DeleteService::recountChat

private function recountChat(): void
{
	$this->updateRecent();
	if (!is_null($this->chatLastMessage))
	{
		$isMessageRead = !!MessageViewedTable::query()
			->addFilter('MESSAGE_ID', $this->chatLastMessage['ID'])
			->fetch();

		$this->chat->setLastMessageId((int)($this->chatLastMessage['ID'] ?? 0));
		$this->chat->setLastMessageStatus($isMessageRead ? IM_MESSAGE_STATUS_DELIVERED : IM_MESSAGE_STATUS_RECEIVED);
	}

	$this->chat->setPrevMessageId($this->chatPrevMessageId ?? 0);

	$this->chat->setMessageCount($this->chat->getMessageCount() - 1);
	$this->chat->save();
	$this->updateRelation();
}