Redirect old slugs

function pm_detect_old_slugs() {
    global $wp_query, $wp, $wpdb;

    // Stop if any post or term was already found by Permalink Manager
    if(!empty($wp_query->query['do_not_redirect']) || !empty($wp_query->query_vars['do_not_redirect']) || (!is_404())) {
        return;
    }

    // Get all the endpoints & pattern
    if(class_exists('Permalink_Manager_Helper_Functions')) {
        $endpoints = Permalink_Manager_Helper_Functions::get_endpoints();
        $pattern = "/^(.+?)(?|\/({$endpoints})(?|\/(.*)|$)|\/()([\d]+)\/?)?$/i";
    } else {
        $pattern = '/([^\/]+)?(?:\/([\d]+))?/';
    }

    // Get the string from URL
    preg_match($pattern, $wp->request, $parts);
    if(!empty($parts[1])) {
        $slug = basename($parts[1]);
        $post_id = $wpdb->get_var($wpdb->prepare("SELECT post_id from {$wpdb->postmeta} WHERE meta_key = '_wp_old_slug' AND meta_value LIKE '%%%s%%'", $slug));

        // Parse the endpoints
        $endpoint = (!empty($parts[2])) ? $parts[2] : '';
        $endpoint_value = (!empty($parts[3])) ? $parts[3] : '';

        // Redirect if any post with old slug was found
        if(!empty($post_id)) {
            $permalink = get_permalink($post_id);

            if(!empty($endpoint_value) || !empty($endpoint)) {
                if(empty($endpoint) && is_numeric($endpoint_value)) {
                    $permalink = sprintf("%s/%d", trim($permalink, "/"), $endpoint_value);
                } else if(isset($endpoint) && !empty($endpoint_value)) {
                    $permalink = sprintf("%s/%s/%s", trim($permalink, "/"), $endpoint, $endpoint_value);
                } else {
                    $permalink = sprintf("%s/%s", trim($permalink, "/"), $endpoint);
                }
            }

            wp_safe_redirect($permalink, 301);
            exit();
        }
    }
}
add_action('template_redirect', 'pm_detect_old_slugs', 0);