From 51b7cbd34213c207584d4180634130e5b9b60e1c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Aar=C3=B3n=20Garc=C3=ADa=20Herv=C3=A1s?= <aaron@mui.com>
Date: Tue, 29 Oct 2024 15:46:33 +0100
Subject: [PATCH] Bring back useIsFocusVisible

---
 packages/mui-utils/src/index.ts               |   1 +
 .../mui-utils/src/useIsFocusVisible/index.ts  |   2 +
 .../useIsFocusVisible.test.js                 | 126 +++++++++++++
 .../useIsFocusVisible/useIsFocusVisible.ts    | 175 ++++++++++++++++++
 4 files changed, 304 insertions(+)
 create mode 100644 packages/mui-utils/src/useIsFocusVisible/index.ts
 create mode 100644 packages/mui-utils/src/useIsFocusVisible/useIsFocusVisible.test.js
 create mode 100644 packages/mui-utils/src/useIsFocusVisible/useIsFocusVisible.ts

diff --git a/packages/mui-utils/src/index.ts b/packages/mui-utils/src/index.ts
index eb8cfe9ed67f1b..d1b651419059a1 100644
--- a/packages/mui-utils/src/index.ts
+++ b/packages/mui-utils/src/index.ts
@@ -27,6 +27,7 @@ export { default as unstable_useForkRef } from './useForkRef';
 export { default as unstable_useLazyRef } from './useLazyRef';
 export { default as unstable_useTimeout, Timeout as unstable_Timeout } from './useTimeout';
 export { default as unstable_useOnMount } from './useOnMount';
+export { default as unstable_useIsFocusVisible } from './useIsFocusVisible';
 export { default as unstable_isFocusVisible } from './isFocusVisible';
 export { default as unstable_getScrollbarSize } from './getScrollbarSize';
 export { default as usePreviousProps } from './usePreviousProps';
diff --git a/packages/mui-utils/src/useIsFocusVisible/index.ts b/packages/mui-utils/src/useIsFocusVisible/index.ts
new file mode 100644
index 00000000000000..9f7a0b9ab5e7ad
--- /dev/null
+++ b/packages/mui-utils/src/useIsFocusVisible/index.ts
@@ -0,0 +1,2 @@
+export { default } from './useIsFocusVisible';
+export * from './useIsFocusVisible';
diff --git a/packages/mui-utils/src/useIsFocusVisible/useIsFocusVisible.test.js b/packages/mui-utils/src/useIsFocusVisible/useIsFocusVisible.test.js
new file mode 100644
index 00000000000000..d0c9350a1e0ad8
--- /dev/null
+++ b/packages/mui-utils/src/useIsFocusVisible/useIsFocusVisible.test.js
@@ -0,0 +1,126 @@
+import { expect } from 'chai';
+import * as React from 'react';
+import * as ReactDOMClient from 'react-dom/client';
+import {
+  act,
+  createRenderer,
+  focusVisible,
+  simulatePointerDevice,
+  programmaticFocusTriggersFocusVisible,
+} from '@mui/internal-test-utils';
+import useIsFocusVisible, { teardown as teardownFocusVisible } from './useIsFocusVisible';
+import useForkRef from '../useForkRef';
+
+const SimpleButton = React.forwardRef(function SimpleButton(props, ref) {
+  const {
+    isFocusVisibleRef,
+    onBlur: handleBlurVisible,
+    onFocus: handleFocusVisible,
+    ref: focusVisibleRef,
+  } = useIsFocusVisible();
+
+  const handleRef = useForkRef(focusVisibleRef, ref);
+
+  const [isFocusVisible, setIsFocusVisible] = React.useState(false);
+
+  const handleBlur = (event) => {
+    handleBlurVisible(event);
+    if (isFocusVisibleRef.current === false) {
+      setIsFocusVisible(false);
+    }
+  };
+
+  const handleFocus = (event) => {
+    handleFocusVisible(event);
+    if (isFocusVisibleRef.current === true) {
+      setIsFocusVisible(true);
+    }
+  };
+
+  return (
+    <button
+      type="button"
+      {...props}
+      ref={handleRef}
+      className={isFocusVisible ? 'focus-visible' : null}
+      onBlur={handleBlur}
+      onFocus={handleFocus}
+    />
+  );
+});
+
+describe('useIsFocusVisible', () => {
+  const { render } = createRenderer();
+
+  before(() => {
+    // isolate test from previous component test that use the polyfill in the document scope
+    teardownFocusVisible(document);
+  });
+
+  describe('focus inside shadowRoot', () => {
+    before(function beforeHook() {
+      // Only run on HeadlessChrome which has native shadowRoot support.
+      // And jsdom which has limited support for shadowRoot (^12.0.0).
+      if (!/HeadlessChrome|jsdom/.test(window.navigator.userAgent)) {
+        this.skip();
+      }
+    });
+
+    let rootElement;
+    let reactRoot;
+
+    beforeEach(() => {
+      rootElement = document.createElement('div');
+      document.body.appendChild(rootElement);
+      rootElement.attachShadow({ mode: 'open' });
+      reactRoot = ReactDOMClient.createRoot(rootElement.shadowRoot);
+    });
+
+    afterEach(() => {
+      act(() => {
+        reactRoot.unmount();
+      });
+
+      teardownFocusVisible(rootElement.shadowRoot);
+      document.body.removeChild(rootElement);
+    });
+
+    it('should set focus state for shadowRoot children', () => {
+      const buttonRef = React.createRef();
+      render(
+        <SimpleButton id="test-button" ref={buttonRef}>
+          Hello
+        </SimpleButton>,
+        {},
+        {
+          container: rootElement.shadowRoot,
+        },
+      );
+      simulatePointerDevice();
+
+      const { current: button } = buttonRef;
+      if (button.nodeName !== 'BUTTON') {
+        throw new Error('missing button');
+      }
+
+      expect(button.classList.contains('focus-visible')).to.equal(false);
+
+      act(() => {
+        button.focus();
+      });
+
+      if (programmaticFocusTriggersFocusVisible()) {
+        expect(button).to.have.class('focus-visible');
+      } else {
+        expect(button).not.to.have.class('focus-visible');
+      }
+
+      act(() => {
+        button.blur();
+      });
+      focusVisible(button);
+
+      expect(button.classList.contains('focus-visible')).to.equal(true);
+    });
+  });
+});
diff --git a/packages/mui-utils/src/useIsFocusVisible/useIsFocusVisible.ts b/packages/mui-utils/src/useIsFocusVisible/useIsFocusVisible.ts
new file mode 100644
index 00000000000000..74d444019e6522
--- /dev/null
+++ b/packages/mui-utils/src/useIsFocusVisible/useIsFocusVisible.ts
@@ -0,0 +1,175 @@
+'use client';
+// based on https://github.com/WICG/focus-visible/blob/v4.1.5/src/focus-visible.js
+import * as React from 'react';
+import { Timeout } from '../useTimeout/useTimeout';
+
+let hadKeyboardEvent = true;
+let hadFocusVisibleRecently = false;
+const hadFocusVisibleRecentlyTimeout = new Timeout();
+
+const inputTypesWhitelist: Record<string, boolean> = {
+  text: true,
+  search: true,
+  url: true,
+  tel: true,
+  email: true,
+  password: true,
+  number: true,
+  date: true,
+  month: true,
+  week: true,
+  time: true,
+  datetime: true,
+  'datetime-local': true,
+};
+
+/**
+ * Computes whether the given element should automatically trigger the
+ * `focus-visible` class being added, i.e. whether it should always match
+ * `:focus-visible` when focused.
+ * @param {Element} node
+ * @returns {boolean}
+ */
+function focusTriggersKeyboardModality(node: Element) {
+  const { type, tagName } = node as HTMLInputElement;
+
+  if (tagName === 'INPUT' && inputTypesWhitelist[type] && !(node as HTMLInputElement).readOnly) {
+    return true;
+  }
+
+  if (tagName === 'TEXTAREA' && !(node as HTMLInputElement).readOnly) {
+    return true;
+  }
+
+  if ((node as HTMLElement).isContentEditable) {
+    return true;
+  }
+
+  return false;
+}
+
+/**
+ * Keep track of our keyboard modality state with `hadKeyboardEvent`.
+ * If the most recent user interaction was via the keyboard;
+ * and the key press did not include a meta, alt/option, or control key;
+ * then the modality is keyboard. Otherwise, the modality is not keyboard.
+ * @param {KeyboardEvent} event
+ */
+function handleKeyDown(event: KeyboardEvent) {
+  if (event.metaKey || event.altKey || event.ctrlKey) {
+    return;
+  }
+  hadKeyboardEvent = true;
+}
+
+/**
+ * If at any point a user clicks with a pointing device, ensure that we change
+ * the modality away from keyboard.
+ * This avoids the situation where a user presses a key on an already focused
+ * element, and then clicks on a different element, focusing it with a
+ * pointing device, while we still think we're in keyboard modality.
+ */
+function handlePointerDown() {
+  hadKeyboardEvent = false;
+}
+
+function handleVisibilityChange(this: Document) {
+  if (this.visibilityState === 'hidden') {
+    // If the tab becomes active again, the browser will handle calling focus
+    // on the element (Safari actually calls it twice).
+    // If this tab change caused a blur on an element with focus-visible,
+    // re-apply the class when the user switches back to the tab.
+    if (hadFocusVisibleRecently) {
+      hadKeyboardEvent = true;
+    }
+  }
+}
+
+function prepare(doc: Document): void {
+  doc.addEventListener('keydown', handleKeyDown, true);
+  doc.addEventListener('mousedown', handlePointerDown, true);
+  doc.addEventListener('pointerdown', handlePointerDown, true);
+  doc.addEventListener('touchstart', handlePointerDown, true);
+  doc.addEventListener('visibilitychange', handleVisibilityChange, true);
+}
+
+export function teardown(doc: Document): void {
+  doc.removeEventListener('keydown', handleKeyDown, true);
+  doc.removeEventListener('mousedown', handlePointerDown, true);
+  doc.removeEventListener('pointerdown', handlePointerDown, true);
+  doc.removeEventListener('touchstart', handlePointerDown, true);
+  doc.removeEventListener('visibilitychange', handleVisibilityChange, true);
+}
+
+function isFocusVisible(event: React.FocusEvent): boolean {
+  const { target } = event;
+  try {
+    return target.matches(':focus-visible');
+  } catch (error) {
+    // Browsers not implementing :focus-visible will throw a SyntaxError.
+    // We use our own heuristic for those browsers.
+    // Rethrow might be better if it's not the expected error but do we really
+    // want to crash if focus-visible malfunctioned?
+  }
+
+  // No need for validFocusTarget check. The user does that by attaching it to
+  // focusable events only.
+  return hadKeyboardEvent || focusTriggersKeyboardModality(target);
+}
+
+export interface UseIsFocusVisibleResult {
+  isFocusVisibleRef: React.MutableRefObject<boolean>;
+  onBlur: (event: React.FocusEvent<any>) => void;
+  onFocus: (event: React.FocusEvent<any>) => void;
+  ref: React.RefCallback<Element>;
+}
+
+export default function useIsFocusVisible(): UseIsFocusVisibleResult {
+  const ref = React.useCallback((node: HTMLElement) => {
+    if (node != null) {
+      prepare(node.ownerDocument);
+    }
+  }, []);
+
+  const isFocusVisibleRef = React.useRef(false);
+
+  /**
+   * Should be called if a blur event is fired
+   */
+  function handleBlurVisible() {
+    // checking against potential state variable does not suffice if we focus and blur synchronously.
+    // React wouldn't have time to trigger a re-render so `focusVisible` would be stale.
+    // Ideally we would adjust `isFocusVisible(event)` to look at `relatedTarget` for blur events.
+    // This doesn't work in IE11 due to https://github.com/facebook/react/issues/3751
+    // TODO: check again if React releases their internal changes to focus event handling (https://github.com/facebook/react/pull/19186).
+    if (isFocusVisibleRef.current) {
+      // To detect a tab/window switch, we look for a blur event followed
+      // rapidly by a visibility change.
+      // If we don't see a visibility change within 100ms, it's probably a
+      // regular focus change.
+      hadFocusVisibleRecently = true;
+      hadFocusVisibleRecentlyTimeout.start(100, () => {
+        hadFocusVisibleRecently = false;
+      });
+
+      isFocusVisibleRef.current = false;
+
+      return true;
+    }
+
+    return false;
+  }
+
+  /**
+   * Should be called if a blur event is fired
+   */
+  function handleFocusVisible(event: React.FocusEvent) {
+    if (isFocusVisible(event)) {
+      isFocusVisibleRef.current = true;
+      return true;
+    }
+    return false;
+  }
+
+  return { isFocusVisibleRef, onFocus: handleFocusVisible, onBlur: handleBlurVisible, ref };
+}