Add liquidity callback (#830)

* give add liquidity the reducer treatment

rename setDefaultsFromURL to setDefaultsFromURLSearch

* fix tests and crash

* rework DOM structure to make flow more natural

* allow slippage + deadline setting in add liquidity

* disable token selection in mint

clear input between pairs

cypress/integration/add-liquidity.test.ts

 describe('Add Liquidity', () => {
   it('loads the two correct tokens', () => {
     cy.visit('/add/0xF9bA5210F91D0474bd1e1DcDAeC4C58E359AaD85-0xc778417E063141139Fce010982780140Aa0cD5Ab')
-    cy.get('#add-liquidity-input-token0 .token-symbol-container').should('contain.text', 'MKR')
-    cy.get('#add-liquidity-input-token1 .token-symbol-container').should('contain.text', 'ETH')
+    cy.get('#add-liquidity-input-tokena .token-symbol-container').should('contain.text', 'MKR')
+    cy.get('#add-liquidity-input-tokenb .token-symbol-container').should('contain.text', 'ETH')
   })
 
   it('does not crash if ETH is duplicated', () => {
     cy.visit('/add/0xc778417E063141139Fce010982780140Aa0cD5Ab-0xc778417E063141139Fce010982780140Aa0cD5Ab')
-    cy.get('#add-liquidity-input-token0 .token-symbol-container').should('contain.text', 'ETH')
-    cy.get('#add-liquidity-input-token1 .token-symbol-container').should('not.contain.text', 'ETH')
+    cy.get('#add-liquidity-input-tokena .token-symbol-container').should('contain.text', 'ETH')
+    cy.get('#add-liquidity-input-tokenb .token-symbol-container').should('not.contain.text', 'ETH')
   })
 
   it('token not in storage is loaded', () => {
     cy.visit('/add/0xb290b2f9f8f108d03ff2af3ac5c8de6de31cdf6d-0xF9bA5210F91D0474bd1e1DcDAeC4C58E359AaD85')
-    cy.get('#add-liquidity-input-token0 .token-symbol-container').should('contain.text', 'SKL')
-    cy.get('#add-liquidity-input-token1 .token-symbol-container').should('contain.text', 'MKR')
+    cy.get('#add-liquidity-input-tokena .token-symbol-container').should('contain.text', 'SKL')
+    cy.get('#add-liquidity-input-tokenb .token-symbol-container').should('contain.text', 'MKR')
   })
 })

src/components/swap/AdvancedSwapDetails.tsx

@@ -15,28 +15,14 @@ import FormattedPriceImpact from './FormattedPriceImpact'
 import TokenLogo from '../TokenLogo'
 import flatMap from 'lodash.flatmap'
 
-export interface AdvancedSwapDetailsProps extends SlippageTabsProps {
-  trade: Trade
-  onDismiss: () => void
-}
-
-export function AdvancedSwapDetails({ trade, onDismiss, ...slippageTabProps }: AdvancedSwapDetailsProps) {
-  const { priceImpactWithoutFee, realizedLPFee } = computeTradePriceBreakdown(trade)
+function TradeSummary({ trade, allowedSlippage }: { trade: Trade; allowedSlippage: number }) {
   const theme = useContext(ThemeContext)
+  const { priceImpactWithoutFee, realizedLPFee } = computeTradePriceBreakdown(trade)
   const isExactIn = trade.tradeType === TradeType.EXACT_INPUT
-  const slippageAdjustedAmounts = computeSlippageAdjustedAmounts(trade, slippageTabProps.rawSlippage)
+  const slippageAdjustedAmounts = computeSlippageAdjustedAmounts(trade, allowedSlippage)
 
   return (
-    <AutoColumn gap="md">
-      <CursorPointer>
-        <RowBetween onClick={onDismiss} padding={'8px 20px'}>
-          <Text fontSize={16} color={theme.text2} fontWeight={500} style={{ userSelect: 'none' }}>
-            Hide Advanced
-          </Text>
-          <ChevronUp color={theme.text2} />
-        </RowBetween>
-      </CursorPointer>
-      <SectionBreak />
+    <>
       <AutoColumn style={{ padding: '0 20px' }}>
         <RowBetween>
           <RowFixed>
@@ -83,16 +69,36 @@ export function AdvancedSwapDetails({ trade, onDismiss, ...slippageTabProps }: A
       </AutoColumn>
 
       <SectionBreak />
+    </>
+  )
+}
+
+export interface AdvancedSwapDetailsProps extends SlippageTabsProps {
+  trade?: Trade
+  onDismiss: () => void
+}
+
+export function AdvancedSwapDetails({ trade, onDismiss, ...slippageTabProps }: AdvancedSwapDetailsProps) {
+  const theme = useContext(ThemeContext)
+
+  return (
+    <AutoColumn gap="md">
+      <CursorPointer>
+        <RowBetween onClick={onDismiss} padding={'8px 20px'}>
+          <Text fontSize={16} color={theme.text2} fontWeight={500} style={{ userSelect: 'none' }}>
+            Hide Advanced
+          </Text>
+          <ChevronUp color={theme.text2} />
+        </RowBetween>
+      </CursorPointer>
+
+      <SectionBreak />
+
+      {trade && <TradeSummary trade={trade} allowedSlippage={slippageTabProps.rawSlippage} />}
 
-      <RowFixed padding={'0 20px'}>
-        <TYPE.black fontWeight={400} fontSize={14} color={theme.text2}>
-          Set slippage tolerance
-        </TYPE.black>
-        <QuestionHelper text="Your transaction will revert if the execution price changes by more than this amount after you submit your trade." />
-      </RowFixed>
       <SlippageTabs {...slippageTabProps} />
 
-      {trade.route.path.length > 2 && (
+      {trade?.route?.path?.length > 2 && (
         <AutoColumn style={{ padding: '0 20px' }}>
           <RowFixed>
             <TYPE.black fontSize={14} fontWeight={400} color={theme.text2}>

src/components/swap/AdvancedSwapDetailsDropdown.tsx

-import { Percent } from '@uniswap/sdk'
 import React, { useContext } from 'react'
 import { ChevronDown } from 'react-feather'
 import { Text } from 'rebass'
 import { ThemeContext } from 'styled-components'
 import { CursorPointer } from '../../theme'
-import { warningServerity } from '../../utils/prices'
-import { AutoColumn } from '../Column'
 import { RowBetween } from '../Row'
 import { AdvancedSwapDetails, AdvancedSwapDetailsProps } from './AdvancedSwapDetails'
-import { PriceSlippageWarningCard } from './PriceSlippageWarningCard'
-import { AdvancedDropwdown, FixedBottom } from './styleds'
+import { AdvancedDropdown } from './styleds'
 
 export default function AdvancedSwapDetailsDropdown({
-  priceImpactWithoutFee,
   showAdvanced,
   setShowAdvanced,
   ...rest
 }: Omit<AdvancedSwapDetailsProps, 'onDismiss'> & {
   showAdvanced: boolean
   setShowAdvanced: (showAdvanced: boolean) => void
-  priceImpactWithoutFee: Percent
 }) {
   const theme = useContext(ThemeContext)
-  const severity = warningServerity(priceImpactWithoutFee)
   return (
-    <AdvancedDropwdown>
+    <AdvancedDropdown>
       {showAdvanced ? (
         <AdvancedSwapDetails {...rest} onDismiss={() => setShowAdvanced(false)} />
       ) : (
@@ -37,11 +30,6 @@ export default function AdvancedSwapDetailsDropdown({
           </RowBetween>
         </CursorPointer>
       )}
-      <FixedBottom>
-        <AutoColumn gap="lg">
-          {severity > 2 && <PriceSlippageWarningCard priceSlippage={priceImpactWithoutFee} />}
-        </AutoColumn>
-      </FixedBottom>
-    </AdvancedDropwdown>
+    </AdvancedDropdown>
   )
 }

src/components/swap/FormattedPriceImpact.tsx

 import { Percent } from '@uniswap/sdk'
 import React from 'react'
 import { ONE_BIPS } from '../../constants'
-import { warningServerity } from '../../utils/prices'
+import { warningSeverity } from '../../utils/prices'
 import { ErrorText } from './styleds'
 
 export default function FormattedPriceImpact({ priceImpact }: { priceImpact?: Percent }) {
   return (
-    <ErrorText fontWeight={500} fontSize={14} severity={warningServerity(priceImpact)}>
+    <ErrorText fontWeight={500} fontSize={14} severity={warningSeverity(priceImpact)}>
       {priceImpact?.lessThan(ONE_BIPS) ? '<0.01%' : `${priceImpact?.toFixed(2)}%` ?? '-'}
     </ErrorText>
   )

src/components/swap/styleds.ts

@@ -28,19 +28,16 @@ export const FixedBottom = styled.div`
   margin-bottom: 40px;
 `
 
-export const AdvancedDropwdown = styled.div`
-  position: absolute;
-  margin-top: -12px;
-  max-width: 455px;
+export const AdvancedDropdown = styled.div`
+  padding-top: calc(10px + 2rem);
+  padding-bottom: 10px;
+  margin-top: -2rem;
   width: 100%;
-  margin-bottom: 100px;
-  padding: 10px 0;
-  padding-top: 36px;
+  max-width: 400px;
   border-bottom-left-radius: 20px;
   border-bottom-right-radius: 20px;
   color: ${({ theme }) => theme.text2};
   background-color: ${({ theme }) => theme.advancedBG};
-  color: ${({ theme }) => theme.text2};
   z-index: -1;
 `
 
@@ -57,7 +54,7 @@ export const BottomGrouping = styled.div`
 
 export const ErrorText = styled(Text)<{ severity?: 0 | 1 | 2 | 3 }>`
   color: ${({ theme, severity }) =>
-    severity === 3 ? theme.red1 : severity === 2 ? theme.yellow2 : severity === 1 ? theme.green1 : theme.text1};
+    severity === 3 ? theme.red1 : severity === 2 ? theme.yellow2 : severity === 1 ? theme.text1 : theme.green1};
 `
 
 export const InputGroup = styled(AutoColumn)`

src/pages/App.tsx

@@ -67,6 +67,10 @@ const BackgroundGradient = styled.div`
   }
 `
 
+const Marginer = styled.div`
+  margin-top: 5rem;
+`
+
 let Router: React.ComponentType
 if (process.env.PUBLIC_URL === '.') {
   Router = HashRouter
@@ -99,6 +103,7 @@ export default function App() {
                 <Route component={RedirectPathToSwapOnly} />
               </Switch>
             </Web3ReactManager>
+            <Marginer />
             <Footer />
           </BodyWrapper>
           <BackgroundGradient />

src/pages/AppBody.tsx

@@ -2,17 +2,15 @@ import React from 'react'
 import styled from 'styled-components'
 import NavigationTabs from '../components/NavigationTabs'
 
-export const Body = styled.div`
+const Body = styled.div`
+  position: relative;
   max-width: 420px;
   width: 100%;
-  /* min-height: 340px; */
   background: ${({ theme }) => theme.bg1};
   box-shadow: 0px 0px 1px rgba(0, 0, 0, 0.01), 0px 4px 8px rgba(0, 0, 0, 0.04), 0px 16px 24px rgba(0, 0, 0, 0.04),
     0px 24px 32px rgba(0, 0, 0, 0.01);
   border-radius: 30px;
   padding: 1rem;
-  position: relative;
-  margin-bottom: 10rem;
 `
 
 /**

src/pages/Send/index.tsx

@@ -30,14 +30,20 @@ import { useSendCallback } from '../../hooks/useSendCallback'
 import { useSwapCallback } from '../../hooks/useSwapCallback'
 import { useWalletModalToggle } from '../../state/application/hooks'
 import { Field } from '../../state/swap/actions'
-import { useDefaultsFromURL, useDerivedSwapInfo, useSwapActionHandlers, useSwapState } from '../../state/swap/hooks'
+import {
+  useDefaultsFromURLSearch,
+  useDerivedSwapInfo,
+  useSwapActionHandlers,
+  useSwapState
+} from '../../state/swap/hooks'
 import { useAllTokenBalancesTreatingWETHasETH } from '../../state/wallet/hooks'
 import { CursorPointer, TYPE } from '../../theme'
-import { computeSlippageAdjustedAmounts, computeTradePriceBreakdown, warningServerity } from '../../utils/prices'
+import { computeSlippageAdjustedAmounts, computeTradePriceBreakdown, warningSeverity } from '../../utils/prices'
 import AppBody from '../AppBody'
+import { PriceSlippageWarningCard } from '../../components/swap/PriceSlippageWarningCard'
 
 export default function Send({ location: { search } }: RouteComponentProps) {
-  useDefaultsFromURL(search)
+  useDefaultsFromURLSearch(search)
 
   // text translation
   // const { t } = useTranslation()
@@ -173,7 +179,7 @@ export default function Send({ location: { search } }: RouteComponentProps) {
   const [showInverted, setShowInverted] = useState<boolean>(false)
 
   // warnings on slippage
-  const severity = !sendingWithSwap ? 0 : warningServerity(priceImpactWithoutFee)
+  const severity = !sendingWithSwap ? 0 : warningSeverity(priceImpactWithoutFee)
 
   function modalHeader() {
     if (!sendingWithSwap) {
@@ -492,20 +498,26 @@ export default function Send({ location: { search } }: RouteComponentProps) {
             )}
             <V1TradeLink v1TradeLinkIfBetter={v1TradeLinkIfBetter} />
           </BottomGrouping>
-          {bestTrade && (
-            <AdvancedSwapDetailsDropdown
-              trade={bestTrade}
-              rawSlippage={allowedSlippage}
-              deadline={deadline}
-              showAdvanced={showAdvanced}
-              setShowAdvanced={setShowAdvanced}
-              priceImpactWithoutFee={priceImpactWithoutFee}
-              setDeadline={setDeadline}
-              setRawSlippage={setAllowedSlippage}
-            />
-          )}
         </Wrapper>
       </AppBody>
+
+      {bestTrade && (
+        <AdvancedSwapDetailsDropdown
+          trade={bestTrade}
+          rawSlippage={allowedSlippage}
+          deadline={deadline}
+          showAdvanced={showAdvanced}
+          setShowAdvanced={setShowAdvanced}
+          setDeadline={setDeadline}
+          setRawSlippage={setAllowedSlippage}
+        />
+      )}
+
+      {priceImpactWithoutFee && severity > 2 && (
+        <AutoColumn gap="lg" style={{ marginTop: '1rem' }}>
+          <PriceSlippageWarningCard priceSlippage={priceImpactWithoutFee} />
+        </AutoColumn>
+      )}
     </>
   )
 }

src/pages/Swap/index.tsx

@@ -27,23 +27,30 @@ import { useApproveCallbackFromTrade, ApprovalState } from '../../hooks/useAppro
 import { useSwapCallback } from '../../hooks/useSwapCallback'
 import { useWalletModalToggle } from '../../state/application/hooks'
 import { Field } from '../../state/swap/actions'
-import { useDefaultsFromURL, useDerivedSwapInfo, useSwapActionHandlers, useSwapState } from '../../state/swap/hooks'
+import {
+  useDefaultsFromURLSearch,
+  useDerivedSwapInfo,
+  useSwapActionHandlers,
+  useSwapState
+} from '../../state/swap/hooks'
 import { CursorPointer, TYPE } from '../../theme'
-import { computeSlippageAdjustedAmounts, computeTradePriceBreakdown, warningServerity } from '../../utils/prices'
+import { computeSlippageAdjustedAmounts, computeTradePriceBreakdown, warningSeverity } from '../../utils/prices'
 import AppBody from '../AppBody'
+import { PriceSlippageWarningCard } from '../../components/swap/PriceSlippageWarningCard'
 
 export default function Swap({ location: { search } }: RouteComponentProps) {
-  useDefaultsFromURL(search)
-  // text translation
-  // const { t } = useTranslation()
+  useDefaultsFromURLSearch(search)
+
   const { chainId, account } = useActiveWeb3React()
   const theme = useContext(ThemeContext)
 
   // toggle wallet when disconnected
   const toggleWalletModal = useWalletModalToggle()
 
+  // swap state
   const { independentField, typedValue } = useSwapState()
   const { bestTrade, tokenBalances, parsedAmounts, tokens, error, v1TradeLinkIfBetter } = useDerivedSwapInfo()
+  const { onSwitchTokens, onTokenSelection, onUserInput } = useSwapActionHandlers()
   const isValid = !error
   const dependentField: Field = independentField === Field.INPUT ? Field.OUTPUT : Field.INPUT
 
@@ -58,6 +65,11 @@ export default function Swap({ location: { search } }: RouteComponentProps) {
   const [deadline, setDeadline] = useState<number>(DEFAULT_DEADLINE_FROM_NOW)
   const [allowedSlippage, setAllowedSlippage] = useState<number>(INITIAL_ALLOWED_SLIPPAGE)
 
+  const formattedAmounts = {
+    [independentField]: typedValue,
+    [dependentField]: parsedAmounts[dependentField] ? parsedAmounts[dependentField].toSignificant(6) : ''
+  }
+
   const route = bestTrade?.route
   const userHasSpecifiedInputOutput =
     !!tokens[Field.INPUT] &&
@@ -69,13 +81,6 @@ export default function Swap({ location: { search } }: RouteComponentProps) {
   // check whether the user has approved the router on the input token
   const [approval, approveCallback] = useApproveCallbackFromTrade(bestTrade, allowedSlippage)
 
-  const formattedAmounts = {
-    [independentField]: typedValue,
-    [dependentField]: parsedAmounts[dependentField] ? parsedAmounts[dependentField].toSignificant(6) : ''
-  }
-
-  const { onSwitchTokens, onTokenSelection, onUserInput } = useSwapActionHandlers()
-
   const maxAmountInput: TokenAmount =
     !!tokenBalances[Field.INPUT] &&
     !!tokens[Field.INPUT] &&
@@ -88,7 +93,7 @@ export default function Swap({ location: { search } }: RouteComponentProps) {
         : tokenBalances[Field.INPUT]
       : undefined
   const atMaxAmountInput: boolean =
-    !!maxAmountInput && !!parsedAmounts[Field.INPUT] ? maxAmountInput.equalTo(parsedAmounts[Field.INPUT]) : undefined
+    maxAmountInput && parsedAmounts[Field.INPUT] ? maxAmountInput.equalTo(parsedAmounts[Field.INPUT]) : undefined
 
   const slippageAdjustedAmounts = computeSlippageAdjustedAmounts(bestTrade, allowedSlippage)
 
@@ -130,7 +135,7 @@ export default function Swap({ location: { search } }: RouteComponentProps) {
   const [showInverted, setShowInverted] = useState<boolean>(false)
 
   // warnings on slippage
-  const priceImpactSeverity = warningServerity(priceImpactWithoutFee)
+  const priceImpactSeverity = warningSeverity(priceImpactWithoutFee)
 
   function modalHeader() {
     return (
@@ -259,13 +264,7 @@ export default function Swap({ location: { search } }: RouteComponentProps) {
           </AutoColumn>
           <BottomGrouping>
             {!account ? (
-              <ButtonLight
-                onClick={() => {
-                  toggleWalletModal()
-                }}
-              >
-                Connect Wallet
-              </ButtonLight>
+              <ButtonLight onClick={toggleWalletModal}>Connect Wallet</ButtonLight>
             ) : noRoute && userHasSpecifiedInputOutput ? (
               <GreyCard style={{ textAlign: 'center' }}>
                 <TYPE.main mb="4px">Insufficient liquidity for this trade.</TYPE.main>
@@ -294,20 +293,26 @@ export default function Swap({ location: { search } }: RouteComponentProps) {
             )}
             <V1TradeLink v1TradeLinkIfBetter={v1TradeLinkIfBetter} />
           </BottomGrouping>
-          {bestTrade && (
-            <AdvancedSwapDetailsDropdown
-              trade={bestTrade}
-              rawSlippage={allowedSlippage}
-              deadline={deadline}
-              showAdvanced={showAdvanced}
-              setShowAdvanced={setShowAdvanced}
-              priceImpactWithoutFee={priceImpactWithoutFee}
-              setDeadline={setDeadline}
-              setRawSlippage={setAllowedSlippage}
-            />
-          )}
         </Wrapper>
       </AppBody>
+
+      {bestTrade && (
+        <AdvancedSwapDetailsDropdown
+          trade={bestTrade}
+          rawSlippage={allowedSlippage}
+          deadline={deadline}
+          showAdvanced={showAdvanced}
+          setShowAdvanced={setShowAdvanced}
+          setDeadline={setDeadline}
+          setRawSlippage={setAllowedSlippage}
+        />
+      )}
+
+      {priceImpactWithoutFee && priceImpactSeverity > 2 && (
+        <AutoColumn gap="lg" style={{ marginTop: '1rem' }}>
+          <PriceSlippageWarningCard priceSlippage={priceImpactWithoutFee} />
+        </AutoColumn>
+      )}
     </>
   )
 }

src/state/index.ts

 import { configureStore, getDefaultMiddleware } from '@reduxjs/toolkit'
+import { save, load } from 'redux-localstorage-simple'
+
 import application from './application/reducer'
-import { updateVersion } from './user/actions'
 import user from './user/reducer'
+import transactions from './transactions/reducer'
 import wallet from './wallet/reducer'
 import swap from './swap/reducer'
-import transactions from './transactions/reducer'
-import { save, load } from 'redux-localstorage-simple'
+import mint from './mint/reducer'
+
+import { updateVersion } from './user/actions'
 
 const PERSISTED_KEYS: string[] = ['user', 'transactions']
 
@@ -15,7 +18,8 @@ const store = configureStore({
     user,
     transactions,
     wallet,
-    swap
+    swap,
+    mint
   },
   middleware: [...getDefaultMiddleware(), save({ states: PERSISTED_KEYS })],
   preloadedState: load({ states: PERSISTED_KEYS })

src/state/mint/actions.ts

+import { createAction } from '@reduxjs/toolkit'
+import { RouteComponentProps } from 'react-router-dom'
+
+export enum Field {
+  TOKEN_A = 'TOKEN_A',
+  TOKEN_B = 'TOKEN_B'
+}
+
+export const setDefaultsFromURLMatchParams = createAction<{
+  chainId: number
+  params: RouteComponentProps<{ [k: string]: string }>['match']['params']
+}>('setDefaultsFromMatch')
+export const typeInput = createAction<{ field: Field; typedValue: string; noLiquidity: boolean }>('typeInputMint')

src/state/mint/hooks.ts

+import { useEffect, useCallback, useMemo } from 'react'
+import { useDispatch, useSelector } from 'react-redux'
+import { Token, TokenAmount, Route, JSBI, Price, Percent, Pair } from '@uniswap/sdk'
+
+import { useActiveWeb3React } from '../../hooks'
+import { AppDispatch, AppState } from '../index'
+import { setDefaultsFromURLMatchParams, Field, typeInput } from './actions'
+import { useTokenByAddressAndAutomaticallyAdd } from '../../hooks/Tokens'
+import { useTokenBalancesTreatWETHAsETH } from '../wallet/hooks'
+import { usePair } from '../../data/Reserves'
+import { useTotalSupply } from '../../data/TotalSupply'
+import { tryParseAmount } from '../swap/hooks'
+
+const ZERO = JSBI.BigInt(0)
+
+export function useMintState(): AppState['mint'] {
+  return useSelector<AppState, AppState['mint']>(state => state.mint)
+}
+
+export function useDerivedMintInfo(): {
+  dependentField: Field
+  tokens: { [field in Field]?: Token }
+  pair?: Pair | null
+  tokenBalances: { [field in Field]?: TokenAmount }
+  parsedAmounts: { [field in Field]?: TokenAmount }
+  price?: Price
+  noLiquidity?: boolean
+  liquidityMinted?: TokenAmount
+  poolTokenPercentage?: Percent
+  error?: string
+} {
+  const { account } = useActiveWeb3React()
+
+  const {
+    independentField,
+    typedValue,
+    otherTypedValue,
+    [Field.TOKEN_A]: { address: tokenAAddress },
+    [Field.TOKEN_B]: { address: tokenBAddress }
+  } = useMintState()
+
+  const dependentField = independentField === Field.TOKEN_A ? Field.TOKEN_B : Field.TOKEN_A
+
+  // tokens
+  const tokenA = useTokenByAddressAndAutomaticallyAdd(tokenAAddress)
+  const tokenB = useTokenByAddressAndAutomaticallyAdd(tokenBAddress)
+  const tokens: { [field in Field]?: Token } = useMemo(
+    () => ({
+      [Field.TOKEN_A]: tokenA,
+      [Field.TOKEN_B]: tokenB
+    }),
+    [tokenA, tokenB]
+  )
+
+  // pair
+  const pair = usePair(tokens[Field.TOKEN_A], tokens[Field.TOKEN_B])
+  const noLiquidity =
+    pair === null || (!!pair && JSBI.equal(pair.reserve0.raw, ZERO) && JSBI.equal(pair.reserve1.raw, ZERO))
+
+  // route
+  const route = useMemo(
+    () =>
+      !noLiquidity && pair && tokens[independentField] ? new Route([pair], tokens[Field.TOKEN_A] as Token) : undefined,
+    [noLiquidity, pair, tokens, independentField]
+  )
+
+  // balances
+  const relevantTokenBalances = useTokenBalancesTreatWETHAsETH(account ?? undefined, [
+    tokens[Field.TOKEN_A],
+    tokens[Field.TOKEN_B]
+  ])
+  const tokenBalances: { [field in Field]?: TokenAmount } = {
+    [Field.TOKEN_A]: relevantTokenBalances?.[tokens[Field.TOKEN_A]?.address ?? ''],
+    [Field.TOKEN_B]: relevantTokenBalances?.[tokens[Field.TOKEN_B]?.address ?? '']
+  }
+
+  // amounts
+  const independentAmount = tryParseAmount(typedValue, tokens[independentField])
+  const dependentAmount = useMemo(() => {
+    if (noLiquidity && otherTypedValue && tokens[dependentField]) {
+      return tryParseAmount(otherTypedValue, tokens[dependentField])
+    } else if (route && independentAmount) {
+      return dependentField === Field.TOKEN_B
+        ? route.midPrice.quote(independentAmount)
+        : route.midPrice.invert().quote(independentAmount)
+    } else {
+      return
+    }
+  }, [noLiquidity, otherTypedValue, tokens, dependentField, independentAmount, route])
+  const parsedAmounts = {
+    [Field.TOKEN_A]: independentField === Field.TOKEN_A ? independentAmount : dependentAmount,
+    [Field.TOKEN_B]: independentField === Field.TOKEN_A ? dependentAmount : independentAmount
+  }
+
+  const price = useMemo(() => {
+    if (
+      noLiquidity &&
+      tokens[Field.TOKEN_A] &&
+      tokens[Field.TOKEN_B] &&
+      parsedAmounts[Field.TOKEN_A] &&
+      parsedAmounts[Field.TOKEN_B]
+    ) {
+      return new Price(
+        tokens[Field.TOKEN_A] as Token,
+        tokens[Field.TOKEN_B] as Token,
+        (parsedAmounts[Field.TOKEN_A] as TokenAmount).raw,
+        (parsedAmounts[Field.TOKEN_B] as TokenAmount).raw
+      )
+    } else if (route) {
+      return route.midPrice
+    } else {
+      return
+    }
+  }, [noLiquidity, tokens, parsedAmounts, route])
+
+  // liquidity minted
+  const totalSupply = useTotalSupply(pair?.liquidityToken)
+  const liquidityMinted = useMemo(() => {
+    if (pair && totalSupply && parsedAmounts[Field.TOKEN_A] && parsedAmounts[Field.TOKEN_B]) {
+      return pair.getLiquidityMinted(
+        totalSupply,
+        parsedAmounts[Field.TOKEN_A] as TokenAmount,
+        parsedAmounts[Field.TOKEN_B] as TokenAmount
+      )
+    } else {
+      return
+    }
+  }, [pair, totalSupply, parsedAmounts])
+
+  const poolTokenPercentage = useMemo(() => {
+    if (liquidityMinted && totalSupply) {
+      return new Percent(liquidityMinted.raw, totalSupply.add(liquidityMinted).raw)
+    } else {
+      return
+    }
+  }, [liquidityMinted, totalSupply])
+
+  let error: string | undefined
+  if (!account) {
+    error = 'Connect Wallet'
+  }
+
+  if (!parsedAmounts[Field.TOKEN_A] || !parsedAmounts[Field.TOKEN_B]) {
+    error = error ?? 'Enter an amount'
+  }
+
+  if (
+    parsedAmounts[Field.TOKEN_A] &&
+    tokenBalances?.[Field.TOKEN_A]?.lessThan(parsedAmounts[Field.TOKEN_A] as TokenAmount)
+  ) {
+    error = 'Insufficient ' + tokens[Field.TOKEN_A]?.symbol + ' balance'
+  }
+
+  if (
+    parsedAmounts[Field.TOKEN_B] &&
+    tokenBalances?.[Field.TOKEN_B]?.lessThan(parsedAmounts[Field.TOKEN_B] as TokenAmount)
+  ) {
+    error = 'Insufficient ' + tokens[Field.TOKEN_B]?.symbol + ' balance'
+  }
+
+  return {
+    dependentField,
+    tokens,
+    pair,
+    tokenBalances,
+    parsedAmounts,
+    price,
+    noLiquidity,
+    liquidityMinted,
+    poolTokenPercentage,
+    error
+  }
+}
+
+export function useMintActionHandlers(): {
+  onUserInput: (field: Field, typedValue: string) => void
+} {
+  const dispatch = useDispatch<AppDispatch>()
+
+  const { noLiquidity } = useDerivedMintInfo()
+
+  const onUserInput = useCallback(
+    (field: Field, typedValue: string) => {
+      dispatch(typeInput({ field, typedValue, noLiquidity: noLiquidity === true ? true : false }))
+    },
+    [dispatch, noLiquidity]
+  )
+
+  return {
+    onUserInput
+  }
+}
+
+// updates the mint state to use the appropriate tokens, given the route
+export function useDefaultsFromURLMatchParams(params: { [k: string]: string }) {
+  const { chainId } = useActiveWeb3React()
+  const dispatch = useDispatch<AppDispatch>()
+  useEffect(() => {
+    if (!chainId) return
+    dispatch(setDefaultsFromURLMatchParams({ chainId, params }))
+  }, [dispatch, chainId, params])
+}

src/state/mint/reducer.test.ts

+import { ChainId, WETH } from '@uniswap/sdk'
+import { createStore, Store } from 'redux'
+
+import { Field, setDefaultsFromURLMatchParams } from './actions'
+import reducer, { MintState } from './reducer'
+
+describe('mint reducer', () => {
+  let store: Store<MintState>
+
+  beforeEach(() => {
+    store = createStore(reducer, {
+      independentField: Field.TOKEN_A,
+      typedValue: '',
+      otherTypedValue: '',
+      [Field.TOKEN_A]: { address: '' },
+      [Field.TOKEN_B]: { address: '' }
+    })
+  })
+
+  describe('setDefaultsFromURLMatchParams', () => {
+    test('ETH to DAI', () => {
+      store.dispatch(
+        setDefaultsFromURLMatchParams({
+          chainId: ChainId.MAINNET,
+          params: {
+            tokens: 'ETH-0x6b175474e89094c44da98b954eedeac495271d0f'
+          }
+        })
+      )
+
+      expect(store.getState()).toEqual({
+        independentField: Field.TOKEN_A,
+        typedValue: '',
+        otherTypedValue: '',
+        [Field.TOKEN_A]: { address: WETH[ChainId.MAINNET].address },
+        [Field.TOKEN_B]: { address: '0x6b175474e89094c44da98b954eedeac495271d0f' }
+      })
+    })
+  })
+})

src/state/mint/reducer.ts

+import { createReducer } from '@reduxjs/toolkit'
+import { ChainId, WETH } from '@uniswap/sdk'
+
+import { isAddress } from '../../utils'
+import { Field, setDefaultsFromURLMatchParams, typeInput } from './actions'
+
+export interface MintState {
+  readonly independentField: Field
+  readonly typedValue: string
+  readonly otherTypedValue: string // for the case when there's no liquidity
+  readonly [Field.TOKEN_A]: {
+    readonly address: string
+  }
+  readonly [Field.TOKEN_B]: {
+    readonly address: string
+  }
+}
+
+const initialState: MintState = {
+  independentField: Field.TOKEN_A,
+  typedValue: '',
+  otherTypedValue: '',
+  [Field.TOKEN_A]: {
+    address: ''
+  },
+  [Field.TOKEN_B]: {
+    address: ''
+  }
+}
+
+function parseTokens(chainId: number, tokens: string): string[] {
+  return (
+    tokens
+      // split by '-'
+      .split('-')
+      // map to addresses
+      .map((token): string =>
+        isAddress(token)
+          ? token
+          : token.toLowerCase() === 'ETH'.toLowerCase()
+          ? WETH[chainId as ChainId]?.address ?? ''
+          : ''
+      )
+      //remove duplicates
+      .filter((token, i, array) => array.indexOf(token) === i)
+      // add two empty elements for cases where the array is length 0
+      .concat(['', ''])
+      // only consider the first 2 elements
+      .slice(0, 2)
+  )
+}
+
+export default createReducer<MintState>(initialState, builder =>
+  builder
+    .addCase(setDefaultsFromURLMatchParams, (state, { payload: { chainId, params } }) => {
+      const tokens = parseTokens(chainId, params?.tokens ?? '')
+      return {
+        independentField: Field.TOKEN_A,
+        typedValue: '',
+        otherTypedValue: '',
+        [Field.TOKEN_A]: {
+          address: tokens[0]
+        },
+        [Field.TOKEN_B]: {
+          address: tokens[1]
+        }
+      }
+    })
+    .addCase(typeInput, (state, { payload: { field, typedValue, noLiquidity } }) => {
+      if (noLiquidity) {
+        // they're typing into the field they've last typed in
+        if (field === state.independentField) {
+          return {
+            ...state,
+            independentField: field,
+            typedValue
+          }
+        }
+        // they're typing into a new field, store the other value
+        else {
+          return {
+            ...state,
+            independentField: field,
+            typedValue,
+            otherTypedValue: state.typedValue
+          }
+        }
+      } else {
+        return {
+          ...state,
+          independentField: field,
+          typedValue,
+          otherTypedValue: ''
+        }
+      }
+    })
+)

src/state/swap/actions.ts

@@ -5,7 +5,7 @@ export enum Field {
   OUTPUT = 'OUTPUT'
 }
 
-export const setDefaultsFromURL = createAction<{ chainId: number; queryString?: string }>('setDefaultsFromURL')
+export const setDefaultsFromURLSearch = createAction<{ chainId: number; queryString?: string }>('setDefaultsFromURL')
 export const selectToken = createAction<{ field: Field; address: string }>('selectToken')
 export const switchTokens = createAction<void>('switchTokens')
 export const typeInput = createAction<{ field: Field; typedValue: string }>('typeInput')

src/state/swap/hooks.ts

@@ -7,7 +7,7 @@ import { useTokenByAddressAndAutomaticallyAdd } from '../../hooks/Tokens'
 import { useTradeExactIn, useTradeExactOut } from '../../hooks/Trades'
 import { AppDispatch, AppState } from '../index'
 import { useTokenBalancesTreatWETHAsETH } from '../wallet/hooks'
-import { Field, selectToken, setDefaultsFromURL, switchTokens, typeInput } from './actions'
+import { Field, selectToken, setDefaultsFromURLSearch, switchTokens, typeInput } from './actions'
 import { useV1TradeLinkIfBetter } from '../../data/V1'
 import { V1_TRADE_LINK_THRESHOLD } from '../../constants'
 
@@ -52,7 +52,7 @@ export function useSwapActionHandlers(): {
 }
 
 // try to parse a user entered amount for a given token
-function tryParseAmount(value?: string, token?: Token): TokenAmount | undefined {
+export function tryParseAmount(value?: string, token?: Token): TokenAmount | undefined {
   if (!value || !token) {
     return
   }
@@ -155,11 +155,11 @@ export function useDerivedSwapInfo(): {
 
 // updates the swap state to use the defaults for a given network whenever the query
 // string updates
-export function useDefaultsFromURL(search?: string) {
+export function useDefaultsFromURLSearch(search?: string) {
   const { chainId } = useActiveWeb3React()
   const dispatch = useDispatch<AppDispatch>()
   useEffect(() => {
     if (!chainId) return
-    dispatch(setDefaultsFromURL({ chainId, queryString: search }))
+    dispatch(setDefaultsFromURLSearch({ chainId, queryString: search }))
   }, [dispatch, search, chainId])
 }

src/state/swap/reducer.test.ts

 import { ChainId, WETH } from '@uniswap/sdk'
 import { createStore, Store } from 'redux'
-import { Field, setDefaultsFromURL } from './actions'
+import { Field, setDefaultsFromURLSearch } from './actions'
 import reducer, { SwapState } from './reducer'
 
 describe('swap reducer', () => {
@@ -18,7 +18,7 @@ describe('swap reducer', () => {
   describe('setDefaultsFromURL', () => {
     test('ETH to DAI', () => {
       store.dispatch(
-        setDefaultsFromURL({
+        setDefaultsFromURLSearch({
           chainId: ChainId.MAINNET,
           queryString:
             '?inputCurrency=ETH&outputCurrency=0x6b175474e89094c44da98b954eedeac495271d0f&exactAmount=20.5&exactField=outPUT'
@@ -35,7 +35,7 @@ describe('swap reducer', () => {
 
     test('does not duplicate eth for invalid output token', () => {
       store.dispatch(
-        setDefaultsFromURL({
+        setDefaultsFromURLSearch({
           chainId: ChainId.MAINNET,
           queryString: '?outputCurrency=invalid'
         })
@@ -51,7 +51,7 @@ describe('swap reducer', () => {
 
     test('output ETH only', () => {
       store.dispatch(
-        setDefaultsFromURL({
+        setDefaultsFromURLSearch({
           chainId: ChainId.MAINNET,
           queryString: '?outputCurrency=eth&exactAmount=20.5'
         })

src/state/swap/reducer.ts

@@ -2,7 +2,7 @@ import { parse } from 'qs'
 import { createReducer } from '@reduxjs/toolkit'
 import { ChainId, WETH } from '@uniswap/sdk'
 import { isAddress } from '../../utils'
-import { Field, selectToken, setDefaultsFromURL, switchTokens, typeInput } from './actions'
+import { Field, selectToken, setDefaultsFromURLSearch, switchTokens, typeInput } from './actions'
 
 export interface SwapState {
   readonly independentField: Field
@@ -47,7 +47,7 @@ function parseIndependentFieldURLParameter(urlParam: any): Field {
 
 export default createReducer<SwapState>(initialState, builder =>
   builder
-    .addCase(setDefaultsFromURL, (state, { payload: { queryString, chainId } }) => {
+    .addCase(setDefaultsFromURLSearch, (_, { payload: { queryString, chainId } }) => {
       if (queryString && queryString.length > 1) {
         const parsedQs = parse(queryString, { parseArrays: false, ignoreQueryPrefix: true })
 

src/utils/prices.ts

@@ -51,7 +51,7 @@ export function computeSlippageAdjustedAmounts(
   }
 }
 
-export function warningServerity(priceImpact: Percent): 0 | 1 | 2 | 3 {
+export function warningSeverity(priceImpact: Percent): 0 | 1 | 2 | 3 {
   if (!priceImpact?.lessThan(ALLOWED_PRICE_IMPACT_HIGH)) return 3
   if (!priceImpact?.lessThan(ALLOWED_PRICE_IMPACT_MEDIUM)) return 2
   if (!priceImpact?.lessThan(ALLOWED_PRICE_IMPACT_LOW)) return 1