Merge pull request #1206 from 0xProject/fix/instant/decimal-fields-scaling-amount-input-bn

[instant] Fix decimal input issues on instant

9 files changed, 85 insertions, 70 deletions

diff --git a/packages/instant/src/components/erc20_asset_amount_input.tsx b/packages/instant/src/components/erc20_asset_amount_input.tsx
index b1fec6405..6fb8f60f0 100644
--- a/packages/instant/src/components/erc20_asset_amount_input.tsx
+++ b/packages/instant/src/components/erc20_asset_amount_input.tsx
@@ -1,10 +1,10 @@
+import { BigNumber } from '@0x/utils';
 import * as _ from 'lodash';
 import * as React from 'react';
 
 import { ColorOption, transparentWhite } from '../style/theme';
 import { ERC20Asset } from '../types';
 import { assetUtils } from '../util/asset';
-import { BigNumberInput } from '../util/big_number_input';
 import { util } from '../util/util';
 
 import { ScalingAmountInput } from './scaling_amount_input';
@@ -13,8 +13,8 @@ import { Container, Flex, Icon, Text } from './ui';
 // Asset amounts only apply to ERC20 assets
 export interface ERC20AssetAmountInputProps {
     asset?: ERC20Asset;
-    value?: BigNumberInput;
-    onChange: (value?: BigNumberInput, asset?: ERC20Asset) => void;
+    value?: BigNumber;
+    onChange: (value?: BigNumber, asset?: ERC20Asset) => void;
     onSelectAssetClick?: (asset?: ERC20Asset) => void;
     startingFontSizePx: number;
     fontColor?: ColorOption;
@@ -54,7 +54,7 @@ export class ERC20AssetAmountInput extends React.Component<ERC20AssetAmountInput
                         {...rest}
                         textLengthThreshold={this._textLengthThresholdForAsset(asset)}
                         maxFontSizePx={this.props.startingFontSizePx}
-                        onChange={this._handleChange}
+                        onAmountChange={this._handleChange}
                         onFontSizeChange={this._handleFontSizeChange}
                     />
                 </Container>
@@ -102,7 +102,7 @@ export class ERC20AssetAmountInput extends React.Component<ERC20AssetAmountInput
             </Container>
         );
     };
-    private readonly _handleChange = (value?: BigNumberInput): void => {
+    private readonly _handleChange = (value?: BigNumber): void => {
         this.props.onChange(value, this.props.asset);
     };
     private readonly _handleFontSizeChange = (fontSizePx: number): void => {
diff --git a/packages/instant/src/components/scaling_amount_input.tsx b/packages/instant/src/components/scaling_amount_input.tsx
index cfbf3b7cc..5dc719293 100644
--- a/packages/instant/src/components/scaling_amount_input.tsx
+++ b/packages/instant/src/components/scaling_amount_input.tsx
@@ -1,8 +1,11 @@
+import { BigNumber } from '@0x/utils';
 import * as _ from 'lodash';
 import * as React from 'react';
 
+import { Maybe } from '../types';
+
 import { ColorOption } from '../style/theme';
-import { BigNumberInput } from '../util/big_number_input';
+import { maybeBigNumberUtil } from '../util/maybe_big_number';
 import { util } from '../util/util';
 
 import { ScalingInput } from './scaling_input';
@@ -12,19 +15,44 @@ export interface ScalingAmountInputProps {
     maxFontSizePx: number;
     textLengthThreshold: number;
     fontColor?: ColorOption;
-    value?: BigNumberInput;
-    onChange: (value?: BigNumberInput) => void;
+    value?: BigNumber;
+    onAmountChange: (value?: BigNumber) => void;
     onFontSizeChange: (fontSizePx: number) => void;
 }
+interface ScalingAmountInputState {
+    stringValue: string;
+}
 
-export class ScalingAmountInput extends React.Component<ScalingAmountInputProps> {
+const { stringToMaybeBigNumber, areMaybeBigNumbersEqual } = maybeBigNumberUtil;
+export class ScalingAmountInput extends React.Component<ScalingAmountInputProps, ScalingAmountInputState> {
     public static defaultProps = {
-        onChange: util.boundNoop,
+        onAmountChange: util.boundNoop,
         onFontSizeChange: util.boundNoop,
         isDisabled: false,
     };
+    public constructor(props: ScalingAmountInputProps) {
+        super(props);
+        this.state = {
+            stringValue: _.isUndefined(props.value) ? '' : props.value.toString(),
+        };
+    }
+    public componentDidUpdate(): void {
+        const parsedStateValue = stringToMaybeBigNumber(this.state.stringValue);
+        const currentValue = this.props.value;
+
+        if (!areMaybeBigNumbersEqual(parsedStateValue, currentValue)) {
+            // we somehow got into the state in which the value passed in and the string value
+            // in state have differed, reset state
+            // we dont expect to ever get into this state, but let's make sure
+            // we reset if we do since we're dealing with important numbers
+            this.setState({
+                stringValue: _.isUndefined(currentValue) ? '' : currentValue.toString(),
+            });
+        }
+    }
+
     public render(): React.ReactNode {
-        const { textLengthThreshold, fontColor, maxFontSizePx, value, onFontSizeChange } = this.props;
+        const { textLengthThreshold, fontColor, maxFontSizePx, onFontSizeChange } = this.props;
         return (
             <ScalingInput
                 maxFontSizePx={maxFontSizePx}
@@ -32,7 +60,7 @@ export class ScalingAmountInput extends React.Component<ScalingAmountInputProps>
                 onFontSizeChange={onFontSizeChange}
                 fontColor={fontColor}
                 onChange={this._handleChange}
-                value={!_.isUndefined(value) ? value.toDisplayString() : ''}
+                value={this.state.stringValue}
                 placeholder="0.00"
                 emptyInputWidthCh={3.5}
                 isDisabled={this.props.isDisabled}
@@ -40,16 +68,16 @@ export class ScalingAmountInput extends React.Component<ScalingAmountInputProps>
         );
     }
     private readonly _handleChange = (event: React.ChangeEvent<HTMLInputElement>): void => {
-        const value = event.target.value;
-        let bigNumberValue;
-        if (!_.isEmpty(value)) {
-            try {
-                bigNumberValue = new BigNumberInput(value);
-            } catch {
-                // We don't want to allow values that can't be a BigNumber, so don't even call onChange.
-                return;
-            }
-        }
-        this.props.onChange(bigNumberValue);
+        const sanitizedValue = event.target.value.replace(/[^0-9.]/g, ''); // only allow numbers and "."
+        this.setState({
+            stringValue: sanitizedValue,
+        });
+
+        // Trigger onAmountChange with a valid BigNumber, or undefined if the sanitizedValue is invalid or empty
+        const bigNumberValue: Maybe<BigNumber> = _.isEmpty(sanitizedValue)
+            ? undefined
+            : stringToMaybeBigNumber(sanitizedValue);
+
+        this.props.onAmountChange(bigNumberValue);
     };
 }
diff --git a/packages/instant/src/components/zero_ex_instant_provider.tsx b/packages/instant/src/components/zero_ex_instant_provider.tsx
index 4bc840862..fe4d37331 100644
--- a/packages/instant/src/components/zero_ex_instant_provider.tsx
+++ b/packages/instant/src/components/zero_ex_instant_provider.tsx
@@ -1,5 +1,6 @@
 import { AssetBuyer } from '@0x/asset-buyer';
 import { ObjectMap, SignedOrder } from '@0x/types';
+import { BigNumber } from '@0x/utils';
 import { Web3Wrapper } from '@0x/web3-wrapper';
 import { Provider } from 'ethereum-types';
 import * as _ from 'lodash';
@@ -14,7 +15,6 @@ import { store, Store } from '../redux/store';
 import { fonts } from '../style/fonts';
 import { AffiliateInfo, AssetMetaData, Network } from '../types';
 import { assetUtils } from '../util/asset';
-import { BigNumberInput } from '../util/big_number_input';
 import { errorFlasher } from '../util/error_flasher';
 import { gasPriceEstimator } from '../util/gas_price_estimator';
 import { getInjectedProvider } from '../util/injected_provider';
@@ -68,7 +68,7 @@ export class ZeroExInstantProvider extends React.Component<ZeroExInstantProvider
             selectedAsset: assetUtils.createAssetFromAssetData(props.assetData, completeAssetMetaDataMap, networkId),
             selectedAssetAmount: _.isUndefined(props.defaultAssetBuyAmount)
                 ? state.selectedAssetAmount
-                : new BigNumberInput(props.defaultAssetBuyAmount),
+                : new BigNumber(props.defaultAssetBuyAmount),
             assetMetaDataMap: completeAssetMetaDataMap,
             affiliateInfo: props.affiliateInfo,
         };
diff --git a/packages/instant/src/containers/selected_erc20_asset_amount_input.ts b/packages/instant/src/containers/selected_erc20_asset_amount_input.ts
index fcbd0efe3..12bc7040e 100644
--- a/packages/instant/src/containers/selected_erc20_asset_amount_input.ts
+++ b/packages/instant/src/containers/selected_erc20_asset_amount_input.ts
@@ -14,7 +14,6 @@ import { State } from '../redux/reducer';
 import { ColorOption } from '../style/theme';
 import { AffiliateInfo, ERC20Asset, OrderProcessState } from '../types';
 import { assetUtils } from '../util/asset';
-import { BigNumberInput } from '../util/big_number_input';
 import { errorFlasher } from '../util/error_flasher';
 
 export interface SelectedERC20AssetAmountInputProps {
@@ -25,7 +24,7 @@ export interface SelectedERC20AssetAmountInputProps {
 
 interface ConnectedState {
     assetBuyer?: AssetBuyer;
-    value?: BigNumberInput;
+    value?: BigNumber;
     asset?: ERC20Asset;
     isDisabled: boolean;
     affiliateInfo?: AffiliateInfo;
@@ -34,16 +33,16 @@ interface ConnectedState {
 interface ConnectedDispatch {
     updateBuyQuote: (
         assetBuyer?: AssetBuyer,
-        value?: BigNumberInput,
+        value?: BigNumber,
         asset?: ERC20Asset,
         affiliateInfo?: AffiliateInfo,
     ) => void;
 }
 
 interface ConnectedProps {
-    value?: BigNumberInput;
+    value?: BigNumber;
     asset?: ERC20Asset;
-    onChange: (value?: BigNumberInput, asset?: ERC20Asset) => void;
+    onChange: (value?: BigNumber, asset?: ERC20Asset) => void;
     isDisabled: boolean;
 }
 
diff --git a/packages/instant/src/redux/actions.ts b/packages/instant/src/redux/actions.ts
index 885f09c7c..9397dcc99 100644
--- a/packages/instant/src/redux/actions.ts
+++ b/packages/instant/src/redux/actions.ts
@@ -2,8 +2,6 @@ import { BuyQuote } from '@0x/asset-buyer';
 import { BigNumber } from '@0x/utils';
 import * as _ from 'lodash';
 
-import { BigNumberInput } from '../util/big_number_input';
-
 import { ActionsUnion } from '../types';
 
 export interface PlainAction<T extends string> {
@@ -42,8 +40,7 @@ export enum ActionTypes {
 
 export const actions = {
     updateEthUsdPrice: (price?: BigNumber) => createAction(ActionTypes.UPDATE_ETH_USD_PRICE, price),
-    updateSelectedAssetAmount: (amount?: BigNumberInput) =>
-        createAction(ActionTypes.UPDATE_SELECTED_ASSET_AMOUNT, amount),
+    updateSelectedAssetAmount: (amount?: BigNumber) => createAction(ActionTypes.UPDATE_SELECTED_ASSET_AMOUNT, amount),
     setBuyOrderStateNone: () => createAction(ActionTypes.SET_BUY_ORDER_STATE_NONE),
     setBuyOrderStateValidating: () => createAction(ActionTypes.SET_BUY_ORDER_STATE_VALIDATING),
     setBuyOrderStateProcessing: (txHash: string, startTimeUnix: number, expectedEndTimeUnix: number) =>
diff --git a/packages/instant/src/redux/reducer.ts b/packages/instant/src/redux/reducer.ts
index d1537b49b..1b4fdabbc 100644
--- a/packages/instant/src/redux/reducer.ts
+++ b/packages/instant/src/redux/reducer.ts
@@ -16,7 +16,6 @@ import {
     OrderState,
 } from '../types';
 import { assetUtils } from '../util/asset';
-import { BigNumberInput } from '../util/big_number_input';
 
 import { Action, ActionTypes } from './actions';
 
@@ -25,7 +24,7 @@ export interface State {
     assetBuyer?: AssetBuyer;
     assetMetaDataMap: ObjectMap<AssetMetaData>;
     selectedAsset?: Asset;
-    selectedAssetAmount?: BigNumberInput;
+    selectedAssetAmount?: BigNumber;
     buyOrderState: OrderState;
     ethUsdPrice?: BigNumber;
     latestBuyQuote?: BuyQuote;
diff --git a/packages/instant/src/types.ts b/packages/instant/src/types.ts
index 82dc77d2e..834127994 100644
--- a/packages/instant/src/types.ts
+++ b/packages/instant/src/types.ts
@@ -1,6 +1,7 @@
 import { AssetProxyId, ObjectMap } from '@0x/types';
 
 // Reusable
+export type Maybe<T> = T | undefined;
 export enum AsyncProcessState {
     NONE = 'None',
     PENDING = 'Pending',
diff --git a/packages/instant/src/util/big_number_input.ts b/packages/instant/src/util/big_number_input.ts
deleted file mode 100644
index 370d91a0a..000000000
--- a/packages/instant/src/util/big_number_input.ts
+++ /dev/null
@@ -1,34 +0,0 @@
-import { BigNumber } from '@0x/utils';
-import * as _ from 'lodash';
-
-/**
- *  A BigNumber extension that is more flexible about decimal strings.
- *  Such as allowing:
- *  new BigNumberInput('0.') => 0
- *  new BigNumberInput('1.') => 1
- *  new BigNumberInput('1..') => still throws
- */
-export class BigNumberInput extends BigNumber {
-    private readonly _isEndingWithDecimal: boolean;
-    constructor(numberOrString: string | number) {
-        if (_.isString(numberOrString)) {
-            const hasDecimalPeriod = _.endsWith(numberOrString, '.');
-            let internalString = numberOrString;
-            if (hasDecimalPeriod) {
-                internalString = numberOrString.slice(0, -1);
-            }
-            super(internalString);
-            this._isEndingWithDecimal = hasDecimalPeriod;
-        } else {
-            super(numberOrString);
-            this._isEndingWithDecimal = false;
-        }
-    }
-    public toDisplayString(): string {
-        const internalString = super.toString();
-        if (this._isEndingWithDecimal) {
-            return `${internalString}.`;
-        }
-        return internalString;
-    }
-}
diff --git a/packages/instant/src/util/maybe_big_number.ts b/packages/instant/src/util/maybe_big_number.ts
new file mode 100644
index 000000000..9d3746e10
--- /dev/null
+++ b/packages/instant/src/util/maybe_big_number.ts
@@ -0,0 +1,25 @@
+import { BigNumber } from '@0x/utils';
+import * as _ from 'lodash';
+
+import { Maybe } from '../types';
+
+export const maybeBigNumberUtil = {
+    // converts a string to a Maybe<BigNumber>
+    // if string is a NaN, considered undefined
+    stringToMaybeBigNumber: (stringValue: string): Maybe<BigNumber> => {
+        let validBigNumber: BigNumber;
+        try {
+            validBigNumber = new BigNumber(stringValue);
+        } catch {
+            return undefined;
+        }
+
+        return validBigNumber.isNaN() ? undefined : validBigNumber;
+    },
+    areMaybeBigNumbersEqual: (val1: Maybe<BigNumber>, val2: Maybe<BigNumber>): boolean => {
+        if (!_.isUndefined(val1) && !_.isUndefined(val2)) {
+            return val1.equals(val2);
+        }
+        return _.isUndefined(val1) && _.isUndefined(val2);
+    },
+};