chore: use monorepo organization

packages/server/lib/commission-math.js

@@ -0,0 +1,40 @@
+const BN = require('./bn')
+const configManager = require('./new-config-manager')
+const { utils: coinUtils } = require('@lamassu/coins')
+
+function truncateCrypto (cryptoAtoms, cryptoCode) {
+  const DECIMAL_PLACES = 6
+  if (cryptoAtoms.eq(0)) return cryptoAtoms
+
+  const scale = coinUtils.getCryptoCurrency(cryptoCode).unitScale
+  const scaleFactor = BN(10).pow(scale)
+
+  return new BN(cryptoAtoms).integerValue(BN.ROUND_DOWN).div(scaleFactor)
+    .decimalPlaces(DECIMAL_PLACES).times(scaleFactor)
+}
+
+function fiatToCrypto (tx, rec, deviceId, config) {
+  const usableFiat = rec.fiat - rec.cashInFee
+
+  const commissions = configManager.getCommissions(tx.cryptoCode, deviceId, config)
+  const tickerRate = new BN(tx.rawTickerPrice)
+  const discount = getDiscountRate(tx.discount, commissions[tx.direction])
+  const rate = tickerRate.times(discount).decimalPlaces(5)
+  const unitScale = coinUtils.getCryptoCurrency(tx.cryptoCode).unitScale
+  const unitScaleFactor = new BN(10).pow(unitScale)
+
+  return truncateCrypto(new BN(usableFiat).div(rate.div(unitScaleFactor)), tx.cryptoCode)
+}
+
+function getDiscountRate (discount, commission) {
+  const bnDiscount = discount ? new BN(discount) : new BN(0)
+  const bnCommission = new BN(commission)
+  const percentageDiscount = new BN(1).minus(bnDiscount.div(100))
+  const percentageCommission = bnCommission.div(100)
+  return new BN(1).plus(percentageDiscount.times(percentageCommission))
+}
+
+module.exports = {
+  fiatToCrypto,
+  getDiscountRate
+}