magento2/app/code/Magento/QuoteGraphQl/Model/Resolver/CreateEmptyCart.php

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
declare(strict_types=1);

namespace Magento\QuoteGraphQl\Model\Resolver;

use Magento\Framework\GraphQl\Config\Element\Field;
use Magento\Framework\GraphQl\Query\ResolverInterface;
use Magento\Framework\GraphQl\Schema\Type\ResolveInfo;
use Magento\Quote\Model\MaskedQuoteIdToQuoteIdInterface;
use Magento\QuoteGraphQl\Model\Cart\CreateEmptyCartForCustomer;
use Magento\QuoteGraphQl\Model\Cart\CreateEmptyCartForGuest;
use Magento\QuoteGraphQl\Model\Cart\ValidateMaskedQuoteId;

/**
 * @inheritdoc
 */
class CreateEmptyCart implements ResolverInterface
{
    /**
     * @var CreateEmptyCartForCustomer
     */
    private $createEmptyCartForCustomer;

    /**
     * @var CreateEmptyCartForGuest
     */
    private $createEmptyCartForGuest;

    /**
     * @var MaskedQuoteIdToQuoteIdInterface
     */
    private $maskedQuoteIdToQuoteId;

    /**
     * @var ValidateMaskedQuoteId
     */
    private ValidateMaskedQuoteId $validateMaskedQuoteId;

    /**
     * @param CreateEmptyCartForCustomer $createEmptyCartForCustomer
     * @param CreateEmptyCartForGuest $createEmptyCartForGuest
     * @param MaskedQuoteIdToQuoteIdInterface $maskedQuoteIdToQuoteId
     * @param ValidateMaskedQuoteId $validateMaskedQuoteId
     */
    public function __construct(
        CreateEmptyCartForCustomer $createEmptyCartForCustomer,
        CreateEmptyCartForGuest $createEmptyCartForGuest,
        MaskedQuoteIdToQuoteIdInterface $maskedQuoteIdToQuoteId,
        ValidateMaskedQuoteId $validateMaskedQuoteId
    ) {
        $this->createEmptyCartForCustomer = $createEmptyCartForCustomer;
        $this->createEmptyCartForGuest = $createEmptyCartForGuest;
        $this->maskedQuoteIdToQuoteId = $maskedQuoteIdToQuoteId;
        $this->validateMaskedQuoteId = $validateMaskedQuoteId;
    }

    /**
     * @inheritdoc
     */
    public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null)
    {
        $customerId = $context->getUserId();

        $predefinedMaskedQuoteId = null;
        if (isset($args['input']['cart_id'])) {
            $predefinedMaskedQuoteId = $args['input']['cart_id'];
            $this->validateMaskedQuoteId->execute($predefinedMaskedQuoteId);
        }

        $maskedQuoteId = (0 === $customerId || null === $customerId)
            ? $this->createEmptyCartForGuest->execute($predefinedMaskedQuoteId)
            : $this->createEmptyCartForCustomer->execute($customerId, $predefinedMaskedQuoteId);
        return $maskedQuoteId;
    }
}