Use forex conversion for Bitstamp on non-USD/EUR (#111)

lib/plugins/ticker/bitstamp/bitstamp.js

@@ -1,7 +1,40 @@
+const axios = require('axios')
+const _ = require('lodash/fp')
+
 const BN = require('../../../bn')
 const common = require('../../common/bitstamp')
 
-function ticker (account, fiatCode, cryptoCode) {
+exports.NAME = 'Bitstamp'
+exports.SUPPORTED_MODULES = ['ticker']
+
+function findCurrency (fxRates, fiatCode) {
+  const rates = _.find(_.matchesProperty('code', fiatCode), fxRates)
+  if (!rates || !rates.rate) throw new Error(`Unsupported currency: ${fiatCode}`)
+  return BN(rates.rate)
+}
+
+exports.ticker = function ticker (account, fiatCode, cryptoCode) {
+  if (fiatCode === 'USD' || fiatCode === 'EUR') {
+    return getCurrencyRates(fiatCode, cryptoCode)
+  }
+
+  return axios.get('https://bitpay.com/api/rates')
+    .then(response => {
+      const fxRates = response.data
+      const usdRate = findCurrency(fxRates, 'USD')
+      const fxRate = findCurrency(fxRates, fiatCode).div(usdRate)
+
+      return getCurrencyRates('USD', cryptoCode)
+        .then(res => ({
+          rates: {
+            ask: res.rates.ask.times(fxRate),
+            bid: res.rates.bid.times(fxRate)
+          }
+        }))
+    })
+}
+
+function getCurrencyRates (fiatCode, cryptoCode) {
   return Promise.resolve()
     .then(() => {
       const market = common.buildMarket(fiatCode, cryptoCode)
@@ -14,7 +47,3 @@ function ticker (account, fiatCode, cryptoCode) {
       }
     }))
 }
-
-module.exports = {
-  ticker
-}