From e1abd81a1dfe21e176dfe5c3774bc8e954c31bf6 Mon Sep 17 00:00:00 2001
From: Ian Lapham <ianlapham@gmail.com>
Date: Fri, 18 Mar 2022 10:11:16 -0700
Subject: [PATCH] fix: add syncing state to trade loading (#3545)

* add syncing state to trade loading

* remove log statement

* update loading state

* update useLast trade logic

* nit fixes
---
 .../routing/clientSideSmartOrderRouter.ts     |  6 +-
 .../useClientSideSmartOrderRouterTrade.ts     | 57 ++++++++++++++-----
 src/state/routing/useRoutingAPITrade.ts       |  4 +-
 3 files changed, 49 insertions(+), 18 deletions(-)

diff --git a/src/lib/hooks/routing/clientSideSmartOrderRouter.ts b/src/lib/hooks/routing/clientSideSmartOrderRouter.ts
index e35ed4fe75..98015eb73f 100644
--- a/src/lib/hooks/routing/clientSideSmartOrderRouter.ts
+++ b/src/lib/hooks/routing/clientSideSmartOrderRouter.ts
@@ -100,7 +100,11 @@ export async function getClientSideQuote(
   )
 }
 
-export function useFreshQuote(quoteResult: GetQuoteResult | undefined, maxBlockAge = 10): GetQuoteResult | undefined {
+/**  Used to keep quotes up to date given a certain block age. Returns undefined if past limit. */
+export function useFilterFreshQuote(
+  quoteResult: GetQuoteResult | undefined,
+  maxBlockAge = 10
+): GetQuoteResult | undefined {
   const block = useBlockNumber()
   if (!block || !quoteResult) return undefined
   if (block - (Number(quoteResult.blockNumber) || 0) > maxBlockAge) return undefined
diff --git a/src/lib/hooks/routing/useClientSideSmartOrderRouterTrade.ts b/src/lib/hooks/routing/useClientSideSmartOrderRouterTrade.ts
index b2dda4a1a1..294047f9a8 100644
--- a/src/lib/hooks/routing/useClientSideSmartOrderRouterTrade.ts
+++ b/src/lib/hooks/routing/useClientSideSmartOrderRouterTrade.ts
@@ -2,6 +2,7 @@ import { Protocol } from '@uniswap/router-sdk'
 import { Currency, CurrencyAmount, TradeType } from '@uniswap/sdk-core'
 import { ChainId } from '@uniswap/smart-order-router'
 import useDebounce from 'hooks/useDebounce'
+import useLast from 'hooks/useLast'
 import { useStablecoinAmountFromFiatValue } from 'hooks/useUSDCPrice'
 import { useCallback, useMemo } from 'react'
 import { GetQuoteResult, InterfaceTrade, TradeState } from 'state/routing/types'
@@ -10,7 +11,7 @@ import { computeRoutes, transformRoutesToTrade } from 'state/routing/utils'
 import useWrapCallback, { WrapType } from '../swap/useWrapCallback'
 import useActiveWeb3React from '../useActiveWeb3React'
 import usePoll from '../usePoll'
-import { getClientSideQuote, useFreshQuote } from './clientSideSmartOrderRouter'
+import { getClientSideQuote, useFilterFreshQuote } from './clientSideSmartOrderRouter'
 import { useRoutingAPIArguments } from './useRoutingAPIArguments'
 
 /**
@@ -78,26 +79,38 @@ export default function useClientSideSmartOrderRouterTrade<TTradeType extends Tr
       return { error: true }
     }
   }, [config, params, queryArgs, wrapType])
+
   const { data, error } = usePoll(getQuoteResult, JSON.stringify(queryArgs)) ?? {
     error: undefined,
   }
-  const quoteResult = useFreshQuote(data)
+
+  const quoteResult = useFilterFreshQuote(data)
+  const isLoading = !quoteResult
 
   const route = useMemo(
     () => computeRoutes(currencyIn, currencyOut, tradeType, quoteResult),
     [currencyIn, currencyOut, quoteResult, tradeType]
   )
   const gasUseEstimateUSD = useStablecoinAmountFromFiatValue(quoteResult?.gasUseEstimateUSD) ?? null
-  const trade = useMemo(() => {
-    if (route) {
-      try {
-        return route && transformRoutesToTrade(route, tradeType, gasUseEstimateUSD)
-      } catch (e: unknown) {
-        console.debug('transformRoutesToTrade failed: ', e)
-      }
-    }
-    return
-  }, [gasUseEstimateUSD, route, tradeType])
+  const trade =
+    useLast(
+      useMemo(() => {
+        if (route) {
+          try {
+            return route && transformRoutesToTrade(route, tradeType, gasUseEstimateUSD)
+          } catch (e: unknown) {
+            console.debug('transformRoutesToTrade failed: ', e)
+          }
+        }
+        return
+      }, [gasUseEstimateUSD, route, tradeType]),
+      Boolean
+    ) ?? undefined
+
+  // Dont return old trade if currencies dont match.
+  const isStale =
+    (currencyIn && !trade?.inputAmount?.currency.equals(currencyIn)) ||
+    (currencyOut && !trade?.outputAmount?.currency.equals(currencyOut))
 
   return useMemo(() => {
     if (!currencyIn || !currencyOut) {
@@ -106,9 +119,11 @@ export default function useClientSideSmartOrderRouterTrade<TTradeType extends Tr
 
     // Returns the last trade state while syncing/loading to avoid jank from clearing the last trade while loading.
     if (!error) {
-      if (isDebouncing) {
+      if (isStale) {
+        return { state: TradeState.LOADING, trade: undefined }
+      } else if (isDebouncing) {
         return { state: TradeState.SYNCING, trade }
-      } else if (!quoteResult) {
+      } else if (isLoading) {
         return { state: TradeState.LOADING, trade }
       }
     }
@@ -133,5 +148,17 @@ export default function useClientSideSmartOrderRouterTrade<TTradeType extends Tr
       return { state: TradeState.VALID, trade }
     }
     return { state: TradeState.INVALID, trade: undefined }
-  }, [currencyIn, currencyOut, quoteResult, error, route, queryArgs, trade, isDebouncing, tradeType])
+  }, [
+    currencyIn,
+    currencyOut,
+    error,
+    quoteResult,
+    route,
+    queryArgs,
+    trade,
+    isStale,
+    isDebouncing,
+    isLoading,
+    tradeType,
+  ])
 }
diff --git a/src/state/routing/useRoutingAPITrade.ts b/src/state/routing/useRoutingAPITrade.ts
index bebd87679a..98eb9a6ea0 100644
--- a/src/state/routing/useRoutingAPITrade.ts
+++ b/src/state/routing/useRoutingAPITrade.ts
@@ -2,7 +2,7 @@ import { skipToken } from '@reduxjs/toolkit/query/react'
 import { Currency, CurrencyAmount, TradeType } from '@uniswap/sdk-core'
 import { IMetric, MetricLoggerUnit, setGlobalMetric } from '@uniswap/smart-order-router'
 import { useStablecoinAmountFromFiatValue } from 'hooks/useUSDCPrice'
-import { useFreshQuote } from 'lib/hooks/routing/clientSideSmartOrderRouter'
+import { useFilterFreshQuote } from 'lib/hooks/routing/clientSideSmartOrderRouter'
 import { useRoutingAPIArguments } from 'lib/hooks/routing/useRoutingAPIArguments'
 import ms from 'ms.macro'
 import { useMemo } from 'react'
@@ -50,7 +50,7 @@ export function useRoutingAPITrade<TTradeType extends TradeType>(
     refetchOnFocus: true,
   })
 
-  const quoteResult: GetQuoteResult | undefined = useFreshQuote(data)
+  const quoteResult: GetQuoteResult | undefined = useFilterFreshQuote(data)
 
   const route = useMemo(
     () => computeRoutes(currencyIn, currencyOut, tradeType, quoteResult),