@atomiqlabs/sdk-lib/src/btc/coinselect2/accumulative.ts

Basic SDK functionality library for atomiq

import {CoinselectAddressTypes, CoinselectTxInput, CoinselectTxOutput, utils} from "./utils";
import {getLogger} from "../../utils/Utils";

const logger = getLogger("CoinSelect: ");

// add inputs until we reach or surpass the target value (or deplete)
// worst-case: O(n)
export function accumulative (
    utxos: CoinselectTxInput[],
    outputs: CoinselectTxOutput[],
    feeRate: number,
    type: CoinselectAddressTypes,
    requiredInputs?: CoinselectTxInput[]
): {
    inputs?: CoinselectTxInput[],
    outputs?: CoinselectTxOutput[],
    fee: number
} {
    if (!isFinite(utils.uintOrNaN(feeRate))) return null;

    const inputs = requiredInputs==null ? [] : [...requiredInputs];
    let bytesAccum = utils.transactionBytes(inputs, outputs, type);
    let fee = feeRate * bytesAccum;
    let cpfpAddFee = 0;
    let inAccum = utils.sumOrNaN(inputs);
    const outAccum = utils.sumOrNaN(outputs);

    logger.debug("accumulative(): total output: ",outAccum);

    for (let i = 0; i < utxos.length; ++i) {
        const utxo = utxos[i];
        const utxoBytes = utils.inputBytes(utxo);
        const utxoFee = feeRate * utxoBytes;
        const utxoValue = utils.uintOrNaN(utxo.value);

        let cpfpFee = 0;
        if(utxo.cpfp!=null && utxo.cpfp.txEffectiveFeeRate<feeRate) cpfpFee = Math.ceil(utxo.cpfp.txVsize * (feeRate - utxo.cpfp.txEffectiveFeeRate));

        // skip detrimental input
        if (utxoFee + cpfpFee > utxo.value) {
            logger.debug("accumulative("+i+"): Skipping detrimental output, cpfpFee: "+cpfpFee+" utxoFee: "+utxoFee+" value: "+utxo.value);
            if (i === utxos.length - 1) return { fee: (feeRate * (bytesAccum + utxoBytes)) + cpfpAddFee + cpfpFee };
            continue
        }

        bytesAccum += utxoBytes;
        inAccum += utxoValue;
        cpfpAddFee += cpfpFee;
        inputs.push(utxo);

        fee = Math.ceil((feeRate * bytesAccum) + cpfpAddFee);

        logger.debug("accumulative("+i+"): total fee: ", fee);
        logger.debug("accumulative("+i+"): input value: ", inAccum);
        logger.debug("accumulative("+i+"): cpfpAddFee: ", cpfpAddFee);

        // go again?
        if (inAccum < outAccum + fee) continue;

        logger.debug("accumulative("+i+"): Finalizing transaction, inputs: ", inputs);
        logger.debug("accumulative("+i+"): Finalizing transaction, outputs: ", outputs);
        logger.debug("accumulative("+i+"): Finalizing transaction, feeRate: ", feeRate);
        return utils.finalize(inputs, outputs, feeRate, type, cpfpAddFee);
    }

    return { fee };
}