Dialog::getTitle

static function getTitle($dialogId, $userId = null):? string
{
	if (Common::isChatId($dialogId))
	{
		if (!Dialog::hasAccess($dialogId, $userId))
		{
			return null;
		}

		$chatId = Dialog::getChatId($dialogId);

		$chatData = ChatTable::getRow([
			'select' => ['TITLE'],
			'filter' => ['=ID' => $chatId],
		]);
		if (!$chatData)
		{
			return null;
		}

		return $chatData['TITLE'];
	}

	$userId = Common::getUserId($userId);
	$chatId = CIMMessage::GetChatId($dialogId, $userId);
	if (!$chatId)
	{
		return null;
	}

	$userNames = [
		User::getInstance($dialogId)->getFullName(false),
		User::getInstance($userId)->getFullName(false),
	];

	return implode(" - ", $userNames);
}