@trezor/utxo-lib/lib/coinselect/inputs/branchAndBound.js

Client-side Bitcoin-like JavaScript library

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.branchAndBound = void 0;
const tslib_1 = require("tslib");
const bn_js_1 = tslib_1.__importDefault(require("bn.js"));
const coinselectUtils_1 = require("../coinselectUtils");
const MAX_TRIES = 1000000;
function calculateEffectiveValues(utxos, feeRate) {
  return utxos.map(utxo => {
    const value = (0, coinselectUtils_1.bignumberOrNaN)(utxo.value);
    if (!value) {
      return {
        utxo,
        effectiveValue: coinselectUtils_1.ZERO
      };
    }
    const effectiveFee = (0, coinselectUtils_1.getFeeForBytes)(feeRate, (0, coinselectUtils_1.inputBytes)(utxo));
    const effectiveValue = value.sub(new bn_js_1.default(effectiveFee));
    return {
      utxo,
      effectiveValue
    };
  });
}
function search(effectiveUtxos, target, costRange) {
  if (effectiveUtxos.length === 0) {
    return null;
  }
  let tries = MAX_TRIES;
  const selected = [];
  let selectedAccum = coinselectUtils_1.ZERO;
  let done = false;
  let backtrack = false;
  let remaining = effectiveUtxos.reduce((a, x) => x.effectiveValue.add(a), coinselectUtils_1.ZERO);
  let depth = 0;
  while (!done) {
    if (tries <= 0) {
      return null;
    }
    if (selectedAccum.gt(costRange)) {
      backtrack = true;
    } else if (selectedAccum.gte(target)) {
      done = true;
    } else if (depth >= effectiveUtxos.length) {
      backtrack = true;
    } else if (selectedAccum.add(remaining).lt(target)) {
      if (depth === 0) {
        return null;
      }
      backtrack = true;
    } else {
      remaining = remaining.sub(effectiveUtxos[depth].effectiveValue);
      selected[depth] = true;
      selectedAccum = selectedAccum.add(effectiveUtxos[depth].effectiveValue);
      depth++;
    }
    if (backtrack) {
      backtrack = false;
      depth--;
      while (!selected[depth]) {
        remaining = remaining.add(effectiveUtxos[depth].effectiveValue);
        depth--;
        if (depth < 0) {
          return null;
        }
      }
      selected[depth] = false;
      selectedAccum = selectedAccum.sub(effectiveUtxos[depth].effectiveValue);
      depth++;
    }
    tries--;
  }
  return selected;
}
const branchAndBound = (utxos, outputs, feeRate, options) => {
  if (options.baseFee) return {
    fee: 0
  };
  if (utxos.find(u => u.required)) return {
    fee: 0
  };
  const changeOutputFee = (0, coinselectUtils_1.getFeeForBytes)(feeRate, (0, coinselectUtils_1.outputBytes)({
    script: {
      length: coinselectUtils_1.OUTPUT_SCRIPT_LENGTH[options.txType]
    }
  }));
  const costOfChange = changeOutputFee + (0, coinselectUtils_1.getDustAmount)(feeRate, options);
  const outputsBytes = (0, coinselectUtils_1.transactionBytes)([], outputs);
  const outputsFee = (0, coinselectUtils_1.getFeeForBytes)(feeRate, outputsBytes);
  const outputsTotalValue = (0, coinselectUtils_1.sumOrNaN)(outputs);
  if (!outputsTotalValue) return {
    fee: 0
  };
  const target = outputsTotalValue.add(new bn_js_1.default(outputsFee));
  const targetRange = target.add(new bn_js_1.default(costOfChange));
  const effectiveUtxos = calculateEffectiveValues(utxos, feeRate).filter(({
    effectiveValue
  }) => effectiveValue.gt(coinselectUtils_1.ZERO) && effectiveValue.lte(targetRange)).sort((a, b) => {
    const subtract = b.effectiveValue.sub(a.effectiveValue).toNumber();
    if (subtract !== 0) {
      return subtract;
    }
    return a.utxo.i - b.utxo.i;
  });
  const utxosTotalEffectiveValue = effectiveUtxos.reduce((total, {
    effectiveValue
  }) => total.add(effectiveValue), coinselectUtils_1.ZERO);
  if (utxosTotalEffectiveValue.lt(target)) {
    return {
      fee: 0
    };
  }
  const selected = search(effectiveUtxos, target, targetRange);
  if (selected !== null) {
    const inputs = [];
    for (let i = 0; i < effectiveUtxos.length; i++) {
      if (selected[i]) {
        inputs.push(effectiveUtxos[i].utxo);
      }
    }
    return (0, coinselectUtils_1.finalize)(inputs, outputs, feeRate, options);
  }
  return {
    fee: 0
  };
};
exports.branchAndBound = branchAndBound;
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