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567 lines
18 KiB
567 lines
18 KiB
import { ethers } from 'ethers'
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import log from 'loglevel'
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import BigNumber from 'bignumber.js'
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import ObservableStore from 'obs-store'
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import { mapValues } from 'lodash'
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import abi from 'human-standard-token-abi'
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import { calcTokenAmount } from '../../../ui/app/helpers/utils/token-util'
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import { calcGasTotal } from '../../../ui/app/pages/send/send.utils'
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import { conversionUtil } from '../../../ui/app/helpers/utils/conversion-util'
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import {
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ETH_SWAPS_TOKEN_ADDRESS,
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DEFAULT_ERC20_APPROVE_GAS,
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QUOTES_EXPIRED_ERROR,
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QUOTES_NOT_AVAILABLE_ERROR,
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} from '../../../ui/app/helpers/constants/swaps'
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import {
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fetchTradesInfo as defaultFetchTradesInfo,
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fetchSwapsFeatureLiveness as defaultFetchSwapsFeatureLiveness,
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} from '../../../ui/app/pages/swaps/swaps.util'
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const METASWAP_ADDRESS = '0x016B4bf68d421147c06f1b8680602c5bf0Df91A8'
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// The MAX_GAS_LIMIT is a number that is higher than the maximum gas costs we have observed on any aggregator
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const MAX_GAS_LIMIT = 2500000
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// To ensure that our serves are not spammed if MetaMask is left idle, we limit the number of fetches for quotes that are made on timed intervals.
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// 3 seems to be an appropriate balance of giving users the time they need when MetaMask is not left idle, and turning polling off when it is.
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const POLL_COUNT_LIMIT = 3
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function calculateGasEstimateWithRefund (maxGas = MAX_GAS_LIMIT, estimatedRefund = 0, estimatedGas = 0) {
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const maxGasMinusRefund = new BigNumber(
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maxGas,
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10,
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)
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.minus(estimatedRefund, 10)
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const gasEstimateWithRefund = maxGasMinusRefund.lt(
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estimatedGas,
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16,
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)
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? maxGasMinusRefund.toString(16)
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: estimatedGas
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return gasEstimateWithRefund
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}
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// This is the amount of time to wait, after successfully fetching quotes and their gas estimates, before fetching for new quotes
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const QUOTE_POLLING_INTERVAL = 50 * 1000
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const initialState = {
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swapsState: {
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quotes: {},
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fetchParams: null,
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tokens: null,
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tradeTxId: null,
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approveTxId: null,
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quotesLastFetched: null,
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customMaxGas: '',
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customGasPrice: null,
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selectedAggId: null,
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customApproveTxData: '',
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errorKey: '',
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topAggId: null,
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routeState: '',
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swapsFeatureIsLive: false,
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},
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}
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export default class SwapsController {
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constructor ({
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getBufferedGasLimit,
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provider,
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getProviderConfig,
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tokenRatesStore,
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fetchTradesInfo = defaultFetchTradesInfo,
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fetchSwapsFeatureLiveness = defaultFetchSwapsFeatureLiveness,
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}) {
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this.store = new ObservableStore({
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swapsState: { ...initialState.swapsState },
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})
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this._fetchTradesInfo = fetchTradesInfo
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this._fetchSwapsFeatureLiveness = fetchSwapsFeatureLiveness
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this.getBufferedGasLimit = getBufferedGasLimit
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this.tokenRatesStore = tokenRatesStore
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this.pollCount = 0
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this.getProviderConfig = getProviderConfig
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this.ethersProvider = new ethers.providers.Web3Provider(provider)
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this._setupSwapsLivenessFetching()
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}
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// Once quotes are fetched, we poll for new ones to keep the quotes up to date. Market and aggregator contract conditions can change fast enough
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// that quotes will no longer be available after 1 or 2 minutes. When fetchAndSetQuotes is first called it, receives fetch that parameters are stored in
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// state. These stored parameters are used on subsequent calls made during polling.
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// Note: we stop polling after 3 requests, until new quotes are explicitly asked for. The logic that enforces that maximum is in the body of fetchAndSetQuotes
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pollForNewQuotes () {
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this.pollingTimeout = setTimeout(() => {
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const { swapsState } = this.store.getState()
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this.fetchAndSetQuotes(swapsState.fetchParams, swapsState.fetchParams.metaData, true)
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}, QUOTE_POLLING_INTERVAL)
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}
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stopPollingForQuotes () {
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clearTimeout(this.pollingTimeout)
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}
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async fetchAndSetQuotes (fetchParams, fetchParamsMetaData = {}, isPolledRequest) {
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if (!fetchParams) {
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return null
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}
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// Every time we get a new request that is not from the polling, we reset the poll count so we can poll for up to three more sets of quotes with these new params.
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if (!isPolledRequest) {
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this.pollCount = 0
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}
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// If there are any pending poll requests, clear them so that they don't get call while this new fetch is in process
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clearTimeout(this.pollingTimeout)
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if (!isPolledRequest) {
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this.setSwapsErrorKey('')
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}
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let newQuotes = await this._fetchTradesInfo(fetchParams)
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newQuotes = mapValues(newQuotes, (quote) => ({
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...quote,
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sourceTokenInfo: fetchParamsMetaData.sourceTokenInfo,
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destinationTokenInfo: fetchParamsMetaData.destinationTokenInfo,
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}))
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const quotesLastFetched = Date.now()
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let approvalRequired = false
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if (fetchParams.sourceToken !== ETH_SWAPS_TOKEN_ADDRESS && Object.values(newQuotes).length) {
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const allowance = await this._getERC20Allowance(
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fetchParams.sourceToken,
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fetchParams.fromAddress,
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)
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// For a user to be able to swap a token, they need to have approved the MetaSwap contract to withdraw that token.
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// _getERC20Allowance() returns the amount of the token they have approved for withdrawal. If that amount is greater
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// than 0, it means that approval has already occured and is not needed. Otherwise, for tokens to be swapped, a new
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// call of the ERC-20 approve method is required.
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approvalRequired = allowance.eq(0)
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if (!approvalRequired) {
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newQuotes = mapValues(newQuotes, (quote) => ({
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...quote,
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approvalNeeded: null,
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}))
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} else if (!isPolledRequest) {
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const { gasLimit: approvalGas } = await this.timedoutGasReturn(Object.values(newQuotes)[0].approvalNeeded)
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newQuotes = mapValues(newQuotes, (quote) => ({
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...quote,
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approvalNeeded: {
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...quote.approvalNeeded,
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gas: approvalGas || DEFAULT_ERC20_APPROVE_GAS,
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},
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}))
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}
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}
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let topAggId = null
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// We can reduce time on the loading screen by only doing this after the
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// loading screen and best quote have rendered.
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if (!approvalRequired && !fetchParams?.balanceError) {
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newQuotes = await this.getAllQuotesWithGasEstimates(newQuotes)
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}
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if (Object.values(newQuotes).length === 0) {
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this.setSwapsErrorKey(QUOTES_NOT_AVAILABLE_ERROR)
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} else {
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const topAggData = await this._findTopQuoteAggId(newQuotes)
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if (topAggData.topAggId) {
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topAggId = topAggData.topAggId
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newQuotes[topAggId].isBestQuote = topAggData.isBest
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}
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}
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const { swapsState } = this.store.getState()
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let { selectedAggId } = swapsState
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if (!newQuotes[selectedAggId]) {
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selectedAggId = null
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}
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this.store.updateState({
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swapsState: {
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...swapsState,
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quotes: newQuotes,
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fetchParams: { ...fetchParams, metaData: fetchParamsMetaData },
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quotesLastFetched,
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selectedAggId,
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topAggId,
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},
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})
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// We only want to do up to a maximum of three requests from polling.
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this.pollCount += 1
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if (this.pollCount < POLL_COUNT_LIMIT + 1) {
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this.pollForNewQuotes()
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} else {
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this.resetPostFetchState()
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this.setSwapsErrorKey(QUOTES_EXPIRED_ERROR)
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return null
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}
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return [newQuotes, topAggId]
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}
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safeRefetchQuotes () {
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const { swapsState } = this.store.getState()
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if (!this.pollingTimeout && swapsState.fetchParams) {
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this.fetchAndSetQuotes(swapsState.fetchParams)
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}
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}
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setSelectedQuoteAggId (selectedAggId) {
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const { swapsState } = this.store.getState()
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this.store.updateState({ swapsState: { ...swapsState, selectedAggId } })
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}
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setSwapsTokens (tokens) {
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const { swapsState } = this.store.getState()
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this.store.updateState({ swapsState: { ...swapsState, tokens } })
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}
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setSwapsErrorKey (errorKey) {
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const { swapsState } = this.store.getState()
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this.store.updateState({ swapsState: { ...swapsState, errorKey } })
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}
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async getAllQuotesWithGasEstimates (quotes) {
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const quoteGasData = await Promise.all(
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Object.values(quotes).map(async (quote) => {
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const { gasLimit, simulationFails } = await this.timedoutGasReturn(quote.trade)
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return [gasLimit, simulationFails, quote.aggregator]
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}),
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)
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const newQuotes = {}
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quoteGasData.forEach(([gasLimit, simulationFails, aggId]) => {
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if (gasLimit && !simulationFails) {
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const gasEstimateWithRefund = calculateGasEstimateWithRefund(quotes[aggId].maxGas, quotes[aggId].estimatedRefund, gasLimit)
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newQuotes[aggId] = {
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...quotes[aggId],
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gasEstimate: gasLimit,
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gasEstimateWithRefund,
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}
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} else if (quotes[aggId].approvalNeeded) {
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// If gas estimation fails, but an ERC-20 approve is needed, then we do not add any estimate property to the quote object
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// Such quotes will rely on the maxGas and averageGas properties from the api
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newQuotes[aggId] = quotes[aggId]
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}
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// If gas estimation fails and no approval is needed, then we filter that quote out, so that it is not shown to the user
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})
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return newQuotes
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}
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timedoutGasReturn (tradeTxParams) {
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return new Promise((resolve) => {
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let gasTimedOut = false
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const gasTimeout = setTimeout(() => {
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gasTimedOut = true
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resolve({ gasLimit: null, simulationFails: true })
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}, 5000)
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// Remove gas from params that will be passed to the `estimateGas` call
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// Including it can cause the estimate to fail if the actual gas needed
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// exceeds the passed gas
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const tradeTxParamsForGasEstimate = {
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data: tradeTxParams.data,
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from: tradeTxParams.from,
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to: tradeTxParams.to,
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value: tradeTxParams.value,
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}
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this.getBufferedGasLimit({ txParams: tradeTxParamsForGasEstimate }, 1)
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.then(({ gasLimit, simulationFails }) => {
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if (!gasTimedOut) {
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clearTimeout(gasTimeout)
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resolve({ gasLimit, simulationFails })
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}
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})
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.catch((e) => {
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log.error(e)
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if (!gasTimedOut) {
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clearTimeout(gasTimeout)
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resolve({ gasLimit: null, simulationFails: true })
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}
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})
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})
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}
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async setInitialGasEstimate (initialAggId) {
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const { swapsState } = this.store.getState()
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const quoteToUpdate = { ...swapsState.quotes[initialAggId] }
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const {
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gasLimit: newGasEstimate,
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simulationFails,
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} = await this.timedoutGasReturn(quoteToUpdate.trade)
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if (newGasEstimate && !simulationFails) {
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const gasEstimateWithRefund = calculateGasEstimateWithRefund(quoteToUpdate.maxGas, quoteToUpdate.estimatedRefund, newGasEstimate)
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quoteToUpdate.gasEstimate = newGasEstimate
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quoteToUpdate.gasEstimateWithRefund = gasEstimateWithRefund
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}
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this.store.updateState({
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swapsState: { ...swapsState, quotes: { ...swapsState.quotes, [initialAggId]: quoteToUpdate } },
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})
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}
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setApproveTxId (approveTxId) {
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const { swapsState } = this.store.getState()
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this.store.updateState({ swapsState: { ...swapsState, approveTxId } })
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}
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setTradeTxId (tradeTxId) {
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const { swapsState } = this.store.getState()
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this.store.updateState({ swapsState: { ...swapsState, tradeTxId } })
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}
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setQuotesLastFetched (quotesLastFetched) {
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const { swapsState } = this.store.getState()
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this.store.updateState({ swapsState: { ...swapsState, quotesLastFetched } })
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}
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setSwapsTxGasPrice (gasPrice) {
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const { swapsState } = this.store.getState()
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this.store.updateState({
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swapsState: { ...swapsState, customGasPrice: gasPrice },
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})
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}
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setSwapsTxGasLimit (gasLimit) {
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const { swapsState } = this.store.getState()
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this.store.updateState({
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swapsState: { ...swapsState, customMaxGas: gasLimit },
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})
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}
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setCustomApproveTxData (data) {
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const { swapsState } = this.store.getState()
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this.store.updateState({
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swapsState: { ...swapsState, customApproveTxData: data },
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})
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}
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setBackgroundSwapRouteState (routeState) {
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const { swapsState } = this.store.getState()
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this.store.updateState({ swapsState: { ...swapsState, routeState } })
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}
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setSwapsLiveness (swapsFeatureIsLive) {
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const { swapsState } = this.store.getState()
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this.store.updateState({ swapsState: { ...swapsState, swapsFeatureIsLive } })
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}
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resetPostFetchState () {
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const { swapsState } = this.store.getState()
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this.store.updateState({
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swapsState: {
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...initialState.swapsState,
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tokens: swapsState.tokens,
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fetchParams: swapsState.fetchParams,
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swapsFeatureIsLive: swapsState.swapsFeatureIsLive,
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},
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})
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clearTimeout(this.pollingTimeout)
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}
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resetSwapsState () {
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const { swapsState } = this.store.getState()
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this.store.updateState({
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swapsState: { ...initialState.swapsState, tokens: swapsState.tokens, swapsFeatureIsLive: swapsState.swapsFeatureIsLive },
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})
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clearTimeout(this.pollingTimeout)
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}
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async _getEthersGasPrice () {
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const ethersGasPrice = await this.ethersProvider.getGasPrice()
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return ethersGasPrice.toHexString()
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}
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async _findTopQuoteAggId (quotes) {
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const tokenConversionRates = this.tokenRatesStore.getState()
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.contractExchangeRates
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const {
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swapsState: { customGasPrice },
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} = this.store.getState()
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if (!Object.values(quotes).length) {
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return {}
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}
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const usedGasPrice = customGasPrice || await this._getEthersGasPrice()
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let topAggId = ''
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let ethValueOfTradeForBestQuote = null
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Object.values(quotes).forEach((quote) => {
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const {
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destinationAmount = 0,
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destinationToken,
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destinationTokenInfo,
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trade,
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approvalNeeded,
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averageGas,
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gasEstimate,
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aggregator,
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} = quote
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const tradeGasLimitForCalculation = gasEstimate
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? new BigNumber(gasEstimate, 16)
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: new BigNumber(averageGas || MAX_GAS_LIMIT, 10)
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const totalGasLimitForCalculation = tradeGasLimitForCalculation
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.plus(approvalNeeded?.gas || '0x0', 16)
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.toString(16)
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const gasTotalInWeiHex = calcGasTotal(
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totalGasLimitForCalculation,
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usedGasPrice,
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)
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const totalEthCost = new BigNumber(gasTotalInWeiHex, 16).plus(
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trade.value,
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16,
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)
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const ethFee = conversionUtil(totalEthCost, {
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fromCurrency: 'ETH',
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fromDenomination: 'WEI',
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toDenomination: 'ETH',
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fromNumericBase: 'BN',
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numberOfDecimals: 6,
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})
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const tokenConversionRate = tokenConversionRates[destinationToken]
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const ethValueOfTrade =
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destinationTokenInfo.symbol === 'ETH'
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? calcTokenAmount(destinationAmount, 18).minus(ethFee, 10)
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: new BigNumber(tokenConversionRate || 1, 10)
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.times(
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calcTokenAmount(
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destinationAmount,
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destinationTokenInfo.decimals,
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),
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10,
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)
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.minus(tokenConversionRate ? ethFee.toString(10) : 0, 10)
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if (
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ethValueOfTradeForBestQuote === null ||
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ethValueOfTrade.gt(ethValueOfTradeForBestQuote)
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) {
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topAggId = aggregator
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ethValueOfTradeForBestQuote = ethValueOfTrade
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}
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})
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const isBest =
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quotes[topAggId]?.destinationTokenInfo?.symbol === 'ETH' ||
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Boolean(tokenConversionRates[quotes[topAggId]?.destinationToken])
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return { topAggId, isBest }
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}
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async _getERC20Allowance (contractAddress, walletAddress) {
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const contract = new ethers.Contract(
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contractAddress, abi, this.ethersProvider,
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)
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return await contract.allowance(walletAddress, METASWAP_ADDRESS)
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}
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/**
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* Sets up the fetching of the swaps feature liveness flag from our API.
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* Performs an initial fetch when called, then fetches on a 10-minute
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* interval.
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*
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* If the browser goes offline, the interval is cleared and swaps are disabled
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* until the value can be fetched again.
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*/
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_setupSwapsLivenessFetching () {
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const TEN_MINUTES_MS = 10 * 60 * 1000
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let intervalId = null
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const fetchAndSetupInterval = () => {
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if (window.navigator.onLine && intervalId === null) {
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// Set the interval first to prevent race condition between listener and
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// initial call to this function.
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intervalId = setInterval(this._fetchAndSetSwapsLiveness.bind(this), TEN_MINUTES_MS)
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this._fetchAndSetSwapsLiveness()
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}
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}
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window.addEventListener('online', fetchAndSetupInterval)
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window.addEventListener('offline', () => {
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if (intervalId !== null) {
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clearInterval(intervalId)
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intervalId = null
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const { swapsState } = this.store.getState()
|
|
if (swapsState.swapsFeatureIsLive) {
|
|
this.setSwapsLiveness(false)
|
|
}
|
|
}
|
|
})
|
|
|
|
fetchAndSetupInterval()
|
|
}
|
|
|
|
/**
|
|
* This function should only be called via _setupSwapsLivenessFetching.
|
|
*
|
|
* Attempts to fetch the swaps feature liveness flag from our API. Tries
|
|
* to fetch three times at 5-second intervals before giving up, in which
|
|
* case the value defaults to 'false'.
|
|
*
|
|
* Only updates state if the fetched/computed flag value differs from current
|
|
* state.
|
|
*/
|
|
async _fetchAndSetSwapsLiveness () {
|
|
const { swapsState } = this.store.getState()
|
|
const { swapsFeatureIsLive: oldSwapsFeatureIsLive } = swapsState
|
|
let swapsFeatureIsLive = false
|
|
let successfullyFetched = false
|
|
let numAttempts = 0
|
|
|
|
const fetchAndIncrementNumAttempts = async () => {
|
|
try {
|
|
swapsFeatureIsLive = Boolean(await this._fetchSwapsFeatureLiveness())
|
|
successfullyFetched = true
|
|
} catch (err) {
|
|
log.error(err)
|
|
numAttempts += 1
|
|
}
|
|
}
|
|
|
|
await fetchAndIncrementNumAttempts()
|
|
|
|
// The loop conditions are modified by fetchAndIncrementNumAttempts.
|
|
// eslint-disable-next-line no-unmodified-loop-condition
|
|
while (!successfullyFetched && numAttempts < 3) {
|
|
await new Promise((resolve) => {
|
|
setTimeout(resolve, 5000) // 5 seconds
|
|
})
|
|
await fetchAndIncrementNumAttempts()
|
|
}
|
|
|
|
if (!successfullyFetched) {
|
|
log.error('Failed to fetch swaps feature flag 3 times. Setting to false and trying again next interval.')
|
|
}
|
|
|
|
if (swapsFeatureIsLive !== oldSwapsFeatureIsLive) {
|
|
this.setSwapsLiveness(swapsFeatureIsLive)
|
|
}
|
|
}
|
|
|
|
}
|
|
|