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const ObservableStore = require('obs-store')
const log = require('loglevel')
const normalizeAddress = require('eth-sig-util').normalize
// By default, poll every 3 minutes
const DEFAULT_INTERVAL = 180 * 1000
/**
* A controller that polls for token exchange
* rates based on a user's current token list
*/
class TokenRatesController {
/**
* Creates a TokenRatesController
*
* @param {Object} [config] - Options to configure controller
*/
constructor ({ interval = DEFAULT_INTERVAL, currency, preferences } = {}) {
this.store = new ObservableStore()
this.currency = currency
this.preferences = preferences
this.interval = interval
}
/**
* Updates exchange rates for all tokens
*/
async updateExchangeRates () {
if (!this.isActive) { return }
const contractExchangeRates = {}
const nativeCurrency = this.currency ? this.currency.getState().nativeCurrency.toUpperCase() : 'ETH'
const pairs = this._tokens.map(token => `pairs[]=${token.address}/${nativeCurrency}`)
const query = pairs.join('&')
if (this._tokens.length > 0) {
try {
const response = await fetch(`https://exchanges.balanc3.net/pie?${query}&autoConversion=false`)
const { prices = [] } = await response.json()
prices.forEach(({ pair, price }) => {
const address = pair.split('/')[0]
contractExchangeRates[normalizeAddress(address)] = typeof price === 'number' ? price : 0
})
} catch (error) {
log.warn(`MetaMask - TokenRatesController exchange rate fetch failed.`, error)
}
}
this.store.putState({ contractExchangeRates })
}
/**
* @type {Number}
*/
set interval (interval) {
this._handle && clearInterval(this._handle)
if (!interval) { return }
this._handle = setInterval(() => { this.updateExchangeRates() }, interval)
}
/**
* @type {Object}
*/
set preferences (preferences) {
this._preferences && this._preferences.unsubscribe()
if (!preferences) { return }
this._preferences = preferences
this.tokens = preferences.getState().tokens
preferences.subscribe(({ tokens = [] }) => { this.tokens = tokens })
}
/**
* @type {Array}
*/
set tokens (tokens) {
this._tokens = tokens
this.updateExchangeRates()
}
}
module.exports = TokenRatesController
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