OrderController.php

<?php

namespace App\Http\Controllers;

use App\Order;
use App\Product;
use App\Mail\NewOrder;
use App\Mail\LowStock;
use Illuminate\Support\Facades\Mail;
use App\Http\Controllers\Controller;

class OrderController extends Controller
{
    public function create()
    {
        // create order
        $order = \App\Order::create(request());
      
        // send confirmation email
        Mail::to($order->customer_email)->send(new NewOrder($order));
      
        // update stock
        foreach ($order->items as $item) {
            $product = Product::find($item->productId);
            
            $quantityLeft = $product->quantity - $item->quantity;
            
            $product->update([
                'quantity' => $quantityLeft
            ]);
          
            // if stock is low
            if ($quantityLeft < 3) {
                
               // send stock is low email
                Mail::to(config('app.admin_email'))->send(new LowStock($product));
            }
        }
    }
}