<?php

namespace Stemcell\Customer\Ui\Component\DataProvider;

use Magento\Framework\Data\OptionSourceInterface;
use Magento\Customer\Model\ResourceModel\Customer\Collection;

class VendorOption implements OptionSourceInterface
{
    private Collection $collection;

    /**
     * @var array
     */
    protected array $customerTree;

    public function __construct(
        Collection $collection
    ) {
        $this->collection = $collection;
    }

    public function toOptionArray()
    {

        $collection = $this->collection->addFieldToSelect('firstname');
        foreach ($collection as $customer) {
            $customerId = $customer->getEntityId();
            if (!isset($customerById[$customerId])) {
                $customerById[$customerId] = [
                    'value' => $customerId
                ];
            }
            $customerById[$customerId]['label'] = $customer->getFirstname();
        }
        $this->customerTree = $customerById;
        return $this->customerTree;
    }
}