CIMRestService::dialogUsersList

static function dialogUsersList($params, $offset, CRestServer $server): Array
{
	$params = array_change_key_case($params, CASE_UPPER);
	if (!BitrixImCommon::isDialogId($params['DIALOG_ID']))
	{
		throw new BitrixRestRestException("Dialog ID can't be empty", "DIALOG_ID_EMPTY", CRestServer::STATUS_WRONG_REQUEST);
	}

	if (!BitrixImDialog::hasAccess($params['DIALOG_ID']))
	{
		throw new BitrixRestRestException("You do not have access to the specified dialog", "ACCESS_ERROR", CRestServer::STATUS_FORBIDDEN);
	}

	$chatId = BitrixImDialog::getChatId($params['DIALOG_ID']);
	if (!$chatId)
	{
		throw new BitrixRestRestException("You don't have access to this chat", "ACCESS_ERROR", CRestServer::STATUS_WRONG_REQUEST);
	}

	$countFilter = [
		'=CHAT_ID' => $chatId,
		'=USER.ACTIVE' => 'Y',
	];
	if (
		isset($params['SKIP_EXTERNAL']) && $params['SKIP_EXTERNAL'] === 'Y'
		|| isset($params['SKIP_EXTERNAL_EXCEPT_TYPES']))
	{
		$options['SKIP_EXTERNAL'] = 'Y';
		$options['SKIP_EXTERNAL_EXCEPT_TYPES'] = array_map('trim', mb_split(',', $params['SKIP_EXTERNAL_EXCEPT_TYPES']));

		$exceptType = $options['SKIP_EXTERNAL_EXCEPT_TYPES'] ?? [];
		$countFilter['!=USER.EXTERNAL_AUTH_ID'] = BitrixImModelUserTable::filterExternalUserTypes($exceptType);
	}

	$options['LIMIT'] = self::getLimit($params);
	$options['JSON'] = true;

	if (isset($params['LAST_ID']) && (int)$params['LAST_ID'] >= 0)
	{
		$options['LAST_ID'] = (int)$params['LAST_ID'];

		return BitrixImChat::getUsers($chatId, $options);
	}

	$counter = BitrixImModelRelationTable::getList([
		'select' => ['CNT' => new BitrixMainEntityExpressionField('CNT', 'COUNT(1)')],
		'filter' => $countFilter
	])->fetch();
	$options['OFFSET'] = self::getOffset($offset, $params);

	$result = Array();
	if ($counter && $counter["CNT"] > 0)
	{
		$result = BitrixImChat::getUsers($chatId, $options);
	}

	return self::setNavData(
		$result,
		array(
			"count" => $counter['CNT'],
			"offset" => $options['OFFSET']
		)
	);
}