nerve-sdk-js/lib/utils/freecash.js

nerve nerve-js nerve-sdk nerve-js-sdk

var nerve = require("../index");

var MAX_SAFE_INTEGER = 9007199254740991;

function checkUInt53(n) {
  if (n < 0 || n > MAX_SAFE_INTEGER || n % 1 !== 0) throw new RangeError('value out of range');
}

function encodingLength(number) {
  checkUInt53(number);
  return number < 0xfd ? 1 : number <= 0xffff ? 3 : number <= 0xffffffff ? 5 : 9;
}
/**
 * calc split number of Transaction Change Spliting by splitGranularity
 *      change = fromTotal - transfer - fee
 *      change = splitNum * splitGranularity
 *      fee = txSize * feeRate
 *      txSize = f(splitNum)
 *      f(splitNum) = f(1) + 43 * (splitNum - 1) ==> Derived from btc.calcTxSizeWithdrawal(inputNum, splitNum)
 *  In summary:
 *      splitNum = (fromTotal - transfer - btc.calcTxSizeWithdrawal(inputNum, 1) * feeRate + 43 * feeRate) / (43 * feeRate + splitGranularity)
 */


function calcSplitNumP2SH(fromTotal, transfer, feeRate, splitGranularity, inputNum) {
  // numerator and denominator
  var numerator = fromTotal - transfer - calcTxSizeWithdrawal(inputNum, 1) * feeRate + 43 * feeRate;
  var denominator = 43 * feeRate + splitGranularity;
  var splitNum = int(numerator / denominator);

  if (splitNum == 0 && numerator % denominator > 0) {
    splitNum = 1;
  }

  return splitNum;
}

function calcFeeMultiSign(inputNum, outputNum, opReturnBytesLen, m, n) {
  var op_mLen = 1;
  var op_nLen = 1;
  var pubKeyLen = 33;
  var pubKeyLenLen = 1;
  var op_checkmultisigLen = 1;
  var redeemScriptLength = op_mLen + n * (pubKeyLenLen + pubKeyLen) + op_nLen + op_checkmultisigLen; //105 n=3

  var redeemScriptVarInt = encodingLength(redeemScriptLength); //1 n=3

  var op_pushDataLen = 1;
  var sigHashLen = 1;
  var signLen = 64;
  var signLenLen = 1;
  var zeroByteLen = 1;
  var mSignLen = m * (signLenLen + signLen + sigHashLen); //132 m=2

  var scriptLength = zeroByteLen + mSignLen + op_pushDataLen + redeemScriptVarInt + redeemScriptLength; //236 m=2

  var scriptVarInt = encodingLength(scriptLength);
  var preTxIdLen = 32;
  var preIndexLen = 4;
  var sequenceLen = 4;
  var inputLength = preTxIdLen + preIndexLen + sequenceLen + scriptVarInt + scriptLength; //240 n=3,m=2

  var opReturnLen = 0;
  if (opReturnBytesLen != 0) opReturnLen = calcOpReturnLen(opReturnBytesLen);
  var outputValueLen = 8;
  var unlockScriptLen = 25; //If sending to multiSignAddr, it will be 23.

  var unlockScriptLenLen = 1;
  var outPutLen = outputValueLen + unlockScriptLenLen + unlockScriptLen;
  var inputCountLen = 1;
  var outputCountLen = 1;
  var txVerLen = 4;
  var nLockTimeLen = 4;
  var txFixedLen = inputCountLen + outputCountLen + txVerLen + nLockTimeLen;
  var length;
  length = txFixedLen + inputLength * inputNum + outPutLen * (outputNum + 1) + opReturnLen;
  return length;
}

function calcOpReturnLen(opReturnBytesLen) {
  var dataLen;

  if (opReturnBytesLen < 76) {
    dataLen = opReturnBytesLen + 1;
  } else if (opReturnBytesLen < 256) {
    dataLen = opReturnBytesLen + 2;
  } else dataLen = opReturnBytesLen + 3;

  var scriptLen;
  scriptLen = dataLen + 1 + encodingLength(dataLen + 1);
  var amountLen = 8;
  return scriptLen + amountLen;
}

function calcTxSizeWithdrawal(utxoSize) {
  var outputNum = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 1;
  var m, n;

  if (nerve.chainId() == 9) {
    m = 10, n = 15;
  } else {
    m = 2, n = 3;
  }

  return calcFeeMultiSign(utxoSize, outputNum, 64, m, n);
}

var fch = {
  getFeeRate() {
    return 1;
  },

  calcFeeWithdrawal(utxos, amount, feeRate) {
    var splitGranularity = arguments.length > 3 && arguments[3] !== undefined ? arguments[3] : 0;

    if (Array.isArray(utxos)) {
      utxos.sort((a, b) => {
        if (a.value !== b.value) {
          return Number(a.value) < Number(b.value) ? -1 : 1;
        } else if (a.txid !== b.txid) {
          return a.txid < b.txid ? -1 : 1;
        } else if (a.vout !== b.vout) {
          return Number(a.vout) < Number(b.vout) ? -1 : 1;
        } else {
          return 0;
        }
      });
    }

    var _fee = 0,
        total = 0,
        totalSpend = 0;
    var resultList = [];
    amount = Number(amount);

    for (var i = 0; i < utxos.length; i++) {
      var utxo = utxos[i];
      total = total + utxo.amount;
      resultList.push(utxo);

      if (splitGranularity > 0) {
        var splitNum = calcSplitNumP2SH(total, amount, feeRate, splitGranularity, resultList.length);
        _fee = calcTxSizeWithdrawal(resultList.length, splitNum) * feeRate;
      } else {
        _fee = calcTxSizeWithdrawal(resultList.length) * feeRate;
      }

      totalSpend = amount + _fee;

      if (total >= totalSpend) {
        break;
      }
    }

    if (total < totalSpend) {
      throw "not enough fee";
    }

    return _fee;
  }

};
module.exports = fch;