Add new WooComerce Webhook topic only for order completed

class-custom-wc-webhook-mangager

<?php 
/*
Custom WC Webhook Manager
Add new webhook topic only for WC order completed.
Developed by Md Jahidul Islam ( oneTarek ) https://onetarek.com
*/ 

//Don't allow direct access
if( ! defined( 'ABSPATH' ) ) exit;


if( ! class_exists( 'Custom_WC_Webhook_Manager' ) ) :
    
    class Custom_WC_Webhook_Manager {
        
        public function __construct() {  
            
            add_filter('woocommerce_webhook_topics', array( $this, 'add_custom_webhook_topics' ), 10, 1 );
            add_action('woocommerce_order_status_completed', array( $this, 'on_woocommerce_order_status_completed' ), 10, 2 );
            add_filter('woocommerce_webhook_payload', array( $this, 'add_custom_webhook_payload' ), 10, 4 );

        }

    
        /*
        Custom topics must start with 'action.woocommerce_' or 'action.wc_'
        described in the function wc_is_webhook_valid_topic
        If the topic name starts with 'action' then there must has a wp hook named with the string used after dot(.)
        So for this Topic we must have a wp hook 'wc_custom_order_completed'.
        Adding custom topic hooks using filter 'woocommerce_webhook_topic_hooks' does not work here.
        */

        public function add_custom_webhook_topics( $topics ){
        	$topics['action.wc_custom_order_completed'] = 'Custom Order completed';
        	return $topics;
        }

        //Trigger wc_custom_order_completed hook on woocommerce_order_status_completed hook.
        public function on_woocommerce_order_status_completed( $order_id, $order ){
        	//We could use 'woocommerce_order_status_completed' hook name directly with the topic name.
        	//But we are not using that direclty because , if in future WC pluign add new topic using that hook.
        	do_action('wc_custom_order_completed', $order_id, $order );
        }

        /*
         * Set payload for our custom topic.
         */
        public function add_custom_webhook_payload( $payload, $resource, $resource_id, $webhook_id ) {
        	
        	if( isset( $payload['action'] ) && $payload['action'] == 'wc_custom_order_completed' && !empty( $payload['arg'] ) ) {
        		$webhook = wc_get_webhook( $webhook_id );
			// Build the payload with the same user context as the user who created
			// the webhook -- this avoids permission errors as background processing
			// runs with no user context.
			//See build_payload() in woocommerce/includes/class-wc-webhook.php
			$current_user = get_current_user_id();
			wp_set_current_user( $webhook->get_user_id() );

        		$version = str_replace( 'wp_api_', '', $webhook->get_api_version() );
        		$resource = 'order';
			$payload = wc()->api->get_endpoint_data( "/wc/{$version}/{$resource}s/{$resource_id}" );
			
			// Restore the current user.
			wp_set_current_user( $current_user );
				
        	}
        	return $payload;
        }
    
    }//end class
    
endif;

$Custom_WC_Webhook_Manager = new Custom_WC_Webhook_Manager();