feat: dynamic FOT tax fetching (#7252)

* feat: disable exact_output FOT swaps

* fix: pr comments

* test: update snapshots

* feat: dynamically fetch tax rates

* remove tax constants file

* test: update useRoutingAPITrade expected args

* fix: useSwapTaxes nits

* lint: useSwapTaxes dependency array

src/abis/fee-on-transfer-detector.json

+[
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "_factoryV2",
+        "type": "address"
+      }
+    ],
+    "stateMutability": "nonpayable",
+    "type": "constructor"
+  },
+  {
+    "inputs": [],
+    "name": "PairLookupFailed",
+    "type": "error"
+  },
+  {
+    "inputs": [],
+    "name": "SameToken",
+    "type": "error"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address[]",
+        "name": "tokens",
+        "type": "address[]"
+      },
+      {
+        "internalType": "address",
+        "name": "baseToken",
+        "type": "address"
+      },
+      {
+        "internalType": "uint256",
+        "name": "amountToBorrow",
+        "type": "uint256"
+      }
+    ],
+    "name": "batchValidate",
+    "outputs": [
+      {
+        "components": [
+          {
+            "internalType": "uint256",
+            "name": "buyFeeBps",
+            "type": "uint256"
+          },
+          {
+            "internalType": "uint256",
+            "name": "sellFeeBps",
+            "type": "uint256"
+          }
+        ],
+        "internalType": "struct TokenFees[]",
+        "name": "fotResults",
+        "type": "tuple[]"
+      }
+    ],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "",
+        "type": "address"
+      },
+      {
+        "internalType": "uint256",
+        "name": "amount0",
+        "type": "uint256"
+      },
+      {
+        "internalType": "uint256",
+        "name": "",
+        "type": "uint256"
+      },
+      {
+        "internalType": "bytes",
+        "name": "data",
+        "type": "bytes"
+      }
+    ],
+    "name": "uniswapV2Call",
+    "outputs": [],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "token",
+        "type": "address"
+      },
+      {
+        "internalType": "address",
+        "name": "baseToken",
+        "type": "address"
+      },
+      {
+        "internalType": "uint256",
+        "name": "amountToBorrow",
+        "type": "uint256"
+      }
+    ],
+    "name": "validate",
+    "outputs": [
+      {
+        "components": [
+          {
+            "internalType": "uint256",
+            "name": "buyFeeBps",
+            "type": "uint256"
+          },
+          {
+            "internalType": "uint256",
+            "name": "sellFeeBps",
+            "type": "uint256"
+          }
+        ],
+        "internalType": "struct TokenFees",
+        "name": "fotResult",
+        "type": "tuple"
+      }
+    ],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  }
+]
\ No newline at end of file

src/constants/tax.ts

-import { ChainId, Currency, Percent } from '@uniswap/sdk-core'
-
-import { ZERO_PERCENT } from './misc'
-
-interface TokenTaxMetadata {
-  buyFee?: Percent
-  sellFee?: Percent
-}
-
-const CHAIN_TOKEN_TAX_MAP: { [chainId in number]?: { [address in string]?: TokenTaxMetadata } } = {
-  [ChainId.MAINNET]: {
-    // BULLET
-    '0x8ef32a03784c8fd63bbf027251b9620865bd54b6': {
-      buyFee: new Percent(5, 100), // 5%
-      sellFee: new Percent(5, 100), // 5%
-    },
-    // X
-    '0xabec00542d141bddf58649bfe860c6449807237c': {
-      buyFee: new Percent(1, 100), // 1%
-      sellFee: new Percent(1, 100), // 1%
-    },
-    // HarryPotterObamaKnuckles9Inu
-    '0x2577944fd4b556a99cc5aa0f072e4b944aa088df': {
-      buyFee: new Percent(1, 100), // 1%
-      sellFee: new Percent(11, 1000), // 1.1%
-    },
-    // QWN
-    '0xb354b5da5ea39dadb1cea8140bf242eb24b1821a': {
-      buyFee: new Percent(5, 100), // 5%
-      sellFee: new Percent(5, 100), // 5%
-    },
-    // HarryPotterObamaPacMan8Inu
-    '0x07e0edf8ce600fb51d44f51e3348d77d67f298ae': {
-      buyFee: new Percent(2, 100), // 2%
-      sellFee: new Percent(2, 100), // 2%
-    },
-    // KUKU
-    '0x27206f5a9afd0c51da95f20972885545d3b33647': {
-      buyFee: new Percent(2, 100), // 2%
-      sellFee: new Percent(21, 1000), // 2.1%
-    },
-    // AIMBOT
-    '0x0c48250eb1f29491f1efbeec0261eb556f0973c7': {
-      buyFee: new Percent(5, 100), // 5%
-      sellFee: new Percent(5, 100), // 5%
-    },
-    // PYUSD
-    '0xe0a8ed732658832fac18141aa5ad3542e2eb503b': {
-      buyFee: new Percent(1, 100), // 1%
-      sellFee: new Percent(13, 1000), // 1.3%
-    },
-    // ND4
-    '0x4f849c55180ddf8185c5cc495ed58c3aea9c9a28': {
-      buyFee: new Percent(1, 100), // 1%
-      sellFee: new Percent(1, 100), // 1%
-    },
-    // COCO
-    '0xcb50350ab555ed5d56265e096288536e8cac41eb': {
-      buyFee: new Percent(2, 100), // 2%
-      sellFee: new Percent(26, 1000), // 2.6%
-    },
-  },
-}
-
-export function getInputTax(currency: Currency): Percent {
-  if (currency.isNative) return ZERO_PERCENT
-
-  return CHAIN_TOKEN_TAX_MAP[currency.chainId]?.[currency.address.toLowerCase()]?.sellFee ?? ZERO_PERCENT
-}
-
-export function getOutputTax(currency: Currency): Percent {
-  if (currency.isNative) return ZERO_PERCENT
-
-  return CHAIN_TOKEN_TAX_MAP[currency.chainId]?.[currency.address.toLowerCase()]?.buyFee ?? ZERO_PERCENT
-}

src/hooks/useDebouncedTrade.test.ts

@@ -46,8 +46,10 @@ describe('#useBestV3Trade ExactIn', () => {
       USDCAmount,
       DAI,
       RouterPreference.CLIENT,
-      true, // skipFetch
-      undefined
+      /* skipFetch = */ true,
+      /* account = */ undefined,
+      /* inputTax = */ undefined,
+      /* outputTax = */ undefined
     )
     expect(result.current).toEqual({ state: TradeState.NO_ROUTE_FOUND, trade: undefined })
   })
@@ -64,8 +66,10 @@ describe('#useDebouncedTrade ExactOut', () => {
       DAIAmount,
       USDC_MAINNET,
       RouterPreference.CLIENT,
-      true, // skipFetch
-      undefined
+      /* skipFetch = */ true,
+      /* account = */ undefined,
+      /* inputTax = */ undefined,
+      /* outputTax = */ undefined
     )
     expect(result.current).toEqual({ state: TradeState.NO_ROUTE_FOUND, trade: undefined })
   })

src/hooks/useDebouncedTrade.ts

-import { Currency, CurrencyAmount, TradeType } from '@uniswap/sdk-core'
+import { Currency, CurrencyAmount, Percent, TradeType } from '@uniswap/sdk-core'
 import { useWeb3React } from '@web3-react/core'
 import { WRAPPED_NATIVE_CURRENCY } from 'constants/tokens'
 import { DebounceSwapQuoteVariant, useDebounceSwapQuoteFlag } from 'featureFlags/flags/debounceSwapQuote'
@@ -22,7 +22,9 @@ export function useDebouncedTrade(
   amountSpecified?: CurrencyAmount<Currency>,
   otherCurrency?: Currency,
   routerPreferenceOverride?: RouterPreference.X,
-  account?: string
+  account?: string,
+  inputTax?: Percent,
+  outputTax?: Percent
 ): {
   state: TradeState
   trade?: InterfaceTrade
@@ -34,7 +36,9 @@ export function useDebouncedTrade(
   amountSpecified?: CurrencyAmount<Currency>,
   otherCurrency?: Currency,
   routerPreferenceOverride?: RouterPreference.API | RouterPreference.CLIENT,
-  account?: string
+  account?: string,
+  inputTax?: Percent,
+  outputTax?: Percent
 ): {
   state: TradeState
   trade?: ClassicTrade
@@ -54,7 +58,9 @@ export function useDebouncedTrade(
   amountSpecified?: CurrencyAmount<Currency>,
   otherCurrency?: Currency,
   routerPreferenceOverride?: RouterPreference,
-  account?: string
+  account?: string,
+  inputTax?: Percent,
+  outputTax?: Percent
 ): {
   state: TradeState
   trade?: InterfaceTrade
@@ -91,6 +97,8 @@ export function useDebouncedTrade(
     otherCurrency,
     routerPreferenceOverride ?? routerPreference,
     skipFetch,
-    account
+    account,
+    inputTax,
+    outputTax
   )
 }

src/hooks/useSwapTaxes.ts

+import * as Sentry from '@sentry/react'
+import { InterfaceEventName } from '@uniswap/analytics-events'
+import { ChainId, Percent } from '@uniswap/sdk-core'
+import { WETH_ADDRESS as getWethAddress } from '@uniswap/universal-router-sdk'
+import { useWeb3React } from '@web3-react/core'
+import FOT_DETECTOR_ABI from 'abis/fee-on-transfer-detector.json'
+import { FeeOnTransferDetector } from 'abis/types'
+import { sendAnalyticsEvent } from 'analytics'
+import { ZERO_PERCENT } from 'constants/misc'
+import { useEffect, useState } from 'react'
+
+import { useContract } from './useContract'
+
+const FEE_ON_TRANSFER_DETECTOR_ADDRESS = '0x19C97dc2a25845C7f9d1d519c8C2d4809c58b43f'
+
+function useFeeOnTransferDetectorContract(): FeeOnTransferDetector | null {
+  const { account } = useWeb3React()
+  const contract = useContract<FeeOnTransferDetector>(FEE_ON_TRANSFER_DETECTOR_ADDRESS, FOT_DETECTOR_ABI)
+
+  useEffect(() => {
+    if (contract && account) {
+      sendAnalyticsEvent(InterfaceEventName.WALLET_PROVIDER_USED, {
+        source: 'useFeeOnTransferDetectorContract',
+        contract,
+      })
+    }
+  }, [account, contract])
+  return contract
+}
+
+// TODO(WEB-2787): add tax-fetching for other chains
+const WETH_ADDRESS = getWethAddress(ChainId.MAINNET)
+const AMOUNT_TO_BORROW = 10000 // smallest amount that has full precision over bps
+
+const FEE_CACHE: { [address in string]?: { sellTax?: Percent; buyTax?: Percent } } = {}
+
+async function getSwapTaxes(
+  fotDetector: FeeOnTransferDetector,
+  inputTokenAddress: string | undefined,
+  outputTokenAddress: string | undefined
+) {
+  const addresses = []
+  if (inputTokenAddress && FEE_CACHE[inputTokenAddress] === undefined) {
+    addresses.push(inputTokenAddress)
+  }
+
+  if (outputTokenAddress && FEE_CACHE[outputTokenAddress] === undefined) {
+    addresses.push(outputTokenAddress)
+  }
+
+  try {
+    if (addresses.length) {
+      const data = await fotDetector.callStatic.batchValidate(addresses, WETH_ADDRESS, AMOUNT_TO_BORROW)
+
+      addresses.forEach((address, index) => {
+        const { sellFeeBps, buyFeeBps } = data[index]
+        const sellTax = new Percent(sellFeeBps.toNumber(), 10000)
+        const buyTax = new Percent(buyFeeBps.toNumber(), 10000)
+
+        FEE_CACHE[address] = { sellTax, buyTax }
+      })
+    }
+  } catch (e) {
+    Sentry.withScope(function (scope) {
+      scope.setTag('method', 'getSwapTaxes')
+      scope.setLevel('warning')
+      Sentry.captureException(e)
+    })
+  }
+
+  const inputTax = (inputTokenAddress ? FEE_CACHE[inputTokenAddress]?.sellTax : ZERO_PERCENT) ?? ZERO_PERCENT
+  const outputTax = (outputTokenAddress ? FEE_CACHE[outputTokenAddress]?.buyTax : ZERO_PERCENT) ?? ZERO_PERCENT
+
+  return { inputTax, outputTax }
+}
+
+export function useSwapTaxes(inputTokenAddress: string | undefined, outputTokenAddress: string | undefined) {
+  const fotDetector = useFeeOnTransferDetectorContract()
+  const [{ inputTax, outputTax }, setTaxes] = useState({ inputTax: ZERO_PERCENT, outputTax: ZERO_PERCENT })
+  const { chainId } = useWeb3React()
+
+  useEffect(() => {
+    if (!fotDetector || chainId !== ChainId.MAINNET) return
+    getSwapTaxes(fotDetector, inputTokenAddress, outputTokenAddress).then(setTaxes)
+  }, [fotDetector, inputTokenAddress, outputTokenAddress, chainId])
+
+  return { inputTax, outputTax }
+}

src/lib/hooks/routing/useRoutingAPIArguments.ts

 import { SkipToken, skipToken } from '@reduxjs/toolkit/query/react'
-import { Currency, CurrencyAmount, TradeType } from '@uniswap/sdk-core'
+import { Currency, CurrencyAmount, Percent, TradeType } from '@uniswap/sdk-core'
 import { useFotAdjustmentsEnabled } from 'featureFlags/flags/fotAdjustments'
 import { useUniswapXEthOutputEnabled } from 'featureFlags/flags/uniswapXEthOutput'
 import { useUniswapXExactOutputEnabled } from 'featureFlags/flags/uniswapXExactOutput'
@@ -21,6 +21,8 @@ export function useRoutingAPIArguments({
   amount,
   tradeType,
   routerPreference,
+  inputTax,
+  outputTax,
 }: {
   account?: string
   tokenIn?: Currency
@@ -28,6 +30,8 @@ export function useRoutingAPIArguments({
   amount?: CurrencyAmount<Currency>
   tradeType: TradeType
   routerPreference: RouterPreference | typeof INTERNAL_ROUTER_PREFERENCE_PRICE
+  inputTax: Percent
+  outputTax: Percent
 }): GetQuoteArgs | SkipToken {
   const uniswapXForceSyntheticQuotes = useUniswapXSyntheticQuoteEnabled()
   const userDisabledUniswapX = useUserDisabledUniswapX()
@@ -58,6 +62,8 @@ export function useRoutingAPIArguments({
             uniswapXEthOutputEnabled,
             uniswapXExactOutputEnabled,
             fotAdjustmentsEnabled,
+            inputTax,
+            outputTax,
           },
     [
       account,
@@ -71,6 +77,8 @@ export function useRoutingAPIArguments({
       userDisabledUniswapX,
       uniswapXEthOutputEnabled,
       fotAdjustmentsEnabled,
+      inputTax,
+      outputTax,
     ]
   )
 }

src/pages/Swap/index.tsx

@@ -31,7 +31,6 @@ import { SwitchLocaleLink } from 'components/SwitchLocaleLink'
 import TokenSafetyModal from 'components/TokenSafety/TokenSafetyModal'
 import { getChainInfo } from 'constants/chainInfo'
 import { asSupportedChain, isSupportedChain } from 'constants/chains'
-import { getInputTax, getOutputTax } from 'constants/tax'
 import { getSwapCurrencyId, TOKEN_SHORTHANDS } from 'constants/tokens'
 import { useCurrency, useDefaultActiveTokens } from 'hooks/Tokens'
 import { useIsSwapUnsupported } from 'hooks/useIsSwapUnsupported'
@@ -279,14 +278,13 @@ export function Swap({
     parsedAmount,
     currencies,
     inputError: swapInputError,
+    inputTax,
+    outputTax,
   } = swapInfo
 
   const [inputTokenHasTax, outputTokenHasTax] = useMemo(
-    () => [
-      !!currencies[Field.INPUT] && !getInputTax(currencies[Field.INPUT]).equalTo(0),
-      !!currencies[Field.OUTPUT] && !getOutputTax(currencies[Field.OUTPUT]).equalTo(0),
-    ],
-    [currencies]
+    () => [!inputTax.equalTo(0), !outputTax.equalTo(0)],
+    [inputTax, outputTax]
   )
 
   useEffect(() => {

src/state/routing/types.ts

@@ -47,6 +47,8 @@ export interface GetQuoteArgs {
   uniswapXExactOutputEnabled: boolean
   userDisabledUniswapX: boolean
   fotAdjustmentsEnabled: boolean
+  inputTax: Percent
+  outputTax: Percent
 }
 
 // from https://github.com/Uniswap/routing-api/blob/main/lib/handlers/schema.ts

src/state/routing/useRoutingAPITrade.ts

 import { skipToken } from '@reduxjs/toolkit/query/react'
-import { Currency, CurrencyAmount, TradeType } from '@uniswap/sdk-core'
+import { Currency, CurrencyAmount, Percent, TradeType } from '@uniswap/sdk-core'
 import { IMetric, MetricLoggerUnit, setGlobalMetric } from '@uniswap/smart-order-router'
 import { sendTiming } from 'components/analytics'
 import { AVERAGE_L1_BLOCK_TIME } from 'constants/chainInfo'
+import { ZERO_PERCENT } from 'constants/misc'
 import { useRoutingAPIArguments } from 'lib/hooks/routing/useRoutingAPIArguments'
 import ms from 'ms'
 import { useMemo } from 'react'
@@ -27,7 +28,9 @@ export function useRoutingAPITrade<TTradeType extends TradeType>(
   otherCurrency: Currency | undefined,
   routerPreference: typeof INTERNAL_ROUTER_PREFERENCE_PRICE,
   skipFetch?: boolean,
-  account?: string
+  account?: string,
+  inputTax?: Percent,
+  outputTax?: Percent
 ): {
   state: TradeState
   trade?: ClassicTrade
@@ -40,7 +43,9 @@ export function useRoutingAPITrade<TTradeType extends TradeType>(
   otherCurrency: Currency | undefined,
   routerPreference: RouterPreference,
   skipFetch?: boolean,
-  account?: string
+  account?: string,
+  inputTax?: Percent,
+  outputTax?: Percent
 ): {
   state: TradeState
   trade?: InterfaceTrade
@@ -59,7 +64,9 @@ export function useRoutingAPITrade<TTradeType extends TradeType>(
   otherCurrency: Currency | undefined,
   routerPreference: RouterPreference | typeof INTERNAL_ROUTER_PREFERENCE_PRICE,
   skipFetch = false,
-  account?: string
+  account?: string,
+  inputTax = ZERO_PERCENT,
+  outputTax = ZERO_PERCENT
 ): {
   state: TradeState
   trade?: InterfaceTrade
@@ -81,6 +88,8 @@ export function useRoutingAPITrade<TTradeType extends TradeType>(
     amount: amountSpecified,
     tradeType,
     routerPreference,
+    inputTax,
+    outputTax,
   })
 
   const { isError, data: tradeResult, error, currentData } = useGetQuoteQueryState(queryArgs)

src/state/routing/utils.ts

@@ -6,9 +6,7 @@ import { DutchOrderInfo, DutchOrderInfoJSON } from '@uniswap/uniswapx-sdk'
 import { Pair, Route as V2Route } from '@uniswap/v2-sdk'
 import { FeeAmount, Pool, Route as V3Route } from '@uniswap/v3-sdk'
 import { asSupportedChain } from 'constants/chains'
-import { ZERO_PERCENT } from 'constants/misc'
 import { RPC_PROVIDERS } from 'constants/providers'
-import { getInputTax, getOutputTax } from 'constants/tax'
 import { isAvalanche, isBsc, isMatic, nativeOnChain } from 'constants/tokens'
 import { toSlippagePercent } from 'utils/slippage'
 
@@ -215,9 +213,6 @@ export async function transformRoutesToTrade(
 
   const approveInfo = await getApproveInfo(account, currencyIn, amount, usdCostPerGas)
 
-  const inputTax = args.fotAdjustmentsEnabled ? getInputTax(currencyIn) : ZERO_PERCENT
-  const outputTax = args.fotAdjustmentsEnabled ? getOutputTax(currencyOut) : ZERO_PERCENT
-
   const classicTrade = new ClassicTrade({
     v2Routes:
       routes
@@ -252,8 +247,8 @@ export async function transformRoutesToTrade(
     isUniswapXBetter,
     requestId: data.quote.requestId,
     quoteMethod,
-    inputTax,
-    outputTax,
+    inputTax: args.inputTax,
+    outputTax: args.outputTax,
   })
 
   // During the opt-in period, only return UniswapX quotes if the user has turned on the setting,

src/state/swap/hooks.tsx

@@ -3,6 +3,7 @@ import { ChainId, Currency, CurrencyAmount, Percent, TradeType } from '@uniswap/
 import { useWeb3React } from '@web3-react/core'
 import useAutoSlippageTolerance from 'hooks/useAutoSlippageTolerance'
 import { useDebouncedTrade } from 'hooks/useDebouncedTrade'
+import { useSwapTaxes } from 'hooks/useSwapTaxes'
 import tryParseCurrencyAmount from 'lib/utils/tryParseCurrencyAmount'
 import { ParsedQs } from 'qs'
 import { ReactNode, useCallback, useEffect, useMemo } from 'react'
@@ -77,6 +78,8 @@ const BAD_RECIPIENT_ADDRESSES: { [address: string]: true } = {
 export type SwapInfo = {
   currencies: { [field in Field]?: Currency | null }
   currencyBalances: { [field in Field]?: CurrencyAmount<Currency> }
+  inputTax: Percent
+  outputTax: Percent
   parsedAmount?: CurrencyAmount<Currency>
   inputError?: ReactNode
   trade: {
@@ -104,6 +107,12 @@ export function useDerivedSwapInfo(state: SwapState, chainId: ChainId | undefine
 
   const inputCurrency = useCurrency(inputCurrencyId, chainId)
   const outputCurrency = useCurrency(outputCurrencyId, chainId)
+
+  const { inputTax, outputTax } = useSwapTaxes(
+    inputCurrency?.isToken ? inputCurrency.address : undefined,
+    outputCurrency?.isToken ? outputCurrency.address : undefined
+  )
+
   const recipientLookup = useENS(recipient ?? undefined)
   const to: string | null = (recipient === null ? account : recipientLookup.address) ?? null
 
@@ -123,7 +132,9 @@ export function useDerivedSwapInfo(state: SwapState, chainId: ChainId | undefine
     parsedAmount,
     (isExactIn ? outputCurrency : inputCurrency) ?? undefined,
     undefined,
-    account
+    account,
+    inputTax,
+    outputTax
   )
 
   const currencyBalances = useMemo(
@@ -198,8 +209,10 @@ export function useDerivedSwapInfo(state: SwapState, chainId: ChainId | undefine
       trade,
       autoSlippage,
       allowedSlippage,
+      inputTax,
+      outputTax,
     }),
-    [allowedSlippage, autoSlippage, currencies, currencyBalances, inputError, parsedAmount, trade]
+    [allowedSlippage, autoSlippage, currencies, currencyBalances, inputError, inputTax, outputTax, parsedAmount, trade]
   )
 }