// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/* eslint-disable rulesdir/no-imperative-dom-api */

/*
 * Copyright (C) 2007, 2008 Apple Inc.  All rights reserved.
 * Copyright (C) 2008 Matt Lilek <webkit@mattlilek.com>
 * Copyright (C) 2009 Joseph Pecoraro
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import * as Common from '../../core/common/common.js';
import * as Host from '../../core/host/host.js';
import * as i18n from '../../core/i18n/i18n.js';
import * as Platform from '../../core/platform/platform.js';
import * as Root from '../../core/root/root.js';
import * as SDK from '../../core/sdk/sdk.js';
import * as Protocol from '../../generated/protocol.js';
import * as Badges from '../../models/badges/badges.js';
import type * as Elements from '../../models/elements/elements.js';
import type * as IssuesManager from '../../models/issues_manager/issues_manager.js';
import * as TextUtils from '../../models/text_utils/text_utils.js';
import * as CodeMirror from '../../third_party/codemirror.next/codemirror.next.js';
import * as Adorners from '../../ui/components/adorners/adorners.js';
import * as Buttons from '../../ui/components/buttons/buttons.js';
import * as CodeHighlighter from '../../ui/components/code_highlighter/code_highlighter.js';
import * as Highlighting from '../../ui/components/highlighting/highlighting.js';
import * as IconButton from '../../ui/components/icon_button/icon_button.js';
import * as TextEditor from '../../ui/components/text_editor/text_editor.js';
import * as Components from '../../ui/legacy/components/utils/utils.js';
import * as UI from '../../ui/legacy/legacy.js';
import * as VisualLogging from '../../ui/visual_logging/visual_logging.js';
import * as Emulation from '../emulation/emulation.js';
import * as Media from '../media/media.js';

import * as ElementsComponents from './components/components.js';
import {canGetJSPath, cssPath, jsPath, xPath} from './DOMPath.js';
import {getElementIssueDetails} from './ElementIssueUtils.js';
import {ElementsPanel} from './ElementsPanel.js';
import {type ElementsTreeOutline, MappedCharToEntity} from './ElementsTreeOutline.js';
import {ImagePreviewPopover} from './ImagePreviewPopover.js';
import {getRegisteredDecorators, type MarkerDecorator, type MarkerDecoratorRegistration} from './MarkerDecorator.js';

const UIStrings = {
  /**
   * @description Title for Ad adorner. This iframe is marked as advertisement frame.
   */
  thisFrameWasIdentifiedAsAnAd: 'This frame was identified as an ad frame',
  /**
   * @description A context menu item in the Elements panel. Force is used as a verb, indicating intention to make the state change.
   */
  forceState: 'Force state',
  /**
   * @description Hint element title in Elements Tree Element of the Elements panel
   * @example {0} PH1
   */
  useSInTheConsoleToReferToThis: 'Use {PH1} in the console to refer to this element.',
  /**
   * @description A context menu item in the Elements Tree Element of the Elements panel
   */
  addAttribute: 'Add attribute',
  /**
   * @description Text to modify the attribute of an item
   */
  editAttribute: 'Edit attribute',
  /**
   * @description Text to focus on something
   */
  focus: 'Focus',
  /**
   * @description Text to scroll the displayed content into view
   */
  scrollIntoView: 'Scroll into view',
  /**
   * @description A context menu item in the Elements Tree Element of the Elements panel
   */
  editText: 'Edit text',
  /**
   * @description A context menu item in the Elements Tree Element of the Elements panel
   */
  editAsHtml: 'Edit as HTML',
  /**
   * @description Text to cut an element, cut should be used as a verb
   */
  cut: 'Cut',
  /**
   * @description Text for copying, copy should be used as a verb
   */
  copy: 'Copy',
  /**
   * @description Text to paste an element, paste should be used as a verb
   */
  paste: 'Paste',
  /**
   * @description Text in Elements Tree Element of the Elements panel, copy should be used as a verb
   */
  copyOuterhtml: 'Copy outerHTML',
  /**
   * @description Text in Elements Tree Element of the Elements panel, copy should be used as a verb
   */
  copySelector: 'Copy `selector`',
  /**
   * @description Text in Elements Tree Element of the Elements panel
   */
  copyJsPath: 'Copy JS path',
  /**
   * @description Text in Elements Tree Element of the Elements panel, copy should be used as a verb
   */
  copyStyles: 'Copy styles',
  /**
   * @description Text in Elements Tree Element of the Elements panel, copy should be used as a verb
   */
  copyXpath: 'Copy XPath',
  /**
   * @description Text in Elements Tree Element of the Elements panel, copy should be used as a verb
   */
  copyFullXpath: 'Copy full XPath',
  /**
   * @description Text in Elements Tree Element of the Elements panel, copy should be used as a verb
   */
  copyElement: 'Copy element',
  /**
   * @description A context menu item in the Elements Tree Element of the Elements panel
   */
  duplicateElement: 'Duplicate element',
  /**
   * @description Text to hide an element
   */
  hideElement: 'Hide element',
  /**
   * @description A context menu item in the Elements Tree Element of the Elements panel
   */
  deleteElement: 'Delete element',
  /**
   * @description Text to expand something recursively
   */
  expandRecursively: 'Expand recursively',
  /**
   * @description Text to collapse children of a parent group
   */
  collapseChildren: 'Collapse children',
  /**
   * @description Title of an action in the emulation tool to capture node screenshot
   */
  captureNodeScreenshot: 'Capture node screenshot',
  /**
   * @description Title of a context menu item. When clicked DevTools goes to the Application panel and shows this specific iframe's details
   */
  showFrameDetails: 'Show `iframe` details',
  /**
   * @description Text in Elements Tree Element of the Elements panel
   */
  valueIsTooLargeToEdit: '<value is too large to edit>',
  /**
   * @description Element text content in Elements Tree Element of the Elements panel
   */
  children: 'Children:',
  /**
   * @description ARIA label for Elements Tree adorners
   */
  enableGridMode: 'Enable grid mode',
  /**
   * @description ARIA label for Elements Tree adorners
   */
  disableGridMode: 'Disable grid mode',
  /**
   * @description ARIA label for Elements Tree adorners
   */
  enableMasonryMode: 'Enable masonry mode',
  /**
   * @description ARIA label for Elements Tree adorners
   */
  disableMasonryMode: 'Disable masonry mode',
  /**
   * @description ARIA label for an elements tree adorner
   */
  forceOpenPopover: 'Keep this popover open',
  /**
   * @description ARIA label for an elements tree adorner
   */
  stopForceOpenPopover: 'Stop keeping this popover open',
  /**
   * @description Label of the adorner for flex elements in the Elements panel
   */
  enableFlexMode: 'Enable flex mode',
  /**
   * @description Label of the adorner for flex elements in the Elements panel
   */
  disableFlexMode: 'Disable flex mode',
  /**
   * @description Label of an adorner in the Elements panel. When clicked, it enables
   * the overlay showing CSS scroll snapping for the current element.
   */
  enableScrollSnap: 'Enable scroll-snap overlay',
  /**
   * @description Label of an adorner in the Elements panel. When clicked, it disables
   * the overlay showing CSS scroll snapping for the current element.
   */
  disableScrollSnap: 'Disable scroll-snap overlay',
  /**
   * @description Label of an adorner in the Elements panel. When clicked, it forces
   * the element into applying its starting-style rules.
   */
  enableStartingStyle: 'Enable @starting-style mode',
  /**
   * @description Label of an adorner in the Elements panel. When clicked, it no longer
   * forces the element into applying its starting-style rules.
   */
  disableStartingStyle: 'Disable @starting-style mode',
  /**
   * @description Label of an adorner in the Elements panel. When clicked, it redirects
   * to the Media Panel.
   */
  openMediaPanel: 'Jump to Media panel',
  /**
   * @description Text of a tooltip to redirect to another element in the Elements panel
   */
  showPopoverTarget: 'Show element associated with the `popovertarget` attribute',
  /**
   * @description Text of a tooltip to redirect to another element in the Elements panel, associated with the `interesttarget` attribute
   */
  showInterestTarget: 'Show element associated with the `interesttarget` attribute',
  /**
   * @description Text of a tooltip to redirect to another element in the Elements panel, associated with the `commandfor` attribute
   */
  showCommandForTarget: 'Show element associated with the `commandfor` attribute',
  /**
   * @description Text of the tooltip for scroll adorner.
   */
  elementHasScrollableOverflow: 'This element has a scrollable overflow',
  /**
   * @description Text of a context menu item to redirect to the AI assistance panel and to start a chat.
   */
  startAChat: 'Start a chat',
  /**
   * @description Context menu item in Elements panel to assess visibility of an element via AI.
   */
  assessVisibility: 'Assess visibility',
  /**
   * @description Context menu item in Elements panel to center an element via AI.
   */
  centerElement: 'Center element',
  /**
   * @description Context menu item in Elements panel to wrap flex items via AI.
   */
  wrapTheseItems: 'Wrap these items',
  /**
   * @description Context menu item in Elements panel to distribute flex items evenly via AI.
   */
  distributeItemsEvenly: 'Distribute items evenly',
  /**
   * @description Context menu item in Elements panel to explain flexbox via AI.
   */
  explainFlexbox: 'Explain flexbox',
  /**
   * @description Context menu item in Elements panel to align grid items via AI.
   */
  alignItems: 'Align items',
  /**
   * @description Context menu item in Elements panel to add padding/gap to grid via AI.
   */
  addPadding: 'Add padding',
  /**
   * @description Context menu item in Elements panel to explain grid layout via AI.
   */
  explainGridLayout: 'Explain grid layout',
  /**
   * @description Context menu item in Elements panel to find grid definition for a subgrid item via AI.
   */
  findGridDefinition: 'Find grid definition',
  /**
   * @description Context menu item in Elements panel to change parent grid properties for a subgrid item via AI.
   */
  changeParentProperties: 'Change parent properties',
  /**
   * @description Context menu item in Elements panel to explain subgrids via AI.
   */
  explainSubgrids: 'Explain subgrids',
  /**
   * @description Context menu item in Elements panel to remove scrollbars via AI.
   */
  removeScrollbars: 'Remove scrollbars',
  /**
   * @description Context menu item in Elements panel to style scrollbars via AI.
   */
  styleScrollbars: 'Style scrollbars',
  /**
   * @description Context menu item in Elements panel to explain scrollbars via AI.
   */
  explainScrollbars: 'Explain scrollbars',
  /**
   * @description Context menu item in Elements panel to explain container queries via AI.
   */
  explainContainerQueries: 'Explain container queries',
  /**
   * @description Context menu item in Elements panel to explain container types via AI.
   */
  explainContainerTypes: 'Explain container types',
  /**
   * @description Context menu item in Elements panel to explain container context via AI.
   */
  explainContainerContext: 'Explain container context',
} as const;
const str_ = i18n.i18n.registerUIStrings('panels/elements/ElementsTreeElement.ts', UIStrings);
const i18nString = i18n.i18n.getLocalizedString.bind(undefined, str_);

const enum TagType {
  OPENING = 'OPENING_TAG',
  CLOSING = 'CLOSING_TAG',
}

interface OpeningTagContext {
  tagType: TagType.OPENING;
  readonly adornerContainer: HTMLElement;
  adorners: Set<Adorners.Adorner.Adorner>;
  styleAdorners: Set<Adorners.Adorner.Adorner>;
  readonly adornersThrottler: Common.Throttler.Throttler;
  canAddAttributes: boolean;
  slot?: Adorners.Adorner.Adorner;
}

interface ClosingTagContext {
  tagType: TagType.CLOSING;
}

export type TagTypeContext = OpeningTagContext|ClosingTagContext;

export function isOpeningTag(context: TagTypeContext): context is OpeningTagContext {
  return context.tagType === TagType.OPENING;
}

export class ElementsTreeElement extends UI.TreeOutline.TreeElement {
  nodeInternal: SDK.DOMModel.DOMNode;
  override treeOutline: ElementsTreeOutline|null;
  private gutterContainer: HTMLElement;
  private readonly decorationsElement: HTMLElement;
  private searchQuery: string|null;
  #expandedChildrenLimit: number;
  private readonly decorationsThrottler: Common.Throttler.Throttler;
  private inClipboard: boolean;
  #hovered: boolean;
  private editing: EditorHandles|null;
  private htmlEditElement?: HTMLElement;
  expandAllButtonElement: UI.TreeOutline.TreeElement|null;
  selectionElement?: HTMLDivElement;
  private hintElement?: HTMLElement;
  private aiButtonContainer?: HTMLElement;
  private contentElement: HTMLElement;
  #elementIssues = new Map<string, IssuesManager.Issue.Issue>();
  #nodeElementToIssue = new Map<Element, IssuesManager.Issue.Issue[]>();
  #highlights: Range[] = [];

  readonly tagTypeContext: TagTypeContext;

  constructor(node: SDK.DOMModel.DOMNode, isClosingTag?: boolean) {
    // The title will be updated in onattach.
    super();
    this.nodeInternal = node;
    this.treeOutline = null;
    this.listItemElement.setAttribute(
        'jslog', `${VisualLogging.treeItem().parent('elementsTreeOutline').track({
          keydown: 'ArrowUp|ArrowDown|ArrowLeft|ArrowRight|Backspace|Delete|Enter|Space|Home|End',
          drag: true,
          click: true,
        })}`);
    this.contentElement = this.listItemElement.createChild('div');
    this.gutterContainer = this.contentElement.createChild('div', 'gutter-container');
    this.gutterContainer.addEventListener('click', this.showContextMenu.bind(this));
    const gutterMenuIcon = new IconButton.Icon.Icon();
    gutterMenuIcon.name = 'dots-horizontal';
    this.gutterContainer.append(gutterMenuIcon);
    this.decorationsElement = this.gutterContainer.createChild('div', 'hidden');

    this.searchQuery = null;
    this.#expandedChildrenLimit = InitialChildrenLimit;
    this.decorationsThrottler = new Common.Throttler.Throttler(100);

    this.inClipboard = false;
    this.#hovered = false;

    this.editing = null;

    if (isClosingTag) {
      this.tagTypeContext = {tagType: TagType.CLOSING};
    } else {
      this.tagTypeContext = {
        tagType: TagType.OPENING,
        adornerContainer: this.contentElement.createChild('div', 'adorner-container hidden'),
        adorners: new Set(),
        styleAdorners: new Set(),
        adornersThrottler: new Common.Throttler.Throttler(100),
        canAddAttributes: this.nodeInternal.nodeType() === Node.ELEMENT_NODE,
      };
      void this.updateStyleAdorners();

      if (node.isAdFrameNode()) {
        const config = ElementsComponents.AdornerManager.getRegisteredAdorner(
            ElementsComponents.AdornerManager.RegisteredAdorners.AD);
        const adorner = this.adorn(config);
        UI.Tooltip.Tooltip.install(adorner, i18nString(UIStrings.thisFrameWasIdentifiedAsAnAd));
      }

      void this.updateScrollAdorner();
    }
    this.expandAllButtonElement = null;

    if (this.nodeInternal.retained && !this.isClosingTag()) {
      const icon = new IconButton.Icon.Icon();
      icon.name = 'small-status-dot';
      icon.style.color = 'var(--icon-error)';
      icon.classList.add('extra-small');
      icon.style.setProperty('vertical-align', 'middle');
      this.setLeadingIcons([icon]);
      this.listItemNode.classList.add('detached-elements-detached-node');
      this.listItemNode.style.setProperty('display', '-webkit-box');
      this.listItemNode.setAttribute('title', 'Retained Node');
    }

    if (this.nodeInternal.detached && !this.isClosingTag()) {
      this.listItemNode.setAttribute('title', 'Detached Tree Node');
    }
  }

  static animateOnDOMUpdate(treeElement: ElementsTreeElement): void {
    const tagName = treeElement.listItemElement.querySelector('.webkit-html-tag-name');
    UI.UIUtils.runCSSAnimationOnce(tagName || treeElement.listItemElement, 'dom-update-highlight');
  }

  static visibleShadowRoots(node: SDK.DOMModel.DOMNode): SDK.DOMModel.DOMNode[] {
    let roots = node.shadowRoots();
    if (roots.length && !Common.Settings.Settings.instance().moduleSetting('show-ua-shadow-dom').get()) {
      roots = roots.filter(filter);
    }

    function filter(root: SDK.DOMModel.DOMNode): boolean {
      return root.shadowRootType() !== SDK.DOMModel.DOMNode.ShadowRootTypes.UserAgent;
    }
    return roots;
  }

  static canShowInlineText(node: SDK.DOMModel.DOMNode): boolean {
    if (node.contentDocument() || node.templateContent() || ElementsTreeElement.visibleShadowRoots(node).length ||
        node.hasPseudoElements()) {
      return false;
    }
    if (node.nodeType() !== Node.ELEMENT_NODE) {
      return false;
    }
    if (!node.firstChild || node.firstChild !== node.lastChild || node.firstChild.nodeType() !== Node.TEXT_NODE) {
      return false;
    }
    const textChild = node.firstChild;
    const maxInlineTextChildLength = 80;
    if (textChild.nodeValue().length < maxInlineTextChildLength) {
      return true;
    }
    return false;
  }

  static populateForcedPseudoStateItems(contextMenu: UI.ContextMenu.ContextMenu, node: SDK.DOMModel.DOMNode): void {
    const pseudoClasses = ['active', 'hover', 'focus', 'visited', 'focus-within', 'focus-visible'];
    const forcedPseudoState = node.domModel().cssModel().pseudoState(node);
    const stateMenu =
        contextMenu.debugSection().appendSubMenuItem(i18nString(UIStrings.forceState), false, 'force-state');
    for (const pseudoClass of pseudoClasses) {
      const pseudoClassForced = forcedPseudoState ? forcedPseudoState.indexOf(pseudoClass) >= 0 : false;
      stateMenu.defaultSection().appendCheckboxItem(
          ':' + pseudoClass, setPseudoStateCallback.bind(null, pseudoClass, !pseudoClassForced),
          {checked: pseudoClassForced, jslogContext: pseudoClass});
    }

    function setPseudoStateCallback(pseudoState: string, enabled: boolean): void {
      node.domModel().cssModel().forcePseudoState(node, pseudoState, enabled);
    }
  }

  highlightAttribute(attributeName: string): void {
    // If the attribute is not found, we highlight the tag name instead.
    let animationElement = this.listItemElement.querySelector('.webkit-html-tag-name') ?? this.listItemElement;

    if (this.nodeInternal.getAttribute(attributeName) !== undefined) {
      const tag = this.listItemElement.getElementsByClassName('webkit-html-tag')[0];
      const attributes = tag.getElementsByClassName('webkit-html-attribute');
      for (const attribute of attributes) {
        const attributeElement = attribute.getElementsByClassName('webkit-html-attribute-name')[0];
        if (attributeElement.textContent === attributeName) {
          animationElement = attributeElement;
          break;
        }
      }
    }
    UI.UIUtils.runCSSAnimationOnce(animationElement, 'dom-update-highlight');
  }

  isClosingTag(): boolean {
    return !isOpeningTag(this.tagTypeContext);
  }

  node(): SDK.DOMModel.DOMNode {
    return this.nodeInternal;
  }

  isEditing(): boolean {
    return Boolean(this.editing);
  }

  highlightSearchResults(searchQuery: string): void {
    this.searchQuery = searchQuery;
    if (!this.editing) {
      this.#highlightSearchResults();
    }
  }

  hideSearchHighlights(): void {
    Highlighting.HighlightManager.HighlightManager.instance().removeHighlights(this.#highlights);
    this.#highlights = [];
  }

  setInClipboard(inClipboard: boolean): void {
    if (this.inClipboard === inClipboard) {
      return;
    }
    this.inClipboard = inClipboard;
    this.listItemElement.classList.toggle('in-clipboard', inClipboard);
  }

  get hovered(): boolean {
    return this.#hovered;
  }

  set hovered(isHovered: boolean) {
    if (this.#hovered === isHovered) {
      return;
    }

    if (isHovered && !this.aiButtonContainer) {
      this.createAiButton();
    } else if (!isHovered && this.aiButtonContainer) {
      this.aiButtonContainer.remove();
      delete this.aiButtonContainer;
    }

    this.#hovered = isHovered;

    if (this.listItemElement) {
      if (isHovered) {
        this.createSelection();
        this.listItemElement.classList.add('hovered');
      } else {
        this.listItemElement.classList.remove('hovered');
      }
    }
  }

  addIssue(newIssue: IssuesManager.Issue.Issue): void {
    if (this.#elementIssues.has(newIssue.primaryKey())) {
      return;
    }

    this.#elementIssues.set(newIssue.primaryKey(), newIssue);
    this.#applyIssueStyleAndTooltip(newIssue);
  }

  #applyIssueStyleAndTooltip(issue: IssuesManager.Issue.Issue): void {
    const elementIssueDetails = getElementIssueDetails(issue);
    if (!elementIssueDetails) {
      return;
    }

    if (elementIssueDetails.attribute) {
      this.#highlightViolatingAttr(elementIssueDetails.attribute, issue);
    } else {
      this.#highlightTagAsViolating(issue);
    }
  }

  get issuesByNodeElement(): Map<Element, IssuesManager.Issue.Issue[]> {
    return this.#nodeElementToIssue;
  }

  #highlightViolatingAttr(name: string, issue: IssuesManager.Issue.Issue): void {
    const tag = this.listItemElement.getElementsByClassName('webkit-html-tag')[0];
    const attributes = tag.getElementsByClassName('webkit-html-attribute');
    for (const attribute of attributes) {
      if (attribute.getElementsByClassName('webkit-html-attribute-name')[0].textContent === name) {
        const attributeElement = attribute.getElementsByClassName('webkit-html-attribute-name')[0];
        attributeElement.classList.add('violating-element');
        this.#updateNodeElementToIssue(attributeElement, issue);
      }
    }
  }

  #highlightTagAsViolating(issue: IssuesManager.Issue.Issue): void {
    const tagElement = this.listItemElement.getElementsByClassName('webkit-html-tag-name')[0];
    tagElement.classList.add('violating-element');
    this.#updateNodeElementToIssue(tagElement, issue);
  }

  #updateNodeElementToIssue(nodeElement: Element, issue: IssuesManager.Issue.Issue): void {
    let issues = this.#nodeElementToIssue.get(nodeElement);
    if (!issues) {
      issues = [];
      this.#nodeElementToIssue.set(nodeElement, issues);
    }
    issues.push(issue);
    this.treeOutline?.updateNodeElementToIssue(nodeElement, issues);
  }

  expandedChildrenLimit(): number {
    return this.#expandedChildrenLimit;
  }

  setExpandedChildrenLimit(expandedChildrenLimit: number): void {
    this.#expandedChildrenLimit = expandedChildrenLimit;
  }

  createSlotLink(nodeShortcut: SDK.DOMModel.DOMNodeShortcut|null): void {
    if (!isOpeningTag(this.tagTypeContext)) {
      return;
    }
    if (nodeShortcut) {
      const config = ElementsComponents.AdornerManager.getRegisteredAdorner(
          ElementsComponents.AdornerManager.RegisteredAdorners.SLOT);
      this.tagTypeContext.slot = this.adornSlot(config, this.tagTypeContext);
      const deferredNode = nodeShortcut.deferredNode;
      this.tagTypeContext.slot.addEventListener('click', () => {
        deferredNode.resolve(node => {
          void Common.Revealer.reveal(node);
        });
      });
      this.tagTypeContext.slot.addEventListener('mousedown', e => e.consume(), false);
    }
  }

  private createSelection(): void {
    const contentElement = this.contentElement;
    if (!contentElement) {
      return;
    }

    if (!this.selectionElement) {
      this.selectionElement = document.createElement('div');
      this.selectionElement.className = 'selection fill';
      this.selectionElement.style.setProperty('margin-left', (-this.computeLeftIndent()) + 'px');
      contentElement.prepend(this.selectionElement);
    }
  }

  private createHint(): void {
    if (this.contentElement && !this.hintElement) {
      this.hintElement = this.contentElement.createChild('span', 'selected-hint');
      const selectedElementCommand = '$0';
      UI.Tooltip.Tooltip.install(
          this.hintElement, i18nString(UIStrings.useSInTheConsoleToReferToThis, {PH1: selectedElementCommand}));
      UI.ARIAUtils.setHidden(this.hintElement, true);
    }
  }

  private createAiButton(): void {
    const isElementNode = this.node().nodeType() === Node.ELEMENT_NODE;
    if (!isElementNode ||
        !UI.ActionRegistry.ActionRegistry.instance().hasAction('freestyler.elements-floating-button')) {
      return;
    }

    const action = UI.ActionRegistry.ActionRegistry.instance().getAction('freestyler.elements-floating-button');
    if (this.contentElement && !this.aiButtonContainer) {
      this.aiButtonContainer = this.contentElement.createChild('span', 'ai-button-container');
      const floatingButton = Buttons.FloatingButton.create('smart-assistant', action.title(), 'ask-ai');
      floatingButton.addEventListener('click', ev => {
        ev.stopPropagation();
        this.select(true, false);
        void action.execute();
      }, {capture: true});
      floatingButton.addEventListener('mousedown', ev => {
        ev.stopPropagation();
      }, {capture: true});
      this.aiButtonContainer.appendChild(floatingButton);
    }
  }

  override onbind(): void {
    if (this.treeOutline && !this.isClosingTag()) {
      this.treeOutline.treeElementByNode.set(this.nodeInternal, this);
    }
  }

  override onunbind(): void {
    if (this.editing) {
      this.editing.cancel();
    }
    if (this.treeOutline && this.treeOutline.treeElementByNode.get(this.nodeInternal) === this) {
      this.treeOutline.treeElementByNode.delete(this.nodeInternal);
    }
  }

  override onattach(): void {
    if (this.#hovered) {
      this.createSelection();
      this.listItemElement.classList.add('hovered');
    }

    this.updateTitle();
    this.listItemElement.draggable = true;
  }

  override async onpopulate(): Promise<void> {
    if (this.treeOutline) {
      return await this.treeOutline.populateTreeElement(this);
    }
  }

  override async expandRecursively(): Promise<void> {
    await this.nodeInternal.getSubtree(-1, true);
    await super.expandRecursively(Number.MAX_VALUE);
  }

  override onexpand(): void {
    if (this.isClosingTag()) {
      return;
    }

    this.updateTitle();
  }

  override oncollapse(): void {
    if (this.isClosingTag()) {
      return;
    }

    this.updateTitle();
  }

  override select(omitFocus?: boolean, selectedByUser?: boolean): boolean {
    if (this.editing) {
      return false;
    }
    return super.select(omitFocus, selectedByUser);
  }

  override onselect(selectedByUser?: boolean): boolean {
    if (!this.treeOutline) {
      return false;
    }
    this.treeOutline.suppressRevealAndSelect = true;
    this.treeOutline.selectDOMNode(this.nodeInternal, selectedByUser);
    if (selectedByUser) {
      this.nodeInternal.highlight();
      Host.userMetrics.actionTaken(Host.UserMetrics.Action.ChangeInspectedNodeInElementsPanel);
    }
    this.createSelection();
    this.createHint();
    this.treeOutline.suppressRevealAndSelect = false;
    return true;
  }

  override ondelete(): boolean {
    if (!this.treeOutline) {
      return false;
    }
    const startTagTreeElement = this.treeOutline.findTreeElement(this.nodeInternal);
    startTagTreeElement ? (void startTagTreeElement.remove()) : (void this.remove());
    return true;
  }

  override onenter(): boolean {
    // On Enter or Return start editing the first attribute
    // or create a new attribute on the selected element.
    if (this.editing) {
      return false;
    }

    this.startEditing();

    // prevent a newline from being immediately inserted
    return true;
  }

  override selectOnMouseDown(event: MouseEvent): void {
    super.selectOnMouseDown(event);

    if (this.editing) {
      return;
    }

    // Prevent selecting the nearest word on double click.
    if (event.detail >= 2) {
      event.preventDefault();
    }
  }

  override ondblclick(event: Event): boolean {
    if (this.editing || this.isClosingTag()) {
      return false;
    }
    if (this.startEditingTarget((event.target as Element))) {
      return false;
    }

    if (this.isExpandable() && !this.expanded) {
      this.expand();
    }
    return false;
  }

  hasEditableNode(): boolean {
    return !this.nodeInternal.isShadowRoot() && !this.nodeInternal.ancestorUserAgentShadowRoot();
  }

  private insertInLastAttributePosition(tag: Element, node: Element): void {
    if (tag.getElementsByClassName('webkit-html-attribute').length > 0) {
      tag.insertBefore(node, tag.lastChild);
    } else if (tag.textContent !== null) {
      const matchResult = tag.textContent.match(/^<(.*?)>$/);
      if (!matchResult) {
        return;
      }
      const nodeName = matchResult[1];
      tag.textContent = '';
      UI.UIUtils.createTextChild(tag, '<' + nodeName);
      tag.appendChild(node);
      UI.UIUtils.createTextChild(tag, '>');
    }
  }

  private startEditingTarget(eventTarget: Element): boolean {
    if (!this.treeOutline || this.treeOutline.selectedDOMNode() !== this.nodeInternal) {
      return false;
    }

    if (this.nodeInternal.nodeType() !== Node.ELEMENT_NODE && this.nodeInternal.nodeType() !== Node.TEXT_NODE) {
      return false;
    }

    const textNode = eventTarget.enclosingNodeOrSelfWithClass('webkit-html-text-node');
    if (textNode) {
      return this.startEditingTextNode(textNode);
    }

    const attribute = eventTarget.enclosingNodeOrSelfWithClass('webkit-html-attribute');
    if (attribute) {
      return this.startEditingAttribute(attribute, eventTarget);
    }

    const tagName = eventTarget.enclosingNodeOrSelfWithClass('webkit-html-tag-name');
    if (tagName) {
      return this.startEditingTagName(tagName);
    }

    const newAttribute = eventTarget.enclosingNodeOrSelfWithClass('add-attribute');
    if (newAttribute) {
      return this.addNewAttribute();
    }

    return false;
  }

  private showContextMenu(event: Event): void {
    this.treeOutline && void this.treeOutline.showContextMenu(this, event);
  }

  async populateTagContextMenu(contextMenu: UI.ContextMenu.ContextMenu, event: Event): Promise<void> {
    // Add attribute-related actions.
    const treeElement =
        this.isClosingTag() && this.treeOutline ? this.treeOutline.findTreeElement(this.nodeInternal) : this;
    if (!treeElement) {
      return;
    }
    contextMenu.editSection().appendItem(
        i18nString(UIStrings.addAttribute), treeElement.addNewAttribute.bind(treeElement),
        {jslogContext: 'add-attribute'});

    const target = (event.target as Element);
    const attribute = target.enclosingNodeOrSelfWithClass('webkit-html-attribute');
    const newAttribute = target.enclosingNodeOrSelfWithClass('add-attribute');
    if (attribute && !newAttribute) {
      contextMenu.editSection().appendItem(
          i18nString(UIStrings.editAttribute), this.startEditingAttribute.bind(this, attribute, target),
          {jslogContext: 'edit-attribute'});
    }
    await this.populateNodeContextMenu(contextMenu);
    ElementsTreeElement.populateForcedPseudoStateItems(contextMenu, treeElement.node());
    this.populateScrollIntoView(contextMenu);
    contextMenu.viewSection().appendItem(i18nString(UIStrings.focus), async () => {
      await this.nodeInternal.focus();
    }, {jslogContext: 'focus'});
  }

  populatePseudoElementContextMenu(contextMenu: UI.ContextMenu.ContextMenu): void {
    if (this.childCount() !== 0) {
      this.populateExpandRecursively(contextMenu);
    }

    this.populateScrollIntoView(contextMenu);
  }

  private populateExpandRecursively(contextMenu: UI.ContextMenu.ContextMenu): void {
    contextMenu.viewSection().appendItem(
        i18nString(UIStrings.expandRecursively), this.expandRecursively.bind(this),
        {jslogContext: 'expand-recursively'});
  }

  private populateScrollIntoView(contextMenu: UI.ContextMenu.ContextMenu): void {
    contextMenu.viewSection().appendItem(
        i18nString(UIStrings.scrollIntoView), () => this.nodeInternal.scrollIntoView(),
        {jslogContext: 'scroll-into-view'});
  }

  async populateTextContextMenu(contextMenu: UI.ContextMenu.ContextMenu, textNode: Element): Promise<void> {
    if (!this.editing) {
      contextMenu.editSection().appendItem(
          i18nString(UIStrings.editText), this.startEditingTextNode.bind(this, textNode), {jslogContext: 'edit-text'});
    }
    return await this.populateNodeContextMenu(contextMenu);
  }

  async populateNodeContextMenu(contextMenu: UI.ContextMenu.ContextMenu): Promise<void> {
    // Add free-form node-related actions.
    const isEditable = this.hasEditableNode();
    // clang-format off
    if (isEditable && !this.editing) {
      contextMenu.editSection().appendItem(i18nString(UIStrings.editAsHtml), this.editAsHTML.bind(this), {jslogContext: 'elements.edit-as-html'});
    }
    // clang-format on
    const isShadowRoot = this.nodeInternal.isShadowRoot();

    const createShortcut = UI.KeyboardShortcut.KeyboardShortcut.shortcutToString.bind(null);
    const modifier = UI.KeyboardShortcut.Modifiers.CtrlOrMeta.value;
    const treeOutline = this.treeOutline;
    if (!treeOutline) {
      return;
    }
    let menuItem;

    const openAiAssistanceId = 'freestyler.element-panel-context';
    if (UI.ActionRegistry.ActionRegistry.instance().hasAction(openAiAssistanceId)) {
      function appendSubmenuPromptAction(
          submenu: UI.ContextMenu.SubMenu, action: UI.ActionRegistration.Action, label: Common.UIString.LocalizedString,
          prompt: string, jslogContext: string): void {
        submenu.defaultSection().appendItem(label, () => {
          void action.execute({prompt});
          UI.UIUtils.PromotionManager.instance().recordFeatureInteraction(openAiAssistanceId);
        }, {disabled: !action.enabled(), jslogContext});
      }

      UI.Context.Context.instance().setFlavor(SDK.DOMModel.DOMNode, this.nodeInternal);
      if (Root.Runtime.hostConfig.devToolsAiSubmenuPrompts?.enabled) {
        const action = UI.ActionRegistry.ActionRegistry.instance().getAction(openAiAssistanceId);
        // Register new badge under the `devToolsAiSubmenuPrompts` feature, as the freestyler one is already used in ViewManager.
        // Additionally register with the PromotionManager. Since we use two features for freeestyler here (submenu or debug with ai),
        // the back-end will not be able to identify them as one as soon as we launch, and show the new badge
        // on the 'Debug with Ai' item even if the user was already seeing it during the study if they were in the other study group.
        const featureName = UI.UIUtils.PromotionManager.instance().maybeShowPromotion(openAiAssistanceId) ?
            Root.Runtime.hostConfig.devToolsAiSubmenuPrompts?.featureName :
            undefined;
        const submenu =
            contextMenu.footerSection().appendSubMenuItem(action.title(), false, openAiAssistanceId, featureName);
        submenu.defaultSection().appendAction(openAiAssistanceId, i18nString(UIStrings.startAChat));

        const submenuConfigs = [
          {
            condition: (props: SDK.CSSModel.LayoutProperties|null): boolean => Boolean(props?.isFlex),
            items: [
              {
                label: i18nString(UIStrings.wrapTheseItems),
                prompt: 'How can I make flex items wrap?',
                jslogContextSuffix: '.flex-wrap',
              },
              {
                label: i18nString(UIStrings.distributeItemsEvenly),
                prompt: 'How do I distribute flex items evenly?',
                jslogContextSuffix: '.flex-distribute',
              },
              {
                label: i18nString(UIStrings.explainFlexbox),
                prompt: 'What is flexbox?',
                jslogContextSuffix: '.flex-what',
              },
            ],
          },
          {
            condition: (props: SDK.CSSModel.LayoutProperties|null): boolean =>
                Boolean(props?.isGrid && !props?.isSubgrid),
            items: [
              {
                label: i18nString(UIStrings.alignItems),
                prompt: 'How do I align items in a grid?',
                jslogContextSuffix: '.grid-align',
              },
              {
                label: i18nString(UIStrings.addPadding),
                prompt: 'How to add spacing between grid items?',
                jslogContextSuffix: '.grid-gap',
              },
              {
                label: i18nString(UIStrings.explainGridLayout),
                prompt: 'How does grid layout work?',
                jslogContextSuffix: '.grid-how',
              },
            ],
          },
          {
            condition: (props: SDK.CSSModel.LayoutProperties|null): boolean => Boolean(props?.isSubgrid),
            items: [
              {
                label: i18nString(UIStrings.findGridDefinition),
                prompt: 'Where is this grid defined?',
                jslogContextSuffix: '.subgrid-where',
              },
              {
                label: i18nString(UIStrings.changeParentProperties),
                prompt: 'How to overwrite parent grid properties?',
                jslogContextSuffix: '.subgrid-override',
              },
              {
                label: i18nString(UIStrings.explainSubgrids),
                prompt: 'How do subgrids work?',
                jslogContextSuffix: '.subgrid-how',
              },
            ],
          },
          {
            condition: (props: SDK.CSSModel.LayoutProperties|null): boolean => Boolean(props?.hasScroll),
            items: [
              {
                label: i18nString(UIStrings.removeScrollbars),
                prompt: 'How do I remove scrollbars for this element?',
                jslogContextSuffix: '.scroll-remove',
              },
              {
                label: i18nString(UIStrings.styleScrollbars),
                prompt: 'How can I style a scrollbar?',
                jslogContextSuffix: '.scroll-style',
              },
              {
                label: i18nString(UIStrings.explainScrollbars),
                prompt: 'Why does this element scroll?',
                jslogContextSuffix: '.scroll-why',
              },
            ],
          },
          {
            condition: (props: SDK.CSSModel.LayoutProperties|null): boolean => Boolean(props?.isContainer),
            items: [
              {
                label: i18nString(UIStrings.explainContainerQueries),
                prompt: 'What are container queries?',
                jslogContextSuffix: '.container-what',
              },
              {
                label: i18nString(UIStrings.explainContainerTypes),
                prompt: 'How do I use container-type?',
                jslogContextSuffix: '.container-how',
              },
              {
                label: i18nString(UIStrings.explainContainerContext),
                prompt: 'What\'s the container context for this element?',
                jslogContextSuffix: '.container-context',
              },
            ],
          },
          {
            // Default items
            condition: (): boolean => true,
            items: [
              {
                label: i18nString(UIStrings.assessVisibility),
                prompt: 'Why isn’t this element visible?',
                jslogContextSuffix: '.visibility',
              },
              {
                label: i18nString(UIStrings.centerElement),
                prompt: 'How do I center this element?',
                jslogContextSuffix: '.center',
              },
            ],
          },
        ];

        const layoutProps =
            await this.nodeInternal.domModel().cssModel().getLayoutPropertiesFromComputedStyle(this.nodeInternal.id);
        const config = submenuConfigs.find(c => c.condition(layoutProps));
        if (config) {
          for (const item of config.items) {
            appendSubmenuPromptAction(
                submenu, action, item.label, item.prompt, openAiAssistanceId + item.jslogContextSuffix);
          }
        }
      } else if (Root.Runtime.hostConfig.devToolsAiDebugWithAi?.enabled) {
        // Register new badge under the `devToolsAiDebugWithAi` feature, as the freestyler one is already used in ViewManager.
        // Additionally register with the PromotionManager. Since we use two different features for freeestyler here (submenu or debug with ai),
        // the back-end will not be able to identify them as one as soon as we launch, and show the new badge
        // on the 'Debug with Ai' item even if the user was already seeing it during the study if they were in the other study group.
        const featureName = UI.UIUtils.PromotionManager.instance().maybeShowPromotion(openAiAssistanceId) ?
            Root.Runtime.hostConfig.devToolsAiDebugWithAi?.featureName :
            undefined;
        const action = UI.ActionRegistry.ActionRegistry.instance().getAction(openAiAssistanceId);
        contextMenu.footerSection().appendItem(action.title(), () => {
          void action.execute();
          UI.UIUtils.PromotionManager.instance().recordFeatureInteraction(openAiAssistanceId);
        }, {jslogContext: openAiAssistanceId, disabled: !action.enabled(), featureName});

      } else {
        contextMenu.footerSection().appendAction(openAiAssistanceId);
      }
    }

    menuItem = contextMenu.clipboardSection().appendItem(
        i18nString(UIStrings.cut), treeOutline.performCopyOrCut.bind(treeOutline, true, this.nodeInternal),
        {disabled: !this.hasEditableNode(), jslogContext: 'cut'});
    menuItem.setShortcut(createShortcut('X', modifier));

    // Place it here so that all "Copy"-ing items stick together.
    const copyMenu = contextMenu.clipboardSection().appendSubMenuItem(i18nString(UIStrings.copy), false, 'copy');
    const section = copyMenu.section();
    if (!isShadowRoot) {
      menuItem = section.appendItem(
          i18nString(UIStrings.copyOuterhtml), treeOutline.performCopyOrCut.bind(treeOutline, false, this.nodeInternal),
          {jslogContext: 'copy-outer-html'});
      menuItem.setShortcut(createShortcut('V', modifier));
    }
    if (this.nodeInternal.nodeType() === Node.ELEMENT_NODE) {
      section.appendItem(
          i18nString(UIStrings.copySelector), this.copyCSSPath.bind(this), {jslogContext: 'copy-selector'});
      section.appendItem(
          i18nString(UIStrings.copyJsPath), this.copyJSPath.bind(this),
          {disabled: !canGetJSPath(this.nodeInternal), jslogContext: 'copy-js-path'});
      section.appendItem(
          i18nString(UIStrings.copyStyles), this.copyStyles.bind(this), {jslogContext: 'elements.copy-styles'});
    }
    if (!isShadowRoot) {
      section.appendItem(i18nString(UIStrings.copyXpath), this.copyXPath.bind(this), {jslogContext: 'copy-xpath'});
      section.appendItem(
          i18nString(UIStrings.copyFullXpath), this.copyFullXPath.bind(this), {jslogContext: 'copy-full-xpath'});
    }

    menuItem = copyMenu.clipboardSection().appendItem(
        i18nString(UIStrings.copyElement),
        treeOutline.performCopyOrCut.bind(treeOutline, false, this.nodeInternal, true), {jslogContext: 'copy-element'});
    menuItem.setShortcut(createShortcut('C', modifier));

    if (!isShadowRoot) {
      // Duplicate element, disabled on root element and ShadowDOM.
      const isRootElement = !this.nodeInternal.parentNode || this.nodeInternal.parentNode.nodeName() === '#document';
      menuItem = contextMenu.editSection().appendItem(
          i18nString(UIStrings.duplicateElement), treeOutline.duplicateNode.bind(treeOutline, this.nodeInternal), {
            disabled: (this.nodeInternal.isInShadowTree() || isRootElement),
            jslogContext: 'elements.duplicate-element',
          });
    }

    menuItem = contextMenu.clipboardSection().appendItem(
        i18nString(UIStrings.paste), treeOutline.pasteNode.bind(treeOutline, this.nodeInternal),
        {disabled: !treeOutline.canPaste(this.nodeInternal), jslogContext: 'paste'});
    menuItem.setShortcut(createShortcut('V', modifier));

    menuItem = contextMenu.debugSection().appendCheckboxItem(
        i18nString(UIStrings.hideElement), treeOutline.toggleHideElement.bind(treeOutline, this.nodeInternal),
        {checked: treeOutline.isToggledToHidden(this.nodeInternal), jslogContext: 'elements.hide-element'});
    menuItem.setShortcut(
        UI.ShortcutRegistry.ShortcutRegistry.instance().shortcutTitleForAction('elements.hide-element') || '');

    if (isEditable) {
      contextMenu.editSection().appendItem(
          i18nString(UIStrings.deleteElement), this.remove.bind(this), {jslogContext: 'delete-element'});
    }

    this.populateExpandRecursively(contextMenu);
    contextMenu.viewSection().appendItem(
        i18nString(UIStrings.collapseChildren), this.collapseChildren.bind(this), {jslogContext: 'collapse-children'});
    const deviceModeWrapperAction = new Emulation.DeviceModeWrapper.ActionDelegate();
    contextMenu.viewSection().appendItem(
        i18nString(UIStrings.captureNodeScreenshot),
        deviceModeWrapperAction.handleAction.bind(
            null, UI.Context.Context.instance(), 'emulation.capture-node-screenshot'),
        {jslogContext: 'emulation.capture-node-screenshot'});
    if (this.nodeInternal.frameOwnerFrameId()) {
      contextMenu.viewSection().appendItem(i18nString(UIStrings.showFrameDetails), () => {
        const frameOwnerFrameId = this.nodeInternal.frameOwnerFrameId();
        if (frameOwnerFrameId) {
          const frame = SDK.FrameManager.FrameManager.instance().getFrame(frameOwnerFrameId);
          void Common.Revealer.reveal(frame);
        }
      }, {jslogContext: 'show-frame-details'});
    }
  }

  private startEditing(): boolean|undefined {
    if (!this.treeOutline || this.treeOutline.selectedDOMNode() !== this.nodeInternal) {
      return;
    }

    const listItem = this.listItemElement;

    if (isOpeningTag(this.tagTypeContext) && this.tagTypeContext.canAddAttributes) {
      const attribute = listItem.getElementsByClassName('webkit-html-attribute')[0];
      if (attribute) {
        return this.startEditingAttribute(
            attribute, attribute.getElementsByClassName('webkit-html-attribute-value')[0]);
      }

      return this.addNewAttribute();
    }

    if (this.nodeInternal.nodeType() === Node.TEXT_NODE) {
      const textNode = listItem.getElementsByClassName('webkit-html-text-node')[0];
      if (textNode) {
        return this.startEditingTextNode(textNode);
      }
    }

    return;
  }

  private addNewAttribute(): boolean {
    // Cannot just convert the textual html into an element without
    // a parent node. Use a temporary span container for the HTML.
    const container = document.createElement('span');
    const attr = this.buildAttributeDOM(container, ' ', '', null);
    attr.style.marginLeft = '2px';   // overrides the .editing margin rule
    attr.style.marginRight = '2px';  // overrides the .editing margin rule
    attr.setAttribute('jslog', `${VisualLogging.value('new-attribute').track({change: true, resize: true})}`);

    const tag = this.listItemElement.getElementsByClassName('webkit-html-tag')[0];
    this.insertInLastAttributePosition(tag, attr);
    attr.scrollIntoViewIfNeeded(true);
    return this.startEditingAttribute(attr, attr);
  }

  private triggerEditAttribute(attributeName: string): boolean|undefined {
    const attributeElements = this.listItemElement.getElementsByClassName('webkit-html-attribute-name');
    for (let i = 0, len = attributeElements.length; i < len; ++i) {
      if (attributeElements[i].textContent === attributeName) {
        for (let elem: (ChildNode|null) = attributeElements[i].nextSibling; elem; elem = elem.nextSibling) {
          if (elem.nodeType !== Node.ELEMENT_NODE) {
            continue;
          }
          if ((elem as Element).classList.contains('webkit-html-attribute-value')) {
            return this.startEditingAttribute((elem.parentElement as HTMLElement), (elem as Element));
          }
        }
      }
    }

    return;
  }

  private startEditingAttribute(attribute: Element, elementForSelection: Element): boolean {
    console.assert(this.listItemElement.isAncestor(attribute));

    if (UI.UIUtils.isBeingEdited(attribute)) {
      return true;
    }

    const attributeNameElement = attribute.getElementsByClassName('webkit-html-attribute-name')[0];
    if (!attributeNameElement) {
      return false;
    }

    const attributeName = attributeNameElement.textContent;
    const attributeValueElement = attribute.getElementsByClassName('webkit-html-attribute-value')[0];

    // Make sure elementForSelection is not a child of attributeValueElement.
    elementForSelection =
        attributeValueElement.isAncestor(elementForSelection) ? attributeValueElement : elementForSelection;

    function removeZeroWidthSpaceRecursive(node: Node): void {
      if (node.nodeType === Node.TEXT_NODE) {
        node.nodeValue = node.nodeValue ? node.nodeValue.replace(/\u200B/g, '') : '';
        return;
      }

      if (node.nodeType !== Node.ELEMENT_NODE) {
        return;
      }

      for (let child: (ChildNode|null) = node.firstChild; child; child = child.nextSibling) {
        removeZeroWidthSpaceRecursive(child);
      }
    }

    const attributeValue = attributeName && attributeValueElement ?
        this.nodeInternal.getAttribute(attributeName)?.replaceAll('"', '&quot;') :
        undefined;
    if (attributeValue !== undefined) {
      attributeValueElement.setTextContentTruncatedIfNeeded(
          attributeValue, i18nString(UIStrings.valueIsTooLargeToEdit));
    }

    // Remove zero-width spaces that were added by nodeTitleInfo.
    removeZeroWidthSpaceRecursive(attribute);

    const config = new UI.InplaceEditor.Config(
        this.attributeEditingCommitted.bind(this), this.editingCancelled.bind(this), attributeName);

    function postKeyDownFinishHandler(event: Event): string {
      UI.UIUtils.handleElementValueModifications(event, attribute);
      return '';
    }

    if (!Common.ParsedURL.ParsedURL.fromString(attributeValueElement.textContent || '')) {
      config.setPostKeydownFinishHandler(postKeyDownFinishHandler);
    }

    this.updateEditorHandles(attribute, config);

    const componentSelection = this.listItemElement.getComponentSelection();
    componentSelection?.selectAllChildren(elementForSelection);

    return true;
  }

  private startEditingTextNode(textNodeElement: Element): boolean {
    if (UI.UIUtils.isBeingEdited(textNodeElement)) {
      return true;
    }

    let textNode: SDK.DOMModel.DOMNode = this.nodeInternal;
    // We only show text nodes inline in elements if the element only
    // has a single child, and that child is a text node.
    if (textNode.nodeType() === Node.ELEMENT_NODE && textNode.firstChild) {
      textNode = textNode.firstChild;
    }

    const container = textNodeElement.enclosingNodeOrSelfWithClass('webkit-html-text-node');
    if (container) {
      container.textContent = textNode.nodeValue();
    }  // Strip the CSS or JS highlighting if present.
    const config = new UI.InplaceEditor.Config(
        this.textNodeEditingCommitted.bind(this, textNode), this.editingCancelled.bind(this), null);
    this.updateEditorHandles(textNodeElement, config);
    const componentSelection = this.listItemElement.getComponentSelection();
    componentSelection?.selectAllChildren(textNodeElement);

    return true;
  }

  private startEditingTagName(tagNameElement?: Element): boolean {
    if (!tagNameElement) {
      tagNameElement = this.listItemElement.getElementsByClassName('webkit-html-tag-name')[0];
      if (!tagNameElement) {
        return false;
      }
    }

    const tagName = tagNameElement.textContent;
    if (tagName !== null && EditTagBlocklist.has(tagName.toLowerCase())) {
      return false;
    }

    if (UI.UIUtils.isBeingEdited(tagNameElement)) {
      return true;
    }

    const closingTagElement = this.distinctClosingTagElement();

    function keyupListener(): void {
      if (closingTagElement && tagNameElement) {
        closingTagElement.textContent = '</' + tagNameElement.textContent + '>';
      }
    }

    const keydownListener = (event: Event): void => {
      if ((event as KeyboardEvent).key !== ' ') {
        return;
      }
      this.editing?.commit();
      event.consume(true);
    };

    function editingCommitted(
        this: ElementsTreeElement,
        element: Element,
        newTagName: string,
        oldText: string|null,
        tagName: string|null,
        moveDirection: string,
        ): void {
      if (!tagNameElement) {
        return;
      }
      tagNameElement.removeEventListener('keyup', keyupListener, false);
      tagNameElement.removeEventListener('keydown', keydownListener, false);
      this.tagNameEditingCommitted(element, newTagName, oldText, tagName, moveDirection);
    }

    function editingCancelled(this: ElementsTreeElement, element: Element, tagName: string|null): void {
      if (!tagNameElement) {
        return;
      }
      tagNameElement.removeEventListener('keyup', keyupListener, false);
      tagNameElement.removeEventListener('keydown', keydownListener, false);
      this.editingCancelled(element, tagName);
    }

    tagNameElement.addEventListener('keyup', keyupListener, false);
    tagNameElement.addEventListener('keydown', keydownListener, false);

    const config =
        new UI.InplaceEditor.Config<string|null>(editingCommitted.bind(this), editingCancelled.bind(this), tagName);
    this.updateEditorHandles(tagNameElement, config);
    const componentSelection = this.listItemElement.getComponentSelection();
    componentSelection?.selectAllChildren(tagNameElement);
    return true;
  }

  private updateEditorHandles<T>(element: Element, config: UI.InplaceEditor.Config<T>): void {
    const editorHandles = UI.InplaceEditor.InplaceEditor.startEditing(element, config);
    if (!editorHandles) {
      this.editing = null;
    } else {
      this.editing = {
        commit: editorHandles.commit,
        cancel: editorHandles.cancel,
        editor: undefined,
        resize: () => {},
      };
    }
  }

  private async startEditingAsHTML(
      commitCallback: (arg0: string, arg1: string) => void, disposeCallback: () => void,
      maybeInitialValue: string|null): Promise<void> {
    if (maybeInitialValue === null) {
      return;
    }
    if (this.editing) {
      return;
    }

    const initialValue = convertUnicodeCharsToHTMLEntities(maybeInitialValue).text;
    this.htmlEditElement = document.createElement('div');
    this.htmlEditElement.className = 'source-code elements-tree-editor';

    // Hide header items.
    let child: (ChildNode|null) = this.listItemElement.firstChild;
    while (child) {
      (child as HTMLElement).style.display = 'none';
      child = child.nextSibling;
    }
    // Hide children item.
    if (this.childrenListElement) {
      this.childrenListElement.style.display = 'none';
    }
    // Append editor.
    this.listItemElement.append(this.htmlEditElement);
    this.htmlEditElement.addEventListener('keydown', event => {
      if (event.key === 'Escape') {
        event.consume(true);
      }
    });

    const editor = new TextEditor.TextEditor.TextEditor(CodeMirror.EditorState.create({
      doc: initialValue,
      extensions: [
        CodeMirror.keymap.of([
          {
            key: 'Mod-Enter',
            run: () => {
              this.editing?.commit();
              return true;
            },
          },
          {
            key: 'Escape',
            run: () => {
              this.editing?.cancel();
              return true;
            },
          },
        ]),
        TextEditor.Config.baseConfiguration(initialValue),
        TextEditor.Config.closeBrackets.instance(),
        TextEditor.Config.autocompletion.instance(),
        CodeMirror.html.html({autoCloseTags: false, selfClosingTags: true}),
        TextEditor.Config.domWordWrap.instance(),
        CodeMirror.EditorView.theme({
          '&.cm-editor': {maxHeight: '300px'},
          '.cm-scroller': {overflowY: 'auto'},
        }),
        CodeMirror.EditorView.domEventHandlers({
          focusout: event => {
            // The relatedTarget is null when no element gains focus, e.g. switching windows.
            const relatedTarget = (event.relatedTarget as Node | null);
            if (relatedTarget && !relatedTarget.isSelfOrDescendant(editor)) {
              this.editing?.commit();
            }
          },
        }),
      ],
    }));
    this.editing = {commit: commit.bind(this), cancel: dispose.bind(this), editor, resize: resize.bind(this)};
    resize.call(this);
    this.htmlEditElement.appendChild(editor);
    editor.editor.focus();

    this.treeOutline?.setMultilineEditing(this.editing);

    function resize(this: ElementsTreeElement): void {
      if (this.treeOutline && this.htmlEditElement) {
        this.htmlEditElement.style.width = this.treeOutline.visibleWidth() - this.computeLeftIndent() - 30 + 'px';
      }
    }

    function commit(this: ElementsTreeElement): void {
      if (this.editing?.editor) {
        commitCallback(initialValue, this.editing.editor.state.doc.toString());
      }
      dispose.call(this);
    }

    function dispose(this: ElementsTreeElement): void {
      if (!this.editing?.editor) {
        return;
      }
      this.editing = null;

      // Remove editor.
      if (this.htmlEditElement) {
        this.listItemElement.removeChild(this.htmlEditElement);
      }
      this.htmlEditElement = undefined;
      // Unhide children item.
      if (this.childrenListElement) {
        this.childrenListElement.style.removeProperty('display');
      }
      // Unhide header items.
      let child: (ChildNode|null) = this.listItemElement.firstChild;
      while (child) {
        (child as HTMLElement).style.removeProperty('display');
        child = child.nextSibling;
      }

      if (this.treeOutline) {
        this.treeOutline.setMultilineEditing(null);
        this.treeOutline.focus();
      }

      disposeCallback();
    }
  }

  private attributeEditingCommitted(
      element: Element,
      newText: string,
      oldText: string|null,
      attributeName: string|null,
      moveDirection: string,
      ): void {
    this.editing = null;

    const treeOutline = this.treeOutline;

    function moveToNextAttributeIfNeeded(this: ElementsTreeElement, error?: string|null): void {
      if (error) {
        this.editingCancelled(element, attributeName);
      }

      if (!moveDirection) {
        return;
      }

      if (treeOutline) {
        treeOutline.runPendingUpdates();
        treeOutline.focus();
      }

      // Search for the attribute's position, and then decide where to move to.
      const attributes = this.nodeInternal.attributes();
      for (let i = 0; i < attributes.length; ++i) {
        if (attributes[i].name !== attributeName) {
          continue;
        }

        if (moveDirection === 'backward') {
          if (i === 0) {
            this.startEditingTagName();
          } else {
            this.triggerEditAttribute(attributes[i - 1].name);
          }
        } else if (i === attributes.length - 1) {
          this.addNewAttribute();
        } else {
          this.triggerEditAttribute(attributes[i + 1].name);
        }
        return;
      }

      // Moving From the "New Attribute" position.
      if (moveDirection === 'backward') {
        if (newText === ' ') {
          // Moving from "New Attribute" that was not edited
          if (attributes.length > 0) {
            this.triggerEditAttribute(attributes[attributes.length - 1].name);
          }
          // Moving from "New Attribute" that holds new value
        } else if (attributes.length > 1) {
          this.triggerEditAttribute(attributes[attributes.length - 2].name);
        }
      } else if (moveDirection === 'forward') {
        if (!Platform.StringUtilities.isWhitespace(newText)) {
          this.addNewAttribute();
        } else {
          this.startEditingTagName();
        }
      }
    }

    if (attributeName !== null && (attributeName.trim() || newText.trim()) && oldText !== newText) {
      this.nodeInternal.setAttribute(attributeName, newText, moveToNextAttributeIfNeeded.bind(this));
      Badges.UserBadges.instance().recordAction(Badges.BadgeAction.DOM_ELEMENT_OR_ATTRIBUTE_EDITED);
      return;
    }

    this.updateTitle();
    moveToNextAttributeIfNeeded.call(this);
  }

  private tagNameEditingCommitted(
      element: Element,
      newText: string,
      oldText: string|null,
      tagName: string|null,
      moveDirection: string,
      ): void {
    this.editing = null;
    const self = this;

    function cancel(): void {
      const closingTagElement = self.distinctClosingTagElement();
      if (closingTagElement) {
        closingTagElement.textContent = '</' + tagName + '>';
      }

      self.editingCancelled(element, tagName);
      moveToNextAttributeIfNeeded.call(self);
    }

    function moveToNextAttributeIfNeeded(this: ElementsTreeElement): void {
      if (moveDirection !== 'forward') {
        this.addNewAttribute();
        return;
      }

      const attributes = this.nodeInternal.attributes();
      if (attributes.length > 0) {
        this.triggerEditAttribute(attributes[0].name);
      } else {
        this.addNewAttribute();
      }
    }

    newText = newText.trim();
    if (newText === oldText) {
      cancel();
      return;
    }

    const treeOutline = this.treeOutline;
    const wasExpanded = this.expanded;

    this.nodeInternal.setNodeName(newText, (error, newNode) => {
      if (error || !newNode) {
        cancel();
        return;
      }
      if (!treeOutline) {
        return;
      }

      Badges.UserBadges.instance().recordAction(Badges.BadgeAction.DOM_ELEMENT_OR_ATTRIBUTE_EDITED);
      const newTreeItem = treeOutline.selectNodeAfterEdit(wasExpanded, error, newNode);
      // TODO(crbug.com/1172300) Ignored during the jsdoc to ts migration
      // @ts-expect-error
      moveToNextAttributeIfNeeded.call(newTreeItem);
    });
  }

  private textNodeEditingCommitted(textNode: SDK.DOMModel.DOMNode, _element: Element, newText: string): void {
    this.editing = null;

    function callback(this: ElementsTreeElement): void {
      this.updateTitle();
    }
    textNode.setNodeValue(newText, callback.bind(this));
  }

  private editingCancelled(_element: Element, _tagName: string|null): void {
    this.editing = null;

    // Need to restore attributes structure.
    this.updateTitle();
  }

  private distinctClosingTagElement(): Element|null {
    // FIXME: Improve the Tree Element / Outline Abstraction to prevent crawling the DOM

    // For an expanded element, it will be the last element with class "close"
    // in the child element list.
    if (this.expanded) {
      const closers = this.childrenListElement.querySelectorAll('.close');
      return closers[closers.length - 1];
    }

    // Remaining cases are single line non-expanded elements with a closing
    // tag, or HTML elements without a closing tag (such as <br>). Return
    // null in the case where there isn't a closing tag.
    const tags = this.listItemElement.getElementsByClassName('webkit-html-tag');
    return tags.length === 1 ? null : tags[tags.length - 1];
  }

  updateTitle(updateRecord?: Elements.ElementUpdateRecord.ElementUpdateRecord|null): void {
    // If we are editing, return early to prevent canceling the edit.
    // After editing is committed updateTitle will be called.
    if (this.editing) {
      return;
    }

    const nodeInfo = this.nodeTitleInfo(updateRecord || null);
    if (this.nodeInternal.nodeType() === Node.DOCUMENT_FRAGMENT_NODE && this.nodeInternal.isInShadowTree() &&
        this.nodeInternal.shadowRootType()) {
      this.childrenListElement.classList.add('shadow-root');
      let depth = 4;
      for (let node: (SDK.DOMModel.DOMNode|null) = (this.nodeInternal as SDK.DOMModel.DOMNode | null); depth && node;
           node = node.parentNode) {
        if (node.nodeType() === Node.DOCUMENT_FRAGMENT_NODE) {
          depth--;
        }
      }
      if (!depth) {
        this.childrenListElement.classList.add('shadow-root-deep');
      } else {
        this.childrenListElement.classList.add('shadow-root-depth-' + depth);
      }
    }
    this.contentElement.removeChildren();
    const highlightElement = this.contentElement.createChild('span', 'highlight');
    highlightElement.append(nodeInfo);
    // fixme: make it clear that `this.title = x` is a setter with significant side effects
    this.title = this.contentElement;
    this.updateDecorations();
    this.contentElement.prepend(this.gutterContainer);
    if (isOpeningTag(this.tagTypeContext)) {
      this.contentElement.append(this.tagTypeContext.adornerContainer);
    }
    delete this.selectionElement;
    delete this.hintElement;
    delete this.aiButtonContainer;
    if (this.selected) {
      this.createSelection();
      this.createHint();
    }

    // If there is an issue with this node, make sure to update it.
    for (const issue of this.#elementIssues.values()) {
      this.#applyIssueStyleAndTooltip(issue);
    }

    this.#highlightSearchResults();
  }

  private computeLeftIndent(): number {
    let treeElement: (UI.TreeOutline.TreeElement|null) = this.parent;
    let depth = 0;
    while (treeElement !== null) {
      depth++;
      treeElement = treeElement.parent;
    }

    /** Keep it in sync with elementsTreeOutline.css **/
    return 12 * (depth - 2) + (this.isExpandable() && this.isCollapsible() ? 1 : 12);
  }

  updateDecorations(): void {
    const indent = this.computeLeftIndent();
    this.gutterContainer.style.left = (-indent) + 'px';
    this.listItemElement.style.setProperty('--indent', indent + 'px');

    if (this.isClosingTag()) {
      return;
    }

    if (this.nodeInternal.nodeType() !== Node.ELEMENT_NODE) {
      return;
    }

    void this.decorationsThrottler.schedule(this.#updateDecorations.bind(this));
  }

  #updateDecorations(): Promise<void> {
    if (!this.treeOutline) {
      return Promise.resolve();
    }

    const node = this.nodeInternal;

    if (!this.treeOutline.decoratorExtensions) {
      this.treeOutline.decoratorExtensions = getRegisteredDecorators();
    }

    const markerToExtension = new Map<string, MarkerDecoratorRegistration>();
    for (const decoratorExtension of this.treeOutline.decoratorExtensions) {
      markerToExtension.set(decoratorExtension.marker, decoratorExtension);
    }

    const promises: Array<Promise<void>> = [];
    const decorations: Array<{
      title: string,
      color: string,
    }> = [];
    const descendantDecorations: Array<{
      title: string,
      color: string,
    }> = [];
    node.traverseMarkers(visitor);

    function visitor(n: SDK.DOMModel.DOMNode, marker: string): void {
      const extension = markerToExtension.get(marker);
      if (!extension) {
        return;
      }
      promises.push(Promise.resolve(extension.decorator()).then(collectDecoration.bind(null, n)));
    }

    function collectDecoration(n: SDK.DOMModel.DOMNode, decorator: MarkerDecorator): void {
      const decoration = decorator.decorate(n);
      if (!decoration) {
        return;
      }
      (n === node ? decorations : descendantDecorations).push(decoration);
    }

    return Promise.all(promises).then(updateDecorationsUI.bind(this));

    function updateDecorationsUI(this: ElementsTreeElement): void {
      this.decorationsElement.removeChildren();
      this.decorationsElement.classList.add('hidden');
      this.gutterContainer.classList.toggle(
          'has-decorations', Boolean(decorations.length || descendantDecorations.length));
      UI.ARIAUtils.setLabel(this.decorationsElement, '');

      if (!decorations.length && !descendantDecorations.length) {
        return;
      }

      const colors = new Set<string>();
      const titles = document.createElement('div');

      for (const decoration of decorations) {
        const titleElement = titles.createChild('div');
        titleElement.textContent = decoration.title;
        colors.add(decoration.color);
      }
      if (this.expanded && !decorations.length) {
        return;
      }

      const descendantColors = new Set<string>();
      if (descendantDecorations.length) {
        let element = titles.createChild('div');
        element.textContent = i18nString(UIStrings.children);
        for (const decoration of descendantDecorations) {
          element = titles.createChild('div');
          element.style.marginLeft = '15px';
          element.textContent = decoration.title;
          descendantColors.add(decoration.color);
        }
      }

      let offset = 0;
      processColors.call(this, colors, 'elements-gutter-decoration');
      if (!this.expanded) {
        processColors.call(this, descendantColors, 'elements-gutter-decoration elements-has-decorated-children');
      }
      UI.Tooltip.Tooltip.install(this.decorationsElement, titles.textContent);
      UI.ARIAUtils.setLabel(this.decorationsElement, titles.textContent || '');

      function processColors(this: ElementsTreeElement, colors: Set<string>, className: string): void {
        for (const color of colors) {
          const child = this.decorationsElement.createChild('div', className);
          this.decorationsElement.classList.remove('hidden');
          child.style.backgroundColor = color;
          child.style.borderColor = color;
          if (offset) {
            child.style.marginLeft = offset + 'px';
          }
          offset += 3;
        }
      }
    }
  }

  private buildAttributeDOM(
      parentElement: Element|DocumentFragment, name: string, value: string,
      updateRecord: Elements.ElementUpdateRecord.ElementUpdateRecord|null, forceValue?: boolean,
      node?: SDK.DOMModel.DOMNode): HTMLElement {
    const closingPunctuationRegex = /[\/;:\)\]\}]/g;
    let highlightIndex = 0;
    let highlightCount = 0;
    let additionalHighlightOffset = 0;

    function setValueWithEntities(this: ElementsTreeElement, element: Element, value: string): void {
      const result = convertUnicodeCharsToHTMLEntities(value);
      highlightCount = result.entityRanges.length;
      value = result.text.replace(closingPunctuationRegex, (match, replaceOffset) => {
        while (highlightIndex < highlightCount && result.entityRanges[highlightIndex].offset < replaceOffset) {
          result.entityRanges[highlightIndex].offset += additionalHighlightOffset;
          ++highlightIndex;
        }
        additionalHighlightOffset += 1;
        return match + '\u200B';
      });

      while (highlightIndex < highlightCount) {
        result.entityRanges[highlightIndex].offset += additionalHighlightOffset;
        ++highlightIndex;
      }
      element.setTextContentTruncatedIfNeeded(value);
      UI.UIUtils.highlightRangesWithStyleClass(element, result.entityRanges, 'webkit-html-entity-value');
    }

    const hasText = (forceValue || value.length > 0);
    const attrSpanElement = parentElement.createChild('span', 'webkit-html-attribute');
    attrSpanElement.setAttribute(
        'jslog', `${VisualLogging.value(name === 'style' ? 'style-attribute' : 'attribute').track({
          change: true,
          dblclick: true,
        })}`);

    const attrNameElement = attrSpanElement.createChild('span', 'webkit-html-attribute-name');
    attrNameElement.textContent = name;

    if (hasText) {
      UI.UIUtils.createTextChild(attrSpanElement, '=\u200B"');
    }

    const attrValueElement = attrSpanElement.createChild('span', 'webkit-html-attribute-value');

    if (updateRecord?.isAttributeModified(name)) {
      UI.UIUtils.runCSSAnimationOnce(hasText ? attrValueElement : attrNameElement, 'dom-update-highlight');
    }

    function linkifyValue(this: ElementsTreeElement, value: string): Element {
      const rewrittenHref = node ? node.resolveURL(value) : null;
      if (rewrittenHref === null) {
        const span = document.createElement('span');
        setValueWithEntities.call(this, span, value);
        return span;
      }
      value = value.replace(closingPunctuationRegex, '$&\u200B');
      if (value.startsWith('data:')) {
        value = Platform.StringUtilities.trimMiddle(value, 60);
      }
      const link = node && node.nodeName().toLowerCase() === 'a' ?
          UI.XLink.XLink.create(rewrittenHref, value, '', true /* preventClick */, 'image-url') :
          Components.Linkifier.Linkifier.linkifyURL(rewrittenHref, {
            text: value,
            preventClick: true,
            showColumnNumber: false,
            inlineFrameIndex: 0,
          });
      return ImagePreviewPopover.setImageUrl(link, rewrittenHref);
    }

    const nodeName = node ? node.nodeName().toLowerCase() : '';
    // If the href/src attribute has a value, attempt to link it.
    // There's no point trying to link it if the value is empty (e.g. <a href=''>).
    if (nodeName && (name === 'src' || name === 'href') && value) {
      attrValueElement.appendChild(linkifyValue.call(this, value));
    } else if ((nodeName === 'img' || nodeName === 'source') && name === 'srcset') {
      attrValueElement.appendChild(linkifySrcset.call(this, value));
    } else if (nodeName === 'image' && (name === 'xlink:href' || name === 'href')) {
      attrValueElement.appendChild(linkifySrcset.call(this, value));
    } else {
      setValueWithEntities.call(this, attrValueElement, value);
    }

    switch (name) {
      case 'popovertarget': {
        const linkedPart = value ? attrValueElement : attrNameElement;
        void this.linkifyElementByRelation(
            linkedPart, Protocol.DOM.GetElementByRelationRequestRelation.PopoverTarget,
            i18nString(UIStrings.showPopoverTarget));
        break;
      }
      case 'interesttarget': {
        const linkedPart = value ? attrValueElement : attrNameElement;
        void this.linkifyElementByRelation(
            linkedPart, Protocol.DOM.GetElementByRelationRequestRelation.InterestTarget,
            i18nString(UIStrings.showInterestTarget));
        break;
      }
      case 'commandfor': {
        const linkedPart = value ? attrValueElement : attrNameElement;
        void this.linkifyElementByRelation(
            linkedPart, Protocol.DOM.GetElementByRelationRequestRelation.CommandFor,
            i18nString(UIStrings.showCommandForTarget));
        break;
      }
    }

    if (hasText) {
      UI.UIUtils.createTextChild(attrSpanElement, '"');
    }

    function linkifySrcset(this: ElementsTreeElement, value: string): DocumentFragment {
      // Splitting normally on commas or spaces will break on valid srcsets "foo 1x,bar 2x" and "data:,foo 1x".
      // 1) Let the index of the next space be `indexOfSpace`.
      // 2a) If the character at `indexOfSpace - 1` is a comma, collect the preceding characters up to
      //     `indexOfSpace - 1` as a URL and repeat step 1).
      // 2b) Else, collect the preceding characters as a URL.
      // 3) Collect the characters from `indexOfSpace` up to the next comma as the size descriptor and repeat step 1).
      // https://html.spec.whatwg.org/C/#parse-a-srcset-attribute
      const fragment = document.createDocumentFragment();
      let i = 0;
      while (value.length) {
        if (i++ > 0) {
          UI.UIUtils.createTextChild(fragment, ' ');
        }
        value = value.trim();
        // The url and descriptor may end with a separating comma.
        let url = '';
        let descriptor = '';
        const indexOfSpace = value.search(/\s/);
        if (indexOfSpace === -1) {
          url = value;
        } else if (indexOfSpace > 0 && value[indexOfSpace - 1] === ',') {
          url = value.substring(0, indexOfSpace);
        } else {
          url = value.substring(0, indexOfSpace);
          const indexOfComma = value.indexOf(',', indexOfSpace);
          if (indexOfComma !== -1) {
            descriptor = value.substring(indexOfSpace, indexOfComma + 1);
          } else {
            descriptor = value.substring(indexOfSpace);
          }
        }

        if (url) {
          // Up to one trailing comma should be removed from `url`.
          if (url.endsWith(',')) {
            fragment.appendChild(linkifyValue.call(this, url.substring(0, url.length - 1)));
            UI.UIUtils.createTextChild(fragment, ',');
          } else {
            fragment.appendChild(linkifyValue.call(this, url));
          }
        }
        if (descriptor) {
          UI.UIUtils.createTextChild(fragment, descriptor);
        }
        value = value.substring(url.length + descriptor.length);
      }
      return fragment;
    }

    return attrSpanElement;
  }

  private async linkifyElementByRelation(
      linkContainer: Element, relation: Protocol.DOM.GetElementByRelationRequestRelation,
      tooltip: string): Promise<void> {
    const relatedElementId = await this.nodeInternal.domModel().getElementByRelation(this.nodeInternal.id, relation);
    const relatedElement = this.nodeInternal.domModel().nodeForId(relatedElementId);
    if (!relatedElement) {
      return;
    }
    const link = await Common.Linkifier.Linkifier.linkify(relatedElement, {
      preventKeyboardFocus: true,
      tooltip,
      textContent: linkContainer.textContent || undefined,
      isDynamicLink: true,
    });
    linkContainer.removeChildren();
    linkContainer.append(link);
  }

  private buildPseudoElementDOM(parentElement: DocumentFragment, pseudoElementName: string): void {
    const pseudoElement = parentElement.createChild('span', 'webkit-html-pseudo-element');
    pseudoElement.textContent = pseudoElementName;
    UI.UIUtils.createTextChild(parentElement, '\u200B');
  }

  private buildTagDOM(
      parentElement: DocumentFragment, tagName: string, isClosingTag: boolean, isDistinctTreeElement: boolean,
      updateRecord: Elements.ElementUpdateRecord.ElementUpdateRecord|null): void {
    const node = this.nodeInternal;
    const classes = ['webkit-html-tag'];
    if (isClosingTag && isDistinctTreeElement) {
      classes.push('close');
    }
    const tagElement = parentElement.createChild('span', classes.join(' '));
    UI.UIUtils.createTextChild(tagElement, '<');
    const tagNameElement =
        tagElement.createChild('span', isClosingTag ? 'webkit-html-close-tag-name' : 'webkit-html-tag-name');
    if (!isClosingTag) {
      tagNameElement.setAttribute('jslog', `${VisualLogging.value('tag-name').track({change: true, dblclick: true})}`);
    }
    tagNameElement.textContent = (isClosingTag ? '/' : '') + tagName;
    if (!isClosingTag) {
      if (node.hasAttributes()) {
        const attributes = node.attributes();
        for (let i = 0; i < attributes.length; ++i) {
          const attr = attributes[i];
          UI.UIUtils.createTextChild(tagElement, ' ');
          this.buildAttributeDOM(tagElement, attr.name, attr.value, updateRecord, false, node);
        }
      }
      if (updateRecord) {
        let hasUpdates: boolean = updateRecord.hasRemovedAttributes() || updateRecord.hasRemovedChildren();
        hasUpdates = hasUpdates || (!this.expanded && updateRecord.hasChangedChildren());
        if (hasUpdates) {
          UI.UIUtils.runCSSAnimationOnce(tagNameElement, 'dom-update-highlight');
        }
      }
    }

    UI.UIUtils.createTextChild(tagElement, '>');
    UI.UIUtils.createTextChild(parentElement, '\u200B');
    if (tagElement.textContent) {
      UI.ARIAUtils.setLabel(tagElement, tagElement.textContent);
    }
  }

  private nodeTitleInfo(updateRecord: Elements.ElementUpdateRecord.ElementUpdateRecord|null): DocumentFragment {
    const node = this.nodeInternal;
    const titleDOM = document.createDocumentFragment();
    const updateSearchHighlight = (): void => {
      this.#highlightSearchResults();
    };

    switch (node.nodeType()) {
      case Node.ATTRIBUTE_NODE:
        this.buildAttributeDOM(titleDOM, (node.name as string), (node.value as string), updateRecord, true);
        break;

      case Node.ELEMENT_NODE: {
        if (node.pseudoType()) {
          let pseudoElementName = node.nodeName();
          const pseudoIdentifier = node.pseudoIdentifier();
          if (pseudoIdentifier) {
            pseudoElementName += `(${pseudoIdentifier})`;
          }
          this.buildPseudoElementDOM(titleDOM, pseudoElementName);
          break;
        }

        const tagName = node.nodeNameInCorrectCase();
        if (this.isClosingTag()) {
          this.buildTagDOM(titleDOM, tagName, true, true, updateRecord);
          break;
        }

        this.buildTagDOM(titleDOM, tagName, false, false, updateRecord);

        if (this.isExpandable()) {
          if (!this.expanded) {
            const expandButton = new ElementsComponents.ElementsTreeExpandButton.ElementsTreeExpandButton();
            expandButton.data = {
              clickHandler: () => this.expand(),
            };
            titleDOM.appendChild(expandButton);

            // This hidden span with … is for blink layout tests.
            // The method dumpElementsTree(front_end/legacy_test_runner/elements_test_runner/ElementsTestRunner.js)
            // dumps … to identify expandable element.
            const hidden = document.createElement('span');
            hidden.textContent = '…';
            hidden.style.fontSize = '0';
            titleDOM.appendChild(hidden);

            UI.UIUtils.createTextChild(titleDOM, '\u200B');
            this.buildTagDOM(titleDOM, tagName, true, false, updateRecord);
          }
          break;
        }

        if (ElementsTreeElement.canShowInlineText(node)) {
          const textNodeElement = titleDOM.createChild('span', 'webkit-html-text-node');
          textNodeElement.setAttribute(
              'jslog', `${VisualLogging.value('text-node').track({change: true, dblclick: true})}`);
          const firstChild = node.firstChild;
          if (!firstChild) {
            throw new Error('ElementsTreeElement._nodeTitleInfo expects node.firstChild to be defined.');
          }
          const result = convertUnicodeCharsToHTMLEntities(firstChild.nodeValue());
          textNodeElement.textContent = Platform.StringUtilities.collapseWhitespace(result.text);
          UI.UIUtils.highlightRangesWithStyleClass(textNodeElement, result.entityRanges, 'webkit-html-entity-value');
          UI.UIUtils.createTextChild(titleDOM, '\u200B');
          this.buildTagDOM(titleDOM, tagName, true, false, updateRecord);
          if (updateRecord?.hasChangedChildren()) {
            UI.UIUtils.runCSSAnimationOnce(textNodeElement, 'dom-update-highlight');
          }
          if (updateRecord?.isCharDataModified()) {
            UI.UIUtils.runCSSAnimationOnce(textNodeElement, 'dom-update-highlight');
          }
          break;
        }

        if (this.treeOutline?.isXMLMimeType || !ForbiddenClosingTagElements.has(tagName)) {
          this.buildTagDOM(titleDOM, tagName, true, false, updateRecord);
        }
        break;
      }

      case Node.TEXT_NODE:
        if (node.parentNode && node.parentNode.nodeName().toLowerCase() === 'script') {
          const newNode = titleDOM.createChild('span', 'webkit-html-text-node webkit-html-js-node');
          newNode.setAttribute(
              'jslog', `${VisualLogging.value('script-text-node').track({change: true, dblclick: true})}`);
          const text = node.nodeValue();
          newNode.textContent = text.replace(/^[\n\r]+|\s+$/g, '');
          void CodeHighlighter.CodeHighlighter.highlightNode(newNode, 'text/javascript').then(updateSearchHighlight);
        } else if (node.parentNode && node.parentNode.nodeName().toLowerCase() === 'style') {
          const newNode = titleDOM.createChild('span', 'webkit-html-text-node webkit-html-css-node');
          newNode.setAttribute(
              'jslog', `${VisualLogging.value('css-text-node').track({change: true, dblclick: true})}`);
          const text = node.nodeValue();
          newNode.textContent = text.replace(/^[\n\r]+|\s+$/g, '');
          void CodeHighlighter.CodeHighlighter.highlightNode(newNode, 'text/css').then(updateSearchHighlight);
        } else {
          UI.UIUtils.createTextChild(titleDOM, '"');
          const textNodeElement = titleDOM.createChild('span', 'webkit-html-text-node');
          textNodeElement.setAttribute(
              'jslog', `${VisualLogging.value('text-node').track({change: true, dblclick: true})}`);
          const result = convertUnicodeCharsToHTMLEntities(node.nodeValue());
          textNodeElement.textContent = Platform.StringUtilities.collapseWhitespace(result.text);
          UI.UIUtils.highlightRangesWithStyleClass(textNodeElement, result.entityRanges, 'webkit-html-entity-value');
          UI.UIUtils.createTextChild(titleDOM, '"');
          if (updateRecord?.isCharDataModified()) {
            UI.UIUtils.runCSSAnimationOnce(textNodeElement, 'dom-update-highlight');
          }
        }
        break;

      case Node.COMMENT_NODE: {
        const commentElement = titleDOM.createChild('span', 'webkit-html-comment');
        UI.UIUtils.createTextChild(commentElement, '<!--' + node.nodeValue() + '-->');
        break;
      }

      case Node.DOCUMENT_TYPE_NODE: {
        const docTypeElement = titleDOM.createChild('span', 'webkit-html-doctype');
        UI.UIUtils.createTextChild(docTypeElement, '<!DOCTYPE ' + node.nodeName());
        if (node.publicId) {
          UI.UIUtils.createTextChild(docTypeElement, ' PUBLIC "' + node.publicId + '"');
          if (node.systemId) {
            UI.UIUtils.createTextChild(docTypeElement, ' "' + node.systemId + '"');
          }
        } else if (node.systemId) {
          UI.UIUtils.createTextChild(docTypeElement, ' SYSTEM "' + node.systemId + '"');
        }

        if (node.internalSubset) {
          UI.UIUtils.createTextChild(docTypeElement, ' [' + node.internalSubset + ']');
        }

        UI.UIUtils.createTextChild(docTypeElement, '>');
        break;
      }

      case Node.CDATA_SECTION_NODE: {
        const cdataElement = titleDOM.createChild('span', 'webkit-html-text-node');
        UI.UIUtils.createTextChild(cdataElement, '<![CDATA[' + node.nodeValue() + ']]>');
        break;
      }

      case Node.DOCUMENT_NODE: {
        const documentElement = titleDOM.createChild('span');
        UI.UIUtils.createTextChild(documentElement, '#document (');
        const text = (node as SDK.DOMModel.DOMDocument).documentURL;
        documentElement.appendChild(Components.Linkifier.Linkifier.linkifyURL(text, {
          text,
          preventClick: true,
          showColumnNumber: false,
          inlineFrameIndex: 0,
        }));
        UI.UIUtils.createTextChild(documentElement, ')');
        break;
      }

      case Node.DOCUMENT_FRAGMENT_NODE: {
        const fragmentElement = titleDOM.createChild('span', 'webkit-html-fragment');
        fragmentElement.textContent = Platform.StringUtilities.collapseWhitespace(node.nodeNameInCorrectCase());
        break;
      }

      default: {
        const nameWithSpaceCollapsed = Platform.StringUtilities.collapseWhitespace(node.nodeNameInCorrectCase());
        UI.UIUtils.createTextChild(titleDOM, nameWithSpaceCollapsed);
      }
    }

    return titleDOM;
  }

  async remove(): Promise<void> {
    if (this.treeOutline?.isToggledToHidden(this.nodeInternal)) {
      // Unhide the node before removing. This avoids inconsistent state if the node is restored via undo.
      await this.treeOutline.toggleHideElement(this.nodeInternal);
    }
    if (this.nodeInternal.pseudoType()) {
      return;
    }
    const parentElement = this.parent;
    if (!parentElement) {
      return;
    }

    if (!this.nodeInternal.parentNode || this.nodeInternal.parentNode.nodeType() === Node.DOCUMENT_NODE) {
      return;
    }
    void this.nodeInternal.removeNode();
  }

  toggleEditAsHTML(callback?: ((arg0: boolean) => void), startEditing?: boolean): void {
    if (this.editing && this.htmlEditElement) {
      this.editing.commit();
      return;
    }

    if (startEditing === false) {
      return;
    }

    function selectNode(error: string|null): void {
      if (callback) {
        callback(!error);
      }
    }

    function commitChange(initialValue: string, value: string): void {
      if (initialValue !== value) {
        node.setOuterHTML(value, selectNode);
      }
    }

    function disposeCallback(): void {
      if (callback) {
        callback(false);
      }
    }

    const node = this.nodeInternal;
    void node.getOuterHTML().then(this.startEditingAsHTML.bind(this, commitChange, disposeCallback));
  }

  private copyCSSPath(): void {
    Host.InspectorFrontendHost.InspectorFrontendHostInstance.copyText(cssPath(this.nodeInternal, true));
  }

  private copyJSPath(): void {
    Host.InspectorFrontendHost.InspectorFrontendHostInstance.copyText(jsPath(this.nodeInternal, true));
  }

  private copyXPath(): void {
    Host.InspectorFrontendHost.InspectorFrontendHostInstance.copyText(xPath(this.nodeInternal, true));
  }

  private copyFullXPath(): void {
    Host.InspectorFrontendHost.InspectorFrontendHostInstance.copyText(xPath(this.nodeInternal, false));
  }

  async copyStyles(): Promise<void> {
    const node = this.nodeInternal;
    const cssModel = node.domModel().cssModel();
    const cascade = await cssModel.cachedMatchedCascadeForNode(node);
    if (!cascade) {
      return;
    }

    const indent = Common.Settings.Settings.instance().moduleSetting('text-editor-indent').get();
    const lines: string[] = [];
    for (const style of cascade.nodeStyles().reverse()) {
      for (const property of style.leadingProperties()) {
        if (!property.parsedOk || property.disabled || !property.activeInStyle() || property.implicit) {
          continue;
        }
        if (cascade.isInherited(style) && !SDK.CSSMetadata.cssMetadata().isPropertyInherited(property.name)) {
          continue;
        }
        if (style.parentRule?.isUserAgent()) {
          continue;
        }
        if (cascade.propertyState(property) !== SDK.CSSMatchedStyles.PropertyState.ACTIVE) {
          continue;
        }
        lines.push(`${indent}${property.name}: ${property.value};`);
      }
    }

    Host.InspectorFrontendHost.InspectorFrontendHostInstance.copyText(lines.join('\n'));
  }

  #highlightSearchResults(): void {
    this.hideSearchHighlights();

    if (!this.searchQuery) {
      return;
    }

    const text = this.listItemElement.textContent || '';
    const regexObject = Platform.StringUtilities.createPlainTextSearchRegex(this.searchQuery, 'gi');

    const matchRanges = [];
    let match = regexObject.exec(text);
    while (match) {
      matchRanges.push(new TextUtils.TextRange.SourceRange(match.index, match[0].length));
      match = regexObject.exec(text);
    }

    // Fall back for XPath, etc. matches.
    if (!matchRanges.length) {
      matchRanges.push(new TextUtils.TextRange.SourceRange(0, text.length));
    }

    this.#highlights = Highlighting.HighlightManager.HighlightManager.instance().highlightOrderedTextRanges(
        this.listItemElement, matchRanges);
  }

  private editAsHTML(): void {
    const promise = Common.Revealer.reveal(this.node());
    void promise.then(() => {
      const action = UI.ActionRegistry.ActionRegistry.instance().getAction('elements.edit-as-html');
      return action.execute();
    });
  }

  // TODO: add unit tests for adorner-related methods after component and TypeScript works are done
  adorn({name}: {name: string}, content?: HTMLElement): Adorners.Adorner.Adorner {
    let adornerContent = content;
    if (!adornerContent) {
      adornerContent = document.createElement('span');
      adornerContent.textContent = name;
    }
    const adorner = new Adorners.Adorner.Adorner();
    adorner.data = {
      name,
      content: adornerContent,
      jslogContext: name,
    };
    if (isOpeningTag(this.tagTypeContext)) {
      this.tagTypeContext.adorners.add(adorner);
      ElementsPanel.instance().registerAdorner(adorner);
      this.updateAdorners(this.tagTypeContext);
    }
    return adorner;
  }

  adornSlot({name}: {name: string}, context: OpeningTagContext): Adorners.Adorner.Adorner {
    const linkIcon = IconButton.Icon.create('select-element');
    const slotText = document.createElement('span');
    slotText.textContent = name;
    const adornerContent = document.createElement('span');
    adornerContent.append(linkIcon);
    adornerContent.append(slotText);
    adornerContent.classList.add('adorner-with-icon');
    const adorner = new Adorners.Adorner.Adorner();
    adorner.data = {
      name,
      content: adornerContent,
      jslogContext: 'slot',
    };
    context.adorners.add(adorner);
    ElementsPanel.instance().registerAdorner(adorner);
    this.updateAdorners(context);
    return adorner;
  }

  adornMedia({name}: {name: string}): Adorners.Adorner.Adorner {
    const adornerContent = document.createElement('span');

    adornerContent.textContent = name;
    adornerContent.classList.add('adorner-with-icon');

    const linkIcon = IconButton.Icon.create('select-element');
    adornerContent.append(linkIcon);

    const adorner = new Adorners.Adorner.Adorner();
    adorner.data = {
      name,
      content: adornerContent,
      jslogContext: 'media',
    };
    if (isOpeningTag(this.tagTypeContext)) {
      this.tagTypeContext.adorners.add(adorner);
      ElementsPanel.instance().registerAdorner(adorner);
      this.updateAdorners(this.tagTypeContext);
    }
    return adorner;
  }

  removeAdorner(adornerToRemove: Adorners.Adorner.Adorner, context: OpeningTagContext): void {
    ElementsPanel.instance().deregisterAdorner(adornerToRemove);
    adornerToRemove.remove();
    context.adorners.delete(adornerToRemove);
    context.styleAdorners.delete(adornerToRemove);
    this.updateAdorners(context);
  }

  /**
   * @param adornerType optional type of adorner to remove. If not provided, remove all adorners.
   */
  removeAdornersByType(adornerType?: ElementsComponents.AdornerManager.RegisteredAdorners): void {
    if (!isOpeningTag(this.tagTypeContext)) {
      return;
    }

    for (const adorner of this.tagTypeContext.adorners) {
      if (adorner.name === adornerType || !adornerType) {
        this.removeAdorner(adorner, this.tagTypeContext);
      }
    }
  }

  private updateAdorners(context: OpeningTagContext): void {
    void context.adornersThrottler.schedule(this.#updateAdorners.bind(null, context));
  }

  #updateAdorners(context: OpeningTagContext): Promise<void> {
    const adornerContainer = context.adornerContainer;
    if (!adornerContainer) {
      return Promise.resolve();
    }
    const adorners = [...context.adorners].sort(adornerComparator);
    if (context.slot) {
      adorners.push(context.slot);
    }

    adornerContainer.removeChildren();
    for (const adorner of adorners) {
      adornerContainer.appendChild(adorner);
    }
    adornerContainer.classList.toggle('hidden', adorners.length === 0);
    return Promise.resolve();
  }

  async updateStyleAdorners(): Promise<void> {
    if (!isOpeningTag(this.tagTypeContext)) {
      return;
    }

    const node = this.node();
    const nodeId = node.id;
    if (node.nodeType() === Node.COMMENT_NODE || node.nodeType() === Node.DOCUMENT_FRAGMENT_NODE ||
        node.nodeType() === Node.TEXT_NODE || nodeId === undefined) {
      return;
    }

    const layout = await node.domModel().cssModel().getLayoutPropertiesFromComputedStyle(nodeId);
    for (const styleAdorner of this.tagTypeContext.styleAdorners) {
      this.removeAdorner(styleAdorner, this.tagTypeContext);
    }
    if (layout) {
      if (layout.isGrid) {
        this.pushGridAdorner(this.tagTypeContext, layout.isSubgrid);
      }
      if (layout.isMasonry) {
        this.pushMasonryAdorner(this.tagTypeContext);
      }
      if (layout.isFlex) {
        this.pushFlexAdorner(this.tagTypeContext);
      }
      if (layout.hasScroll) {
        this.pushScrollSnapAdorner(this.tagTypeContext);
      }
      if (layout.isContainer) {
        this.pushContainerAdorner(this.tagTypeContext);
      }
    }

    if (node.isMediaNode()) {
      this.pushMediaAdorner(this.tagTypeContext);
    }

    if (Root.Runtime.hostConfig.devToolsStartingStyleDebugging?.enabled) {
      const affectedByStartingStyles = node.affectedByStartingStyles();
      if (affectedByStartingStyles) {
        this.pushStartingStyleAdorner(this.tagTypeContext);
      }
    }

    if (node.attributes().find(attr => attr.name === 'popover')) {
      this.pushPopoverAdorner(this.tagTypeContext);
    }
  }

  pushPopoverAdorner(context: OpeningTagContext): void {
    if (!Root.Runtime.hostConfig.devToolsAllowPopoverForcing?.enabled) {
      return;
    }
    const node = this.node();
    const nodeId = node.id;

    const config = ElementsComponents.AdornerManager.getRegisteredAdorner(
        ElementsComponents.AdornerManager.RegisteredAdorners.POPOVER);
    const adorner = this.adorn(config);
    const onClick = async(): Promise<void> => {
      const {nodeIds} = await node.domModel().agent.invoke_forceShowPopover({nodeId, enable: adorner.isActive()});
      if (adorner.isActive()) {
        Badges.UserBadges.instance().recordAction(Badges.BadgeAction.MODERN_DOM_BADGE_CLICKED);
      }
      for (const closedPopoverNodeId of nodeIds) {
        const node = this.node().domModel().nodeForId(closedPopoverNodeId);
        const treeElement = node && this.treeOutline?.treeElementByNode.get(node);
        if (!treeElement || !isOpeningTag(treeElement.tagTypeContext)) {
          return;
        }
        const adorner = treeElement.tagTypeContext.adorners.values().find(adorner => adorner.name === config.name);
        adorner?.toggle(false);
      }
    };
    adorner.addInteraction(onClick, {
      isToggle: true,
      shouldPropagateOnKeydown: false,
      ariaLabelDefault: i18nString(UIStrings.forceOpenPopover),
      ariaLabelActive: i18nString(UIStrings.stopForceOpenPopover),
    });

    context.styleAdorners.add(adorner);
  }

  pushGridAdorner(context: OpeningTagContext, isSubgrid: boolean): void {
    const node = this.node();
    const nodeId = node.id;
    if (!nodeId) {
      return;
    }

    const config = ElementsComponents.AdornerManager.getRegisteredAdorner(
        isSubgrid ? ElementsComponents.AdornerManager.RegisteredAdorners.SUBGRID :
                    ElementsComponents.AdornerManager.RegisteredAdorners.GRID);
    const adorner = this.adorn(config);
    adorner.classList.add('grid');

    const onClick = ((() => {
                       if (adorner.isActive()) {
                         node.domModel().overlayModel().highlightGridInPersistentOverlay(nodeId);
                         if (isSubgrid) {
                           Badges.UserBadges.instance().recordAction(Badges.BadgeAction.MODERN_DOM_BADGE_CLICKED);
                         }
                       } else {
                         node.domModel().overlayModel().hideGridInPersistentOverlay(nodeId);
                       }
                     }) as EventListener);
    adorner.addInteraction(onClick, {
      isToggle: true,
      shouldPropagateOnKeydown: false,
      ariaLabelDefault: i18nString(UIStrings.enableGridMode),
      ariaLabelActive: i18nString(UIStrings.disableGridMode),
    });

    node.domModel().overlayModel().addEventListener(
        SDK.OverlayModel.Events.PERSISTENT_GRID_OVERLAY_STATE_CHANGED, event => {
          const {nodeId: eventNodeId, enabled} = event.data;
          if (eventNodeId !== nodeId) {
            return;
          }
          adorner.toggle(enabled);
        });

    context.styleAdorners.add(adorner);
    if (node.domModel().overlayModel().isHighlightedGridInPersistentOverlay(nodeId)) {
      adorner.toggle(true);
    }
  }

  pushMasonryAdorner(context: OpeningTagContext): void {
    const node = this.node();
    const nodeId = node.id;
    if (!nodeId) {
      return;
    }

    const config = ElementsComponents.AdornerManager.getRegisteredAdorner(
        ElementsComponents.AdornerManager.RegisteredAdorners.MASONRY);
    const adorner = this.adorn(config);
    adorner.classList.add('masonry');

    const onClick = ((() => {
                       if (adorner.isActive()) {
                         node.domModel().overlayModel().highlightGridInPersistentOverlay(nodeId);
                         Badges.UserBadges.instance().recordAction(Badges.BadgeAction.MODERN_DOM_BADGE_CLICKED);
                       } else {
                         node.domModel().overlayModel().hideGridInPersistentOverlay(nodeId);
                       }
                     }) as EventListener);
    adorner.addInteraction(onClick, {
      isToggle: true,
      shouldPropagateOnKeydown: false,
      ariaLabelDefault: i18nString(UIStrings.enableMasonryMode),
      ariaLabelActive: i18nString(UIStrings.disableMasonryMode),
    });

    node.domModel().overlayModel().addEventListener(
        SDK.OverlayModel.Events.PERSISTENT_GRID_OVERLAY_STATE_CHANGED, event => {
          const {nodeId: eventNodeId, enabled} = event.data;
          if (eventNodeId !== nodeId) {
            return;
          }
          adorner.toggle(enabled);
        });

    context.styleAdorners.add(adorner);
    if (node.domModel().overlayModel().isHighlightedGridInPersistentOverlay(nodeId)) {
      adorner.toggle(true);
    }
  }

  pushScrollSnapAdorner(context: OpeningTagContext): void {
    const node = this.node();
    const nodeId = node.id;
    if (!nodeId) {
      return;
    }
    const config = ElementsComponents.AdornerManager.getRegisteredAdorner(
        ElementsComponents.AdornerManager.RegisteredAdorners.SCROLL_SNAP);
    const adorner = this.adorn(config);
    adorner.classList.add('scroll-snap');

    const onClick = ((() => {
                       const model = node.domModel().overlayModel();
                       if (adorner.isActive()) {
                         model.highlightScrollSnapInPersistentOverlay(nodeId);
                       } else {
                         model.hideScrollSnapInPersistentOverlay(nodeId);
                       }
                     }) as EventListener);

    adorner.addInteraction(onClick, {
      isToggle: true,
      shouldPropagateOnKeydown: false,
      ariaLabelDefault: i18nString(UIStrings.enableScrollSnap),
      ariaLabelActive: i18nString(UIStrings.disableScrollSnap),
    });

    node.domModel().overlayModel().addEventListener(
        SDK.OverlayModel.Events.PERSISTENT_SCROLL_SNAP_OVERLAY_STATE_CHANGED, event => {
          const {nodeId: eventNodeId, enabled} = event.data;
          if (eventNodeId !== nodeId) {
            return;
          }
          adorner.toggle(enabled);
        });

    context.styleAdorners.add(adorner);

    if (node.domModel().overlayModel().isHighlightedScrollSnapInPersistentOverlay(nodeId)) {
      adorner.toggle(true);
    }
  }

  pushStartingStyleAdorner(context: OpeningTagContext): void {
    const node = this.node();
    const nodeId = node.id;
    if (!nodeId) {
      return;
    }
    const config = ElementsComponents.AdornerManager.getRegisteredAdorner(
        ElementsComponents.AdornerManager.RegisteredAdorners.STARTING_STYLE);
    const adorner = this.adorn(config);
    adorner.classList.add('starting-style');

    const onClick = ((() => {
                       const model = node.domModel().cssModel();
                       if (adorner.isActive()) {
                         model.forceStartingStyle(node, true);
                       } else {
                         model.forceStartingStyle(node, false);
                       }
                     }) as EventListener);

    adorner.addInteraction(onClick, {
      isToggle: true,
      shouldPropagateOnKeydown: false,
      ariaLabelDefault: i18nString(UIStrings.enableStartingStyle),
      ariaLabelActive: i18nString(UIStrings.disableStartingStyle),
    });

    context.styleAdorners.add(adorner);
  }

  pushFlexAdorner(context: OpeningTagContext): void {
    const node = this.node();
    const nodeId = node.id;
    if (!nodeId) {
      return;
    }
    const config = ElementsComponents.AdornerManager.getRegisteredAdorner(
        ElementsComponents.AdornerManager.RegisteredAdorners.FLEX);
    const adorner = this.adorn(config);
    adorner.classList.add('flex');

    const onClick = ((() => {
                       const model = node.domModel().overlayModel();
                       if (adorner.isActive()) {
                         model.highlightFlexContainerInPersistentOverlay(nodeId);
                       } else {
                         model.hideFlexContainerInPersistentOverlay(nodeId);
                       }
                     }) as EventListener);

    adorner.addInteraction(onClick, {
      isToggle: true,
      shouldPropagateOnKeydown: false,
      ariaLabelDefault: i18nString(UIStrings.enableFlexMode),
      ariaLabelActive: i18nString(UIStrings.disableFlexMode),
    });

    node.domModel().overlayModel().addEventListener(
        SDK.OverlayModel.Events.PERSISTENT_FLEX_CONTAINER_OVERLAY_STATE_CHANGED, event => {
          const {nodeId: eventNodeId, enabled} = event.data;
          if (eventNodeId !== nodeId) {
            return;
          }

          adorner.toggle(enabled);
        });

    context.styleAdorners.add(adorner);

    if (node.domModel().overlayModel().isHighlightedFlexContainerInPersistentOverlay(nodeId)) {
      adorner.toggle(true);
    }
  }

  pushContainerAdorner(context: OpeningTagContext): void {
    const node = this.node();
    const nodeId = node.id;
    if (!nodeId) {
      return;
    }
    const config = ElementsComponents.AdornerManager.getRegisteredAdorner(
        ElementsComponents.AdornerManager.RegisteredAdorners.CONTAINER);
    const adorner = this.adorn(config);
    adorner.classList.add('container');

    const onClick = ((() => {
                       const model = node.domModel().overlayModel();
                       if (adorner.isActive()) {
                         model.highlightContainerQueryInPersistentOverlay(nodeId);
                         Badges.UserBadges.instance().recordAction(Badges.BadgeAction.MODERN_DOM_BADGE_CLICKED);
                       } else {
                         model.hideContainerQueryInPersistentOverlay(nodeId);
                       }
                     }) as EventListener);

    adorner.addInteraction(onClick, {
      isToggle: true,
      shouldPropagateOnKeydown: false,
      ariaLabelDefault: i18nString(UIStrings.enableScrollSnap),
      ariaLabelActive: i18nString(UIStrings.disableScrollSnap),
    });

    node.domModel().overlayModel().addEventListener(
        SDK.OverlayModel.Events.PERSISTENT_CONTAINER_QUERY_OVERLAY_STATE_CHANGED, event => {
          const {nodeId: eventNodeId, enabled} = event.data;
          if (eventNodeId !== nodeId) {
            return;
          }
          adorner.toggle(enabled);
        });

    context.styleAdorners.add(adorner);
    if (node.domModel().overlayModel().isHighlightedContainerQueryInPersistentOverlay(nodeId)) {
      adorner.toggle(true);
    }
  }

  pushMediaAdorner(context: OpeningTagContext): void {
    const node = this.node();
    const nodeId = node.id;
    if (!nodeId) {
      return;
    }
    const config = ElementsComponents.AdornerManager.getRegisteredAdorner(
        ElementsComponents.AdornerManager.RegisteredAdorners.MEDIA);
    const adorner = this.adornMedia(config);
    adorner.classList.add('media');
    const onClick = (async(): Promise<void> => {
                      await UI.ViewManager.ViewManager.instance().showView('medias');
                      const view = UI.ViewManager.ViewManager.instance().view('medias');
                      if (view) {
                        const widget = await view.widget();
                        if (widget instanceof Media.MainView.MainView) {
                          await widget.waitForInitialPlayers();
                          widget.selectPlayerByDOMNodeId(node.backendNodeId());
                        }
                      }
                    }) as EventListener;

    adorner.addInteraction(onClick, {
      isToggle: false,
      shouldPropagateOnKeydown: false,
      ariaLabelDefault: i18nString(UIStrings.openMediaPanel),
      ariaLabelActive: i18nString(UIStrings.openMediaPanel),
    });

    context.styleAdorners.add(adorner);
  }

  updateScrollAdorner(): void {
    if (!isOpeningTag(this.tagTypeContext)) {
      return;
    }
    const scrollAdorner = this.tagTypeContext.adorners.values().find(
        x => x.name === ElementsComponents.AdornerManager.RegisteredAdorners.SCROLL);
    // Check if the node is scrollable, or if it's the <html> element and the document is scrollable
    // because the top-level document (#document) doesn't have a corresponding tree element.
    const needsAScrollAdorner = (this.node().nodeName() === 'HTML' && this.node().ownerDocument?.isScrollable()) ||
        (this.node().nodeName() !== '#document' && this.node().isScrollable());
    if (needsAScrollAdorner && !scrollAdorner) {
      this.pushScrollAdorner();
    } else if (!needsAScrollAdorner && scrollAdorner) {
      this.removeAdorner(scrollAdorner, this.tagTypeContext);
    }
  }

  pushScrollAdorner(): void {
    const config = ElementsComponents.AdornerManager.getRegisteredAdorner(
        ElementsComponents.AdornerManager.RegisteredAdorners.SCROLL);
    const adorner = this.adorn(config);
    UI.Tooltip.Tooltip.install(adorner, i18nString(UIStrings.elementHasScrollableOverflow));
    adorner.classList.add('scroll');
  }
}

export const InitialChildrenLimit = 500;

/**
 * A union of HTML4 and HTML5-Draft elements that explicitly
 * or implicitly (for HTML5) forbid the closing tag.
 **/
export const ForbiddenClosingTagElements = new Set<string>([
  'area', 'base',  'basefont', 'br',   'canvas',   'col',  'command', 'embed',  'frame', 'hr',
  'img',  'input', 'keygen',   'link', 'menuitem', 'meta', 'param',   'source', 'track', 'wbr',
]);

/** These tags we do not allow editing their tag name. **/
export const EditTagBlocklist = new Set<string>(['html', 'head', 'body']);

export function adornerComparator(adornerA: Adorners.Adorner.Adorner, adornerB: Adorners.Adorner.Adorner): number {
  const compareCategories =
      ElementsComponents.AdornerManager.compareAdornerNamesByCategory(adornerB.name, adornerB.name);
  if (compareCategories === 0) {
    return adornerA.name.localeCompare(adornerB.name);
  }
  return compareCategories;
}

export function convertUnicodeCharsToHTMLEntities(text: string): {
  text: string,
  entityRanges: TextUtils.TextRange.SourceRange[],
} {
  let result = '';
  let lastIndexAfterEntity = 0;
  const entityRanges = [];
  const charToEntity = MappedCharToEntity;
  for (let i = 0, size = text.length; i < size; ++i) {
    const char = text.charAt(i);
    if (charToEntity.has(char)) {
      result += text.substring(lastIndexAfterEntity, i);
      const entityValue = '&' + charToEntity.get(char) + ';';
      entityRanges.push(new TextUtils.TextRange.SourceRange(result.length, entityValue.length));
      result += entityValue;
      lastIndexAfterEntity = i + 1;
    }
  }
  if (result) {
    result += text.substring(lastIndexAfterEntity);
  }
  return {text: result || text, entityRanges};
}

export interface EditorHandles {
  commit: () => void;
  cancel: () => void;
  editor?: TextEditor.TextEditor.TextEditor;
  resize: () => void;
}

/**
 * As a privacy measure we are logging elements tree outline as a flat list where every tree item is a
 * child of a tree outline.
 **/
function loggingParentProvider(e: Element): Element|undefined {
  const treeElement = UI.TreeOutline.TreeElement.getTreeElementBylistItemNode(e);
  return treeElement?.treeOutline?.contentElement;
}

VisualLogging.registerParentProvider('elementsTreeOutline', loggingParentProvider);