updated to new ticker api; fixed fiatBalance for trade exchange with different currency

lib/trader.js

@@ -17,6 +17,7 @@ var Trader = module.exports = function (db) {
   this.rates = {};
   this._tradeQueue = [];
   this._sessionInfo = {};
+  this.rateInfo = null;
 };
 
 Trader.prototype._findExchange = function (name) {
@@ -258,20 +259,51 @@ Trader.prototype.stopPolling = function () {
   clearInterval(this.rateInterval);
 };
 
+// Trade exchange could be in a different currency than Bitcoin Machine.
+// For instance, trade exchange could be Bitstamp, denominated in USD,
+// while Bitcoin Machine is set to ILS.
+//
+// We need this function to convert the trade exchange balance into the
+// Bitcoin Machine denomination, in the example case: ILS.
+//
+// The best way to do that with available data is to take the ratio between
+// the exchange rates for the Bitcoin Machine and the trade exchange.
+Trader.prototype._tradeForexMultiplier = function _tradeForexMultiplier() {
+  var deviceCurrency = this.config.exchanges.settings.currency;
+  var tradeCurrency = this.tradeExchange.currency();
+  var deviceRate = this._deviceRate();
+  var tradeRate = this._tradeRate();
+
+  var forexMultiplier = deviceRate && tradeRate ?
+    deviceRate / tradeRate :
+    null;
+
+  return deviceCurrency === tradeCurrency ?
+    1 :
+    forexMultiplier;
+};
+
+Trader.prototype._tradeBalanceFunc = function _tradeBalanceFunc(callback) {
+  if (!this.tradeExchange) return callback(null, null);
+  var forexMultiplier = this._tradeForexMultiplier();
+  if (!forexMultiplier) return callback(new Error('Can\'t compute balance, no tickers yet.')); 
+  this.tradeExchange.balance(function (err, localBalance) {
+    if (err) return callback(err);
+    callback(null, localBalance * forexMultiplier);
+  });
+};
+
 Trader.prototype.pollBalance = function (callback) {
   var self = this;
 
   logger.debug('collecting balance');
 
-  async.parallel({
-    transferBalance: self.transferExchange.balance.bind(self.transferExchange),
-    tradeBalance: function (next) {
-      if (!self.tradeExchange) {
-        return next(null, null);
-      }
+  var transferBalanceFunc = this.transferExchange.balance.bind(this.transferExchange);
+  var tradeBalanceFunc = this._tradeBalanceFunc.bind(this);
 
-      self.tradeExchange.balance(next);
-    }
+  async.parallel({
+    transferBalance: transferBalanceFunc,
+    tradeBalance: tradeBalanceFunc
   }, function (err, balance) {
     if (err) {
       return callback && callback(err);
@@ -281,7 +313,7 @@ Trader.prototype.pollBalance = function (callback) {
     logger.debug('Balance update:', balance);
     self.balance = balance;
 
-    return callback && callback(null, balance);
+    return callback && callback();
   });
 };
 
@@ -289,7 +321,14 @@ Trader.prototype.pollRate = function (callback) {
   var self = this;
 
   logger.debug('polling for rates...');
-  self.tickerExchange.ticker(function(err, resRates) {
+  var deviceCurrency = this.config.exchanges.settings.currency;
+  var currencies = [deviceCurrency];
+  if (this.tradeExchange) {
+    var tradeCurrency = this.tradeExchange.currency();
+    if (tradeCurrency !== deviceCurrency) currencies.push(tradeCurrency);
+  }
+
+  self.tickerExchange.ticker(currencies, function(err, resRates) {
     if (err) {
       logger.error(err);
       return callback && callback(err);
@@ -297,13 +336,25 @@ Trader.prototype.pollRate = function (callback) {
 
     logger.debug('got rates: %j', resRates);
     self.rateInfo = {rates: resRates, timestamp: new Date()};
+    callback && callback();
   });
 };
 
-// This is the rate in local currency quote to the user
+Trader.prototype._deviceRate = function _deviceRate() {
+  if (!this.rateInfo) return null;
+  return this.rateInfo.rates[this.config.exchanges.settings.currency].rate;
+};
+
+Trader.prototype._tradeRate = function _tradeRate() {
+  if (!this.tradeExchange || !this.rateInfo) return null;
+  return this.rateInfo.rates[this.tradeExchange.currency()].rate;
+};
+
+// This is the rate in local currency to quote to the user
 Trader.prototype.rate = function () {
+  if (!this.rateInfo) return null;
   return {
-    rate: this.rateInfo.rates[this.config.exchanges.settings.currency],
+    rate: this._deviceRate(),
     timestamp: this.rateInfo.timestamp
   };
 };