WitShop/app/Http/Controllers/Shop/CartController.php

<?php

namespace App\Http\Controllers\Shop;

use App\Http\Controllers\Controller;
use App\Models\ShippingRate;
use App\Services\CartService;
use Illuminate\Http\Request;

class CartController extends Controller
{
    public function __construct(private CartService $cart) {}

    public function index()
    {
        $items        = $this->cart->get();
        $subtotal     = $this->cart->subtotal();
        $shippingRate = ShippingRate::forCart($subtotal);
        $shippingCost = $shippingRate ? $shippingRate->getCostForTotal($subtotal) : 0;
        $total        = $subtotal + $shippingCost;

        return view('shop.cart.index', compact('items', 'subtotal', 'shippingRate', 'shippingCost', 'total'));
    }

    public function add(Request $request)
    {
        $request->validate(['variant_id' => 'required|exists:product_variants,id', 'qty' => 'integer|min:1']);
        $this->cart->add($request->variant_id, $request->integer('qty', 1));
        return back()->with('success', 'Artikel zum Warenkorb hinzugefügt.');
    }

    public function update(Request $request)
    {
        foreach ($request->input('qty', []) as $key => $qty) {
            $this->cart->update($key, (int) $qty);
        }
        return back()->with('success', 'Warenkorb aktualisiert.');
    }

    public function remove(string $key)
    {
        $this->cart->remove($key);
        return back()->with('success', 'Artikel entfernt.');
    }
}