bwc

src/js/services/rateService.js

@@ -0,0 +1,182 @@
+'use strict';
+
+//var util = require('util');
+//var _ = require('lodash');
+//var log = require('../util/log');
+//var preconditions = require('preconditions').singleton();
+//var request = require('request');
+
+/*
+  This class lets interfaces with BitPay's exchange rate API.
+*/
+
+var RateService = function(opts) {
+  var self = this;
+
+  opts = opts || {};
+  self.httprequest = opts.httprequest; // || request;
+  self.lodash = opts.lodash;
+
+  self.SAT_TO_BTC = 1 / 1e8;
+  self.BTC_TO_SAT = 1e8;
+  self.UNAVAILABLE_ERROR = 'Service is not available - check for service.isAvailable() or use service.whenAvailable()';
+  self.UNSUPPORTED_CURRENCY_ERROR = 'Currency not supported';
+
+  self._url = opts.url || 'https://insight.bitpay.com:443/api/rates';
+
+  self._isAvailable = false;
+  self._rates = {};
+  self._alternatives = [];
+  self._queued = [];
+
+  self._fetchCurrencies();
+};
+
+
+var _instance;
+RateService.singleton = function(opts) {
+  if (!_instance) {
+    _instance = new RateService(opts);
+  }
+  return _instance;
+};
+
+RateService.prototype._fetchCurrencies = function() {
+  var self = this;
+
+  var backoffSeconds = 5;
+  var updateFrequencySeconds = 3600;
+  var rateServiceUrl = 'https://bitpay.com/api/rates';
+
+  var retrieve = function() {
+    //log.info('Fetching exchange rates');
+    self.httprequest.get(rateServiceUrl).success(function(res) {
+      self.lodash.each(res, function(currency) {
+        self._rates[currency.code] = currency.rate;
+        self._alternatives.push({
+          name: currency.name,
+          isoCode: currency.code,
+          rate: currency.rate
+        });
+      });
+      self._isAvailable = true;
+      self.lodash.each(self._queued, function(callback) {
+        setTimeout(callback, 1);
+      });
+      setTimeout(retrieve, updateFrequencySeconds * 1000);
+    }).error(function(err) {
+      //log.debug('Error fetching exchange rates', err);
+      setTimeout(function() {
+        backoffSeconds *= 1.5;
+        retrieve();
+      }, backoffSeconds * 1000);
+      return;
+    });
+
+  };
+
+  retrieve();
+};
+
+RateService.prototype.getRate = function(code) {
+  return this._rates[code];
+};
+
+RateService.prototype.getHistoricRate = function(code, date, cb) {
+  var self = this;
+
+  self.httprequest.get(self._url + '/' + code + '?ts=' + date)
+    .success(function(body) {
+      return cb(null, body.rate)
+    })
+    .error(function(err) {
+      return cb(err)
+    });
+
+};
+
+RateService.prototype.getHistoricRates = function(code, dates, cb) {
+  var self = this;
+
+  var tsList = dates.join(',');
+
+  self.httprequest.get(self._url + '/' + code + '?ts=' + tsList)
+    .success(function(body) {
+      if (!self.lodash.isArray(body)) {
+        body = [{
+          ts: dates[0],
+          rate: body.rate
+        }];
+      }
+      return cb(null, body);
+    })
+    .error(function(err) {
+      return cb(err)
+    });
+};
+
+RateService.prototype.getAlternatives = function() {
+  return this._alternatives;
+};
+
+RateService.prototype.isAvailable = function() {
+  return this._isAvailable;
+};
+
+RateService.prototype.whenAvailable = function(callback) {
+  if (this.isAvailable()) {
+    setTimeout(callback, 1);
+  } else {
+    this._queued.push(callback);
+  }
+};
+
+RateService.prototype.toFiat = function(satoshis, code) {
+  if (!this.isAvailable()) {
+    return null;
+  }
+
+  return satoshis * this.SAT_TO_BTC * this.getRate(code);
+};
+
+RateService.prototype.toFiatHistoric = function(satoshis, code, date, cb) {
+  var self = this;
+
+  self.getHistoricRate(code, date, function(err, rate) {
+    if (err) return cb(err);
+    return cb(null, satoshis * self.SAT_TO_BTC * rate);
+  });
+};
+
+RateService.prototype.fromFiat = function(amount, code) {
+  if (!this.isAvailable()) {
+    return null;
+  }
+  return amount / this.getRate(code) * this.BTC_TO_SAT;
+};
+
+RateService.prototype.listAlternatives = function() {
+  var self = this;
+  if (!this.isAvailable()) {
+    return [];
+  }
+
+  return self.lodash.map(this.getAlternatives(), function(item) {
+    return {
+      name: item.name,
+      isoCode: item.isoCode
+    }
+  });
+};
+
+angular.module('copayApp.services').factory('rateService', function($http, lodash) {
+  // var cfg = _.extend(config.rates, {
+  //   httprequest: $http
+  // });
+
+  var cfg = {
+    httprequest: $http,
+    lodash: lodash
+  };
+  return RateService.singleton(cfg);
+});