<?php

namespace rbRedirection;

defined( 'ABSPATH' ) || exit;

/**
 * A published post gets a new address (slug, parent, date in the permalink):
 * the old address redirects to the post with a 301, so links and search
 * results keep working.
 */
class SlugWatcher {

	/** permalinks before the save, by post id */
	private static $before = array();

	public static function init(): void {
		add_action( 'pre_post_update', array( self::class, 'remember' ), 10, 1 );
		add_action( 'post_updated', array( self::class, 'compare' ), 10, 3 );
		add_action( 'wp_after_insert_post', array( self::class, 'claim' ), 10, 2 );
	}

	/**
	 * A published post at an address an automatic redirect still sends away
	 * (a freed slug taken by a new post): the redirect is no longer needed.
	 * A redirect someone made by hand stays.
	 */
	public static function claim( $post_id, $post ): void {
		if ( ! self::watched( $post ) ) {
			return;
		}
		$address = Url::normalize( (string) get_permalink( $post ) );
		if ( $address === '' || $address === '/' ) {
			return;
		}
		$row = Redirects::find_exact( $address, false );
		if ( $row && Redirects::is_automatic( $row ) ) {
			Redirects::delete( array( (int) $row->id ) );
		}
	}

	public static function remember( $post_id ): void {
		if ( ! Settings::get( 'slugWatch' ) || ! self::watched( get_post( $post_id ) ) ) {
			return;
		}
		self::$before[ (int) $post_id ] = get_permalink( $post_id );
	}

	public static function compare( $post_id, $after, $before ): void {
		$post_id = (int) $post_id;
		if ( ! isset( self::$before[ $post_id ] ) ) {
			return;
		}
		$old_link = self::$before[ $post_id ];
		unset( self::$before[ $post_id ] );
		// only a page people could have found: published before and after
		if ( $before->post_status !== 'publish' || $after->post_status !== 'publish' ) {
			return;
		}
		$new_link = get_permalink( $post_id );
		$old      = Url::normalize( (string) $old_link );
		$new      = Url::normalize( (string) $new_link );
		if ( $old === '' || $old === $new || $old === '/' ) {
			return;
		}

		// the post goes back to an address it had: that redirect would loop
		$back = Redirects::find_exact( $new, false );
		if ( $back && (int) $back->target_post_id === $post_id ) {
			Redirects::delete( array( (int) $back->id ) );
		}

		$existing = Redirects::find_exact( $old, false );
		if ( $existing ) {
			if ( (int) $existing->target_post_id === $post_id ) {
				return;
			}
			if ( $existing->origin !== 'slug' ) {
				return; // a redirect someone made by hand wins
			}
		}
		Redirects::add( array(
			'source'         => $old,
			'target'         => Url::path( $new ),
			'target_post_id' => $post_id,
			'code'           => 301,
			'origin'         => 'slug',
			/* translators: %s: post title */
			'note'           => sprintf( __( 'Address of "%s" changed', 'rb-links-redirection' ), get_the_title( $post_id ) ),
		) );

		// a page with subpages: their addresses moved too — one rule for the whole branch
		if ( is_post_type_hierarchical( $after->post_type ) && get_children( array( 'post_parent' => $post_id, 'post_type' => $after->post_type, 'post_status' => 'publish', 'numberposts' => 1, 'fields' => 'ids' ) ) ) {
			Redirects::add( array(
				'source'     => '^' . preg_quote( Url::path( $old ), '' ) . '/(.+)$',
				'match_type' => 'regex',
				'target'     => Url::path( $new ) . '/$1',
				'code'       => 301,
				'origin'     => 'slug',
				/* translators: %s: page title */
				'note'       => sprintf( __( 'Subpages of "%s" moved', 'rb-links-redirection' ), get_the_title( $post_id ) ),
			) );
		}
	}

	private static function watched( $post ): bool {
		if ( ! $post instanceof \WP_Post || $post->post_status !== 'publish' ) {
			return false;
		}
		$type = get_post_type_object( $post->post_type );
		return $type && $type->public && ! in_array( $post->post_type, array( 'attachment' ), true );
	}
}