Code-Snippets-Functions/Execute a function on a child site/WooCommerce/display-a-different-message-if-its-customer-first-order.txt

function action_wpo_wcpdf_after_document_label( $document_type, $order ) { 
    if ( 'packing-slip' !== $document_type ) return; // Target only Packing slip
    
    // Get customer ID or billing email
    $customer = $order->get_user_id() ?: $order->get_billing_email();
  
    if ( ! $customer ) return; // Exit if no customer ID or billing email

    // Get the previous customer payed order ID (array)
    $previous_order_id = wc_get_orders( array(
        'type'        => 'shop_order',
        'status'      => wc_get_is_paid_statuses(),
        'customer'    => $customer,
        'exclude'     => array( $order->get_id() ),
        'limit'       => 1, 
        'return'      => 'ids'
    ) );
        
    printf( "\n".'<p class="form-field form-field-wide" style="font-weight:bold;margin-top:-60px;border:1px solid;width:90px;padding:3px 10px 5px 10px;line-height:1;text-align:center;">%s</p>'."\n",
        $previous_order_id ? esc_html__('Existing Customer') : esc_html__('New Customer') 
    );
}

add_action( 'wpo_wcpdf_after_document_label', 'action_wpo_wcpdf_after_document_label', 10, 2 );