basic wordpress custom endpoint

wordpress-custom-endpoint.php

<?php
  /**
   *
   * Change 'custom-request' to anything you want
   *
	 * Register custom rules
	 * Hooked via filter generate_rewrite_rules, priority 999
	 * @param Object $wp_rewrite
	 */
  function set_custom_rules($wp_rewrite)
	{
		$wp_rewrite->rules = array_merge([
			'custom-request/([^/]+)/?$'	=> 'index.php?custom-request=$matches[1]'
		],$wp_rewrite->rules);
	}

	/**
	 * Add custom query vars
	 * Hooked via filter query_vars, priority 999
	 * @param 	array $vars
	 * @return 	array
	 */
	function add_query_vars($vars)
	{
		$vars[]	= 'custom-request';
		return $vars;
	}

	/**
	 * Check endpoint request
	 * Hooked via action template_redirect, priority 999
	 * @return void
	 */
	function check_request()
	{
		global $wp_query;
		if(get_query_var('valor-data')) :
			header("HTTP/1.1 200 OK");
			if('cart' === get_query_var('valor-data')) :
				$this->do_cart();
			elseif('submit' === get_query_var('valor-data')) :
				$this->do_order();
			endif;
		endif;
	}
?>