CIMRestService::chatGet

static function chatGet($arParams, $n, CRestServer $server)
{
	global $USER;
	if (!$USER->IsAuthorized())
	{
		throw new BitrixRestRestException("Method not available for guest session.", "AUTHORIZE_ERROR", CRestServer::STATUS_FORBIDDEN);
	}

	$arParams = array_change_key_case($arParams, CASE_UPPER);

	if (isset($arParams['DIALOG_ID']))
	{
		if (!BitrixImCommon::isDialogId($arParams['DIALOG_ID']))
		{
			throw new BitrixRestRestException("Dialog ID can't be empty", "DIALOG_ID_EMPTY", CRestServer::STATUS_WRONG_REQUEST);
		}

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

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

		$result = BitrixImChat::getById($chatId, ['LOAD_READED' => true, 'JSON' => true]);
		if (!$result)
		{
			throw new BitrixRestRestException("You don't have access to this chat", "ACCESS_ERROR", CRestServer::STATUS_WRONG_REQUEST);
		}

		$result['dialog_id'] = $arParams['DIALOG_ID'];

		return $result;
	}
	else if (
		isset($arParams['ENTITY_TYPE']) && isset($arParams['ENTITY_ID'])
		&& !empty($arParams['ENTITY_TYPE']) && !empty($arParams['ENTITY_ID'])
	)
	{
		$chatData = BitrixImModelChatTable::getList(Array(
															'select' => ['ID'],
															'filter' => [
																'=ENTITY_TYPE' => $arParams['ENTITY_TYPE'],
																'=ENTITY_ID' => $arParams['ENTITY_ID'],
															]
														))->fetch();
		if ($chatData)
		{
			return Array(
				'ID' => (int)$chatData['ID']
			);
		}
	}

	return null;
}