/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

const flags = require("resource://devtools/shared/flags.js");
const nodeConstants = require("resource://devtools/shared/dom-node-constants.js");
const nodeFilterConstants = require("resource://devtools/shared/dom-node-filter-constants.js");
const EventEmitter = require("resource://devtools/shared/event-emitter.js");
const { LocalizationHelper } = require("resource://devtools/shared/l10n.js");
const { PluralForm } = require("resource://devtools/shared/plural-form.js");
const AutocompletePopup = require("resource://devtools/client/shared/autocomplete-popup.js");
const KeyShortcuts = require("resource://devtools/client/shared/key-shortcuts.js");
const {
  scrollIntoViewIfNeeded,
} = require("resource://devtools/client/shared/scroll.js");
const { PrefObserver } = require("resource://devtools/client/shared/prefs.js");
const MarkupElementContainer = require("resource://devtools/client/inspector/markup/views/element-container.js");
const MarkupReadOnlyContainer = require("resource://devtools/client/inspector/markup/views/read-only-container.js");
const MarkupTextContainer = require("resource://devtools/client/inspector/markup/views/text-container.js");
const RootContainer = require("resource://devtools/client/inspector/markup/views/root-container.js");
const WalkerEventListener = require("resource://devtools/client/inspector/shared/walker-event-listener.js");

loader.lazyRequireGetter(
  this,
  ["createDOMMutationBreakpoint", "deleteDOMMutationBreakpoint"],
  "resource://devtools/client/framework/actions/index.js",
  true
);
loader.lazyRequireGetter(
  this,
  "MarkupContextMenu",
  "resource://devtools/client/inspector/markup/markup-context-menu.js"
);
loader.lazyRequireGetter(
  this,
  "SlottedNodeContainer",
  "resource://devtools/client/inspector/markup/views/slotted-node-container.js"
);
loader.lazyRequireGetter(
  this,
  "getLongString",
  "resource://devtools/client/inspector/shared/utils.js",
  true
);
loader.lazyRequireGetter(
  this,
  "openContentLink",
  "resource://devtools/client/shared/link.js",
  true
);
loader.lazyRequireGetter(
  this,
  "HTMLTooltip",
  "resource://devtools/client/shared/widgets/tooltip/HTMLTooltip.js",
  true
);
loader.lazyRequireGetter(
  this,
  "UndoStack",
  "resource://devtools/client/shared/undo.js",
  true
);
loader.lazyRequireGetter(
  this,
  "clipboardHelper",
  "resource://devtools/shared/platform/clipboard.js"
);
loader.lazyRequireGetter(
  this,
  "beautify",
  "resource://devtools/shared/jsbeautify/beautify.js"
);
loader.lazyRequireGetter(
  this,
  "getTabPrefs",
  "resource://devtools/shared/indentation.js",
  true
);

const INSPECTOR_L10N = new LocalizationHelper(
  "devtools/client/locales/inspector.properties"
);

// Page size for pageup/pagedown
const PAGE_SIZE = 10;
const DEFAULT_MAX_CHILDREN = 100;
const DRAG_DROP_AUTOSCROLL_EDGE_MAX_DISTANCE = 50;
const DRAG_DROP_AUTOSCROLL_EDGE_RATIO = 0.1;
const DRAG_DROP_MIN_AUTOSCROLL_SPEED = 2;
const DRAG_DROP_MAX_AUTOSCROLL_SPEED = 8;
const DRAG_DROP_HEIGHT_TO_SPEED = 500;
const DRAG_DROP_HEIGHT_TO_SPEED_MIN = 0.5;
const DRAG_DROP_HEIGHT_TO_SPEED_MAX = 1;
const ATTR_COLLAPSE_ENABLED_PREF = "devtools.markup.collapseAttributes";
const ATTR_COLLAPSE_LENGTH_PREF = "devtools.markup.collapseAttributeLength";
const BEAUTIFY_HTML_ON_COPY_PREF = "devtools.markup.beautifyOnCopy";

/**
 * These functions are called when a shortcut (as defined in `_initShortcuts`) occurs.
 * Each property in the following object corresponds to one of the shortcut that is
 * handled by the markup-view.
 * Each property value is a function that takes the markup-view instance as only
 * argument, and returns a boolean that signifies whether the event should be consumed.
 * By default, the event gets consumed after the shortcut handler returns,
 * this means its propagation is stopped. If you do want the shortcut event
 * to continue propagating through DevTools, then return true from the handler.
 */
const shortcutHandlers = {
  // Localizable keys
  "markupView.hide.key": markupView => {
    const node = markupView._selectedContainer.node;
    const walkerFront = node.walkerFront;

    if (node.hidden) {
      walkerFront.unhideNode(node);
    } else {
      walkerFront.hideNode(node);
    }
  },
  "markupView.edit.key": markupView => {
    markupView.beginEditingHTML(markupView._selectedContainer.node);
  },
  "markupView.scrollInto.key": markupView => {
    markupView.scrollNodeIntoView();
  },
  // Generic keys
  Delete: markupView => {
    markupView.deleteNodeOrAttribute();
  },
  Backspace: markupView => {
    markupView.deleteNodeOrAttribute(true);
  },
  Home: markupView => {
    const rootContainer = markupView.getContainer(markupView._rootNode);
    markupView.navigate(rootContainer.children.firstChild.container);
  },
  Left: markupView => {
    if (markupView._selectedContainer.expanded) {
      markupView.collapseNode(markupView._selectedContainer.node);
    } else {
      const parent = markupView._selectionWalker().parentNode();
      if (parent) {
        markupView.navigate(parent.container);
      }
    }
  },
  Right: markupView => {
    if (
      !markupView._selectedContainer.expanded &&
      markupView._selectedContainer.hasChildren
    ) {
      markupView._expandContainer(markupView._selectedContainer);
    } else {
      const next = markupView._selectionWalker().nextNode();
      if (next) {
        markupView.navigate(next.container);
      }
    }
  },
  Up: markupView => {
    const previousNode = markupView._selectionWalker().previousNode();
    if (previousNode) {
      markupView.navigate(previousNode.container);
    }
  },
  Down: markupView => {
    const nextNode = markupView._selectionWalker().nextNode();
    if (nextNode) {
      markupView.navigate(nextNode.container);
    }
  },
  PageUp: markupView => {
    const walker = markupView._selectionWalker();
    let selection = markupView._selectedContainer;
    for (let i = 0; i < PAGE_SIZE; i++) {
      const previousNode = walker.previousNode();
      if (!previousNode) {
        break;
      }
      selection = previousNode.container;
    }
    markupView.navigate(selection);
  },
  PageDown: markupView => {
    const walker = markupView._selectionWalker();
    let selection = markupView._selectedContainer;
    for (let i = 0; i < PAGE_SIZE; i++) {
      const nextNode = walker.nextNode();
      if (!nextNode) {
        break;
      }
      selection = nextNode.container;
    }
    markupView.navigate(selection);
  },
  Enter: markupView => {
    if (!markupView._selectedContainer.canFocus) {
      markupView._selectedContainer.canFocus = true;
      markupView._selectedContainer.focus();
      return false;
    }
    return true;
  },
  Space: markupView => {
    if (!markupView._selectedContainer.canFocus) {
      markupView._selectedContainer.canFocus = true;
      markupView._selectedContainer.focus();
      return false;
    }
    return true;
  },
  Esc: markupView => {
    if (markupView.isDragging) {
      markupView.cancelDragging();
      return false;
    }
    // Prevent cancelling the event when not
    // dragging, to allow the split console to be toggled.
    return true;
  },
};

/**
 * Vocabulary for the purposes of this file:
 *
 * MarkupContainer - the structure that holds an editor and its
 *  immediate children in the markup panel.
 *  - MarkupElementContainer: markup container for element nodes
 *  - MarkupTextContainer: markup container for text / comment nodes
 *  - MarkupReadonlyContainer: markup container for other nodes
 * Node - A content node.
 * object.elt - A UI element in the markup panel.
 */

/**
 * The markup tree.  Manages the mapping of nodes to MarkupContainers,
 * updating based on mutations, and the undo/redo bindings.
 *
 * @param  {Inspector} inspector
 *         The inspector we're watching.
 * @param  {iframe} frame
 *         An iframe in which the caller has kindly loaded markup.xhtml.
 * @param  {XULWindow} controllerWindow
 *         Will enable the undo/redo feature from devtools/client/shared/undo.
 *         Should be a XUL window, will typically point to the toolbox window.
 */
function MarkupView(inspector, frame, controllerWindow) {
  EventEmitter.decorate(this);

  this.controllerWindow = controllerWindow;
  this.inspector = inspector;
  this.highlighters = inspector.highlighters;
  this.walker = this.inspector.walker;
  this._frame = frame;
  this.win = this._frame.contentWindow;
  this.doc = this._frame.contentDocument;
  this._elt = this.doc.getElementById("root");
  this.telemetry = this.inspector.telemetry;
  this._breakpointIDsInLocalState = new Map();
  this._containersToUpdate = new Map();

  this.maxChildren = Services.prefs.getIntPref(
    "devtools.markup.pagesize",
    DEFAULT_MAX_CHILDREN
  );

  this.collapseAttributes = Services.prefs.getBoolPref(
    ATTR_COLLAPSE_ENABLED_PREF
  );
  this.collapseAttributeLength = Services.prefs.getIntPref(
    ATTR_COLLAPSE_LENGTH_PREF
  );

  // Creating the popup to be used to show CSS suggestions.
  // The popup will be attached to the toolbox document.
  this.popup = new AutocompletePopup(inspector.toolbox.doc, {
    autoSelect: true,
  });

  this._containers = new Map();
  // This weakmap will hold keys used with the _containers map, in order to retrieve the
  // slotted container for a given node front.
  this._slottedContainerKeys = new WeakMap();

  // Binding functions that need to be called in scope.
  this._handleRejectionIfNotDestroyed =
    this._handleRejectionIfNotDestroyed.bind(this);
  this._isImagePreviewTarget = this._isImagePreviewTarget.bind(this);
  this._onWalkerMutations = this._onWalkerMutations.bind(this);
  this._onBlur = this._onBlur.bind(this);
  this._onContextMenu = this._onContextMenu.bind(this);
  this._onCopy = this._onCopy.bind(this);
  this._onCollapseAttributesPrefChange =
    this._onCollapseAttributesPrefChange.bind(this);
  this._onWalkerNodeStatesChanged = this._onWalkerNodeStatesChanged.bind(this);
  this._onFocus = this._onFocus.bind(this);
  this._onResourceAvailable = this._onResourceAvailable.bind(this);
  this._onTargetAvailable = this._onTargetAvailable.bind(this);
  this._onTargetDestroyed = this._onTargetDestroyed.bind(this);
  this._onMouseClick = this._onMouseClick.bind(this);
  this._onMouseMove = this._onMouseMove.bind(this);
  this._onMouseOut = this._onMouseOut.bind(this);
  this._onMouseUp = this._onMouseUp.bind(this);
  this._onNewSelection = this._onNewSelection.bind(this);
  this._onToolboxPickerCanceled = this._onToolboxPickerCanceled.bind(this);
  this._onToolboxPickerHover = this._onToolboxPickerHover.bind(this);
  this._onDomMutation = this._onDomMutation.bind(this);

  // Listening to various events.
  this._elt.addEventListener("blur", this._onBlur, true);
  this._elt.addEventListener("click", this._onMouseClick);
  this._elt.addEventListener("contextmenu", this._onContextMenu);
  this._elt.addEventListener("mousemove", this._onMouseMove);
  this._elt.addEventListener("mouseout", this._onMouseOut);
  this._frame.addEventListener("focus", this._onFocus);
  this.inspector.selection.on("new-node-front", this._onNewSelection);
  this._unsubscribeFromToolboxStore = this.inspector.toolbox.store.subscribe(
    this._onDomMutation
  );

  if (flags.testing) {
    // In tests, we start listening immediately to avoid having to simulate a mousemove.
    this._initTooltips();
  }

  this.win.addEventListener("copy", this._onCopy);
  this.win.addEventListener("mouseup", this._onMouseUp);
  this.inspector.toolbox.nodePicker.on(
    "picker-node-canceled",
    this._onToolboxPickerCanceled
  );
  this.inspector.toolbox.nodePicker.on(
    "picker-node-hovered",
    this._onToolboxPickerHover
  );

  // Event listeners for highlighter events
  this.onHighlighterShown = data =>
    this.handleHighlighterEvent("highlighter-shown", data);
  this.onHighlighterHidden = data =>
    this.handleHighlighterEvent("highlighter-hidden", data);
  this.inspector.highlighters.on("highlighter-shown", this.onHighlighterShown);
  this.inspector.highlighters.on(
    "highlighter-hidden",
    this.onHighlighterHidden
  );

  this._onNewSelection();
  if (this.inspector.selection.nodeFront) {
    this.expandNode(this.inspector.selection.nodeFront);
  }

  this._prefObserver = new PrefObserver("devtools.markup");
  this._prefObserver.on(
    ATTR_COLLAPSE_ENABLED_PREF,
    this._onCollapseAttributesPrefChange
  );
  this._prefObserver.on(
    ATTR_COLLAPSE_LENGTH_PREF,
    this._onCollapseAttributesPrefChange
  );

  this._initShortcuts();

  this._walkerEventListener = new WalkerEventListener(this.inspector, {
    "container-type-change": this._onWalkerNodeStatesChanged,
    "display-change": this._onWalkerNodeStatesChanged,
    "scrollable-change": this._onWalkerNodeStatesChanged,
    "overflow-change": this._onWalkerNodeStatesChanged,
    mutations: this._onWalkerMutations,
  });

  this.resourceCommand = this.inspector.toolbox.resourceCommand;
  this.resourceCommand.watchResources([this.resourceCommand.TYPES.ROOT_NODE], {
    onAvailable: this._onResourceAvailable,
  });

  this.targetCommand = this.inspector.commands.targetCommand;
  this.targetCommand.watchTargets({
    types: [this.targetCommand.TYPES.FRAME],
    onAvailable: this._onTargetAvailable,
    onDestroyed: this._onTargetDestroyed,
  });
}

MarkupView.prototype = {
  /**
   * How long does a node flash when it mutates (in ms).
   */
  CONTAINER_FLASHING_DURATION: 500,

  _selectedContainer: null,

  get contextMenu() {
    if (!this._contextMenu) {
      this._contextMenu = new MarkupContextMenu(this);
    }

    return this._contextMenu;
  },

  hasEventDetailsTooltip() {
    return !!this._eventDetailsTooltip;
  },

  get eventDetailsTooltip() {
    if (!this._eventDetailsTooltip) {
      // This tooltip will be attached to the toolbox document.
      this._eventDetailsTooltip = new HTMLTooltip(this.toolbox.doc, {
        type: "arrow",
        consumeOutsideClicks: false,
      });
    }

    return this._eventDetailsTooltip;
  },

  get toolbox() {
    return this.inspector.toolbox;
  },

  get undo() {
    if (!this._undo) {
      this._undo = new UndoStack();
      this._undo.installController(this.controllerWindow);
    }

    return this._undo;
  },

  _onDomMutation() {
    const domMutationBreakpoints =
      this.inspector.toolbox.store.getState().domMutationBreakpoints
        .breakpoints;
    const breakpointIDsInCurrentState = [];
    for (const breakpoint of domMutationBreakpoints) {
      const nodeFront = breakpoint.nodeFront;
      const mutationType = breakpoint.mutationType;
      const enabledStatus = breakpoint.enabled;
      breakpointIDsInCurrentState.push(breakpoint.id);
      // If breakpoint is not in local state
      if (!this._breakpointIDsInLocalState.has(breakpoint.id)) {
        this._breakpointIDsInLocalState.set(breakpoint.id, breakpoint);
        if (!this._containersToUpdate.has(nodeFront)) {
          this._containersToUpdate.set(nodeFront, new Map());
        }
      }
      this._containersToUpdate.get(nodeFront).set(mutationType, enabledStatus);
    }
    // If a breakpoint is in local state but not current state, it has been
    // removed by the user.
    for (const id of this._breakpointIDsInLocalState.keys()) {
      if (breakpointIDsInCurrentState.includes(id) === false) {
        const nodeFront = this._breakpointIDsInLocalState.get(id).nodeFront;
        const mutationType =
          this._breakpointIDsInLocalState.get(id).mutationType;
        this._containersToUpdate.get(nodeFront).delete(mutationType);
        this._breakpointIDsInLocalState.delete(id);
      }
    }
    // Update each container
    for (const nodeFront of this._containersToUpdate.keys()) {
      const mutationBreakpoints = this._containersToUpdate.get(nodeFront);
      const container = this.getContainer(nodeFront);
      container.update(mutationBreakpoints);
      if (this._containersToUpdate.get(nodeFront).size === 0) {
        this._containersToUpdate.delete(nodeFront);
      }
    }
  },

  /**
   * Handle promise rejections for various asynchronous actions, and only log errors if
   * the markup view still exists.
   * This is useful to silence useless errors that happen when the markup view is
   * destroyed while still initializing (and making protocol requests).
   */
  _handleRejectionIfNotDestroyed(e) {
    if (!this._destroyed) {
      console.error(e);
    }
  },

  _initTooltips() {
    if (this.imagePreviewTooltip) {
      return;
    }
    // The tooltips will be attached to the toolbox document.
    this.imagePreviewTooltip = new HTMLTooltip(this.toolbox.doc, {
      type: "arrow",
      useXulWrapper: true,
    });
    this._enableImagePreviewTooltip();
  },

  _enableImagePreviewTooltip() {
    if (!this.imagePreviewTooltip) {
      return;
    }
    this.imagePreviewTooltip.startTogglingOnHover(
      this._elt,
      this._isImagePreviewTarget
    );
  },

  _disableImagePreviewTooltip() {
    if (!this.imagePreviewTooltip) {
      return;
    }
    this.imagePreviewTooltip.stopTogglingOnHover();
  },

  _onToolboxPickerHover(nodeFront) {
    this.showNode(nodeFront).then(() => {
      this._showNodeAsHovered(nodeFront);
    }, console.error);
  },

  /**
   * If the element picker gets canceled, make sure and re-center the view on the
   * current selected element.
   */
  _onToolboxPickerCanceled() {
    if (this._selectedContainer) {
      scrollIntoViewIfNeeded(this._selectedContainer.editor.elt);
    }
  },

  isDragging: false,
  _draggedContainer: null,

  _onMouseMove(event) {
    // Note that in tests, we start listening immediately from the constructor to avoid having to simulate a mousemove.
    // Also note that initTooltips bails out if it is called many times, so it isn't an issue to call it a second
    // time from here in case tests are doing a mousemove.
    this._initTooltips();

    let target = event.target;

    if (this._draggedContainer) {
      this._draggedContainer.onMouseMove(event);
    }
    // Auto-scroll if we're dragging.
    if (this.isDragging) {
      event.preventDefault();
      this._autoScroll(event);
      return;
    }

    // Show the current container as hovered and highlight it.
    // This requires finding the current MarkupContainer (walking up the DOM).
    while (!target.container) {
      if (target.tagName.toLowerCase() === "body") {
        return;
      }
      target = target.parentNode;
    }

    const container = target.container;
    if (this._hoveredContainer !== container) {
      this._showBoxModel(container.node);
    }
    this._showContainerAsHovered(container);

    this.emit("node-hover");
  },

  /**
   * If focus is moved outside of the markup view document and there is a
   * selected container, make its contents not focusable by a keyboard.
   */
  _onBlur(event) {
    if (!this._selectedContainer) {
      return;
    }

    const { relatedTarget } = event;
    if (relatedTarget && relatedTarget.ownerDocument === this.doc) {
      return;
    }

    if (this._selectedContainer) {
      this._selectedContainer.clearFocus();
    }
  },

  _onContextMenu(event) {
    this.contextMenu.show(event);
  },

  /**
   * Executed on each mouse-move while a node is being dragged in the view.
   * Auto-scrolls the view to reveal nodes below the fold to drop the dragged
   * node in.
   */
  _autoScroll(event) {
    const docEl = this.doc.documentElement;

    if (this._autoScrollAnimationFrame) {
      this.win.cancelAnimationFrame(this._autoScrollAnimationFrame);
    }

    // Auto-scroll when the mouse approaches top/bottom edge.
    const fromBottom = docEl.clientHeight - event.pageY + this.win.scrollY;
    const fromTop = event.pageY - this.win.scrollY;
    const edgeDistance = Math.min(
      DRAG_DROP_AUTOSCROLL_EDGE_MAX_DISTANCE,
      docEl.clientHeight * DRAG_DROP_AUTOSCROLL_EDGE_RATIO
    );

    // The smaller the screen, the slower the movement.
    const heightToSpeedRatio = Math.max(
      DRAG_DROP_HEIGHT_TO_SPEED_MIN,
      Math.min(
        DRAG_DROP_HEIGHT_TO_SPEED_MAX,
        docEl.clientHeight / DRAG_DROP_HEIGHT_TO_SPEED
      )
    );

    if (fromBottom <= edgeDistance) {
      // Map our distance range to a speed range so that the speed is not too
      // fast or too slow.
      const speed = map(
        fromBottom,
        0,
        edgeDistance,
        DRAG_DROP_MIN_AUTOSCROLL_SPEED,
        DRAG_DROP_MAX_AUTOSCROLL_SPEED
      );

      this._runUpdateLoop(() => {
        docEl.scrollTop -=
          heightToSpeedRatio * (speed - DRAG_DROP_MAX_AUTOSCROLL_SPEED);
      });
    }

    if (fromTop <= edgeDistance) {
      const speed = map(
        fromTop,
        0,
        edgeDistance,
        DRAG_DROP_MIN_AUTOSCROLL_SPEED,
        DRAG_DROP_MAX_AUTOSCROLL_SPEED
      );

      this._runUpdateLoop(() => {
        docEl.scrollTop +=
          heightToSpeedRatio * (speed - DRAG_DROP_MAX_AUTOSCROLL_SPEED);
      });
    }
  },

  /**
   * Run a loop on the requestAnimationFrame.
   */
  _runUpdateLoop(update) {
    const loop = () => {
      update();
      this._autoScrollAnimationFrame = this.win.requestAnimationFrame(loop);
    };
    loop();
  },

  _onMouseClick(event) {
    // From the target passed here, let's find the parent MarkupContainer
    // and forward the event if needed.
    let parentNode = event.target;
    let container;
    while (parentNode !== this.doc.body) {
      if (parentNode.container) {
        container = parentNode.container;
        break;
      }
      parentNode = parentNode.parentNode;
    }

    if (typeof container.onContainerClick === "function") {
      // Forward the event to the container if it implements onContainerClick.
      container.onContainerClick(event);
    }
  },

  _onMouseUp(event) {
    if (this._draggedContainer) {
      this._draggedContainer.onMouseUp(event);
    }

    this.indicateDropTarget(null);
    this.indicateDragTarget(null);
    if (this._autoScrollAnimationFrame) {
      this.win.cancelAnimationFrame(this._autoScrollAnimationFrame);
    }
  },

  _onCollapseAttributesPrefChange() {
    this.collapseAttributes = Services.prefs.getBoolPref(
      ATTR_COLLAPSE_ENABLED_PREF
    );
    this.collapseAttributeLength = Services.prefs.getIntPref(
      ATTR_COLLAPSE_LENGTH_PREF
    );
    this.update();
  },

  cancelDragging() {
    if (!this.isDragging) {
      return;
    }

    for (const [, container] of this._containers) {
      if (container.isDragging) {
        container.cancelDragging();
        break;
      }
    }

    this.indicateDropTarget(null);
    this.indicateDragTarget(null);
    if (this._autoScrollAnimationFrame) {
      this.win.cancelAnimationFrame(this._autoScrollAnimationFrame);
    }
  },

  _hoveredContainer: null,

  /**
   * Show a NodeFront's container as being hovered
   *
   * @param  {NodeFront} nodeFront
   *         The node to show as hovered
   */
  _showNodeAsHovered(nodeFront) {
    const container = this.getContainer(nodeFront);
    this._showContainerAsHovered(container);
  },

  _showContainerAsHovered(container) {
    if (this._hoveredContainer === container) {
      return;
    }

    if (this._hoveredContainer) {
      this._hoveredContainer.hovered = false;
    }

    container.hovered = true;
    this._hoveredContainer = container;
  },

  async _onMouseOut(event) {
    // Emulate mouseleave by skipping any relatedTarget inside the markup-view.
    if (this._elt.contains(event.relatedTarget)) {
      return;
    }

    if (this._autoScrollAnimationFrame) {
      this.win.cancelAnimationFrame(this._autoScrollAnimationFrame);
    }
    if (this.isDragging) {
      return;
    }

    await this._hideBoxModel();
    if (this._hoveredContainer) {
      this._hoveredContainer.hovered = false;
    }
    this._hoveredContainer = null;

    this.emit("leave");
  },

  /**
   * Show the Box Model Highlighter on a given node front
   *
   * @param  {NodeFront} nodeFront
   *         The node for which to show the highlighter.
   * @param  {Object} options
   *         Configuration object with options for the Box Model Highlighter.
   * @return {Promise} Resolves after the highlighter for this nodeFront is shown.
   */
  _showBoxModel(nodeFront, options) {
    return this.inspector.highlighters.showHighlighterTypeForNode(
      this.inspector.highlighters.TYPES.BOXMODEL,
      nodeFront,
      options
    );
  },

  /**
   * Hide the Box Model Highlighter for any node that may be highlighted.
   *
   * @return {Promise} Resolves when the highlighter is hidden.
   */
  _hideBoxModel() {
    return this.inspector.highlighters.hideHighlighterType(
      this.inspector.highlighters.TYPES.BOXMODEL
    );
  },

  /**
   * Delegate handler for highlighter events.
   *
   * This is the place to observe for highlighter events, check the highlighter type and
   * event name, then react for example by modifying the DOM.
   *
   * @param {String} eventName
   *        Highlighter event name. One of: "highlighter-hidden", "highlighter-shown"
   * @param {Object} data
   *        Object with data associated with the highlighter event.
   *        {String} data.type
   *        Highlighter type
   *        {NodeFront} data.nodeFront
   *        NodeFront of the node associated with the highlighter event
   *        {Object} data.options
   *        Optional configuration passed to the highlighter when shown
   *        {CustomHighlighterFront} data.highlighter
   *        Highlighter instance
   *
   */
  handleHighlighterEvent(eventName, data) {
    switch (data.type) {
      // Toggle the "active" CSS class name on flex and grid display badges next to
      // elements in the Markup view when a coresponding flex or grid highlighter is
      // shown or hidden for a node.
      case this.inspector.highlighters.TYPES.FLEXBOX:
      case this.inspector.highlighters.TYPES.GRID:
        const { nodeFront } = data;
        if (!nodeFront) {
          return;
        }

        // Find the badge corresponding to the node from the highlighter event payload.
        const container = this.getContainer(nodeFront);
        const badge = container?.editor?.displayBadge;
        if (badge) {
          const isActive = eventName == "highlighter-shown";
          badge.classList.toggle("active", isActive);
          badge.setAttribute("aria-pressed", isActive);
        }

        // There is a limit to how many grid highlighters can be active at the same time.
        // If the limit was reached, disable all non-active grid badges.
        if (data.type === this.inspector.highlighters.TYPES.GRID) {
          // Matches badges for "grid", "inline-grid" and "subgrid"
          const selector = "[data-display*='grid']:not(.active)";
          const isLimited =
            this.inspector.highlighters.isGridHighlighterLimitReached();
          Array.from(this._elt.querySelectorAll(selector)).map(el => {
            el.classList.toggle("interactive", !isLimited);
          });
        }
        break;
    }
  },

  /**
   * Used by tests
   */
  getSelectedContainer() {
    return this._selectedContainer;
  },

  /**
   * Get the MarkupContainer object for a given node, or undefined if
   * none exists.
   *
   * @param  {NodeFront} nodeFront
   *         The node to get the container for.
   * @param  {Boolean} slotted
   *         true to get the slotted version of the container.
   * @return {MarkupContainer} The container for the provided node.
   */
  getContainer(node, slotted) {
    const key = this._getContainerKey(node, slotted);
    return this._containers.get(key);
  },

  /**
   * Register a given container for a given node/slotted node.
   *
   * @param  {NodeFront} nodeFront
   *         The node to set the container for.
   * @param  {Boolean} slotted
   *         true if the container represents the slotted version of the node.
   */
  setContainer(node, container, slotted) {
    const key = this._getContainerKey(node, slotted);
    return this._containers.set(key, container);
  },

  /**
   * Check if a MarkupContainer object exists for a given node/slotted node
   *
   * @param  {NodeFront} nodeFront
   *         The node to check.
   * @param  {Boolean} slotted
   *         true to check for a container matching the slotted version of the node.
   * @return {Boolean} True if a container exists, false otherwise.
   */
  hasContainer(node, slotted) {
    const key = this._getContainerKey(node, slotted);
    return this._containers.has(key);
  },

  _getContainerKey(node, slotted) {
    if (!slotted) {
      return node;
    }

    if (!this._slottedContainerKeys.has(node)) {
      this._slottedContainerKeys.set(node, { node });
    }
    return this._slottedContainerKeys.get(node);
  },

  _isContainerSelected(container) {
    if (!container) {
      return false;
    }

    const selection = this.inspector.selection;
    return (
      container.node == selection.nodeFront &&
      container.isSlotted() == selection.isSlotted()
    );
  },

  update() {
    const updateChildren = node => {
      this.getContainer(node).update();
      for (const child of node.treeChildren()) {
        updateChildren(child);
      }
    };

    // Start with the documentElement
    let documentElement;
    for (const node of this._rootNode.treeChildren()) {
      if (node.isDocumentElement === true) {
        documentElement = node;
        break;
      }
    }

    // Recursively update each node starting with documentElement.
    updateChildren(documentElement);
  },

  /**
   * Executed when the mouse hovers over a target in the markup-view and is used
   * to decide whether this target should be used to display an image preview
   * tooltip.
   * Delegates the actual decision to the corresponding MarkupContainer instance
   * if one is found.
   *
   * @return {Promise} the promise returned by
   *         MarkupElementContainer._isImagePreviewTarget
   */
  async _isImagePreviewTarget(target) {
    // From the target passed here, let's find the parent MarkupContainer
    // and ask it if the tooltip should be shown
    if (this.isDragging) {
      return false;
    }

    let parent = target,
      container;
    while (parent) {
      if (parent.container) {
        container = parent.container;
        break;
      }
      parent = parent.parentNode;
    }

    if (container instanceof MarkupElementContainer) {
      return container.isImagePreviewTarget(target, this.imagePreviewTooltip);
    }

    return false;
  },

  /**
   * Given the known reason, should the current selection be briefly highlighted
   * In a few cases, we don't want to highlight the node:
   * - If the reason is null (used to reset the selection),
   * - if it's "inspector-default-selection" (initial node selected, either when
   *   opening the inspector or after a navigation/reload)
   * - if it's "picker-node-picked" or "picker-node-previewed" (node selected with the
   *   node picker. Note that this does not include the "Inspect element" context menu,
   *   which has a dedicated reason, "browser-context-menu").
   * - if it's "test" (this is a special case for mochitest. In tests, we often
   * need to select elements but don't necessarily want the highlighter to come
   * and go after a delay as this might break test scenarios)
   * We also do not want to start a brief highlight timeout if the node is
   * already being hovered over, since in that case it will already be
   * highlighted.
   */
  _shouldNewSelectionBeHighlighted() {
    const reason = this.inspector.selection.reason;
    const unwantedReasons = [
      "inspector-default-selection",
      "nodeselected",
      "picker-node-picked",
      "picker-node-previewed",
      "test",
    ];

    const isHighlight = this._isContainerSelected(this._hoveredContainer);
    return !isHighlight && reason && !unwantedReasons.includes(reason);
  },

  /**
   * React to new-node-front selection events.
   * Highlights the node if needed, and make sure it is shown and selected in
   * the view.
   */
  _onNewSelection(nodeFront, reason) {
    const selection = this.inspector.selection;
    // this will probably leak.
    // TODO: use resource api listeners?
    if (nodeFront) {
      nodeFront.walkerFront.on(
        "container-type-change",
        this._onWalkerNodeStatesChanged
      );
      nodeFront.walkerFront.on(
        "display-change",
        this._onWalkerNodeStatesChanged
      );
      nodeFront.walkerFront.on(
        "scrollable-change",
        this._onWalkerNodeStatesChanged
      );
      nodeFront.walkerFront.on(
        "overflow-change",
        this._onWalkerNodeStatesChanged
      );
      nodeFront.walkerFront.on("mutations", this._onWalkerMutations);
    }

    if (this.htmlEditor) {
      this.htmlEditor.hide();
    }
    if (this._isContainerSelected(this._hoveredContainer)) {
      this._hoveredContainer.hovered = false;
      this._hoveredContainer = null;
    }

    if (!selection.isNode()) {
      this.unmarkSelectedNode();
      return;
    }

    const done = this.inspector.updating("markup-view");
    let onShowBoxModel;

    // Highlight the element briefly if needed.
    if (this._shouldNewSelectionBeHighlighted()) {
      onShowBoxModel = this._showBoxModel(nodeFront, {
        duration: this.inspector.HIGHLIGHTER_AUTOHIDE_TIMER,
      });
    }

    const slotted = selection.isSlotted();
    const smoothScroll = reason === "reveal-from-slot";
    const onShow = this.showNode(selection.nodeFront, { slotted, smoothScroll })
      .then(() => {
        // We could be destroyed by now.
        if (this._destroyed) {
          return Promise.reject("markupview destroyed");
        }

        // Mark the node as selected.
        const container = this.getContainer(selection.nodeFront, slotted);
        this._markContainerAsSelected(container);

        // Make sure the new selection is navigated to.
        this.maybeNavigateToNewSelection();
        return undefined;
      })
      .catch(this._handleRejectionIfNotDestroyed);

    Promise.all([onShowBoxModel, onShow]).then(done);
  },

  /**
   * Maybe make selected the current node selection's MarkupContainer depending
   * on why the current node got selected.
   */
  async maybeNavigateToNewSelection() {
    const { reason, nodeFront } = this.inspector.selection;

    // The list of reasons that should lead to navigating to the node.
    const reasonsToNavigate = [
      // If the user picked an element with the element picker.
      "picker-node-picked",
      // If the user shift-clicked (previewed) an element.
      "picker-node-previewed",
      // If the user selected an element with the browser context menu.
      "browser-context-menu",
      // If the user added a new node by clicking in the inspector toolbar.
      "node-inserted",
    ];

    // If the user performed an action with a keyboard, move keyboard focus to
    // the markup tree container.
    if (reason && reason.endsWith("-keyboard")) {
      this.getContainer(this._rootNode).elt.focus();
    }

    if (reasonsToNavigate.includes(reason)) {
      // not sure this is necessary
      const root = await nodeFront.walkerFront.getRootNode();
      this.getContainer(root).elt.focus();
      this.navigate(this.getContainer(nodeFront));
    }
  },

  /**
   * Create a TreeWalker to find the next/previous
   * node for selection.
   */
  _selectionWalker(start) {
    const walker = this.doc.createTreeWalker(
      start || this._elt,
      nodeFilterConstants.SHOW_ELEMENT,
      function (element) {
        if (
          element.container &&
          element.container.elt === element &&
          element.container.visible
        ) {
          return nodeFilterConstants.FILTER_ACCEPT;
        }
        return nodeFilterConstants.FILTER_SKIP;
      }
    );
    walker.currentNode = this._selectedContainer.elt;
    return walker;
  },

  _onCopy(evt) {
    // Ignore copy events from editors
    if (this._isInputOrTextarea(evt.target)) {
      return;
    }

    const selection = this.inspector.selection;
    if (selection.isNode()) {
      this.copyOuterHTML();
    }
    evt.stopPropagation();
    evt.preventDefault();
  },

  /**
   * Copy the outerHTML of the selected Node to the clipboard.
   */
  copyOuterHTML() {
    if (!this.inspector.selection.isNode()) {
      return;
    }
    const node = this.inspector.selection.nodeFront;

    switch (node.nodeType) {
      case nodeConstants.ELEMENT_NODE:
        copyLongHTMLString(node.walkerFront.outerHTML(node));
        break;
      case nodeConstants.COMMENT_NODE:
        getLongString(node.getNodeValue()).then(comment => {
          clipboardHelper.copyString("<!--" + comment + "-->");
        });
        break;
      case nodeConstants.DOCUMENT_TYPE_NODE:
        clipboardHelper.copyString(node.doctypeString);
        break;
    }
  },

  /**
   * Copy the innerHTML of the selected Node to the clipboard.
   */
  copyInnerHTML() {
    const nodeFront = this.inspector.selection.nodeFront;
    if (!this.inspector.selection.isNode()) {
      return;
    }

    copyLongHTMLString(nodeFront.walkerFront.innerHTML(nodeFront));
  },

  /**
   * Given a type and link found in a node's attribute in the markup-view,
   * attempt to follow that link (which may result in opening a new tab, the
   * style editor or debugger).
   */
  followAttributeLink(type, link) {
    if (!type || !link) {
      return;
    }

    const nodeFront = this.inspector.selection.nodeFront;
    if (type === "uri" || type === "cssresource" || type === "jsresource") {
      // Open link in a new tab.
      nodeFront.inspectorFront
        .resolveRelativeURL(link, this.inspector.selection.nodeFront)
        .then(url => {
          if (type === "uri") {
            openContentLink(url);
          } else if (type === "cssresource") {
            return this.toolbox.viewGeneratedSourceInStyleEditor(url);
          } else if (type === "jsresource") {
            return this.toolbox.viewGeneratedSourceInDebugger(url);
          }
          return null;
        })
        .catch(console.error);
    } else if (type == "idref") {
      // Select the node in the same document.
      nodeFront.walkerFront
        .getIdrefNode(nodeFront, CSS.escape(link))
        .then(node => {
          if (!node) {
            this.emitForTests("idref-attribute-link-failed");
            return;
          }
          this.inspector.selection.setNodeFront(node, {
            reason: "markup-attribute-link",
          });
        })
        .catch(console.error);
    }
  },

  /**
   * Register all key shortcuts.
   */
  _initShortcuts() {
    const shortcuts = new KeyShortcuts({
      window: this.win,
    });

    // Keep a pointer on shortcuts to destroy them when destroying the markup
    // view.
    this._shortcuts = shortcuts;

    this._onShortcut = this._onShortcut.bind(this);

    // Process localizable keys
    [
      "markupView.hide.key",
      "markupView.edit.key",
      "markupView.scrollInto.key",
    ].forEach(name => {
      const key = INSPECTOR_L10N.getStr(name);
      shortcuts.on(key, event => this._onShortcut(name, event));
    });

    // Process generic keys:
    [
      "Delete",
      "Backspace",
      "Home",
      "Left",
      "Right",
      "Up",
      "Down",
      "PageUp",
      "PageDown",
      "Esc",
      "Enter",
      "Space",
    ].forEach(key => {
      shortcuts.on(key, event => this._onShortcut(key, event));
    });
  },

  /**
   * Key shortcut listener.
   */
  _onShortcut(name, event) {
    if (this._isInputOrTextarea(event.target)) {
      return;
    }

    // If the selected element is a button (e.g. `flex` badge), we don't want to highjack
    // keyboard activation.
    if (
      event.target.closest(":is(button, [role=button])") &&
      (name === "Enter" || name === "Space")
    ) {
      return;
    }

    const handler = shortcutHandlers[name];
    const shouldPropagate = handler(this);
    if (shouldPropagate) {
      return;
    }

    event.stopPropagation();
    event.preventDefault();
  },

  /**
   * Check if a node is an input or textarea
   */
  _isInputOrTextarea(element) {
    const name = element.tagName.toLowerCase();
    return name === "input" || name === "textarea";
  },

  /**
   * If there's an attribute on the current node that's currently focused, then
   * delete this attribute, otherwise delete the node itself.
   *
   * @param  {Boolean} moveBackward
   *         If set to true and if we're deleting the node, focus the previous
   *         sibling after deletion, otherwise the next one.
   */
  deleteNodeOrAttribute(moveBackward) {
    const focusedAttribute = this.doc.activeElement
      ? this.doc.activeElement.closest(".attreditor")
      : null;
    if (focusedAttribute) {
      // The focused attribute might not be in the current selected container.
      const container = focusedAttribute.closest("li.child").container;
      container.removeAttribute(focusedAttribute.dataset.attr);
    } else {
      this.deleteNode(this._selectedContainer.node, moveBackward);
    }
  },

  /**
   * Returns a value indicating whether a node can be deleted.
   *
   * @param {NodeFront} nodeFront
   *        The node to test for deletion
   */
  isDeletable(nodeFront) {
    return !(
      nodeFront.isDocumentElement ||
      nodeFront.nodeType == nodeConstants.DOCUMENT_NODE ||
      nodeFront.nodeType == nodeConstants.DOCUMENT_TYPE_NODE ||
      nodeFront.nodeType == nodeConstants.DOCUMENT_FRAGMENT_NODE ||
      nodeFront.isAnonymous
    );
  },

  /**
   * Delete a node from the DOM.
   * This is an undoable action.
   *
   * @param  {NodeFront} node
   *         The node to remove.
   * @param  {Boolean} moveBackward
   *         If set to true, focus the previous sibling, otherwise the next one.
   */
  deleteNode(node, moveBackward) {
    if (!this.isDeletable(node)) {
      return;
    }

    const container = this.getContainer(node);

    // Retain the node so we can undo this...
    node.walkerFront
      .retainNode(node)
      .then(() => {
        const parent = node.parentNode();
        let nextSibling = null;
        this.undo.do(
          () => {
            node.walkerFront.removeNode(node).then(siblings => {
              nextSibling = siblings.nextSibling;
              const prevSibling = siblings.previousSibling;
              let focusNode = moveBackward ? prevSibling : nextSibling;

              // If we can't move as the user wants, we move to the other direction.
              // If there is no sibling elements anymore, move to the parent node.
              if (!focusNode) {
                focusNode = nextSibling || prevSibling || parent;
              }

              const isNextSiblingText = nextSibling
                ? nextSibling.nodeType === nodeConstants.TEXT_NODE
                : false;
              const isPrevSiblingText = prevSibling
                ? prevSibling.nodeType === nodeConstants.TEXT_NODE
                : false;

              // If the parent had two children and the next or previous sibling
              // is a text node, then it now has only a single text node, is about
              // to be in-lined; and focus should move to the parent.
              if (
                parent.numChildren === 2 &&
                (isNextSiblingText || isPrevSiblingText)
              ) {
                focusNode = parent;
              }

              if (container.selected) {
                this.navigate(this.getContainer(focusNode));
              }
            });
          },
          () => {
            const isValidSibling = nextSibling && !nextSibling.isPseudoElement;
            nextSibling = isValidSibling ? nextSibling : null;
            node.walkerFront.insertBefore(node, parent, nextSibling);
          }
        );
      })
      .catch(console.error);
  },

  /**
   * Scroll the node into view.
   */
  scrollNodeIntoView() {
    if (!this.inspector.selection.isNode()) {
      return;
    }

    this.inspector.selection.nodeFront.scrollIntoView();
  },

  async toggleMutationBreakpoint(name) {
    if (!this.inspector.selection.isElementNode()) {
      return;
    }

    const toolboxStore = this.inspector.toolbox.store;
    const nodeFront = this.inspector.selection.nodeFront;

    if (nodeFront.mutationBreakpoints[name]) {
      toolboxStore.dispatch(deleteDOMMutationBreakpoint(nodeFront, name));
    } else {
      toolboxStore.dispatch(createDOMMutationBreakpoint(nodeFront, name));
    }
  },

  /**
   * If an editable item is focused, select its container.
   */
  _onFocus(event) {
    let parent = event.target;
    while (!parent.container) {
      parent = parent.parentNode;
    }
    if (parent) {
      this.navigate(parent.container);
    }
  },

  /**
   * Handle a user-requested navigation to a given MarkupContainer,
   * updating the inspector's currently-selected node.
   *
   * @param  {MarkupContainer} container
   *         The container we're navigating to.
   */
  navigate(container) {
    if (!container) {
      return;
    }

    this._markContainerAsSelected(container, "treepanel");
  },

  /**
   * Make sure a node is included in the markup tool.
   *
   * @param  {NodeFront} node
   *         The node in the content document.
   * @param  {Boolean} flashNode
   *         Whether the newly imported node should be flashed
   * @param  {Boolean} slotted
   *         Whether we are importing the slotted version of the node.
   * @return {MarkupContainer} The MarkupContainer object for this element.
   */
  importNode(node, flashNode, slotted) {
    if (!node) {
      return null;
    }

    if (this.hasContainer(node, slotted)) {
      return this.getContainer(node, slotted);
    }

    let container;
    const { nodeType, isPseudoElement } = node;
    if (node === node.walkerFront.rootNode) {
      container = new RootContainer(this, node);
      this._elt.appendChild(container.elt);
    }
    if (node === this.walker.rootNode) {
      this._rootNode = node;
    } else if (slotted) {
      container = new SlottedNodeContainer(this, node, this.inspector);
    } else if (nodeType == nodeConstants.ELEMENT_NODE && !isPseudoElement) {
      container = new MarkupElementContainer(this, node, this.inspector);
    } else if (
      nodeType == nodeConstants.COMMENT_NODE ||
      nodeType == nodeConstants.TEXT_NODE
    ) {
      container = new MarkupTextContainer(this, node, this.inspector);
    } else {
      container = new MarkupReadOnlyContainer(this, node, this.inspector);
    }

    if (flashNode) {
      container.flashMutation();
    }

    this.setContainer(node, container, slotted);
    this._forceUpdateChildren(container);

    this.inspector.emit("container-created", container);

    return container;
  },

  async _onResourceAvailable(resources) {
    for (const resource of resources) {
      if (
        !this.resourceCommand ||
        resource.resourceType !== this.resourceCommand.TYPES.ROOT_NODE ||
        resource.isDestroyed()
      ) {
        // Only handle alive root-node resources
        continue;
      }

      if (resource.targetFront.isTopLevel && resource.isTopLevelDocument) {
        // The topmost root node will lead to the destruction and recreation of
        // the MarkupView. This is handled by the inspector.
        continue;
      }

      const parentNodeFront = resource.parentNode();
      const container = this.getContainer(parentNodeFront);
      if (container) {
        // If there is no container for the parentNodeFront, the markup view is
        // currently not watching this part of the tree.
        this._forceUpdateChildren(container, {
          flash: true,
          updateLevel: true,
        });
      }
    }
  },

  _onTargetAvailable() {},

  _onTargetDestroyed({ targetFront, isModeSwitching }) {
    // Bug 1776250: We only watch targets in order to update containers which
    // might no longer be able to display children hosted in remote processes,
    // which corresponds to a Browser Toolbox mode switch.
    if (isModeSwitching) {
      const container = this.getContainer(targetFront.getParentNodeFront());
      if (container) {
        this._forceUpdateChildren(container, {
          updateLevel: true,
        });
      }
    }
  },

  /**
   * Mutation observer used for included nodes.
   */
  _onWalkerMutations(mutations) {
    for (const mutation of mutations) {
      const type = mutation.type;
      const target = mutation.target;

      const container = this.getContainer(target);
      if (!container) {
        // Container might not exist if this came from a load event for a node
        // we're not viewing.
        continue;
      }

      if (
        type === "attributes" ||
        type === "characterData" ||
        type === "customElementDefined" ||
        type === "events" ||
        type === "pseudoClassLock"
      ) {
        container.update();
      } else if (
        type === "childList" ||
        type === "slotchange" ||
        type === "shadowRootAttached"
      ) {
        this._forceUpdateChildren(container, {
          flash: true,
          updateLevel: true,
        });
      } else if (type === "inlineTextChild") {
        this._forceUpdateChildren(container, { flash: true });
        container.update();
      }
    }

    this._waitForChildren().then(() => {
      if (this._destroyed) {
        // Could not fully update after markup mutations, the markup-view was destroyed
        // while waiting for children. Bail out silently.
        return;
      }
      this._flashMutatedNodes(mutations);
      this.inspector.emit("markupmutation", mutations);

      // Since the htmlEditor is absolutely positioned, a mutation may change
      // the location in which it should be shown.
      if (this.htmlEditor) {
        this.htmlEditor.refresh();
      }
    });
  },

  /**
   * React to display-change and scrollable-change events from the walker. These are
   * events that tell us when something of interest changed on a collection of nodes:
   * whether their display type changed, or whether they became scrollable.
   *
   * @param  {Array} nodes
   *         An array of nodeFronts
   */
  _onWalkerNodeStatesChanged(nodes) {
    for (const node of nodes) {
      const container = this.getContainer(node);
      if (container) {
        container.update();
      }
    }
  },

  /**
   * Given a list of mutations returned by the mutation observer, flash the
   * corresponding containers to attract attention.
   */
  _flashMutatedNodes(mutations) {
    const addedOrEditedContainers = new Set();
    const removedContainers = new Set();

    for (const { type, target, added, removed, newValue } of mutations) {
      const container = this.getContainer(target);

      if (container) {
        if (type === "characterData") {
          addedOrEditedContainers.add(container);
        } else if (type === "attributes" && newValue === null) {
          // Removed attributes should flash the entire node.
          // New or changed attributes will flash the attribute itself
          // in ElementEditor.flashAttribute.
          addedOrEditedContainers.add(container);
        } else if (type === "childList") {
          // If there has been removals, flash the parent
          if (removed.length) {
            removedContainers.add(container);
          }

          // If there has been additions, flash the nodes if their associated
          // container exist (so if their parent is expanded in the inspector).
          added.forEach(node => {
            const addedContainer = this.getContainer(node);
            if (addedContainer) {
              addedOrEditedContainers.add(addedContainer);

              // The node may be added as a result of an append, in which case
              // it will have been removed from another container first, but in
              // these cases we don't want to flash both the removal and the
              // addition
              removedContainers.delete(container);
            }
          });
        }
      }
    }

    for (const container of removedContainers) {
      container.flashMutation();
    }
    for (const container of addedOrEditedContainers) {
      container.flashMutation();
    }
  },

  /**
   * Make sure the given node's parents are expanded and the
   * node is scrolled on to screen.
   */
  showNode(node, { centered = true, slotted, smoothScroll = false } = {}) {
    if (slotted && !this.hasContainer(node, slotted)) {
      throw new Error("Tried to show a slotted node not previously imported");
    } else {
      this._ensureNodeImported(node);
    }

    return this._waitForChildren()
      .then(() => {
        if (this._destroyed) {
          return Promise.reject("markupview destroyed");
        }
        return this._ensureVisible(node);
      })
      .then(() => {
        const container = this.getContainer(node, slotted);
        scrollIntoViewIfNeeded(container.editor.elt, centered, smoothScroll);
      }, this._handleRejectionIfNotDestroyed);
  },

  _ensureNodeImported(node) {
    let parent = node;

    this.importNode(node);

    while ((parent = this._getParentInTree(parent))) {
      this.importNode(parent);
      this.expandNode(parent);
    }
  },

  /**
   * Expand the container's children.
   */
  _expandContainer(container) {
    return this._updateChildren(container, { expand: true }).then(() => {
      if (this._destroyed) {
        // Could not expand the node, the markup-view was destroyed in the meantime. Just
        // silently give up.
        return;
      }
      container.setExpanded(true);
    });
  },

  /**
   * Expand the node's children.
   */
  expandNode(node) {
    const container = this.getContainer(node);
    return this._expandContainer(container);
  },

  /**
   * Expand the entire tree beneath a container.
   *
   * @param  {MarkupContainer} container
   *         The container to expand.
   */
  _expandAll(container) {
    return this._expandContainer(container)
      .then(() => {
        let child = container.children.firstChild;
        const promises = [];
        while (child) {
          promises.push(this._expandAll(child.container));
          child = child.nextSibling;
        }
        return Promise.all(promises);
      })
      .catch(console.error);
  },

  /**
   * Expand the entire tree beneath a node.
   *
   * @param  {DOMNode} node
   *         The node to expand, or null to start from the top.
   * @return {Promise} promise that resolves once all children are expanded.
   */
  expandAll(node) {
    node = node || this._rootNode;
    return this._expandAll(this.getContainer(node));
  },

  /**
   * Collapse the node's children.
   */
  collapseNode(node) {
    const container = this.getContainer(node);
    container.setExpanded(false);
  },

  _collapseAll(container) {
    container.setExpanded(false);
    const children = container.getChildContainers() || [];
    children.forEach(child => this._collapseAll(child));
  },

  /**
   * Collapse the entire tree beneath a node.
   *
   * @param  {DOMNode} node
   *         The node to collapse.
   * @return {Promise} promise that resolves once all children are collapsed.
   */
  collapseAll(node) {
    this._collapseAll(this.getContainer(node));

    // collapseAll is synchronous, return a promise for consistency with expandAll.
    return Promise.resolve();
  },

  /**
   * Returns either the innerHTML or the outerHTML for a remote node.
   *
   * @param  {NodeFront} node
   *         The NodeFront to get the outerHTML / innerHTML for.
   * @param  {Boolean} isOuter
   *         If true, makes the function return the outerHTML,
   *         otherwise the innerHTML.
   * @return {Promise} that will be resolved with the outerHTML / innerHTML.
   */
  _getNodeHTML(node, isOuter) {
    let walkerPromise = null;

    if (isOuter) {
      walkerPromise = node.walkerFront.outerHTML(node);
    } else {
      walkerPromise = node.walkerFront.innerHTML(node);
    }

    return getLongString(walkerPromise);
  },

  /**
   * Retrieve the outerHTML for a remote node.
   *
   * @param  {NodeFront} node
   *         The NodeFront to get the outerHTML for.
   * @return {Promise} that will be resolved with the outerHTML.
   */
  getNodeOuterHTML(node) {
    return this._getNodeHTML(node, true);
  },

  /**
   * Retrieve the innerHTML for a remote node.
   *
   * @param  {NodeFront} node
   *         The NodeFront to get the innerHTML for.
   * @return {Promise} that will be resolved with the innerHTML.
   */
  getNodeInnerHTML(node) {
    return this._getNodeHTML(node);
  },

  /**
   * Listen to mutations, expect a given node to be removed and try and select
   * the node that sits at the same place instead.
   * This is useful when changing the outerHTML or the tag name so that the
   * newly inserted node gets selected instead of the one that just got removed.
   */
  reselectOnRemoved(removedNode, reason) {
    // Only allow one removed node reselection at a time, so that when there are
    // more than 1 request in parallel, the last one wins.
    this.cancelReselectOnRemoved();

    // Get the removedNode index in its parent node to reselect the right node.
    const isRootElement = ["html", "svg"].includes(
      removedNode.tagName.toLowerCase()
    );
    const oldContainer = this.getContainer(removedNode);
    const parentContainer = this.getContainer(removedNode.parentNode());
    const childIndex = parentContainer
      .getChildContainers()
      .indexOf(oldContainer);

    const onMutations = (this._removedNodeObserver = mutations => {
      let isNodeRemovalMutation = false;
      for (const mutation of mutations) {
        const containsRemovedNode =
          mutation.removed && mutation.removed.some(n => n === removedNode);
        if (
          mutation.type === "childList" &&
          (containsRemovedNode || isRootElement)
        ) {
          isNodeRemovalMutation = true;
          break;
        }
      }
      if (!isNodeRemovalMutation) {
        return;
      }

      this.inspector.off("markupmutation", onMutations);
      this._removedNodeObserver = null;

      // Don't select the new node if the user has already changed the current
      // selection.
      if (
        this.inspector.selection.nodeFront === parentContainer.node ||
        (this.inspector.selection.nodeFront === removedNode && isRootElement)
      ) {
        const childContainers = parentContainer.getChildContainers();
        if (childContainers?.[childIndex]) {
          const childContainer = childContainers[childIndex];
          this._markContainerAsSelected(childContainer, reason);
          if (childContainer.hasChildren) {
            this.expandNode(childContainer.node);
          }
          this.emit("reselectedonremoved");
        }
      }
    });

    // Start listening for mutations until we find a childList change that has
    // removedNode removed.
    this.inspector.on("markupmutation", onMutations);
  },

  /**
   * Make sure to stop listening for node removal markupmutations and not
   * reselect the corresponding node when that happens.
   * Useful when the outerHTML/tagname edition failed.
   */
  cancelReselectOnRemoved() {
    if (this._removedNodeObserver) {
      this.inspector.off("markupmutation", this._removedNodeObserver);
      this._removedNodeObserver = null;
      this.emit("canceledreselectonremoved");
    }
  },

  /**
   * Replace the outerHTML of any node displayed in the inspector with
   * some other HTML code
   *
   * @param  {NodeFront} node
   *         Node which outerHTML will be replaced.
   * @param  {String} newValue
   *         The new outerHTML to set on the node.
   * @param  {String} oldValue
   *         The old outerHTML that will be used if the user undoes the update.
   * @return {Promise} that will resolve when the outer HTML has been updated.
   */
  updateNodeOuterHTML(node, newValue) {
    const container = this.getContainer(node);
    if (!container) {
      return Promise.reject();
    }

    // Changing the outerHTML removes the node which outerHTML was changed.
    // Listen to this removal to reselect the right node afterwards.
    this.reselectOnRemoved(node, "outerhtml");
    return node.walkerFront.setOuterHTML(node, newValue).catch(() => {
      this.cancelReselectOnRemoved();
    });
  },

  /**
   * Replace the innerHTML of any node displayed in the inspector with
   * some other HTML code
   * @param  {Node} node
   *         node which innerHTML will be replaced.
   * @param  {String} newValue
   *         The new innerHTML to set on the node.
   * @param  {String} oldValue
   *         The old innerHTML that will be used if the user undoes the update.
   * @return {Promise} that will resolve when the inner HTML has been updated.
   */
  updateNodeInnerHTML(node, newValue, oldValue) {
    const container = this.getContainer(node);
    if (!container) {
      return Promise.reject();
    }

    return new Promise((resolve, reject) => {
      container.undo.do(
        () => {
          node.walkerFront.setInnerHTML(node, newValue).then(resolve, reject);
        },
        () => {
          node.walkerFront.setInnerHTML(node, oldValue);
        }
      );
    });
  },

  /**
   * Insert adjacent HTML to any node displayed in the inspector.
   *
   * @param  {NodeFront} node
   *         The reference node.
   * @param  {String} position
   *         The position as specified for Element.insertAdjacentHTML
   *         (i.e. "beforeBegin", "afterBegin", "beforeEnd", "afterEnd").
   * @param  {String} newValue
   *         The adjacent HTML.
   * @return {Promise} that will resolve when the adjacent HTML has
   *         been inserted.
   */
  insertAdjacentHTMLToNode(node, position, value) {
    const container = this.getContainer(node);
    if (!container) {
      return Promise.reject();
    }

    let injectedNodes = [];

    return new Promise((resolve, reject) => {
      container.undo.do(
        () => {
          // eslint-disable-next-line no-unsanitized/method
          node.walkerFront
            .insertAdjacentHTML(node, position, value)
            .then(nodeArray => {
              injectedNodes = nodeArray.nodes;
              return nodeArray;
            })
            .then(resolve, reject);
        },
        () => {
          node.walkerFront.removeNodes(injectedNodes);
        }
      );
    });
  },

  /**
   * Open an editor in the UI to allow editing of a node's html.
   *
   * @param  {NodeFront} node
   *         The NodeFront to edit.
   */
  beginEditingHTML(node) {
    // We use outer html for elements, but inner html for fragments.
    const isOuter = node.nodeType == nodeConstants.ELEMENT_NODE;
    const html = isOuter
      ? this.getNodeOuterHTML(node)
      : this.getNodeInnerHTML(node);
    html.then(oldValue => {
      const container = this.getContainer(node);
      if (!container) {
        return;
      }
      // Load load and create HTML Editor as it is rarely used and fetch complex deps
      if (!this.htmlEditor) {
        const HTMLEditor = require("resource://devtools/client/inspector/markup/views/html-editor.js");
        this.htmlEditor = new HTMLEditor(this.doc);
      }
      this.htmlEditor.show(container.tagLine, oldValue);
      const start = this.telemetry.msSystemNow();
      this.htmlEditor.once("popuphidden", (commit, value) => {
        // Need to focus the <html> element instead of the frame / window
        // in order to give keyboard focus back to doc (from editor).
        this.doc.documentElement.focus();

        if (commit) {
          if (isOuter) {
            this.updateNodeOuterHTML(node, value, oldValue);
          } else {
            this.updateNodeInnerHTML(node, value, oldValue);
          }
        }

        const end = this.telemetry.msSystemNow();
        this.telemetry.recordEvent("edit_html", "inspector", null, {
          made_changes: commit,
          time_open: end - start,
        });
      });

      this.emit("begin-editing");
    });
  },

  /**
   * Expand or collapse the given node.
   *
   * @param  {NodeFront} node
   *         The NodeFront to update.
   * @param  {Boolean} expanded
   *         Whether the node should be expanded/collapsed.
   * @param  {Boolean} applyToDescendants
   *         Whether all descendants should also be expanded/collapsed
   */
  setNodeExpanded(node, expanded, applyToDescendants) {
    if (expanded) {
      if (applyToDescendants) {
        this.expandAll(node);
      } else {
        this.expandNode(node);
      }
    } else if (applyToDescendants) {
      this.collapseAll(node);
    } else {
      this.collapseNode(node);
    }
  },

  /**
   * Mark the given node selected, and update the inspector.selection
   * object's NodeFront to keep consistent state between UI and selection.
   *
   * @param  {NodeFront} node
   *         The NodeFront to mark as selected.
   * @return {Boolean} False if the node is already marked as selected, true
   *         otherwise.
   */
  markNodeAsSelected(node) {
    const container = this.getContainer(node);
    return this._markContainerAsSelected(container);
  },

  _markContainerAsSelected(container, reason) {
    if (!container || this._selectedContainer === container) {
      return false;
    }

    const { node } = container;

    // Un-select and remove focus from the previous container.
    if (this._selectedContainer) {
      this._selectedContainer.selected = false;
      this._selectedContainer.clearFocus();
    }

    // Select the new container.
    this._selectedContainer = container;
    if (node) {
      this._selectedContainer.selected = true;
    }

    // Change the current selection if needed.
    if (!this._isContainerSelected(this._selectedContainer)) {
      const isSlotted = container.isSlotted();
      this.inspector.selection.setNodeFront(node, { reason, isSlotted });
    }

    return true;
  },

  /**
   * Make sure that every ancestor of the selection are updated
   * and included in the list of visible children.
   */
  _ensureVisible(node) {
    while (node) {
      const container = this.getContainer(node);
      const parent = this._getParentInTree(node);
      if (!container.elt.parentNode) {
        const parentContainer = this.getContainer(parent);
        if (parentContainer) {
          this._forceUpdateChildren(parentContainer, { expand: true });
        }
      }

      node = parent;
    }
    return this._waitForChildren();
  },

  /**
   * Unmark selected node (no node selected).
   */
  unmarkSelectedNode() {
    if (this._selectedContainer) {
      this._selectedContainer.selected = false;
      this._selectedContainer = null;
    }
  },

  /**
   * Check if the current selection is a descendent of the container.
   * if so, make sure it's among the visible set for the container,
   * and set the dirty flag if needed.
   *
   * @return The node that should be made visible, if any.
   */
  _checkSelectionVisible(container) {
    let centered = null;
    let node = this.inspector.selection.nodeFront;
    while (node) {
      if (this._getParentInTree(node) === container.node) {
        centered = node;
        break;
      }
      node = this._getParentInTree(node);
    }

    return centered;
  },

  async _forceUpdateChildren(container, options = {}) {
    const { flash, updateLevel, expand } = options;

    // Set childrenDirty to true to force fetching new children.
    container.childrenDirty = true;

    // Update the children to take care of changes in the markup view DOM
    await this._updateChildren(container, { expand, flash });

    // The markup view may have been destroyed in the meantime
    if (this._destroyed) {
      return;
    }

    if (updateLevel) {
      // Update container (and its subtree) DOM tree depth level for
      // accessibility where necessary.
      container.updateLevel();
    }
  },

  /**
   * Make sure all children of the given container's node are
   * imported and attached to the container in the right order.
   *
   * Children need to be updated only in the following circumstances:
   * a) We just imported this node and have never seen its children.
   *    container.childrenDirty will be set by importNode in this case.
   * b) We received a childList mutation on the node.
   *    container.childrenDirty will be set in that case too.
   * c) We have changed the selection, and the path to that selection
   *    wasn't loaded in a previous children request (because we only
   *    grab a subset).
   *    container.childrenDirty should be set in that case too!
   *
   * @param  {MarkupContainer} container
   *         The markup container whose children need updating
   * @param  {Object} options
   *         Options are {expand:boolean,flash:boolean}
   * @return {Promise} that will be resolved when the children are ready
   *         (which may be immediately).
   */
  _updateChildren(container, options) {
    // Slotted containers do not display any children.
    if (container.isSlotted()) {
      return Promise.resolve(container);
    }

    const expand = options?.expand;
    const flash = options?.flash;

    container.hasChildren = container.node.hasChildren;
    // Accessibility should either ignore empty children or semantically
    // consider them a group.
    container.setChildrenRole();

    if (!this._queuedChildUpdates) {
      this._queuedChildUpdates = new Map();
    }

    if (this._queuedChildUpdates.has(container)) {
      return this._queuedChildUpdates.get(container);
    }

    if (!container.childrenDirty) {
      return Promise.resolve(container);
    }

    // Before bailing out for other conditions, check if the unavailable
    // children badge needs updating (Bug 1776250).
    if (
      typeof container?.editor?.hasUnavailableChildren == "function" &&
      container.editor.hasUnavailableChildren() !=
        container.node.childrenUnavailable
    ) {
      container.update();
    }

    if (
      container.inlineTextChild &&
      container.inlineTextChild != container.node.inlineTextChild
    ) {
      // This container was doing double duty as a container for a single
      // text child, back that out.
      this._containers.delete(container.inlineTextChild);
      container.clearInlineTextChild();

      if (container.hasChildren && container.selected) {
        container.setExpanded(true);
      }
    }

    if (container.node.inlineTextChild) {
      container.setExpanded(false);
      // this container will do double duty as the container for the single
      // text child.
      while (container.children.firstChild) {
        container.children.firstChild.remove();
      }

      container.setInlineTextChild(container.node.inlineTextChild);

      this.setContainer(container.node.inlineTextChild, container);
      container.childrenDirty = false;
      return Promise.resolve(container);
    }

    if (!container.hasChildren) {
      while (container.children.firstChild) {
        container.children.firstChild.remove();
      }
      container.childrenDirty = false;
      container.setExpanded(false);
      return Promise.resolve(container);
    }

    // If we're not expanded (or asked to update anyway), we're done for
    // now.  Note that this will leave the childrenDirty flag set, so when
    // expanded we'll refresh the child list.
    if (!(container.expanded || expand)) {
      return Promise.resolve(container);
    }

    // We're going to issue a children request, make sure it includes the
    // centered node.
    const centered = this._checkSelectionVisible(container);

    // Children aren't updated yet, but clear the childrenDirty flag anyway.
    // If the dirty flag is re-set while we're fetching we'll need to fetch
    // again.
    container.childrenDirty = false;

    const isShadowHost = container.node.isShadowHost;
    const updatePromise = this._getVisibleChildren(container, centered)
      .then(children => {
        if (!this._containers) {
          return Promise.reject("markup view destroyed");
        }
        this._queuedChildUpdates.delete(container);

        // If children are dirty, we got a change notification for this node
        // while the request was in progress, we need to do it again.
        if (container.childrenDirty) {
          return this._updateChildren(container, {
            expand: centered || expand,
          });
        }

        const fragment = this.doc.createDocumentFragment();

        for (const child of children.nodes) {
          const slotted = !isShadowHost && child.isDirectShadowHostChild;
          const childContainer = this.importNode(child, flash, slotted);
          fragment.appendChild(childContainer.elt);
        }

        while (container.children.firstChild) {
          container.children.firstChild.remove();
        }

        if (!children.hasFirst) {
          const topItem = this.buildMoreNodesButtonMarkup(container);
          fragment.insertBefore(topItem, fragment.firstChild);
        }
        if (!children.hasLast) {
          const bottomItem = this.buildMoreNodesButtonMarkup(container);
          fragment.appendChild(bottomItem);
        }

        container.children.appendChild(fragment);
        return container;
      })
      .catch(this._handleRejectionIfNotDestroyed);
    this._queuedChildUpdates.set(container, updatePromise);
    return updatePromise;
  },

  buildMoreNodesButtonMarkup(container) {
    const elt = this.doc.createElement("li");
    elt.classList.add("more-nodes", "devtools-class-comment");

    const label = this.doc.createElement("span");
    label.textContent = INSPECTOR_L10N.getStr("markupView.more.showing");
    elt.appendChild(label);

    const button = this.doc.createElement("button");
    button.setAttribute("href", "#");
    const showAllString = PluralForm.get(
      container.node.numChildren,
      INSPECTOR_L10N.getStr("markupView.more.showAll2")
    );
    button.textContent = showAllString.replace(
      "#1",
      container.node.numChildren
    );
    elt.appendChild(button);

    button.addEventListener("click", () => {
      container.maxChildren = -1;
      this._forceUpdateChildren(container);
    });

    return elt;
  },

  _waitForChildren() {
    if (!this._queuedChildUpdates) {
      return Promise.resolve(undefined);
    }

    return Promise.all([...this._queuedChildUpdates.values()]);
  },

  /**
   * Return a list of the children to display for this container.
   */
  async _getVisibleChildren(container, centered) {
    let maxChildren = container.maxChildren || this.maxChildren;
    if (maxChildren == -1) {
      maxChildren = undefined;
    }

    // We have to use node's walker and not a top level walker
    // as for fission frames, we are going to have multiple walkers
    const inspectorFront =
      await container.node.targetFront.getFront("inspector");
    return inspectorFront.walker.children(container.node, {
      maxNodes: maxChildren,
      center: centered,
    });
  },

  /**
   * The parent of a given node as rendered in the markup view is not necessarily
   * node.parentNode(). For instance, shadow roots don't have a parentNode, but a host
   * element. However they are represented as parent and children in the markup view.
   *
   * Use this method when you are interested in the parent of a node from the perspective
   * of the markup-view tree, and not from the perspective of the actual DOM.
   */
  _getParentInTree(node) {
    const parent = node.parentOrHost();
    if (!parent) {
      return null;
    }

    // If the parent node belongs to a different target while the node's target is the
    // one selected by the user in the iframe picker, we don't want to go further up.
    if (
      node.targetFront !== parent.targetFront &&
      node.targetFront ==
        this.inspector.commands.targetCommand.selectedTargetFront
    ) {
      return null;
    }

    return parent;
  },

  /**
   * Tear down the markup panel.
   */
  destroy() {
    if (this._destroyed) {
      return;
    }

    this._destroyed = true;

    this._hoveredContainer = null;

    if (this._contextMenu) {
      this._contextMenu.destroy();
      this._contextMenu = null;
    }

    if (this._eventDetailsTooltip) {
      this._eventDetailsTooltip.destroy();
      this._eventDetailsTooltip = null;
    }

    if (this.htmlEditor) {
      this.htmlEditor.destroy();
      this.htmlEditor = null;
    }

    if (this.imagePreviewTooltip) {
      this.imagePreviewTooltip.destroy();
      this.imagePreviewTooltip = null;
    }

    if (this._undo) {
      this._undo.destroy();
      this._undo = null;
    }

    if (this._shortcuts) {
      this._shortcuts.destroy();
      this._shortcuts = null;
    }

    this.popup.destroy();
    this.popup = null;
    this._selectedContainer = null;

    this._elt.removeEventListener("blur", this._onBlur, true);
    this._elt.removeEventListener("click", this._onMouseClick);
    this._elt.removeEventListener("contextmenu", this._onContextMenu);
    this._elt.removeEventListener("mousemove", this._onMouseMove);
    this._elt.removeEventListener("mouseout", this._onMouseOut);
    this._frame.removeEventListener("focus", this._onFocus);
    this._unsubscribeFromToolboxStore();
    this.inspector.selection.off("new-node-front", this._onNewSelection);
    this.resourceCommand.unwatchResources(
      [this.resourceCommand.TYPES.ROOT_NODE],
      { onAvailable: this._onResourceAvailable }
    );
    this.targetCommand.unwatchTargets({
      types: [this.targetCommand.TYPES.FRAME],
      onAvailable: this._onTargetAvailable,
      onDestroyed: this._onTargetDestroyed,
    });
    this.inspector.toolbox.nodePicker.off(
      "picker-node-hovered",
      this._onToolboxPickerHover
    );
    this.inspector.toolbox.nodePicker.off(
      "picker-node-canceled",
      this._onToolboxPickerCanceled
    );
    this.inspector.highlighters.off(
      "highlighter-shown",
      this.onHighlighterShown
    );
    this.inspector.highlighters.off(
      "highlighter-hidden",
      this.onHighlighterHidden
    );
    this.win.removeEventListener("copy", this._onCopy);
    this.win.removeEventListener("mouseup", this._onMouseUp);

    this._walkerEventListener.destroy();
    this._walkerEventListener = null;

    this._prefObserver.off(
      ATTR_COLLAPSE_ENABLED_PREF,
      this._onCollapseAttributesPrefChange
    );
    this._prefObserver.off(
      ATTR_COLLAPSE_LENGTH_PREF,
      this._onCollapseAttributesPrefChange
    );
    this._prefObserver.destroy();

    for (const [, container] of this._containers) {
      container.destroy();
    }
    this._containers = null;

    this._elt.innerHTML = "";
    this._elt = null;

    this.controllerWindow = null;
    this.doc = null;
    this.highlighters = null;
    this.walker = null;
    this.resourceCommand = null;
    this.win = null;

    this._lastDropTarget = null;
    this._lastDragTarget = null;
  },

  /**
   * Find the closest element with class tag-line. These are used to indicate
   * drag and drop targets.
   *
   * @param  {DOMNode} el
   * @return {DOMNode}
   */
  findClosestDragDropTarget(el) {
    return el.classList.contains("tag-line")
      ? el
      : el.querySelector(".tag-line") || el.closest(".tag-line");
  },

  /**
   * Takes an element as it's only argument and marks the element
   * as the drop target
   */
  indicateDropTarget(el) {
    if (this._lastDropTarget) {
      this._lastDropTarget.classList.remove("drop-target");
    }

    if (!el) {
      return;
    }

    const target = this.findClosestDragDropTarget(el);
    if (target) {
      target.classList.add("drop-target");
      this._lastDropTarget = target;
    }
  },

  /**
   * Takes an element to mark it as indicator of dragging target's initial place
   */
  indicateDragTarget(el) {
    if (this._lastDragTarget) {
      this._lastDragTarget.classList.remove("drag-target");
    }

    if (!el) {
      return;
    }

    const target = this.findClosestDragDropTarget(el);
    if (target) {
      target.classList.add("drag-target");
      this._lastDragTarget = target;
    }
  },

  /**
   * Used to get the nodes required to modify the markup after dragging the
   * element (parent/nextSibling).
   */
  get dropTargetNodes() {
    const target = this._lastDropTarget;

    if (!target) {
      return null;
    }

    let parent, nextSibling;

    if (
      target.previousElementSibling &&
      target.previousElementSibling.nodeName.toLowerCase() === "ul"
    ) {
      parent = target.parentNode.container.node;
      nextSibling = null;
    } else {
      parent = target.parentNode.container.node.parentNode();
      nextSibling = target.parentNode.container.node;
    }

    if (nextSibling) {
      while (
        nextSibling.isMarkerPseudoElement ||
        nextSibling.isBeforePseudoElement
      ) {
        nextSibling =
          this.getContainer(nextSibling).elt.nextSibling.container.node;
      }
      if (nextSibling.isAfterPseudoElement) {
        parent = target.parentNode.container.node.parentNode();
        nextSibling = null;
      }
    }

    if (parent.nodeType !== nodeConstants.ELEMENT_NODE) {
      return null;
    }

    return { parent, nextSibling };
  },
};

/**
 * Copy the content of a longString containing HTML code to the clipboard.
 * The string is retrieved, and possibly beautified if the user has the right pref set and
 * then placed in the clipboard.
 *
 * @param  {Promise} longStringActorPromise
 *         The promise expected to resolve a LongStringActor instance
 */
async function copyLongHTMLString(longStringActorPromise) {
  let string = await getLongString(longStringActorPromise);

  if (Services.prefs.getBoolPref(BEAUTIFY_HTML_ON_COPY_PREF)) {
    const { indentUnit, indentWithTabs } = getTabPrefs();
    string = beautify.html(string, {
      // eslint-disable-next-line camelcase
      preserve_newlines: false,
      // eslint-disable-next-line camelcase
      indent_size: indentWithTabs ? 1 : indentUnit,
      // eslint-disable-next-line camelcase
      indent_char: indentWithTabs ? "\t" : " ",
      unformatted: [],
    });
  }

  clipboardHelper.copyString(string);
}

/**
 * Map a number from one range to another.
 */
function map(value, oldMin, oldMax, newMin, newMax) {
  const ratio = oldMax - oldMin;
  if (ratio == 0) {
    return value;
  }
  return newMin + (newMax - newMin) * ((value - oldMin) / ratio);
}

module.exports = MarkupView;
