60 lines
1.9 KiB
JavaScript
60 lines
1.9 KiB
JavaScript
const _ = require('lodash/fp')
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const axios = require('axios')
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const mem = require('mem')
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const BN = require('./bn')
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const T = require('./time')
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const MAX_ROTATIONS = 5
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const _getFiatRates = () => (
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axios.get('https://bitpay.com/api/rates')
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.then(response => response.data)
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)
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const getFiatRates = mem(_getFiatRates, {
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maxAge: 6 * T.hours,
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cacheKey: () => ''
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})
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const API_QUEUE = [
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{ api: getBitPayFxRate, name: 'bitpay', fiatCodeProperty: 'code', rateProperty: 'rate' }
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]
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function getBitPayFxRate (fiatCode, defaultFiatMarket, fiatCodeProperty, rateProperty) {
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return getFiatRates()
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.then(({ data: fxRates }) => {
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const defaultFiatRate = findCurrencyRates(fxRates, defaultFiatMarket, fiatCodeProperty, rateProperty)
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const fxRate = findCurrencyRates(fxRates, fiatCode, fiatCodeProperty, rateProperty).div(defaultFiatRate)
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return {
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fxRate
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}
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})
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}
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function findCurrencyRates (fxRates, fiatCode, fiatCodeProperty, rateProperty) {
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const rates = _.find(_.matchesProperty(fiatCodeProperty, fiatCode), fxRates)
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if (!rates || !rates[rateProperty]) throw new Error(`Unsupported currency: ${fiatCode}`)
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return new BN(rates[rateProperty].toString())
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}
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const getRate = (retries = 1, fiatCode, defaultFiatMarket) => {
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const selected = _.first(API_QUEUE).name
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const activeAPI = _.first(API_QUEUE).api
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const fiatCodeProperty = _.first(API_QUEUE).fiatCodeProperty
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const rateProperty = _.first(API_QUEUE).rateProperty
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if (!activeAPI) throw new Error(`FOREX api ${selected} does not exist.`)
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return activeAPI(fiatCode, defaultFiatMarket, fiatCodeProperty, rateProperty)
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.catch(() => {
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// Switch service
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const erroredService = API_QUEUE.shift()
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API_QUEUE.push(erroredService)
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if (retries >= MAX_ROTATIONS) throw new Error(`FOREX API error from ${erroredService.name}`)
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return getRate(++retries, fiatCode)
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})
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}
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module.exports = { getFiatRates, getRate }
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