show currency values and price impact in the confirmation modal (fixes https://github.com/Uniswap/v3-interface/issues/92)

src/components/CurrencyInputPanel/FiatValue.tsx

@@ -0,0 +1,32 @@
+import { CurrencyAmount, Percent } from '@uniswap/sdk-core'
+import React, { useMemo } from 'react'
+import useTheme from '../../hooks/useTheme'
+import { TYPE } from '../../theme'
+import { warningSeverity } from '../../utils/prices'
+
+export function FiatValue({
+  fiatValue,
+  priceImpact,
+}: {
+  fiatValue: CurrencyAmount | null | undefined
+  priceImpact?: Percent
+}) {
+  const theme = useTheme()
+  const priceImpactColor = useMemo(() => {
+    if (!priceImpact) return undefined
+    if (priceImpact.lessThan('0')) return theme.green1
+    const severity = warningSeverity(priceImpact)
+    if (severity < 1) return theme.text4
+    if (severity < 3) return theme.yellow1
+    return theme.red1
+  }, [priceImpact, theme.green1, theme.red1, theme.text4, theme.yellow1])
+
+  return (
+    <TYPE.body fontSize={14} color={fiatValue ? theme.text2 : theme.text4}>
+      {fiatValue ? '~' : ''}${fiatValue ? Number(fiatValue?.toSignificant(6)).toLocaleString('en') : '-'}
+      {priceImpact ? (
+        <span style={{ color: priceImpactColor }}> ({priceImpact.multiply(-100).toSignificant(3)}%)</span>
+      ) : null}
+    </TYPE.body>
+  )
+}

src/components/CurrencyInputPanel/index.tsx

@@ -1,10 +1,9 @@
 import { Pair } from '@uniswap/v2-sdk'
 import { Currency, CurrencyAmount, Percent } from '@uniswap/sdk-core'
-import React, { useState, useCallback, useMemo } from 'react'
+import React, { useState, useCallback } from 'react'
 import styled from 'styled-components'
 import { darken } from 'polished'
 import { useCurrencyBalance } from '../../state/wallet/hooks'
-import { warningSeverity } from '../../utils/prices'
 import CurrencySearchModal from '../SearchModal/CurrencySearchModal'
 import CurrencyLogo from '../CurrencyLogo'
 import DoubleCurrencyLogo from '../DoubleLogo'
@@ -18,6 +17,7 @@ import { useTranslation } from 'react-i18next'
 import useTheme from '../../hooks/useTheme'
 import { Lock } from 'react-feather'
 import { AutoColumn } from 'components/Column'
+import { FiatValue } from './FiatValue'
 
 const InputPanel = styled.div<{ hideInput?: boolean }>`
   ${({ theme }) => theme.flexColumnNoWrap}
@@ -196,15 +196,6 @@ export default function CurrencyInputPanel({
     setModalOpen(false)
   }, [setModalOpen])
 
-  const priceImpactColor = useMemo(() => {
-    if (!priceImpact) return undefined
-    if (priceImpact.lessThan('0')) return theme.green1
-    const severity = warningSeverity(priceImpact)
-    if (severity < 1) return theme.text4
-    if (severity < 3) return theme.yellow1
-    return theme.red1
-  }, [priceImpact, theme.green1, theme.red1, theme.text4, theme.yellow1])
-
   return (
     <InputPanel id={id} hideInput={hideInput} {...rest}>
       {locked && (
@@ -291,12 +282,7 @@ export default function CurrencyInputPanel({
                 </RowFixed>
               )}
 
-              <TYPE.body fontSize={14} color={fiatValue ? theme.text2 : theme.text4}>
-                {fiatValue ? '~' : ''}${fiatValue ? Number(fiatValue?.toSignificant(6)).toLocaleString('en') : '-'}
-                {priceImpact ? (
-                  <span style={{ color: priceImpactColor }}> ({priceImpact.multiply(-100).toSignificant(3)}%)</span>
-                ) : null}
-              </TYPE.body>
+              <FiatValue fiatValue={fiatValue} priceImpact={priceImpact} />
             </RowBetween>
           </FiatRow>
         )}

src/components/swap/SwapModalHeader.tsx

@@ -5,10 +5,12 @@ import React, { useContext, useState } from 'react'
 import { ArrowDown, AlertTriangle } from 'react-feather'
 import { Text } from 'rebass'
 import styled, { ThemeContext } from 'styled-components'
+import { useUSDCValue } from '../../hooks/useUSDCPrice'
 import { TYPE } from '../../theme'
 import { ButtonPrimary } from '../Button'
-import { isAddress, shortenAddress } from '../../utils'
+import { computeFiatValuePriceImpact, isAddress, shortenAddress } from '../../utils'
 import { AutoColumn } from '../Column'
+import { FiatValue } from '../CurrencyInputPanel/FiatValue'
 import CurrencyLogo from '../CurrencyLogo'
 import { RowBetween, RowFixed } from '../Row'
 import { TruncatedText, SwapShowAcceptChanges } from './styleds'
@@ -57,17 +59,18 @@ export default function SwapModalHeader({
 
   const [showInverted, setShowInverted] = useState<boolean>(false)
 
+  const fiatValueInput = useUSDCValue(maximumAmountIn)
+  const fiatValueOutput = useUSDCValue(minimumAmountOut)
+
   return (
     <AutoColumn gap={'4px'} style={{ marginTop: '1rem' }}>
       <DarkGreyCard padding="0.75rem 1rem">
         <AutoColumn gap={'8px'}>
           <RowBetween>
             <TYPE.body color={theme.text3} fontWeight={500} fontSize={14}>
-              {'From'}
-            </TYPE.body>
-            <TYPE.body fontSize={14} color={theme.text3}>
-              {'$-'}
+              From
             </TYPE.body>
+            <FiatValue fiatValue={fiatValueInput} />
           </RowBetween>
           <RowBetween align="center">
             <RowFixed gap={'0px'}>
@@ -95,10 +98,13 @@ export default function SwapModalHeader({
         <AutoColumn gap={'8px'}>
           <RowBetween>
             <TYPE.body color={theme.text3} fontWeight={500} fontSize={14}>
-              {'To'}
+              To
             </TYPE.body>
             <TYPE.body fontSize={14} color={theme.text3}>
-              {'$-'}
+              <FiatValue
+                fiatValue={fiatValueOutput}
+                priceImpact={computeFiatValuePriceImpact(fiatValueInput, fiatValueOutput)}
+              />
             </TYPE.body>
           </RowBetween>
           <RowBetween align="flex-end">

src/pages/Swap/index.tsx

@@ -1,4 +1,4 @@
-import { CurrencyAmount, currencyEquals, Percent, Token } from '@uniswap/sdk-core'
+import { CurrencyAmount, Token } from '@uniswap/sdk-core'
 import { Trade as V2Trade } from '@uniswap/v2-sdk'
 import { Trade as V3Trade } from '@uniswap/v3-sdk'
 import { AdvancedSwapDetails } from 'components/swap/AdvancedSwapDetails'
@@ -6,26 +6,27 @@ import UnsupportedCurrencyFooter from 'components/swap/UnsupportedCurrencyFooter
 import { MouseoverTooltip, MouseoverTooltipContent } from 'components/Tooltip'
 import JSBI from 'jsbi'
 import React, { useCallback, useContext, useEffect, useMemo, useState } from 'react'
-import { ArrowDown, HelpCircle, CheckCircle, Info, X } from 'react-feather'
+import { ArrowDown, CheckCircle, HelpCircle, Info, X } from 'react-feather'
 import ReactGA from 'react-ga'
-import { RouteComponentProps } from 'react-router-dom'
+import { Link, RouteComponentProps } from 'react-router-dom'
 import { Text } from 'rebass'
 import { ThemeContext } from 'styled-components'
 import AddressInputPanel from '../../components/AddressInputPanel'
-import { ButtonConfirmed, ButtonError, ButtonLight, ButtonPrimary, ButtonGray } from '../../components/Button'
+import { ButtonConfirmed, ButtonError, ButtonGray, ButtonLight, ButtonPrimary } from '../../components/Button'
 import { GreyCard } from '../../components/Card'
 import { AutoColumn } from '../../components/Column'
 import CurrencyInputPanel from '../../components/CurrencyInputPanel'
 import CurrencyLogo from '../../components/CurrencyLogo'
 import Loader from '../../components/Loader'
 import { AutoRow, RowBetween, RowFixed } from '../../components/Row'
+import BetterTradeLink from '../../components/swap/BetterTradeLink'
 import confirmPriceImpactWithoutFee from '../../components/swap/confirmPriceImpactWithoutFee'
 import ConfirmSwapModal from '../../components/swap/ConfirmSwapModal'
 
 import { ArrowWrapper, BottomGrouping, Dots, SwapCallbackError, Wrapper } from '../../components/swap/styleds'
+import SwapHeader from '../../components/swap/SwapHeader'
 import TradePrice from '../../components/swap/TradePrice'
 import TokenWarningModal from '../../components/TokenWarningModal'
-import { ONE_HUNDRED_PERCENT } from '../../constants'
 import { useActiveWeb3React } from '../../hooks'
 import { useAllTokens, useCurrency } from '../../hooks/Tokens'
 import { ApprovalState, useApproveCallbackFromTrade } from '../../hooks/useApproveCallback'
@@ -47,27 +48,13 @@ import {
 } from '../../state/swap/hooks'
 import { useExpertModeManager, useUserSingleHopOnly, useUserSlippageTolerance } from '../../state/user/hooks'
 import { LinkStyledButton, TYPE } from '../../theme'
+import { computeFiatValuePriceImpact } from '../../utils'
 import { getTradeVersion } from '../../utils/getTradeVersion'
+import { isTradeBetter } from '../../utils/isTradeBetter'
 import { maxAmountSpend } from '../../utils/maxAmountSpend'
 import { warningSeverity } from '../../utils/prices'
 import AppBody from '../AppBody'
 
-import { Link } from 'react-router-dom'
-import { isTradeBetter } from '../../utils/isTradeBetter'
-import BetterTradeLink from '../../components/swap/BetterTradeLink'
-import SwapHeader from '../../components/swap/SwapHeader'
-
-function computeFiatValuePriceImpact(
-  fiatValueInput: CurrencyAmount | undefined | null,
-  fiatValueOutput: CurrencyAmount | undefined | null
-): Percent | undefined {
-  if (!fiatValueOutput || !fiatValueInput) return undefined
-  if (!currencyEquals(fiatValueInput.currency, fiatValueOutput.currency)) return undefined
-  if (JSBI.equal(fiatValueInput.raw, JSBI.BigInt(0))) return undefined
-  const pct = ONE_HUNDRED_PERCENT.subtract(fiatValueOutput.divide(fiatValueInput))
-  return new Percent(pct.numerator, pct.denominator)
-}
-
 export default function Swap({ history }: RouteComponentProps) {
   const loadedUrlParams = useDefaultsFromURLSearch()
 

src/utils/computeFiatValuePriceImpact.tsx

@@ -0,0 +1,14 @@
+import { CurrencyAmount, currencyEquals, Percent } from '@uniswap/sdk-core'
+import JSBI from 'jsbi'
+import { ONE_HUNDRED_PERCENT } from '../constants'
+
+export function computeFiatValuePriceImpact(
+  fiatValueInput: CurrencyAmount | undefined | null,
+  fiatValueOutput: CurrencyAmount | undefined | null
+): Percent | undefined {
+  if (!fiatValueOutput || !fiatValueInput) return undefined
+  if (!currencyEquals(fiatValueInput.currency, fiatValueOutput.currency)) return undefined
+  if (JSBI.equal(fiatValueInput.raw, JSBI.BigInt(0))) return undefined
+  const pct = ONE_HUNDRED_PERCENT.subtract(fiatValueOutput.divide(fiatValueInput))
+  return new Percent(pct.numerator, pct.denominator)
+}

src/utils/index.ts

@@ -119,3 +119,4 @@ export function supportedChainId(chainId: number): ChainId | undefined {
 export function formattedFeeAmount(feeAmount: FeeAmount): number {
   return feeAmount / 10000
 }
+export { computeFiatValuePriceImpact } from './computeFiatValuePriceImpact'