CounterService::getIdFirstUnreadMessage

public function getIdFirstUnreadMessage(int $chatId): ?int
{
	$result = MessageUnreadTable::query()
		->setSelect(['MIN'])
		->where('CHAT_ID', $chatId)
		->where('USER_ID', $this->getContext()->getUserId())
		->registerRuntimeField('MIN', new ExpressionField('MIN', 'MIN(%s)', ['MESSAGE_ID']))
		->fetch()
	;

	return isset($result['MIN']) ? (int)$result['MIN'] : null;
}