Create WooCommerce coupons programmatically - a proof of concept - Experiment creating virtual coupons for WooCommerce. This is a proof of concept that will be developed to verify a coupon code with an external source. https://www.damiencarbery.com/2018/10/create-woocommerce-coupons-programmatically-a-proof-of-concept/

wc-virtual-coupons.php

<?php
/*
Plugin Name: Virtual Coupons for WooCommerce
Plugin URI: https://www.damiencarbery.com/2018/10/create-woocommerce-coupons-programmatically-a-proof-of-concept/
Description: Experiment with a virtual coupon, based on a conversation with Mark Davenport.
Author: Damien Carbery
Author URI: https://www.damiencarbery.com
Version: 0.2
*/


function dcwd_is_coupon_code_valid( $coupon_code ) {
	if ( 0 === strpos( $coupon_code, 'gr-' ) ) {  // Coupon codes are lowercased.
		// TODO: Also check that the coupon is available for use and not already used.
		return true;
	}
	return false;
}


// Inspired by https://www.mootpoint.org/blog/create-woocommerce-coupon-programmatically/
add_filter ( 'woocommerce_get_shop_coupon_data', 'dcwd_create_virtual_coupon', 10, 2  );
function dcwd_create_virtual_coupon( $false, $data ) {
	// Do not interfere with coupon creation and editing.
	if ( is_admin() ) {
		return $false;
	}

	$coupon_code_valid = false;
	$coupon_settings = null;

	if ( dcwd_is_coupon_code_valid( $data ) ) {  
		$coupon_code_valid = true;
	}

	if ( $coupon_code_valid ) {
		// Create a coupon with the properties you need
		$coupon_settings = array(
			'discount_type'              => 'percent', // 'fixed_cart', 'percent' or 'fixed_product'
			'amount'                     => 50, // value or percentage.
			'expiry_date'                => '2019-09-01', // YYYY-MM-DD

			'individual_use'             => false,
			'product_ids'                => array(),
			'exclude_product_ids'        => array(),
			'usage_limit'                => '',
			'usage_limit_per_user'       => '1',
			'limit_usage_to_x_items'     => '',
			'usage_count'                => '',
			'free_shipping'              => false,
			'product_categories'         => array(),
			'exclude_product_categories' => array(),
			'exclude_sale_items'         => false,
			'minimum_amount'             => '',
			'maximum_amount'             => '',
			'customer_email'             => array(),
			);

		return $coupon_settings;
	}
	return $false;
}


// From: https://stackoverflow.com/questions/49675017/woocommerce-get-shop-coupon-data-being-called-3-times
add_action('woocommerce_applied_coupon', 'action_applied_coupon' );
function action_applied_coupon( $coupon_code ) {
	if ( dcwd_is_coupon_code_valid( $coupon_code ) ) {
		error_log( "Coupon '$coupon_code' has been applied. Mark as used." );
	}
}
add_action('woocommerce_removed_coupon', 'action_removed_coupon' );
function action_removed_coupon( $coupon_code ) {
	if ( dcwd_is_coupon_code_valid( $coupon_code ) ) {
		error_log( "Coupon '$coupon_code' has been removed. Mark as UNused." );
	}
}

using this approach, is the virtual coupon not stored to the WooCommerce coupon?