affiliatewp-woocommerce-product-cat-fix.php

<?php
/**
 * Plugin Name: AffiliateWP - WooCommerce Product Categories Fix
 * Plugin URI: https://affiliatewp.com
 * Description: Fixes product category 404s when used in conjunction with pretty affiliate URLs.
 * Author: AffiliateWP, LLC
 * Author URI: https://affiliatewp.com
 * Version: 1.0
 *
 * AffiliateWP Debug is distributed under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * any later version.
 *
 * AffiliateWP is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with AffiliateWP. If not, see <http://www.gnu.org/licenses/>.
 *
 * @package AffiliateWP
 * @category Add-on
 * @author Drew Jaynes
 * @version 1.0
 */

add_filter( 'rewrite_rules_array', function( $rules ) {

	if ( ! function_exists( 'WC' ) || ! function_exists( 'affiliate_wp' ) ) {
		return $rules;
	}

	if ( true === version_compare( WC()->version, '3.0.0', '>=' ) ) {
		$permalinks = wc_get_permalink_structure();
	} else {
		$permalinks = get_option( 'woocommerce_permalinks' );
	}

	$category_base = empty( $permalinks['category_base'] ) ? _x( 'product-category', 'slug', 'woocommerce' ) : $permalinks['category_base'];
	$ref           = affiliate_wp()->tracking->get_referral_var();

	$category_rules = array(
		$category_base . '/(.+?)/' . $ref . '(/(.*))?/?$' => 'index.php?product_cat=$matches[1]&' . $ref . '=$matches[3]'
	);

	$rules = array_merge( $category_rules, $rules );

	return $rules;

}, 11 );