Fix SwapsController handling of insufficient balance for gas when in max ETH mode

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) {
@@ -582,37 +583,40 @@ 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 {
+      if ((new BigNumber(newSourceAmount, 10).gt(0))) {
+        mappedNewQuotes[quote.aggregator] = {
           ...quote,
           trade: {
             ...quote.trade,
-          value: newValue,
+            value: ethUtil.addHexPrefix(newValue),
           },
           destinationAmount: newDestinationAmount,
           sourceAmount: newSourceAmount,
         }
+      }
     })
 
     return mappedNewQuotes