Calculate NFToken ID from transaction

getNFTokenID.js

const { decodeAccountID } = require('ripple-address-codec');
const BigNumber = require('bignumber.js');

const getTokenID = (transaction) => {
    const { Account, Issuer, NFTokenTaxon, TransferFee, Flags, meta } = transaction || {};

    // Validate transaction input data
    if (!Account || !Issuer || !NFTokenTaxon || !TransferFee || !Flags) {
        throw new Error('Invalid transaction data.');
    }

    // Validate meta data
    if (typeof meta !== 'object' || !Array.isArray(meta.AffectedNodes)) {
        throw new Error('Invalid meta data.');
    }

    // fixNFTokenRemint amendment will include the minted nfTokenId in the metaData
    // Amendment: AE35ABDEFBDE520372B31C957020B34A7A4A9DC3115A69803A44016477C84D6E

    // Check if 'nftoken_id' presence in meta
    if (Object.prototype.hasOwnProperty.call(meta, 'nftoken_id')) {
        return meta.nftoken_id;
    }

    // Fetch minted token sequence
    let TokenSequence;
    let NextTokenSequence;
    let FirstNFTokenSequence;

    meta.AffectedNodes.forEach((node) => {
        if (node.ModifiedNode && node.ModifiedNode.LedgerEntryType === 'AccountRoot') {
            const { PreviousFields, FinalFields } = node.ModifiedNode;
            if (PreviousFields && FinalFields && FinalFields.Account === (Issuer || Account)) {
                TokenSequence = PreviousFields.MintedNFTokens;
                NextTokenSequence = FinalFields.MintedNFTokens;
                FirstNFTokenSequence = PreviousFields.FirstNFTokenSequence || FinalFields.FirstNFTokenSequence;
            }
        }
    });

    // First minted token, set token sequence to zero
    if (typeof TokenSequence === 'undefined' && NextTokenSequence === 1) {
        TokenSequence = 0;
    }

    // Include first NFToken Sequence, introduced in `fixNFTokenRemint`
    TokenSequence += FirstNFTokenSequence ?? 0;

    // Decode account id
    const DecodedIssuerID = decodeAccountID(Issuer || Account);

    // Using BigNumber.js guarantees that we are getting correct result when TokenSequence value is big
    const UnscrambleTaxon = new BigNumber(384160001)
        .multipliedBy(TokenSequence)
        .modulo(4294967296)
        .plus(2459)
        .modulo(4294967296)
        .toNumber();

    // Calculate ciphered taxon
    const CipheredTaxon = (NFTokenTaxon ^ UnscrambleTaxon) >>> 0;

    const TokenID = Buffer.concat([
        Buffer.from([(Flags >> 8) & 0xff, Flags & 0xff]),
        Buffer.from([(TransferFee >> 8) & 0xff, TransferFee & 0xff]),
        DecodedIssuerID,
        Buffer.from([
            (CipheredTaxon >> 24) & 0xff,
            (CipheredTaxon >> 16) & 0xff,
            (CipheredTaxon >> 8) & 0xff,
            CipheredTaxon & 0xff,
        ]),
        Buffer.from([
            (TokenSequence >> 24) & 0xff,
            (TokenSequence >> 16) & 0xff,
            (TokenSequence >> 8) & 0xff,
            TokenSequence & 0xff,
        ]),
    ]);

    // should be 32 bytes
    if (TokenID.length !== 32) {
        throw new Error(`Calculated TokenID have unexpected length, expected 32, received ${TokenID.length}`);
    }

    return TokenID.toString('hex').toUpperCase();
};

const tokenID = getTokenID(transaction);
console.log(tokenID);

@N3TC4T

Voting is reaching go-live on this amendment:
https://xrpl.org/known-amendments.html#fixnftokenremint

And since we use the sequence (minted tokens) here:
https://gist.github.com/N3TC4T/a20fb528931ed009ebdd708be4938748

To compute NFT, this amendment would change this calculation as that field from accountroot becomes part of the NFT sequence.

Changes required to make this compatible with the new amendment (and keep it backwards compatible):

This is backwards compatible because it will do nothing if the AccountRoot didn't have, and didn't get, the new FirstNFTokenSequence field.

If the field was there or has been created, it adds the value to the TokenSequence as per new behaviour past activation of the amendment: https://xrpl.org/known-amendments.html#fixnftokenremint

Add (on top)

let FirstNFTokenSequence;

Add (in AccountRoot fields condition)

FirstNFTokenSequence = PreviousFields?.FirstNFTokenSequence || FinalFields?.FirstNFTokenSequence;

After the TokenSequence = 0 fallback:

TokenSequence += FirstNFTokenSequence ?? 0

Thank god someone is here to help us!! Thanks for publishing this mate and making it public.