Code-Snippets-Functions/Execute a function on a child site/WooCommerce/add-free-product-when-coupon-is-applied.txt

function action_woocommerce_applied_coupon( $coupon_code ) {
    // Settings
    $product_id = 131468;
    $quantity = 1;
    $free_price = 0;
    $coupon_codes = array( 'coupon1', 'mybday' );

    // Compare
    if ( in_array( $coupon_code, $coupon_codes ) ) {
        // Add product to cart
        WC()->cart->add_to_cart( $product_id, $quantity, 0, array(), array( 'free_price' => $free_price ) );
    }
}
add_action( 'woocommerce_applied_coupon', 'action_woocommerce_applied_coupon', 10, 1 );

// Set free price from custom cart item data
function action_woocommerce_before_calculate_totals( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) ) return;

    if ( did_action( 'woocommerce_before_calculate_totals' ) >= 2 ) return;

    // Loop through cart contents
    foreach ( $cart->get_cart_contents() as $cart_item ) {       
        if ( isset( $cart_item['free_price'] ) ) {
            $cart_item['data']->set_price( $cart_item['free_price'] );
        }
    }
}
add_action( 'woocommerce_before_calculate_totals', 'action_woocommerce_before_calculate_totals', 10, 1 );