Add QuadrigaCX exchange and ticker (#176)

* Add QuadrigaCX exchange and ticker

* Clean up code from QuadrigaCX

lib/plugins/ticker/quadrigacx/quadrigacx.js

@@ -0,0 +1,49 @@
+const axios = require('axios')
+const _ = require('lodash/fp')
+
+const BN = require('../../../bn')
+const common = require('../../common/quadrigacx')
+
+exports.NAME = 'QuadrigaCX'
+exports.SUPPORTED_MODULES = ['ticker']
+
+function findCurrency (fxRates, fiatCode) {
+  const rates = _.find(_.matchesProperty('code', fiatCode), fxRates)
+  if (!rates || !rates.rate) throw new Error(`Unsupported currency: ${fiatCode}`)
+  return BN(rates.rate)
+}
+
+exports.ticker = function ticker (account, fiatCode, cryptoCode) {
+  if (fiatCode === 'USD' && cryptoCode === 'BTC' || fiatCode === 'CAD') {
+    return getCurrencyRates(fiatCode, cryptoCode)
+  }
+
+  return axios.get('https://bitpay.com/api/rates')
+    .then(response => {
+      const fxRates = response.data
+      const cadRate = findCurrency(fxRates, 'CAD')
+      const fxRate = findCurrency(fxRates, fiatCode).div(cadRate)
+
+      return getCurrencyRates('CAD', cryptoCode)
+        .then(res => ({
+          rates: {
+            ask: res.rates.ask.times(fxRate),
+            bid: res.rates.bid.times(fxRate)
+          }
+        }))
+    })
+}
+
+function getCurrencyRates (fiatCode, cryptoCode) {
+  return Promise.resolve()
+    .then(() => {
+      const market = common.buildMarket(fiatCode, cryptoCode)
+      return common.request(`/ticker?book=${market}`, 'GET')
+    })
+    .then(r => ({
+      rates: {
+        ask: BN(r.ask),
+        bid: BN(r.bid)
+      }
+    }))
+}