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Fix finance USD conversion mechanism (#1177)
* Fix finance USD conversion mechanism * Add Jest * Simplify conversion function * Add some tests for the conversion utility Co-authored-by: Pierre Bertet <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,61 @@ | ||
| import { useEffect, useState, useRef } from 'react' | ||
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| const CONVERT_API_RETRY_DELAY = 2 * 1000 | ||
| const CONVERT_API_RETRY_DELAY_MAX = 60 * 1000 | ||
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| function convertRatesUrl(symbolsQuery) { | ||
| return `https://min-api.cryptocompare.com/data/price?fsym=USD&tsyms=${symbolsQuery}` | ||
| } | ||
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| export function useConvertRates(symbols) { | ||
| const [rates, setRates] = useState({}) | ||
| const retryDelay = useRef(CONVERT_API_RETRY_DELAY) | ||
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| const symbolsQuery = symbols.join(',') | ||
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| useEffect(() => { | ||
| let cancelled = false | ||
| let retryTimer = null | ||
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| const update = async () => { | ||
| if (!symbolsQuery) { | ||
| setRates({}) | ||
| return | ||
| } | ||
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| try { | ||
| const response = await fetch(convertRatesUrl(symbolsQuery)) | ||
| const rates = await response.json() | ||
| if (!cancelled) { | ||
| setRates(rates) | ||
| retryDelay.current = CONVERT_API_RETRY_DELAY | ||
| } | ||
| } catch (err) { | ||
| // The !cancelled check is needed in case: | ||
| // 1. The fetch() request is ongoing. | ||
| // 2. The component gets unmounted. | ||
| // 3. An error gets thrown. | ||
| // | ||
| // Assuming the fetch() request keeps throwing, it would create new | ||
| // requests even though the useEffect() got cancelled. | ||
| if (!cancelled) { | ||
| // Add more delay after every failed attempt | ||
| retryDelay.current = Math.min( | ||
| CONVERT_API_RETRY_DELAY_MAX, | ||
| retryDelay.current * 1.2 | ||
| ) | ||
| retryTimer = setTimeout(update, retryDelay.current) | ||
| } | ||
| } | ||
| } | ||
| update() | ||
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| return () => { | ||
| cancelled = true | ||
| clearTimeout(retryTimer) | ||
| retryDelay.current = CONVERT_API_RETRY_DELAY | ||
| } | ||
| }, [symbolsQuery]) | ||
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| return rates | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,16 @@ | ||
| import BN from 'bn.js' | ||
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| export function getConvertedAmount(amount, convertRate) { | ||
| const [whole = '', dec = ''] = convertRate.toString().split('.') | ||
| // Remove any trailing zeros from the decimal part | ||
| const parsedDec = dec.replace(/0*$/, '') | ||
| // Construct the final rate, and remove any leading zeros | ||
| const rate = `${whole}${parsedDec}`.replace(/^0*/, '') | ||
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| // Number of decimals to shift the amount of the token passed in, | ||
| // resulting from converting the rate to a number without any decimal | ||
| // places | ||
| const carryAmount = new BN(parsedDec.length.toString()) | ||
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| return amount.mul(new BN('10').pow(carryAmount)).div(new BN(rate)) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,29 @@ | ||
| import BN from 'bn.js' | ||
| import { getConvertedAmount } from './conversion-utils' | ||
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| const ONE_ETH = new BN('10').pow(new BN('18')) | ||
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| describe('getConvertedAmount tests', () => { | ||
| test('Converts amounts correctly', () => { | ||
| expect(getConvertedAmount(new BN('1'), 1).toString()).toEqual('1') | ||
| expect(getConvertedAmount(new BN(ONE_ETH), 1).toString()).toEqual( | ||
| ONE_ETH.toString() | ||
| ) | ||
| expect(getConvertedAmount(new BN('1'), 0.5).toString()).toEqual('2') | ||
| expect(getConvertedAmount(new BN('1'), 0.25).toString()).toEqual('4') | ||
| expect(getConvertedAmount(new BN('1'), 0.125).toString()).toEqual('8') | ||
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| expect(getConvertedAmount(new BN('100'), 50).toString()).toEqual('2') | ||
| // This is the exact case that broke the previous implementation, | ||
| // which is AAVE's amount of WBTC + the exchange rate at a certain | ||
| // hour on 2020-06-24 | ||
| expect( | ||
| getConvertedAmount(new BN('1145054'), 0.00009248).toString() | ||
| ).toEqual('12381639273') | ||
| }) | ||
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| test('Throws on invalid inputs', () => { | ||
| expect(() => getConvertedAmount(new BN('1'), 0)).toThrow() | ||
| expect(() => getConvertedAmount('1000', 0)).toThrow() | ||
| }) | ||
| }) |