coinselect/split.js
2017-08-10 15:18:50 +10:00

45 lines
1.4 KiB
JavaScript

var utils = require('./utils')
// split utxos between each output, ignores outputs with .value defined
module.exports = function split (utxos, outputs, feeRate) {
if (!isFinite(utils.uintOrNaN(feeRate))) return {}
var bytesAccum = utils.transactionBytes(utxos, outputs)
var fee = feeRate * bytesAccum
if (outputs.length === 0) return { fee: fee }
var inAccum = utils.sumOrNaN(utxos)
var outAccum = utils.sumForgiving(outputs)
var remaining = inAccum - outAccum - fee
if (!isFinite(remaining) || remaining < 0) return { fee: fee }
var unspecified = outputs.reduce(function (a, x) {
return a + !isFinite(x.value)
}, 0)
if (remaining === 0 && unspecified === 0) return utils.finalize(utxos, outputs, feeRate)
var splitOutputsCount = outputs.reduce(function (a, x) {
return a + !x.value
}, 0)
var splitValue = (remaining / splitOutputsCount) >>> 0
// ensure every output is either user defined, or over the threshold
if (!outputs.every(function (x) {
return x.value !== undefined || (splitValue > utils.dustThreshold(x, feeRate))
})) return { fee: fee }
// assign splitValue to outputs not user defined
outputs = outputs.map(function (x) {
if (x.value !== undefined) return x
// not user defined, but still copy over any non-value fields
var y = {}
for (var k in x) y[k] = x[k]
y.value = splitValue
return y
})
return utils.finalize(utxos, outputs, feeRate)
}