong( __FUNCTION__, __( 'Cheatin&#8217; huh?', 'schedule-zoninator' ), '1.0.1' );
	}

	/**
	 * Disable unserializing of the class
	 *
	 * @since 1.0.1
	 * @return void
	 */
	public function __wakeup() {
		// Unserializing instances of the class is forbidden
		_doing_it_wrong( __FUNCTION__, __( 'Cheatin&#8217; huh?', 'schedule-zoninator' ), '1.0.1' );
	}

	/**
	 * @return Pojo_Schedule_Zoninator
	 */
	public static function get_instance() {
		if ( is_null( self::$_instance ) )
			self::$_instance = new Pojo_Schedule_Zoninator();
		return self::$_instance;
	}

	public function check_zoninator() {
		global $zoninator;
		if (
			isset( $zoninator ) &&
			$zoninator instanceof Zoninator
		) {
			$this->zoninator = $zoninator;
			$this->init_plugin();
		} else {
			add_action( 'admin_notices', array( $this, 'zoninator_not_found_notice' ) );
		}

		load_plugin_textdomain( 'schedule-zoninator', false, basename( dirname( __FILE__ ) ) . '/languages' );
	}

	private function init_plugin() {
		add_action( 'add_meta_boxes', array( $this, 'add_meta_boxes' ) );
		add_action( 'save_post', array( $this, 'save_post' ) );
		add_action( 'publish_future_post', array( $this, 'publish_future_post' ) );
	}
	
	public function zoninator_not_found_notice() {
		?>
		<div class="error">
			<p>
				<?php _e(
					'Zoninator plugin is not installed or not activated! Zoninator schedule will not work.',
					'schedule-zoninator'
				);
				?>
			</p>
		</div>
	<?php
	}

	public function add_meta_boxes() {
		add_meta_box(
			'schedule_zone',
			__( 'Schedule post into zone', 'schedule-zoninator' ),
			array( $this, 'metaboxes_zone' ),
			'post',
			'side'
		);
	}

	public function metaboxes_zone( $post ) {
		$available_zones  = $this->zoninator->get_zones();
		$selected_zone_id = get_post_meta( $post->ID, self::zone_id_key, true );
		$current_position = get_post_meta( $post->ID, self::position_key, true );
		wp_nonce_field( self::nonce_field, self::nonce_field );
		?>
		<p>
			<label for="<?php echo self::zone_id_key; ?>"><?php _e( 'Zone', 'schedule-zoninator' ); ?>
			</label><br />
			<select name="<?php echo self::zone_id_key; ?>"
			        id="<?php echo self::zone_id_key; ?>">
				<option value=""><?php _e( 'Select zone', 'schedule-zoninator' ); ?></option>
				<?php foreach ( $available_zones as $available_zone ): ?>
					<option value="<?php echo $available_zone->term_id; ?>"
						<?php
						echo ( $selected_zone_id == $available_zone->term_id ) ?
							'selected="selected"' :
							'';
						?>
						>
						<?php echo $available_zone->name; ?>
					</option>
				<?php endforeach; ?>
			</select>
		</p>
		<p>
			<label for="<?php echo self::position_key; ?>"><?php _e( 'Position', 'schedule-zoninator' ); ?>
			</label><br />
			<input type="number"
			       value="<?php echo $current_position; ?>"
			       name="<?php echo self::position_key; ?>"
			       id="<?php echo self::position_key; ?>" />
		</p>
		<?php if (
			( $selected_zone_id && ! $current_position ) ||
			( ! $selected_zone_id && $current_position )
		): ?>
			<p>
				<?php _e( 'You have selected only one setting. Post will not be put into zone without both settings.', 'schedule-zoninator' ); ?>
			</p>
		<?php endif; ?>
		<p class="description">
			<?php _e( 'Your scheduled post will be put into the selected zone.', 'schedule-zoninator' ); ?>
		</p>
		<p class="description">
			<?php _e( 'Position is a number, usually from 1 to 10.', 'schedule-zoninator' ); ?>
		</p>
	<?php
	}

	public function save_post( $post_id ) {
		if ( wp_is_post_revision( $post_id ) )
			return;
		if ( ! isset( $_POST[ self::nonce_field ] ) || ! wp_verify_nonce( $_POST[ self::nonce_field ], self::nonce_field ) )
			return;
		if ( ! current_user_can( 'edit_post', $post_id ) )
			return;
		if ( isset( $_POST[ self::zone_id_key ] ) && $_POST[ self::zone_id_key ] ) {
			$zone_id = absint( $_POST[ self::zone_id_key ] );
			if ( $this->zoninator->zone_exists( $zone_id ) )
				update_metadata( 'post', $post_id, self::zone_id_key, $zone_id );
		} else {
			delete_metadata( 'post', $post_id, self::zone_id_key );
		}
		if ( isset( $_POST[ self::position_key ] ) && $_POST[ self::position_key ] ) {
			$position = absint( $_POST[ self::position_key ] );
			if ( $position > 0 )
				update_metadata( 'post', $post_id, self::position_key, $position );
		} else {
			delete_metadata( 'post', $post_id, self::position_key );
		}
	}

	public function publish_future_post( $post_id ) {
		$zone_id  = intval( get_metadata( 'post', $post_id, self::zone_id_key, true ) );
		$position = intval( get_metadata( 'post', $post_id, self::position_key, true ) );
		delete_metadata( 'post', $post_id, self::zone_id_key );
		delete_metadata( 'post', $post_id, self::position_key );
		if ( ! $zone_id ) {
			return;
		}
		if ( ! $position ) {
			return;
		}
		if ( ! $this->zone_exists( $zone_id ) ) {
			return;
		}
		$posts = $this->get_zone_posts( $zone_id );
		if ( count( $posts ) < $position ) {
			$posts[] = $post_id;
		} else {
			array_splice( $posts, ( $position - 1 ), 0, array( $post_id ) );
		}
		$this->update_zone_posts( $zone_id, $posts );
	}

	/*
	   * I had to create the following four functions because the Zoninator's ones 
	   * are not working during the publish_future_post hook execution:
	   * zone_exists()
	   * get_zone_posts()
	   * update_zone_posts()
	   * clear_zone_posts()
	   */
	/**
	 * Check whether the Zoninator zone exists
	 *
	 * @param int $zone_id
	 *
	 * @return boolean
	 */
	private function zone_exists( $zone_id ) {
		global $wpdb;

		return ( $wpdb->get_var(
				"SELECT COUNT(term_taxonomy_id)
						FROM {$wpdb->term_taxonomy}
						WHERE term_id = $zone_id
							AND taxonomy = '{$this->zoninator->zone_taxonomy}'"
			) > 0 );
	}

	/**
	 * Get the Zoninator zone's posts
	 *
	 * @param int $zone_id
	 *
	 * @return array posts IDs
	 */
	private function get_zone_posts( $zone_id ) {
		if (
			isset( $this->zone_posts[ $zone_id ] ) &&
			is_array( $this->zone_posts[ $zone_id ] )
		) {
			return $this->zone_posts[ $zone_id ];
		}
		global $wpdb;
		$this->zone_posts[ $zone_id ] = $wpdb->get_col(
			"SELECT {$wpdb->postmeta}.post_id
					FROM {$wpdb->postmeta}
					WHERE {$wpdb->postmeta}.meta_key = 
						'{$this->zoninator->zone_meta_prefix}$zone_id'
					ORDER BY {$wpdb->postmeta}.meta_value ASC"
		);

		return $this->zone_posts[ $zone_id ];
	}

	/**
	 * Overwrite zone posts
	 *
	 * @param int   $zone_id
	 * @param array $posts
	 *
	 * @return boolean
	 */
	private function update_zone_posts( $zone_id, $posts ) {
		$this->clear_zone_posts( $zone_id );
		foreach ( $posts as $n => $post_id ) {
			update_metadata(
				'post',
				$post_id,
				$this->zoninator->zone_meta_prefix . $zone_id,
				$n + 1
			);
		}
		clean_term_cache( $zone_id, $this->zoninator->zone_taxonomy );

		return true;
	}

	/**
	 * Clear zone from posts
	 *
	 * @param int $zone_id
	 *
	 * @return boolean
	 */
	private function clear_zone_posts( $zone_id ) {
		foreach ( $this->get_zone_posts( $zone_id ) as $post_id ) {
			delete_post_meta(
				$post_id,
				$this->zoninator->zone_meta_prefix . $zone_id
			);
		}
		$this->zone_posts[ $zone_id ] = null;

		return true;
	}
}
Pojo_Schedule_Zoninator::get_instance();