InputControl: Fix undo when changing padding values (#40518)

* Fix undo when changing padding values

* Add changelog entry

* Have `InputControl` favor entered value for a render cycle

* Run propagation effect when `isDirty` changes

* Use event existence to eliminate extraneous `onChange` calls

* Keep change handler in a ref to pass `react-hooks/exhaustive-deps`

* Cleanup legacy `event.persist` calls

Co-authored-by: Mitchell Austin <mr.fye@oneandthesame.net>

packages/components/CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Bug Fix
 
 -   `Popover`, `Dropdown`, `CustomGradientPicker`: Fix dropdown positioning by always targeting the rendered toggle, and switch off width in the Popover size middleware to stop reducing the width of the popover. ([#41361](https://github.com/WordPress/gutenberg/pull/41361))
+-   Fix `InputControl` blocking undo/redo while focused. ([#40518](https://github.com/WordPress/gutenberg/pull/40518))
 
 ### Enhancements
 

packages/components/src/input-control/index.tsx

@@ -17,6 +17,7 @@ import { useState, forwardRef } from '@wordpress/element';
 import InputBase from './input-base';
 import InputField from './input-field';
 import type { InputControlProps } from './types';
+import { useDraft } from './utils';
 
 function useUniqueId( idProp?: string ) {
 	const instanceId = useInstanceId( InputControl );
@@ -52,6 +53,12 @@ export function UnforwardedInputControl(
 	const id = useUniqueId( idProp );
 	const classes = classNames( 'components-input-control', className );
 
+	const draftHookProps = useDraft( {
+		value,
+		onBlur: props.onBlur,
+		onChange,
+	} );
+
 	return (
 		<InputBase
 			__unstableInputWidth={ __unstableInputWidth }
@@ -75,14 +82,13 @@ export function UnforwardedInputControl(
 				id={ id }
 				isFocused={ isFocused }
 				isPressEnterToChange={ isPressEnterToChange }
-				onChange={ onChange }
 				onKeyDown={ onKeyDown }
 				onValidate={ onValidate }
 				ref={ ref }
 				setIsFocused={ setIsFocused }
 				size={ size }
 				stateReducer={ stateReducer }
-				value={ value }
+				{ ...draftHookProps }
 			/>
 		</InputBase>
 	);

packages/components/src/input-control/input-field.tsx

@@ -24,7 +24,6 @@ import type { WordPressComponentProps } from '../ui/context';
 import { useDragCursor } from './utils';
 import { Input } from './styles/input-control-styles';
 import { useInputControlStateReducer } from './reducer/reducer';
-import { useUpdateEffect } from '../utils';
 import type { InputFieldProps } from './types';
 
 function InputField(
@@ -67,40 +66,21 @@ function InputField(
 		pressEnter,
 		pressUp,
 		reset,
-	} = useInputControlStateReducer( stateReducer, {
-		isDragEnabled,
-		value: valueProp,
-		isPressEnterToChange,
-	} );
+	} = useInputControlStateReducer(
+		stateReducer,
+		{
+			isDragEnabled,
+			value: valueProp,
+			isPressEnterToChange,
+		},
+		onChange
+	);
 
-	const { _event, value, isDragging, isDirty } = state;
+	const { value, isDragging, isDirty } = state;
 	const wasDirtyOnBlur = useRef( false );
 
 	const dragCursor = useDragCursor( isDragging, dragDirection );
 
-	/*
-	 * Handles synchronization of external and internal value state.
-	 * If not focused and did not hold a dirty value[1] on blur
-	 * updates the value from the props. Otherwise if not holding
-	 * a dirty value[1] propagates the value and event through onChange.
-	 * [1] value is only made dirty if isPressEnterToChange is true
-	 */
-	useUpdateEffect( () => {
-		if ( valueProp === value ) {
-			return;
-		}
-		if ( ! isFocused && ! wasDirtyOnBlur.current ) {
-			commit( valueProp, _event as SyntheticEvent );
-		} else if ( ! isDirty ) {
-			onChange( value, {
-				event: _event as
-					| ChangeEvent< HTMLInputElement >
-					| PointerEvent< HTMLInputElement >,
-			} );
-			wasDirtyOnBlur.current = false;
-		}
-	}, [ value, isDirty, isFocused, valueProp ] );
-
 	const handleOnBlur = ( event: FocusEvent< HTMLInputElement > ) => {
 		onBlur( event );
 		setIsFocused?.( false );

packages/components/src/input-control/reducer/reducer.ts

@@ -1,12 +1,12 @@
 /**
  * External dependencies
  */
-import type { SyntheticEvent } from 'react';
+import type { SyntheticEvent, ChangeEvent, PointerEvent } from 'react';
 
 /**
  * WordPress dependencies
  */
-import { useReducer } from '@wordpress/element';
+import { useReducer, useLayoutEffect, useRef } from '@wordpress/element';
 
 /**
  * Internal dependencies
@@ -18,6 +18,7 @@ import {
 	initialStateReducer,
 } from './state';
 import * as actions from './actions';
+import type { InputChangeCallback } from '../types';
 
 /**
  * Prepares initialState for the reducer.
@@ -108,9 +109,7 @@ function inputControlStateReducer(
 				break;
 		}
 
-		if ( action.payload.event ) {
-			nextState._event = action.payload.event;
-		}
+		nextState._event = action.payload.event;
 
 		/**
 		 * Send the nextState + action to the composedReducers via
@@ -131,13 +130,15 @@ function inputControlStateReducer(
  * This technique uses the "stateReducer" design pattern:
  * https://kentcdodds.com/blog/the-state-reducer-pattern/
  *
- * @param  stateReducer An external state reducer.
- * @param  initialState The initial state for the reducer.
+ * @param  stateReducer    An external state reducer.
+ * @param  initialState    The initial state for the reducer.
+ * @param  onChangeHandler A handler for the onChange event.
  * @return State, dispatch, and a collection of actions.
  */
 export function useInputControlStateReducer(
 	stateReducer: StateReducer = initialStateReducer,
-	initialState: Partial< InputState > = initialInputControlState
+	initialState: Partial< InputState > = initialInputControlState,
+	onChangeHandler: InputChangeCallback
 ) {
 	const [ state, dispatch ] = useReducer< StateReducer >(
 		inputControlStateReducer( stateReducer ),
@@ -148,15 +149,6 @@ export function useInputControlStateReducer(
 		nextValue: actions.ChangeEventAction[ 'payload' ][ 'value' ],
 		event: actions.ChangeEventAction[ 'payload' ][ 'event' ]
 	) => {
-		/**
-		 * Persist allows for the (Synthetic) event to be used outside of
-		 * this function call.
-		 * https://reactjs.org/docs/events.html#event-pooling
-		 */
-		if ( event && event.persist ) {
-			event.persist();
-		}
-
 		dispatch( {
 			type,
 			payload: { value: nextValue, event },
@@ -166,15 +158,6 @@ export function useInputControlStateReducer(
 	const createKeyEvent = ( type: actions.KeyEventAction[ 'type' ] ) => (
 		event: actions.KeyEventAction[ 'payload' ][ 'event' ]
 	) => {
-		/**
-		 * Persist allows for the (Synthetic) event to be used outside of
-		 * this function call.
-		 * https://reactjs.org/docs/events.html#event-pooling
-		 */
-		if ( event && event.persist ) {
-			event.persist();
-		}
-
 		dispatch( { type, payload: { event } } );
 	};
 
@@ -201,6 +184,37 @@ export function useInputControlStateReducer(
 	const pressDown = createKeyEvent( actions.PRESS_DOWN );
 	const pressEnter = createKeyEvent( actions.PRESS_ENTER );
 
+	const currentState = useRef( state );
+	const refProps = useRef( { value: initialState.value, onChangeHandler } );
+	useLayoutEffect( () => {
+		currentState.current = state;
+		refProps.current = { value: initialState.value, onChangeHandler };
+	} );
+	useLayoutEffect( () => {
+		if (
+			currentState.current._event !== undefined &&
+			state.value !== refProps.current.value &&
+			! state.isDirty
+		) {
+			refProps.current.onChangeHandler( state.value ?? '', {
+				event: currentState.current._event as
+					| ChangeEvent< HTMLInputElement >
+					| PointerEvent< HTMLInputElement >,
+			} );
+		}
+	}, [ state.value, state.isDirty ] );
+	useLayoutEffect( () => {
+		if (
+			initialState.value !== currentState.current.value &&
+			! currentState.current.isDirty
+		) {
+			dispatch( {
+				type: actions.RESET,
+				payload: { value: initialState.value },
+			} );
+		}
+	}, [ initialState.value ] );
+
 	return {
 		change,
 		commit,

packages/components/src/input-control/reducer/state.ts

@@ -1,15 +1,15 @@
 /**
  * External dependencies
  */
-import type { Reducer } from 'react';
+import type { Reducer, SyntheticEvent } from 'react';
 
 /**
  * Internal dependencies
  */
 import type { InputAction } from './actions';
 
 export interface InputState {
-	_event: Event | {};
+	_event?: SyntheticEvent;
 	error: unknown;
 	initialValue?: string;
 	isDirty: boolean;
@@ -24,7 +24,6 @@ export type StateReducer = Reducer< InputState, InputAction >;
 export const initialStateReducer: StateReducer = ( state: InputState ) => state;
 
 export const initialInputControlState: InputState = {
-	_event: {},
 	error: null,
 	initialValue: '',
 	isDirty: false,

packages/components/src/input-control/utils.ts

@@ -1,7 +1,22 @@
+/**
+ * External dependencies
+ */
+import type { FocusEventHandler } from 'react';
+
 /**
  * WordPress dependencies
  */
-import { useEffect } from '@wordpress/element';
+import {
+	useEffect,
+	useLayoutEffect,
+	useRef,
+	useState,
+} from '@wordpress/element';
+
+/**
+ * Internal dependencies
+ */
+import type { InputChangeCallback } from './types';
 
 /**
  * Gets a CSS cursor value based on a drag direction.
@@ -52,3 +67,42 @@ export function useDragCursor(
 
 	return dragCursor;
 }
+
+export function useDraft( props: {
+	value: string | undefined;
+	onBlur?: FocusEventHandler;
+	onChange: InputChangeCallback;
+} ) {
+	const refPreviousValue = useRef( props.value );
+	const [ draft, setDraft ] = useState< {
+		value?: string;
+		isStale?: boolean;
+	} >( {} );
+	const value = draft.value !== undefined ? draft.value : props.value;
+
+	// Determines when to discard the draft value to restore controlled status.
+	// To do so, it tracks the previous value and marks the draft value as stale
+	// after each render.
+	useLayoutEffect( () => {
+		const { current: previousValue } = refPreviousValue;
+		refPreviousValue.current = props.value;
+		if ( draft.value !== undefined && ! draft.isStale )
+			setDraft( { ...draft, isStale: true } );
+		else if ( draft.isStale && props.value !== previousValue )
+			setDraft( {} );
+	}, [ props.value, draft ] );
+
+	const onChange: InputChangeCallback = ( nextValue, extra ) => {
+		// Mutates the draft value to avoid an extra effect run.
+		setDraft( ( current ) =>
+			Object.assign( current, { value: nextValue, isStale: false } )
+		);
+		props.onChange( nextValue, extra );
+	};
+	const onBlur: FocusEventHandler = ( event ) => {
+		setDraft( {} );
+		props.onBlur?.( event );
+	};
+
+	return { value, onBlur, onChange };
+}