Fix #9872 - Show price difference warning on swaps price quote

app/_locales/en/messages.json

@@ -1741,6 +1741,20 @@
     "message": "Your $1 will be added to your account once this transaction has processed.",
     "description": "This message communicates the token that is being transferred. It is shown on the awaiting swap screen. The $1 will be a token symbol."
   },
+  "swapPriceDifference": {
+    "message": "You are about to swap $1 $2 (~$3) for $4 $5 (~$6).",
+    "description": "This message represents the price slippage for the swap.  $1 and $4 are a number (ex: 2.89), $2 and $5 are symbols (ex: ETH), and $3 and $6 are fiat currency amounts."
+  },
+  "swapPriceDifferenceTitle": {
+    "message": "Price difference of ~$1%",
+    "description": "$1 is a number (ex: 1.23) that represents the price difference."
+  },
+  "swapPriceDifferenceTooltip": {
+    "message": "The difference in market prices can be affected by fees taken by intermediaries, size of market, size of trade, or market inefficiencies."
+  },
+  "swapPriceDifferenceUnavailable": {
+    "message": "Market price is unavailable.  Make sure you feel comfortable with the returned amount before proceeding."
+  },
   "swapProcessing": {
     "message": "Processing"
   },

ui/app/components/app/user-preferenced-currency-display/user-preferenced-currency-display.component.js

@@ -19,7 +19,6 @@ export default function UserPreferencedCurrencyDisplay({
     fiatNumberOfDecimals,
     numberOfDecimals: propsNumberOfDecimals,
   })
-
   const prefixComponent = useMemo(() => {
     return (
       currency === ETH &&

ui/app/pages/swaps/swaps-footer/swaps-footer.js

@@ -13,13 +13,14 @@ export default function SwapsFooter({
   disabled,
   showTermsOfService,
   showTopBorder,
+  className = '',
 }) {
   const t = useContext(I18nContext)
 
   return (
     <div className="swaps-footer">
       <div
-        className={classnames('swaps-footer__buttons', {
+        className={classnames('swaps-footer__buttons', className, {
           'swaps-footer__buttons--border': showTopBorder,
         })}
       >
@@ -62,4 +63,5 @@ SwapsFooter.propTypes = {
   disabled: PropTypes.bool,
   showTermsOfService: PropTypes.bool,
   showTopBorder: PropTypes.bool,
+  className: PropTypes.string,
 }

ui/app/pages/swaps/view-quote/index.scss

@@ -86,14 +86,60 @@
     };
   }
 
-  &__insufficient-eth-warning-wrapper {
-    margin-top: 8px;
+  &__price-difference-warning {
+    &-wrapper {
+      width: 100%;
+
+      &.medium .actionable-message,
+      &.fiat-error .actionable-message {
+        border-color: $Yellow-500;
+        background: $Yellow-100;
+
+        .actionable-message__message {
+          color: inherit;
+        }
+      }
+
+      &.high .actionable-message {
+        border-color: $Red-500;
+        background: $Red-100;
+
+        .actionable-message__message {
+          color: $Red-500;
+        }
+      }
+
+      /* Hides info tooltip if there's a fiat error message */
+      &.fiat-error div[data-tooltipped] {
+        /* !important overrides style being applied directly to tooltip by component */
+        display: none !important;
+      }
+    }
+
+    &-contents {
+      display: flex;
+
+      &-title {
+        font-weight: bold;
+      }
+
+      i {
+        margin-inline-start: 10px;
+      }
+    }
+  }
+
+  &__warning-wrapper {
     width: 100%;
     align-items: center;
     justify-content: center;
+    margin-top: 8px;
 
     @media screen and (min-width: 576px) {
-      min-height: 36px;
+      &--thin {
+        min-height: 36px;
+      }
+
       display: flex;
     }
   }
@@ -165,4 +211,8 @@
   &__metamask-rate-info-icon {
     margin-left: 4px;
   }
+
+  &__thin-swaps-footer {
+    max-height: 82px;
+  }
 }

ui/app/pages/swaps/view-quote/tests/view-quote-price-difference.test.js

@@ -0,0 +1,149 @@
+import assert from 'assert'
+import React from 'react'
+import { shallow } from 'enzyme'
+import { Provider } from 'react-redux'
+import configureMockStore from 'redux-mock-store'
+import ViewQuotePriceDifference from '../view-quote-price-difference'
+
+describe('View Price Quote Difference', function () {
+  const t = (key) => `translate ${key}`
+
+  const state = {
+    metamask: {
+      tokens: [],
+      provider: { type: 'rpc', nickname: '', rpcUrl: '' },
+      preferences: { showFiatInTestnets: true },
+      currentCurrency: 'usd',
+      conversionRate: 600.0,
+    },
+  }
+
+  const store = configureMockStore()(state)
+
+  // Sample transaction is 1 $ETH to ~42.880915 $LINK
+  const DEFAULT_PROPS = {
+    usedQuote: {
+      trade: {
+        data:
+          '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',
+        from: '0xd7440fdcb70a9fba55dfe06942ddbc17679c90ac',
+        value: '0xde0b6b3a7640000',
+        gas: '0xbbfd0',
+        to: '0x881D40237659C251811CEC9c364ef91dC08D300C',
+      },
+      sourceAmount: '1000000000000000000',
+      destinationAmount: '42947749216634160067',
+      error: null,
+      sourceToken: '0x0000000000000000000000000000000000000000',
+      destinationToken: '0x514910771af9ca656af840dff83e8264ecf986ca',
+      approvalNeeded: null,
+      maxGas: 770000,
+      averageGas: 210546,
+      estimatedRefund: 80000,
+      fetchTime: 647,
+      aggregator: 'uniswap',
+      aggType: 'DEX',
+      fee: 0.875,
+      gasMultiplier: 1.5,
+      priceSlippage: {
+        ratio: 1.007876641534847,
+        calculationError: '',
+        bucket: 'low',
+        sourceAmountInETH: 1,
+        destinationAmountInEth: 0.9921849150875727,
+      },
+      slippage: 2,
+      sourceTokenInfo: {
+        symbol: 'ETH',
+        name: 'Ether',
+        address: '0x0000000000000000000000000000000000000000',
+        decimals: 18,
+        iconUrl: 'images/black-eth-logo.svg',
+      },
+      destinationTokenInfo: {
+        address: '0x514910771af9ca656af840dff83e8264ecf986ca',
+        symbol: 'LINK',
+        decimals: 18,
+        occurances: 12,
+        iconUrl:
+          'https://cloudflare-ipfs.com/ipfs/QmQhZAdcZvW9T2tPm516yHqbGkfhyZwTZmLixW9MXJudTA',
+      },
+      ethFee: '0.011791',
+      ethValueOfTokens: '0.99220724791716534441',
+      overallValueOfQuote: '0.98041624791716534441',
+      metaMaskFeeInEth: '0.00875844985551091729',
+      isBestQuote: true,
+      savings: {
+        performance: '0.00207907025112527799',
+        fee: '0.005581',
+        metaMaskFee: '0.00875844985551091729',
+        total: '-0.0010983796043856393',
+        medianMetaMaskFee: '0.00874009740688812165',
+      },
+    },
+    sourceTokenValue: '1',
+    destinationTokenValue: '42.947749',
+  }
+
+  let component
+  function renderComponent(props) {
+    component = shallow(
+      <Provider store={store}>
+        <ViewQuotePriceDifference {...props} />
+      </Provider>,
+      {
+        context: { t },
+      },
+    )
+  }
+
+  afterEach(function () {
+    component.unmount()
+  })
+
+  it('does not render when there is no quote', function () {
+    const props = { ...DEFAULT_PROPS, usedQuote: null }
+    renderComponent(props)
+
+    const wrappingDiv = component.find(
+      '.view-quote__price-difference-warning-wrapper',
+    )
+    assert.strictEqual(wrappingDiv.length, 0)
+  })
+
+  it('does not render when the item is in the low bucket', function () {
+    const props = { ...DEFAULT_PROPS }
+    props.usedQuote.priceSlippage.bucket = 'low'
+
+    renderComponent(props)
+    const wrappingDiv = component.find(
+      '.view-quote__price-difference-warning-wrapper',
+    )
+    assert.strictEqual(wrappingDiv.length, 0)
+  })
+
+  it('displays an error when in medium bucket', function () {
+    const props = { ...DEFAULT_PROPS }
+    props.usedQuote.priceSlippage.bucket = 'medium'
+
+    renderComponent(props)
+    assert.strictEqual(component.html().includes('medium'), true)
+  })
+
+  it('displays an error when in high bucket', function () {
+    const props = { ...DEFAULT_PROPS }
+    props.usedQuote.priceSlippage.bucket = 'high'
+
+    renderComponent(props)
+    assert.strictEqual(component.html().includes('high'), true)
+  })
+
+  it('displays a fiat error when calculationError is present', function () {
+    const props = { ...DEFAULT_PROPS }
+    props.usedQuote.priceSlippage.calculationError =
+      'Could not determine price.'
+
+    renderComponent(props)
+    assert.strictEqual(component.html().includes('fiat-error'), true)
+  })
+})

ui/app/pages/swaps/view-quote/view-quote-price-difference.js

@@ -0,0 +1,114 @@
+import React, { useContext } from 'react'
+
+import PropTypes from 'prop-types'
+import classnames from 'classnames'
+import BigNumber from 'bignumber.js'
+import { useEthFiatAmount } from '../../../hooks/useEthFiatAmount'
+import { I18nContext } from '../../../contexts/i18n'
+
+import ActionableMessage from '../actionable-message'
+import Tooltip from '../../../components/ui/tooltip'
+
+export default function ViewQuotePriceDifference(props) {
+  const { usedQuote, sourceTokenValue, destinationTokenValue } = props
+
+  const t = useContext(I18nContext)
+
+  const priceSlippageFromSource = useEthFiatAmount(
+    usedQuote?.priceSlippage?.sourceAmountInETH || 0,
+  )
+  const priceSlippageFromDestination = useEthFiatAmount(
+    usedQuote?.priceSlippage?.destinationAmountInEth || 0,
+  )
+
+  if (!usedQuote || !usedQuote.priceSlippage) {
+    return null
+  }
+
+  const { priceSlippage } = usedQuote
+
+  // We cannot present fiat value if there is a calculation error or no slippage
+  // from source or destination
+  const priceSlippageUnknownFiatValue =
+    !priceSlippageFromSource ||
+    !priceSlippageFromDestination ||
+    priceSlippage.calculationError
+
+  let priceDifferencePercentage = 0
+  if (priceSlippage.ratio) {
+    priceDifferencePercentage = parseFloat(
+      new BigNumber(priceSlippage.ratio, 10)
+        .minus(1, 10)
+        .times(100, 10)
+        .toFixed(2),
+      10,
+    )
+  }
+
+  const shouldShowPriceDifferenceWarning =
+    ['high', 'medium'].includes(priceSlippage.bucket) ||
+    priceSlippageUnknownFiatValue
+
+  if (!shouldShowPriceDifferenceWarning) {
+    return null
+  }
+
+  let priceDifferenceTitle = ''
+  let priceDifferenceMessage = ''
+  let priceDifferenceClass = ''
+  if (priceSlippageUnknownFiatValue) {
+    // A calculation error signals we cannot determine dollar value
+    priceDifferenceMessage = t('swapPriceDifferenceUnavailable')
+    priceDifferenceClass = 'fiat-error'
+  } else {
+    priceDifferenceTitle = t('swapPriceDifferenceTitle', [
+      priceDifferencePercentage,
+    ])
+    priceDifferenceMessage = t('swapPriceDifference', [
+      sourceTokenValue, // Number of source token to swap
+      usedQuote.sourceTokenInfo.symbol, // Source token symbol
+      priceSlippageFromSource, // Source tokens total value
+      destinationTokenValue, // Number of destination tokens in return
+      usedQuote.destinationTokenInfo.symbol, // Destination token symbol,
+      priceSlippageFromDestination, // Destination tokens total value
+    ])
+    priceDifferenceClass = priceSlippage.bucket
+  }
+
+  return (
+    <div
+      className={classnames(
+        'view-quote__price-difference-warning-wrapper',
+        priceDifferenceClass,
+      )}
+    >
+      <ActionableMessage
+        message={
+          <div className="view-quote__price-difference-warning-contents">
+            <div className="view-quote__price-difference-warning-contents-text">
+              {priceDifferenceTitle && (
+                <div className="view-quote__price-difference-warning-contents-title">
+                  {priceDifferenceTitle}
+                </div>
+              )}
+              {priceDifferenceMessage}
+            </div>
+            <Tooltip
+              position="bottom"
+              theme="white"
+              title={t('swapPriceDifferenceTooltip')}
+            >
+              <i className="fa fa-info-circle" />
+            </Tooltip>
+          </div>
+        }
+      />
+    </div>
+  )
+}
+
+ViewQuotePriceDifference.propTypes = {
+  usedQuote: PropTypes.object,
+  sourceTokenValue: PropTypes.string,
+  destinationTokenValue: PropTypes.string,
+}