JezK

Edit File: monitor.php

<?php

class Red_Monitor {
	private $monitor_group_id;
	private $updated_posts = array();
	private $monitor_types = array();
	private $associated = '';

public function __construct( $options ) {
		$this->monitor_types = apply_filters( 'redirection_monitor_types', isset( $options['monitor_types'] ) ? $options['monitor_types'] : array() );

if ( count( $this->monitor_types ) > 0 && $options['monitor_post'] > 0 ) {
			$this->monitor_group_id = intval( $options['monitor_post'], 10 );
			$this->associated = isset( $options['associated_redirect'] ) ? $options['associated_redirect'] : '';

// Only monitor if permalinks enabled
			if ( get_option( 'permalink_structure' ) ) {
				add_action( 'pre_post_update', array( $this, 'pre_post_update' ), 10, 2 );
				add_action( 'post_updated', array( $this, 'post_updated' ), 11, 3 );
				add_filter( 'redirection_remove_existing', array( $this, 'remove_existing_redirect' ) );
				add_filter( 'redirection_permalink_changed', array( $this, 'has_permalink_changed' ), 10, 3 );

if ( in_array( 'trash', $this->monitor_types ) ) {
					add_action( 'wp_trash_post', array( $this, 'post_trashed' ) );
				}
			}
		}
	}

public function remove_existing_redirect( $url ) {
		Red_Item::disable_where_matches( $url );
	}

public function can_monitor_post( $post, $post_before ) {
		// Check this is for the expected post
		if ( ! isset( $post->ID ) || ! isset( $this->updated_posts[ $post->ID ] ) ) {
			return false;
		}

// Don't do anything if we're not published
		if ( $post->post_status !== 'publish' || $post_before->post_status !== 'publish' ) {
			return false;
		}

$type = get_post_type( $post->ID );
		if ( ! in_array( $type, $this->monitor_types ) ) {
			return false;
		}

return true;
	}

/**
	 * Called when a post has been updated - check if the slug has changed
	 */
	public function post_updated( $post_id, $post, $post_before ) {
		if ( isset( $this->updated_posts[ $post_id ] ) && $this->can_monitor_post( $post, $post_before ) ) {
			$this->check_for_modified_slug( $post_id, $this->updated_posts[ $post_id ] );
		}
	}

/**
	 * Remember the previous post permalink
	 */
	public function pre_post_update( $post_id, $data ) {
		$this->updated_posts[ $post_id ] = get_permalink( $post_id );
	}

public function post_trashed( $post_id ) {
		$data = array(
			'url'         => wp_parse_url( get_permalink( $post_id ), PHP_URL_PATH ),
			'action_data' => array( 'url' => '/' ),
			'match_type'  => 'url',
			'action_type' => 'url',
			'action_code' => 301,
			'group_id'    => $this->monitor_group_id,
			'status'      => 'disabled',
		);

// Create a new redirect for this post, but only if not draft
		if ( $data['url'] !== '/' ) {
			Red_Item::create( $data );
		}
	}

/**
	 * Changed if permalinks are different and the before wasn't the site url (we don't want to redirect the site URL)
	 */
	public function has_permalink_changed( $result, $before, $after ) {
		// Check it's not redirecting from the root
		if ( $this->get_site_path() === $before || $before === '/' ) {
			return false;
		}

// Are the URLs the same?
		if ( $before === $after ) {
			return false;
		}

return true;
	}

private function get_site_path() {
		$path = wp_parse_url( get_site_url(), PHP_URL_PATH );

if ( $path ) {
			return rtrim( $path, '/' ) . '/';
		}

return '/';
	}

public function check_for_modified_slug( $post_id, $before ) {
		$after  = wp_parse_url( get_permalink( $post_id ), PHP_URL_PATH );
		$before = wp_parse_url( esc_url( $before ), PHP_URL_PATH );

if ( apply_filters( 'redirection_permalink_changed', false, $before, $after ) ) {
			do_action( 'redirection_remove_existing', $after, $post_id );

$data = array(
				'url'         => $before,
				'action_data' => array( 'url' => $after ),
				'match_type'  => 'url',
				'action_type' => 'url',
				'action_code' => 301,
				'group_id'    => $this->monitor_group_id,
			);

// Create a new redirect for this post
			$new_item = Red_Item::create( $data );

if ( ! is_wp_error( $new_item ) ) {
				do_action( 'redirection_monitor_created', $new_item, $before, $post_id );

if ( ! empty( $this->associated ) ) {
					// Create an associated redirect for this post
					$data['url'] = trailingslashit( $data['url'] ) . ltrim( $this->associated, '/' );
					$data['action_data'] = array( 'url' => trailingslashit( $data['action_data']['url'] ) . ltrim( $this->associated, '/' ) );
					Red_Item::create( $data );
				}
			}

return true;
		}

return false;
	}
}