Stricter balance checks during swap (#793)

* check currentBalance before showing Amount Field and GenerateTx button

* add token balance check

* check wallet balance

* comments

* simplify wallet balance check

common/components/GenerateTransaction/GenerateTransaction.tsx

@@ -4,7 +4,7 @@ import EthTx from 'ethereumjs-tx';
 import React, { Component } from 'react';
 import { connect } from 'react-redux';
 import { AppState } from 'reducers';
-import { getTransaction, isNetworkRequestPending } from 'selectors/transaction';
+import { getTransaction, isNetworkRequestPending, isValidAmount } from 'selectors/transaction';
 import { getWalletType } from 'selectors/wallet';
 
 interface StateProps {
@@ -12,17 +12,24 @@ interface StateProps {
   networkRequestPending: boolean;
   isFullTransaction: boolean;
   isWeb3Wallet: boolean;
+  validAmount: boolean;
 }
 
 class GenerateTransactionClass extends Component<StateProps> {
   public render() {
-    const { isFullTransaction, isWeb3Wallet, transaction, networkRequestPending } = this.props;
+    const {
+      isFullTransaction,
+      isWeb3Wallet,
+      transaction,
+      networkRequestPending,
+      validAmount
+    } = this.props;
     return (
       <WithSigner
         isWeb3={isWeb3Wallet}
         withSigner={signer => (
           <button
-            disabled={!isFullTransaction || networkRequestPending}
+            disabled={!isFullTransaction || networkRequestPending || !validAmount}
             className="btn btn-info btn-block"
             onClick={signer(transaction)}
           >
@@ -37,5 +44,6 @@ class GenerateTransactionClass extends Component<StateProps> {
 export const GenerateTransaction = connect((state: AppState) => ({
   ...getTransaction(state),
   networkRequestPending: isNetworkRequestPending(state),
-  isWeb3Wallet: getWalletType(state).isWeb3Wallet
+  isWeb3Wallet: getWalletType(state).isWeb3Wallet,
+  validAmount: isValidAmount(state)
 }))(GenerateTransactionClass);

common/containers/Tabs/Swap/components/LiteSend/Fields.tsx

@@ -7,15 +7,20 @@ import { GenerateTransaction, SendButton, SigningStatus, GasSlider } from 'compo
 import { resetWallet, TResetWallet } from 'actions/wallet';
 import translate from 'translations';
 import { getUnit } from 'selectors/transaction';
+import { getCurrentBalance } from 'selectors/wallet';
+import Spinner from 'components/ui/Spinner';
+import { Wei, TokenValue } from 'libs/units';
 
 interface StateProps {
   unit: string;
   resetWallet: TResetWallet;
+  currentBalance: Wei | TokenValue | null;
 }
 
 type Props = StateProps;
 class FieldsClass extends Component<Props> {
   public render() {
+    const { currentBalance } = this.props;
     return (
       <div className="Tab-content-pane">
         <div className="row form-group">
@@ -41,7 +46,11 @@ class FieldsClass extends Component<Props> {
         <div className="row form-group">
           <div className="col-xs-12">
             <label>{translate('SEND_amount')}</label>
-
+            {currentBalance === null ? (
+              <div className="row text-center">
+                <Spinner />
+              </div>
+            ) : (
               <AmountFieldFactory
                 withProps={({ currentValue, isValid }) => (
                   <React.Fragment>
@@ -62,6 +71,7 @@ class FieldsClass extends Component<Props> {
                   </React.Fragment>
                 )}
               />
+            )}
           </div>
         </div>
         <div className="row form-group">
@@ -72,7 +82,13 @@ class FieldsClass extends Component<Props> {
         <SigningStatus />
         <div className="row form-group">
           <div className="col-xs-12 clearfix">
+            {currentBalance === null ? (
+              <div className="row text-center">
+                <Spinner />
+              </div>
+            ) : (
               <GenerateTransaction />
+            )}
           </div>
         </div>
         <div className="row form-group">
@@ -86,6 +102,7 @@ class FieldsClass extends Component<Props> {
   };
 }
 
-export const Fields = connect((state: AppState) => ({ unit: getUnit(state) }), { resetWallet })(
+export const Fields = connect(
-  FieldsClass
+  (state: AppState) => ({ unit: getUnit(state), currentBalance: getCurrentBalance(state) }),
-);
+  { resetWallet }
+)(FieldsClass);

common/libs/wallet/balance.ts

@@ -1,6 +1,6 @@
 import { Wei } from 'libs/units';
 
 export interface Balance {
-  wei: Wei;
+  wei: Wei | null;
   isPending: boolean;
 }

common/reducers/wallet.ts

@@ -15,7 +15,7 @@ export interface State {
   inst?: IWallet | null;
   config?: WalletConfig | null;
   // in ETH
-  balance: Balance | { wei: null };
+  balance: Balance;
   tokens: {
     [key: string]: {
       balance: TokenValue;

common/selectors/transaction/current.ts

@@ -3,6 +3,7 @@ import { getUnit, getTokenTo, getTokenValue } from './meta';
 import { AppState } from 'reducers';
 import { isEtherUnit, TokenValue, Wei, Address } from 'libs/units';
 import { getDataExists, getValidGasCost } from 'selectors/transaction';
+import { getCurrentBalance } from 'selectors/wallet';
 
 interface ICurrentValue {
   raw: string;
@@ -38,18 +39,40 @@ const isValidCurrentTo = (state: AppState) => {
   }
 };
 
-const isValidAmount = (state: AppState) => {
+const isValidAmount = (state: AppState): boolean => {
   const currentValue = getCurrentValue(state);
   const dataExists = getDataExists(state);
   const validGasCost = getValidGasCost(state);
+
+  // We do some wallet validation here.
+  // For some reason with MetaMask, sometimes the currentValue.value is not a null
+  // but instead a BN with a value equal to currentValue.raw - even though the wallet
+  // doesn't have enough of a balance.
+
+  // Get the wallet balance (token value or ether value)
+  const walletBalance = getCurrentBalance(state);
+
+  // We ensure that we have a valid walletBalance (token or Ether is fine)
+  if (!walletBalance) {
+    return false;
+  }
+
   if (isEtherTransaction(state)) {
     // if data exists with no value, just check if gas is enough
     if (dataExists && !currentValue.value && currentValue.raw === '') {
       return validGasCost;
     }
+    // if the currentValue.value is not null, then compare it against the walletBalance.
+    if (currentValue.value) {
+      return walletBalance.cmp(currentValue.value) > 0;
+    }
 
     return !!currentValue.value;
   } else {
+    // if the currentValue.value is not null, then compare it against the walletBalance.
+    if (currentValue.value) {
+      return walletBalance.cmp(currentValue.value) > 0;
+    }
     return !!currentValue.value;
   }
 };