ap_delete_images_not_in_content( integer $post_id )

function ap_delete_images_not_in_content( $post_id ) {
	$_post = ap_get_post( $post_id );

	preg_match_all( '/<img.*?src\s*="([^"]+)".*?>/', $_post->post_content, $matches, PREG_SET_ORDER );

	$new_matches = array();

	if ( ! empty( $matches ) ) {
		foreach ( $matches as $m ) {
			$new_matches[] = basename( $m[1] );
		}
	}

	$images = get_post_meta( $post_id, 'anspress-image' );

	// Make sure WP_Filesystem is loaded.
	if ( ! function_exists( 'WP_Filesystem' ) ) {
		require_once ABSPATH . 'wp-admin/includes/file.php';
	}

	// Initialize WP_Filesystem.
	if ( ! \WP_Filesystem() ) {
		// Unable to initialize WP_Filesystem, handle error accordingly.
		return;
	}

	global $wp_filesystem;

	if ( ! empty( $images ) ) {
		// Delete image if not in $matches.
		foreach ( $images as $img ) {
			if ( ! in_array( $img, $new_matches, true ) ) {
				delete_post_meta( $post_id, 'anspress-image', $img );

				$uploads = wp_upload_dir();
				$file    = $uploads['basedir'] . "/anspress-uploads/$img";
				$wp_filesystem->delete( $file );
			}
		}
	}
}