From 1062e2a97d4c04e4e2a159e55f7d61fea4112f3c Mon Sep 17 00:00:00 2001
From: Dan J Miller <danjm.com@gmail.com>
Date: Tue, 6 Oct 2020 17:47:58 -0230
Subject: [PATCH] Fix SwapsController handling of insufficient balance for gas
 when in max ETH mode

---
 app/scripts/controllers/swaps.js | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/app/scripts/controllers/swaps.js b/app/scripts/controllers/swaps.js
index 31e669c8b..2114341fc 100644
--- a/app/scripts/controllers/swaps.js
+++ b/app/scripts/controllers/swaps.js
@@ -3,6 +3,7 @@ import log from 'loglevel'
 import BigNumber from 'bignumber.js'
 import ObservableStore from 'obs-store'
 import { mapValues } from 'lodash'
+import ethUtil from 'ethereumjs-util'
 import abi from 'human-standard-token-abi'
 import { calcTokenAmount } from '../../../ui/app/helpers/utils/token-util'
 import { calcGasTotal } from '../../../ui/app/pages/send/send.utils'
@@ -182,7 +183,7 @@ export default class SwapsController {
       newQuotes = await this.getAllQuotesWithGasEstimates(newQuotes)
 
       if (fetchParamsMetaData.maxMode && fetchParams.sourceToken === ETH_SWAPS_TOKEN_ADDRESS) {
-        newQuotes = await this._modifyValuesForMaxEthMode(newQuotes, fetchParamsMetaData.accountBalance)
+        newQuotes = await this._modifyAndFilterValuesForMaxEthMode(newQuotes, fetchParamsMetaData.accountBalance)
       }
 
       if (Object.values(newQuotes).length === 0) {
@@ -582,36 +583,39 @@ export default class SwapsController {
     }
   }
 
-  async _modifyValuesForMaxEthMode (newQuotes, accountBalance) {
+  async _modifyAndFilterValuesForMaxEthMode (newQuotes, accountBalance) {
     const {
       swapsState: { customGasPrice },
     } = this.store.getState()
 
     const usedGasPrice = customGasPrice || await this._getEthersGasPrice()
 
-    const mappedNewQuotes = mapValues(newQuotes, (quote) => {
+    const mappedNewQuotes = {}
+    Object.values(newQuotes).forEach((quote) => {
       const oldSourceAmount = quote.sourceAmount
 
       const gasTotalInWeiHex = calcGasTotal((new BigNumber(quote.maxGas, 10)).toString(16), usedGasPrice)
       const newSourceAmount = (new BigNumber(accountBalance, 16)).minus(gasTotalInWeiHex, 16).toString(10)
 
       const newOldRatio = (new BigNumber(newSourceAmount, 10)).div(oldSourceAmount, 10)
-      const oldNewDifference = (new BigNumber(oldSourceAmount, 10)).minus(newSourceAmount, 10)
+      const oldNewDifference = (new BigNumber(oldSourceAmount, 10)).minus(newSourceAmount, 10).toString(10)
 
       const oldDestinationAmount = quote.destinationAmount
-      const newDestinationAmount = (new BigNumber(oldDestinationAmount, 10)).times(newOldRatio)
+      const newDestinationAmount = (new BigNumber(oldDestinationAmount, 10)).times(newOldRatio).toString(10)
 
       const oldValue = quote.trade.value
-      const newValue = (new BigNumber(oldValue, 16)).minus(oldNewDifference, 10)
+      const newValue = (new BigNumber(oldValue, 16)).minus(oldNewDifference, 10).toString(16)
 
-      return {
-        ...quote,
-        trade: {
-          ...quote.trade,
-          value: newValue,
-        },
-        destinationAmount: newDestinationAmount,
-        sourceAmount: newSourceAmount,
+      if ((new BigNumber(newSourceAmount, 10).gt(0))) {
+        mappedNewQuotes[quote.aggregator] = {
+          ...quote,
+          trade: {
+            ...quote.trade,
+            value: ethUtil.addHexPrefix(newValue),
+          },
+          destinationAmount: newDestinationAmount,
+          sourceAmount: newSourceAmount,
+        }
       }
     })