History::downloadAction

public function downloadAction(int $chatId, CurrentUser $currentUser): ?BitrixMainHttpResponse
{
	$liveChat = new Chat($chatId);
	$chatAuthorId = (int)$liveChat->getData('AUTHOR_ID');
	$currentUserId = (int)$currentUser->getId();
	if ($chatAuthorId !== $currentUserId)
	{
		return null;
	}

	$chatFieldSession = $liveChat->getFieldData(Chat::FIELD_LIVECHAT);
	$sessionId = $chatFieldSession['SESSION_ID'];
	if ($sessionId <= 0)
	{
		return null;
	}

	ob_start();
	global $APPLICATION;
	$APPLICATION->IncludeComponent(
		"bitrix:imopenlines.mail.history",
		"html",
		[
			"TEMPLATE_SERVER_ADDRESS" => BitrixImOpenLinesCommon::getServerAddress(),
			"TEMPLATE_SESSION_ID" => $sessionId,
			"TEMPLATE_WIDGET_LOCATION" => $this->request->getHeader('referer'),
			"TEMPLATE_TYPE" => 'HISTORY',
		]
	);
	$historyComponentContent = ob_get_clean();

	$response = new BitrixMainHttpResponse();
	$response->addHeader('Content-Type', 'application/octet-stream');
	$response->setContent($historyComponentContent);

	return $response;
}