mirror of https://github.com/BTCPrivate/copay.git
169 lines
4.0 KiB
JavaScript
169 lines
4.0 KiB
JavaScript
'use strict';
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var util = require('util');
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var _ = require('lodash');
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var log = require('../util/log');
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var preconditions = require('preconditions').singleton();
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var request = require('request');
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/*
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This class lets interfaces with BitPay's exchange rate API.
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*/
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var RateService = function(opts) {
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var self = this;
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opts = opts || {};
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self.request = opts.request || request;
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self.SAT_TO_BTC = 1 / 1e8;
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self.BTC_TO_SAT = 1e8;
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self.UNAVAILABLE_ERROR = 'Service is not available - check for service.isAvailable() or use service.whenAvailable()';
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self.UNSUPPORTED_CURRENCY_ERROR = 'Currency not supported';
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self._url = opts.url || 'https://insight.bitpay.com:443/api/rates';
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self._isAvailable = false;
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self._rates = {};
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self._alternatives = [];
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self._queued = [];
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self._fetchCurrencies();
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};
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var _instance;
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RateService.singleton = function(opts) {
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if (!_instance) {
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_instance = new RateService(opts);
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}
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return _instance;
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};
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RateService.prototype._fetchCurrencies = function() {
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var self = this;
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var backoffSeconds = 5;
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var updateFrequencySeconds = 3600;
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var rateServiceUrl = 'https://bitpay.com/api/rates';
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var retrieve = function() {
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log.info('Fetching exchange rates');
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self.request.get({
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url: rateServiceUrl,
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json: true
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}, function(err, res, body) {
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if (err || !body) {
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log.debug('Error fetching exchange rates', err);
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setTimeout(function() {
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backoffSeconds *= 1.5;
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retrieve();
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}, backoffSeconds * 1000);
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return;
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}
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_.each(body, function(currency) {
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self._rates[currency.code] = currency.rate;
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self._alternatives.push({
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name: currency.name,
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isoCode: currency.code,
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rate: currency.rate
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});
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});
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self._isAvailable = true;
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_.each(self._queued, function(callback) {
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setTimeout(callback, 1);
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});
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setTimeout(retrieve, updateFrequencySeconds * 1000);
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});
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};
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retrieve();
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};
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RateService.prototype.getRate = function(code) {
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return this._rates[code];
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};
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RateService.prototype.getHistoricRate = function(code, date, cb) {
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var self = this;
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self.request.get({
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url: self._url + '/' + code + '?ts=' + date,
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json: true
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}, function(err, res, body) {
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if (err || res.statusCode != 200 || !body) return cb(err || res);
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return cb(null, body.rate);
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});
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};
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RateService.prototype.getHistoricRates = function(code, dates, cb) {
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var self = this;
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var tsList = dates.join(',');
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self.request.get({
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url: self._url + '/' + code + '?ts=' + tsList,
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json: true
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}, function(err, res, body) {
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if (err || res.statusCode != 200 || !body) return cb(err || res);
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if (!_.isArray(body)) {
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body = [{ ts: dates[0], rate: body.rate }];
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}
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return cb(null, body);
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});
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};
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RateService.prototype.getAlternatives = function() {
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return this._alternatives;
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};
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RateService.prototype.isAvailable = function() {
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return this._isAvailable;
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};
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RateService.prototype.whenAvailable = function(callback) {
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if (this.isAvailable()) {
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setTimeout(callback, 1);
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} else {
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this._queued.push(callback);
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}
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};
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RateService.prototype.toFiat = function(satoshis, code) {
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if (!this.isAvailable()) {
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throw new Error(this.UNAVAILABLE_ERROR);
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}
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return satoshis * this.SAT_TO_BTC * this.getRate(code);
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};
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RateService.prototype.toFiatHistoric = function(satoshis, code, date, cb) {
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var self = this;
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self.getHistoricRate(code, date, function(err, rate) {
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if (err) return cb(err);
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return cb(null, satoshis * self.SAT_TO_BTC * rate);
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});
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};
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RateService.prototype.fromFiat = function(amount, code) {
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if (!this.isAvailable()) {
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throw new Error(this.UNAVAILABLE_ERROR);
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}
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return amount / this.getRate(code) * this.BTC_TO_SAT;
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};
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RateService.prototype.listAlternatives = function() {
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if (!this.isAvailable()) {
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throw new Error(this.UNAVAILABLE_ERROR);
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}
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return _.map(this.getAlternatives(), function(item) {
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return {
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name: item.name,
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isoCode: item.isoCode
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}
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});
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};
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module.exports = RateService;
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