[Incsub Support] - Redirects to custom thank you page after new ticket submit.

incsub-support-custom-redirect.php

<?php
/**
* Plugin Name: [Incsub Support] - Custom redirect
* Plugin URI: https://premium.wpmudev.org/
* Description: Redirects to custom thank you page after ticket submit.
* Author: Panos Lyrakis @ WPMUDEV
* Author URI: https://premium.wpmudev.org/
* License: GPLv2 or later
*/
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

if ( ! class_exists( 'WPMUDEV_PS_Sites_Options' ) ) {
    
    class WPMUDEV_PS_Sites_Options {
        private static $_instance = null;
        private static $_thank_you_page = null;
        
        public static function get_instance() {
            if( is_null( self::$_instance ) ){
                self::$_instance = new WPMUDEV_PS_Sites_Options();
            }
            return self::$_instance;
            
        }

        private function __construct() {

            self::$_thank_you_page = 2746;
            add_action( 'support_system_insert_ticket', array( $this, 'custom_redirect' ), 10 );
            add_shortcode( 'wpmudev_support_ticket_link', array( $this, 'ticket_link_sh' ) );
            add_filter( 'query_vars', array( $this, 'query_vars' ), 10 );

        }

        public function custom_redirect(){

            wp_redirect( add_query_arg( 'tid', $ticket_id, get_permalink( self::$_thank_you_page ) ) );
            exit;
            
        }

        public function ticket_link_sh( $atts ){

            $atts = shortcode_atts(
            array(
                'tid' => null
            ), $atts, 'wpmudev_support_ticket_link_sc' );
        
            if( is_null( $tid ) ){
                $tid = get_query_var('tid');
            }

            $out = '';
            $redirect_to = incsub_support_get_support_page_url();
			if ( $redirect_to ) {
                $out = sprintf( '<a href="%1s">%2s</a>', 
                    add_query_arg( 'tid', $tid, $redirect_to ),
                    __( 'View ticket' ) );
			}
            
            return $out;
        }

        public function query_vars( $vars ){

            $vars[] = 'tid';
            return $vars;
        }

    }

    add_action( 'plugins_loaded', function(){
        $GLOBALS['WPMUDEV_PS_Sites_Options'] = WPMUDEV_PS_Sites_Options::get_instance();
    }, 10 );

}