Add RateService to get info about fiat currencies

js/services/rate.js

@@ -0,0 +1,40 @@
+'use strict';
+
+var RateService = function($http) {
+  this.isAvailable = false;
+  this.SAT_TO_BTC = 1 / 1e8;
+  var that = this;
+  var backoff = 5;
+  var retrieve = function() {
+    $http({method: 'GET', url: 'https://bitpay.com/api/rates'}).
+    success(function(data, status, headers, config) {
+      var rates = {};
+      data.forEach(function(element) {
+        rates[element.code] = element.rate;
+      });
+      that.isAvailable = true;
+      that.rates = rates;
+    }).
+    error(function(data, status, headers, config) {
+      backoff *= 1.5;
+      setTimeout(retrieve, backoff * 1000);
+    });
+  };
+  retrieve();
+};
+
+RateService.prototype.toFiat = function(satoshis, code) {
+  if (!this.isAvailable) {
+    return 0;
+  }
+  return satoshis * this.SAT_TO_BTC * this.rates[code];
+};
+
+RateService.prototype.fromFiat = function(amount, code) {
+  if (!this.isAvailable) {
+    return 0;
+  }
+  return amount / this.rates[code] / this.SAT_TO_BTC;
+};
+
+angular.module('copayApp.services').service('rateService', RateService);