shopit-back/app/Domains/Purchase/Services/UserPurchaseLimitService.php

<?php

namespace App\Domains\Purchase\Services;

use App\Domains\Cart\Models\CartItem;
use App\Domains\Catalog\Models\CatalogItem;
use App\Domains\Purchase\Models\Purchase;
use App\Domains\Purchase\Models\PurchaseItem;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\ValidationException;

class UserPurchaseLimitService
{
    public function assertCanPurchase(
        CatalogItem $catalogItem,
        int $userId,
        int $requestedQuantity,
        ?int $excludedPurchaseId = null,
        string $field = 'quantity',
    ): void {
        DB::transaction(function () use (
            $catalogItem,
            $userId,
            $requestedQuantity,
            $excludedPurchaseId,
            $field,
        ): void {
            /** @var CatalogItem $catalogItem */
            $catalogItem = CatalogItem::query()
                ->whereKey($catalogItem->getKey())
                ->lockForUpdate()
                ->firstOrFail();
            $limit = $catalogItem->max_units_per_user;

            if ($limit === null) {
                return;
            }

            $purchasedQuantity = (int) PurchaseItem::query()
                ->where('source_catalog_item_id', $catalogItem->getKey())
                ->whereHas('purchase', function ($query) use ($userId, $excludedPurchaseId): void {
                    $query
                        ->where('user_id', $userId)
                        ->whereIn('status', [
                            Purchase::STATUS_CREATED,
                            Purchase::STATUS_PENDING_PAYMENT,
                            Purchase::STATUS_PAID,
                        ])
                        ->when(
                            $excludedPurchaseId !== null,
                            fn ($query) => $query->whereKeyNot($excludedPurchaseId),
                        );
                })
                ->sum('cantidad');

            $checkoutQuantity = (int) CartItem::query()
                ->where('catalog_item_id', $catalogItem->getKey())
                ->whereHas('cart.purchases', function ($query) use ($userId, $excludedPurchaseId): void {
                    $query
                        ->where('user_id', $userId)
                        ->whereIn('status', [
                            Purchase::STATUS_CREATED,
                            Purchase::STATUS_PENDING_PAYMENT,
                        ])
                        ->whereDoesntHave('items')
                        ->when(
                            $excludedPurchaseId !== null,
                            fn ($query) => $query->whereKeyNot($excludedPurchaseId),
                        );
                })
                ->sum('cantidad');

            if ($purchasedQuantity + $checkoutQuantity + $requestedQuantity > $limit) {
                throw ValidationException::withMessages([
                    $field => __('api.purchase_limit.exceeded', ['max' => $limit]),
                ]);
            }
        });
    }
}