e url of the link.
	 * @param array  $home_url The home url, as parsed by wp_parse_url.
	 *
	 * @return string The link's permalink.
	 */
	protected function build_permalink( $url, $home_url ) {
		$permalink = $this->get_permalink( $url, $home_url );

		if ( $this->url_helper->is_relative( $permalink ) ) {
			// Make sure we're checking against the absolute URL, and add a trailing slash if the site has a trailing slash in its permalink settings.
			$permalink = $this->url_helper->ensure_absolute_url( \user_trailingslashit( $permalink ) );
		}

		return $permalink;
	}

	/**
	 * Filters out links that point to the same page with a fragment or query.
	 *
	 * @param SEO_Links $link        The link.
	 * @param array     $current_url The url of the page the link is on, as parsed by wp_parse_url.
	 *
	 * @return bool Whether or not the link should be filtered.
	 */
	protected function filter_link( SEO_Links $link, $current_url ) {
		$url = $link->parsed_url;

		// Always keep external links.
		if ( $link->type === SEO_Links::TYPE_EXTERNAL ) {
			return true;
		}

		// Always keep links with an empty path or pointing to other pages.
		if ( isset( $url['path'] ) ) {
			return empty( $url['path'] ) || $url['path'] !== $current_url['path'];
		}

		// Only keep links to the current page without a fragment or query.
		return ( ! isset( $url['fragment'] ) && ! isset( $url['query'] ) );
	}

	/**
	 * Updates the link counts for related indexables.
	 *
	 * @param Indexable   $indexable The indexable.
	 * @param SEO_Links[] $links     The link models.
	 *
	 * @return void
	 */
	protected function update_related_indexables( $indexable, $links ) {
		// Old links were only stored by post id, so remove all old seo links for this post that have no indexable id.
		// This can be removed if we ever fully clear all seo links.
		if ( $indexable->object_type === 'post' ) {
			$this->seo_links_repository->delete_all_by_post_id_where_indexable_id_null( $indexable->object_id );
		}

		$updated_indexable_ids = [];
		$old_links             = $this->seo_links_repository->find_all_by_indexable_id( $indexable->id );

		$links_to_remove = $this->links_diff( $old_links, $links );
		$links_to_add    = $this->links_diff( $links, $old_links );

		if ( ! empty( $links_to_remove ) ) {
			$this->seo_links_repository->delete_many_by_id( \wp_list_pluck( $links_to_remove, 'id' ) );
		}

		if ( ! empty( $links_to_add ) ) {
			$this->seo_links_repository->insert_many( $links_to_add );
		}

		foreach ( $links_to_add as $link ) {
			if ( $link->target_indexable_id ) {
				$updated_indexable_ids[] = $link->target_indexable_id;
			}
		}
		foreach ( $links_to_remove as $link ) {
			if ( $link->target_indexable_id ) {
				$updated_indexable_ids[] = $link->target_indexable_id;
			}
		}

		$this->update_incoming_links_for_related_indexables( $updated_indexable_ids );
	}

	/**
	 * Creates a diff between two arrays of SEO links, based on urls.
	 *
	 * @param SEO_Links[] $links_a The array to compare.
	 * @param SEO_Links[] $links_b The array to compare against.
	 *
	 * @return SEO_Links[] Links that are in $links_a, but not in $links_b.
	 */
	protected function links_diff( $links_a, $links_b ) {
		return \array_udiff(
			$links_a,
			$links_b,
			static function ( SEO_Links $link_a, SEO_Links $link_b ) {
				return \strcmp( $link_a->url, $link_b->url );
			}
		);
	}

	/**
	 * Returns the number of internal links in an array of link models.
	 *
	 * @param SEO_Links[] $links The link models.
	 *
	 * @return int The number of internal links.
	 */
	protected function get_internal_link_count( $links ) {
		$internal_link_count = 0;

		foreach ( $links as $link ) {
			if ( $link->type === SEO_Links::TYPE_INTERNAL ) {
				++$internal_link_count;
			}
		}

		return $internal_link_count;
	}

	/**
	 * Returns a cleaned permalink for a given link.
	 *
	 * @param string $link     The raw URL.
	 * @param array  $home_url The home URL, as parsed by wp_parse_url.
	 *
	 * @return string The cleaned permalink.
	 */
	protected function get_permalink( $link, $home_url ) {
		// Get rid of the #anchor.
		$url_split = \explode( '#', $link );
		$link      = $url_split[0];

		// Get rid of URL ?query=string.
		$url_split = \explode( '?', $link );
		$link      = $url_split[0];

		// Set the correct URL scheme.
		$link = \set_url_scheme( $link, $home_url['scheme'] );

		// Add 'www.' if it is absent and should be there.
		if ( \strpos( $home_url['host'], 'www.' ) === 0 && \strpos( $link, '://www.' ) === false ) {
			$link = \str_replace( '://', '://www.', $link );
		}

		// Strip 'www.' if it is present and shouldn't be.
		if ( \strpos( $home_url['host'], 'www.' ) !== 0 ) {
			$link = \str_replace( '://www.', '://', $link );
		}

		return $link;
	}

	/**
	 * Updates incoming link counts for related indexables.
	 *
	 * @param int[] $related_indexable_ids The IDs of all related indexables.
	 *
	 * @return void
	 */
	protected function update_incoming_links_for_related_indexables( $related_indexable_ids ) {
		if ( empty( $related_indexable_ids ) ) {
			return;
		}

		$counts = $this->seo_links_repository->get_incoming_link_counts_for_indexable_ids( $related_indexable_ids );
		if ( \wp_cache_supports( 'flush_group' ) ) {
			\wp_cache_flush_group( 'orphaned_counts' );
		}

		foreach ( $counts as $count ) {
			$this->indexable_repository->update_incoming_link_count( $count['target_indexable_id'], $count['incoming'] );
		}
	}
}