User.php

<?php
 
namespace Bitrix\Im\V2\Controller\Chat;
 
use Bitrix\Im\V2\Controller\BaseController;
 
class User extends BaseController
{
    public function listAction(\Bitrix\Im\V2\Chat $chat, array $order = [], int $limit = self::DEFAULT_LIMIT): ?array
    {
        $relationOrder = $this->prepareRelationOrder($order);
        $limit = $this->getLimit($limit);
 
        return $this->toRestFormat($chat->getRelations(['ORDER' => $relationOrder, 'LIMIT' => $limit])->getUsers());
    }
 
    private function prepareRelationOrder(array $order): array
    {
        if (isset($order['id']))
        {
            return ['ID' => strtoupper($order['id'])];
        }
        if (isset($order['lastSendMessageId']))
        {
            return ['LAST_SEND_MESSAGE_ID' => strtoupper($order['lastSendMessageId'])];
        }
        if (isset($order['userId']))
        {
            return ['USER_ID' => strtoupper($order['USER_ID'])];
        }
 
        return [];
    }
}