Mark invoice transaction to ledger journal transaction using x++ D365fo

public void markTransaction(LedgerJournalTrans _journalTrans)

{

    CustTransOpen                          custTransOpen;

    CustTrans                                   custTrans;

    CustVendOpenTransManager     manager          = CustVendOpenTransManager::construct(_journalTrans);

    SpecTransManager                     specTransManager = manager.parmSpecTransManager();

    AmountCur                                unmarkedAmount;

    // 🔹 Find the matching CustTrans record

    select firstonly custTrans

        where custTrans.Invoice    == _journalTrans.MarkedInvoice  // Probably should map to invoice reference

              && custTrans.AccountNum == 'Test001';        // Replace hardcode with _journalTrans.CustomerAccount if possible

    // 🔹 Find the open transaction for settlement

    custTransOpen = CustTransOpen::findRefId(custTrans.RecId);

    // 🔹 Check unmarked amount for this transaction

    unmarkedAmount = specTransManager.findUnmarkedAmountForRef(custTransOpen.AmountCur,

                        custTransOpen.company(),custTransOpen.TableId,custTransOpen.RecId);

    if (unmarkedAmount <= 0)

    {

        warning("Nothing left to settle for this transaction.");

    }

    // 🔹 Ensure not already marked by another specTrans

    if (!manager.checkTransFullyMarkedByOtherSpec(custTransOpen))

    {

        manager.updateTransMarked(custTransOpen, NoYes::Yes);

        manager.updateSettleAmountPaymCur(custTransOpen, custTransOpen.AmountCur);

    }

    ttsbegin;

    _journalTrans.selectForUpdate(true);

    _journalTrans.MarkedInvoice = custTrans.Invoice;

    _journalTrans.SettleVoucher = SettlementType::SelectedTransact;

    _journalTrans.doUpdate();

    ttscommit;

}