Reset Invoice Number Monthly

Hello @janbong

If you set the the prefix with the placeholders for year and month correctly, the number can be reset with this code snippet:

do_action( 'wpo_wcpdf_before_sequential_number_increment', 'wpo_wcpdf_reset_invoice_number_monthly', 10, 3 );
function wpo_wcpdf_reset_invoice_number_monthly( $number_store, $order_id, $date ) {
    $current_month = date('n');
    $last_number_month = $number_store->get_last_date('n');
    // check if we need to reset
    if ( $current_month != $last_number_month ) {
        $number_store->set_next( 1 );
    }
}