topnotch_website/app/Observers/OrderObserver.php

<?php

namespace App\Observers;

use App\Models\Invoice;
use App\Models\Order;

class OrderObserver
{
    /**
     * Handle the Order "created" event.
     */
    public function created(Order $order): void
    {
        if ($order->invoice != null) {
            $order->invoice->calculateTotals();
        }
    }

    /**
     * Handle the Order "updated" event.
     */
    public function updated(Order $order): void
    {
        if ($order->invoice != null) {
            $order->invoice->calculateTotals();
        }
    }

    /**
     * Handle the Order "saving" event.
     */
    public function saved(Order $order): void
    {
        if ($order->isDirty(['invoice_id']) && Invoice::where('id', $order->invoice_id)->exists()) {
            if ($order->invoice != null) {
                $order->invoice->calculateTotals();
            }
        }
    }

    /**
     * Handle the Order "deleted" event.
     */
    public function deleted(Order $order): void
    {
        if ($order->invoice != null) {
            $order->invoice->calculateTotals();
        }
    }

    /**
     * Handle the Order "restored" event.
     */
    public function restored(Order $order): void
    {
        //
    }

    /**
     * Handle the Order "force deleted" event.
     */
    public function forceDeleted(Order $order): void
    {
        //
    }
}