src/third_party/devtools/front_end/sources/NavigatorView.js

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY GOOGLE INC. 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 GOOGLE INC.
 * 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.
 */
/**
 * @implements {SDK.TargetManager.Observer}
 * @unrestricted
 */
Sources.NavigatorView = class extends UI.VBox {
  constructor() {
    super(true);
    this.registerRequiredCSS('sources/navigatorView.css');

    /** @type {?UI.Widget} */
    this._placeholder = null;
    this._scriptsTree = new UI.TreeOutlineInShadow();
    this._scriptsTree.registerRequiredCSS('sources/navigatorTree.css');
    this._scriptsTree.setComparator(Sources.NavigatorView._treeElementsCompare);
    this.contentElement.appendChild(this._scriptsTree.element);
    this.setDefaultFocusedElement(this._scriptsTree.element);

    /** @type {!Platform.Multimap<!Workspace.UISourceCode, !Sources.NavigatorUISourceCodeTreeNode>} */
    this._uiSourceCodeNodes = new Platform.Multimap();
    /** @type {!Map.<string, !Sources.NavigatorFolderTreeNode>} */
    this._subfolderNodes = new Map();

    this._rootNode = new Sources.NavigatorRootTreeNode(this);
    this._rootNode.populate();

    /** @type {!Map.<!SDK.ResourceTreeFrame, !Sources.NavigatorGroupTreeNode>} */
    this._frameNodes = new Map();

    this.contentElement.addEventListener('contextmenu', this.handleContextMenu.bind(this), false);
    UI.shortcutRegistry.addShortcutListener(
        this.contentElement, 'sources.rename', this._renameShortcut.bind(this), true);

    this._navigatorGroupByFolderSetting = Common.moduleSetting('navigatorGroupByFolder');
    this._navigatorGroupByFolderSetting.addChangeListener(this._groupingChanged.bind(this));

    this._initGrouping();

    Persistence.persistence.addEventListener(
        Persistence.Persistence.Events.BindingCreated, this._onBindingChanged, this);
    Persistence.persistence.addEventListener(
        Persistence.Persistence.Events.BindingRemoved, this._onBindingChanged, this);
    SDK.targetManager.addEventListener(SDK.TargetManager.Events.NameChanged, this._targetNameChanged, this);

    SDK.targetManager.observeTargets(this);
    this._resetWorkspace(Workspace.workspace);
    this._workspace.uiSourceCodes().forEach(this._addUISourceCode.bind(this));
    Bindings.networkProjectManager.addEventListener(
        Bindings.NetworkProjectManager.Events.FrameAttributionAdded, this._frameAttributionAdded, this);
    Bindings.networkProjectManager.addEventListener(
        Bindings.NetworkProjectManager.Events.FrameAttributionRemoved, this._frameAttributionRemoved, this);
  }

  /**
   * @param {!UI.TreeElement} treeElement
   */
  static _treeElementOrder(treeElement) {
    if (treeElement._boostOrder) {
      return 0;
    }

    if (!Sources.NavigatorView._typeOrders) {
      const weights = {};
      const types = Sources.NavigatorView.Types;
      weights[types.Root] = 1;
      weights[types.Domain] = 10;
      weights[types.FileSystemFolder] = 1;
      weights[types.NetworkFolder] = 1;
      weights[types.SourceMapFolder] = 2;
      weights[types.File] = 10;
      weights[types.Frame] = 70;
      weights[types.Worker] = 90;
      weights[types.FileSystem] = 100;
      Sources.NavigatorView._typeOrders = weights;
    }

    let order = Sources.NavigatorView._typeOrders[treeElement._nodeType];
    if (treeElement._uiSourceCode) {
      const contentType = treeElement._uiSourceCode.contentType();
      if (contentType.isDocument()) {
        order += 3;
      } else if (contentType.isScript()) {
        order += 5;
      } else if (contentType.isStyleSheet()) {
        order += 10;
      } else {
        order += 15;
      }
    }

    return order;
  }

  /**
   * @param {!UI.ContextMenu} contextMenu
   * @param {string=} path
   */
  static appendSearchItem(contextMenu, path) {
    function searchPath() {
      Sources.SearchSourcesView.openSearch(`file:${path.trim()}`);
    }

    let searchLabel = Common.UIString('Search in folder');
    if (!path || !path.trim()) {
      path = '*';
      searchLabel = Common.UIString('Search in all files');
    }
    contextMenu.viewSection().appendItem(searchLabel, searchPath);
  }

  /**
   * @param {!UI.TreeElement} treeElement1
   * @param {!UI.TreeElement} treeElement2
   * @return {number}
   */
  static _treeElementsCompare(treeElement1, treeElement2) {
    const typeWeight1 = Sources.NavigatorView._treeElementOrder(treeElement1);
    const typeWeight2 = Sources.NavigatorView._treeElementOrder(treeElement2);

    if (typeWeight1 > typeWeight2) {
      return 1;
    }
    if (typeWeight1 < typeWeight2) {
      return -1;
    }
    return treeElement1.titleAsText().compareTo(treeElement2.titleAsText());
  }

  /**
   * @param {!UI.Widget} placeholder
   */
  setPlaceholder(placeholder) {
    console.assert(!this._placeholder, 'A placeholder widget was already set');
    this._placeholder = placeholder;
    placeholder.show(this.contentElement, this.contentElement.firstChild);
    updateVisibility.call(this);
    this._scriptsTree.addEventListener(UI.TreeOutline.Events.ElementAttached, updateVisibility.bind(this));
    this._scriptsTree.addEventListener(UI.TreeOutline.Events.ElementsDetached, updateVisibility.bind(this));

    /**
     * @this {!Sources.NavigatorView}
     */
    function updateVisibility() {
      const showTree = this._scriptsTree.firstChild();
      if (showTree) {
        placeholder.hideWidget();
      } else {
        placeholder.showWidget();
      }
      this._scriptsTree.element.classList.toggle('hidden', !showTree);
    }
  }

  /**
   * @param {!Common.Event} event
   */
  _onBindingChanged(event) {
    const binding = /** @type {!Persistence.PersistenceBinding} */ (event.data);

    // Update UISourceCode titles.
    const networkNodes = this._uiSourceCodeNodes.get(binding.network);
    for (const networkNode of networkNodes) {
      networkNode.updateTitle();
    }
    const fileSystemNodes = this._uiSourceCodeNodes.get(binding.fileSystem);
    for (const fileSystemNode of fileSystemNodes) {
      fileSystemNode.updateTitle();
    }

    // Update folder titles.
    const pathTokens = Persistence.FileSystemWorkspaceBinding.relativePath(binding.fileSystem);
    let folderPath = '';
    for (let i = 0; i < pathTokens.length - 1; ++i) {
      folderPath += pathTokens[i];
      const folderId =
          this._folderNodeId(binding.fileSystem.project(), null, null, binding.fileSystem.origin(), folderPath);
      const folderNode = this._subfolderNodes.get(folderId);
      if (folderNode) {
        folderNode.updateTitle();
      }
      folderPath += '/';
    }

    // Update fileSystem root title.
    const fileSystemRoot = this._rootNode.child(binding.fileSystem.project().id());
    if (fileSystemRoot) {
      fileSystemRoot.updateTitle();
    }
  }

  /**
   * @override
   */
  focus() {
    this._scriptsTree.focus();
  }

  /**
   * @param {!Workspace.Workspace} workspace
   */
  _resetWorkspace(workspace) {
    this._workspace = workspace;
    this._workspace.addEventListener(Workspace.Workspace.Events.UISourceCodeAdded, this._uiSourceCodeAdded, this);
    this._workspace.addEventListener(Workspace.Workspace.Events.UISourceCodeRemoved, this._uiSourceCodeRemoved, this);
    this._workspace.addEventListener(Workspace.Workspace.Events.ProjectAdded, event => {
      const project = /** @type {!Workspace.Project} */ (event.data);
      this._projectAdded(project);
      if (project.type() === Workspace.projectTypes.FileSystem) {
        this._computeUniqueFileSystemProjectNames();
      }
    });
    this._workspace.addEventListener(Workspace.Workspace.Events.ProjectRemoved, event => {
      const project = /** @type {!Workspace.Project} */ (event.data);
      this._removeProject(project);
      if (project.type() === Workspace.projectTypes.FileSystem) {
        this._computeUniqueFileSystemProjectNames();
      }
    });
    this._workspace.projects().forEach(this._projectAdded.bind(this));
    this._computeUniqueFileSystemProjectNames();
  }

  /**
   * @return {!Workspace.Workspace}
   * @protected
   */
  workspace() {
    return this._workspace;
  }

  /**
   * @param {!Workspace.Project} project
   * @return {boolean}
   */
  acceptProject(project) {
    return !project.isServiceProject();
  }

  /**
   * @param {!Common.Event} event
   */
  _frameAttributionAdded(event) {
    const uiSourceCode = /** @type {!Workspace.UISourceCode} */ (event.data.uiSourceCode);
    if (!this._acceptsUISourceCode(uiSourceCode)) {
      return;
    }

    const addedFrame = /** @type {?SDK.ResourceTreeFrame} */ (event.data.frame);
    // This event does not happen for UISourceCodes without initial attribution.
    this._addUISourceCodeNode(uiSourceCode, addedFrame);
  }

  /**
   * @param {!Common.Event} event
   */
  _frameAttributionRemoved(event) {
    const uiSourceCode = /** @type {!Workspace.UISourceCode} */ (event.data.uiSourceCode);
    if (!this._acceptsUISourceCode(uiSourceCode)) {
      return;
    }

    const removedFrame = /** @type {?SDK.ResourceTreeFrame} */ (event.data.frame);
    const node = Array.from(this._uiSourceCodeNodes.get(uiSourceCode)).find(node => node.frame() === removedFrame);
    this._removeUISourceCodeNode(node);
  }

  /**
   * @param {!Workspace.UISourceCode} uiSourceCode
   * @return {boolean}
   */
  _acceptsUISourceCode(uiSourceCode) {
    return this.acceptProject(uiSourceCode.project());
  }

  /**
   * @param {!Workspace.UISourceCode} uiSourceCode
   */
  _addUISourceCode(uiSourceCode) {
    if (!this._acceptsUISourceCode(uiSourceCode)) {
      return;
    }

    const frames = Bindings.NetworkProject.framesForUISourceCode(uiSourceCode);
    if (frames.length) {
      for (const frame of frames) {
        this._addUISourceCodeNode(uiSourceCode, frame);
      }
    } else {
      this._addUISourceCodeNode(uiSourceCode, null);
    }
    this.uiSourceCodeAdded(uiSourceCode);
  }

  /**
   * @param {!Workspace.UISourceCode} uiSourceCode
   * @param {?SDK.ResourceTreeFrame} frame
   */
  _addUISourceCodeNode(uiSourceCode, frame) {
    const isFromSourceMap = uiSourceCode.contentType().isFromSourceMap();
    let path;
    if (uiSourceCode.project().type() === Workspace.projectTypes.FileSystem) {
      path = Persistence.FileSystemWorkspaceBinding.relativePath(uiSourceCode).slice(0, -1);
    } else {
      path = Common.ParsedURL.extractPath(uiSourceCode.url()).split('/').slice(1, -1);
    }

    const project = uiSourceCode.project();
    const target = Bindings.NetworkProject.targetForUISourceCode(uiSourceCode);
    const folderNode =
        this._folderNode(uiSourceCode, project, target, frame, uiSourceCode.origin(), path, isFromSourceMap);
    const uiSourceCodeNode = new Sources.NavigatorUISourceCodeTreeNode(this, uiSourceCode, frame);
    folderNode.appendChild(uiSourceCodeNode);
    this._uiSourceCodeNodes.set(uiSourceCode, uiSourceCodeNode);
    this._selectDefaultTreeNode();
  }

  /**
   * @param {!Workspace.UISourceCode} uiSourceCode
   */
  uiSourceCodeAdded(uiSourceCode) {
  }

  /**
   * @param {!Common.Event} event
   */
  _uiSourceCodeAdded(event) {
    const uiSourceCode = /** @type {!Workspace.UISourceCode} */ (event.data);
    this._addUISourceCode(uiSourceCode);
  }

  /**
   * @param {!Common.Event} event
   */
  _uiSourceCodeRemoved(event) {
    const uiSourceCode = /** @type {!Workspace.UISourceCode} */ (event.data);
    this._removeUISourceCode(uiSourceCode);
  }

  /**
   * @protected
   * @param {!Workspace.Project} project
   */
  tryAddProject(project) {
    this._projectAdded(project);
    project.uiSourceCodes().forEach(this._addUISourceCode.bind(this));
  }

  /**
   * @param {!Workspace.Project} project
   */
  _projectAdded(project) {
    if (!this.acceptProject(project) || project.type() !== Workspace.projectTypes.FileSystem ||
        Snippets.isSnippetsProject(project) || this._rootNode.child(project.id())) {
      return;
    }
    this._rootNode.appendChild(new Sources.NavigatorGroupTreeNode(
        this, project, project.id(), Sources.NavigatorView.Types.FileSystem, project.displayName()));
    this._selectDefaultTreeNode();
  }

  // TODO(einbinder) remove this code after crbug.com/964075 is fixed
  _selectDefaultTreeNode() {
    const children = this._rootNode.children();
    if (children.length && !this._scriptsTree.selectedTreeElement) {
      children[0].treeNode().select(true /* omitFocus */, false /* selectedByUser */);
    }
  }

  _computeUniqueFileSystemProjectNames() {
    const fileSystemProjects = this._workspace.projectsForType(Workspace.projectTypes.FileSystem);
    if (!fileSystemProjects.length) {
      return;
    }
    const encoder = new Persistence.PathEncoder();
    const reversedPaths = fileSystemProjects.map(project => {
      const fileSystem = /** @type {!Persistence.FileSystemWorkspaceBinding.FileSystem} */ (project);
      return encoder.encode(fileSystem.fileSystemPath()).reverse();
    });
    const reversedIndex = new Common.Trie();
    for (const reversedPath of reversedPaths) {
      reversedIndex.add(reversedPath);
    }

    for (let i = 0; i < fileSystemProjects.length; ++i) {
      const reversedPath = reversedPaths[i];
      const project = fileSystemProjects[i];
      reversedIndex.remove(reversedPath);
      const commonPrefix = reversedIndex.longestPrefix(reversedPath, false /* fullWordOnly */);
      reversedIndex.add(reversedPath);
      const path = encoder.decode(reversedPath.substring(0, commonPrefix.length + 1).reverse());
      const fileSystemNode = this._rootNode.child(project.id());
      if (fileSystemNode) {
        fileSystemNode.setTitle(path);
      }
    }
  }

  /**
   * @param {!Workspace.Project} project
   */
  _removeProject(project) {
    const uiSourceCodes = project.uiSourceCodes();
    for (let i = 0; i < uiSourceCodes.length; ++i) {
      this._removeUISourceCode(uiSourceCodes[i]);
    }
    if (project.type() !== Workspace.projectTypes.FileSystem) {
      return;
    }
    const fileSystemNode = this._rootNode.child(project.id());
    if (!fileSystemNode) {
      return;
    }
    this._rootNode.removeChild(fileSystemNode);
  }

  /**
   * @param {!Workspace.Project} project
   * @param {?SDK.Target} target
   * @param {?SDK.ResourceTreeFrame} frame
   * @param {string} projectOrigin
   * @param {string} path
   * @return {string}
   */
  _folderNodeId(project, target, frame, projectOrigin, path) {
    const targetId = target ? target.id() : '';
    const projectId = project.type() === Workspace.projectTypes.FileSystem ? project.id() : '';
    const frameId = this._groupByFrame && frame ? frame.id : '';
    return targetId + ':' + projectId + ':' + frameId + ':' + projectOrigin + ':' + path;
  }

  /**
   * @param {!Workspace.UISourceCode} uiSourceCode
   * @param {!Workspace.Project} project
   * @param {?SDK.Target} target
   * @param {?SDK.ResourceTreeFrame} frame
   * @param {string} projectOrigin
   * @param {!Array<string>} path
   * @param {boolean} fromSourceMap
   * @return {!Sources.NavigatorTreeNode}
   */
  _folderNode(uiSourceCode, project, target, frame, projectOrigin, path, fromSourceMap) {
    if (Snippets.isSnippetsUISourceCode(uiSourceCode)) {
      return this._rootNode;
    }

    if (target && !this._groupByFolder && !fromSourceMap) {
      return this._domainNode(uiSourceCode, project, target, frame, projectOrigin);
    }

    const folderPath = path.join('/');
    const folderId = this._folderNodeId(project, target, frame, projectOrigin, folderPath);
    let folderNode = this._subfolderNodes.get(folderId);
    if (folderNode) {
      return folderNode;
    }

    if (!path.length) {
      if (target) {
        return this._domainNode(uiSourceCode, project, target, frame, projectOrigin);
      }
      return /** @type {!Sources.NavigatorTreeNode} */ (this._rootNode.child(project.id()));
    }

    const parentNode =
        this._folderNode(uiSourceCode, project, target, frame, projectOrigin, path.slice(0, -1), fromSourceMap);
    let type = fromSourceMap ? Sources.NavigatorView.Types.SourceMapFolder : Sources.NavigatorView.Types.NetworkFolder;
    if (project.type() === Workspace.projectTypes.FileSystem) {
      type = Sources.NavigatorView.Types.FileSystemFolder;
    }
    const name = path[path.length - 1];

    folderNode = new Sources.NavigatorFolderTreeNode(this, project, folderId, type, folderPath, name);
    this._subfolderNodes.set(folderId, folderNode);
    parentNode.appendChild(folderNode);
    return folderNode;
  }

  /**
   * @param {!Workspace.UISourceCode} uiSourceCode
   * @param {!Workspace.Project} project
   * @param {!SDK.Target} target
   * @param {?SDK.ResourceTreeFrame} frame
   * @param {string} projectOrigin
   * @return {!Sources.NavigatorTreeNode}
   */
  _domainNode(uiSourceCode, project, target, frame, projectOrigin) {
    const frameNode = this._frameNode(project, target, frame);
    if (!this._groupByDomain) {
      return frameNode;
    }
    let domainNode = frameNode.child(projectOrigin);
    if (domainNode) {
      return domainNode;
    }

    domainNode = new Sources.NavigatorGroupTreeNode(
        this, project, projectOrigin, Sources.NavigatorView.Types.Domain,
        this._computeProjectDisplayName(target, projectOrigin));
    if (frame && projectOrigin === Common.ParsedURL.extractOrigin(frame.url)) {
      domainNode.treeNode()._boostOrder = true;
    }
    frameNode.appendChild(domainNode);
    return domainNode;
  }

  /**
   * @param {!Workspace.Project} project
   * @param {!SDK.Target} target
   * @param {?SDK.ResourceTreeFrame} frame
   * @return {!Sources.NavigatorTreeNode}
   */
  _frameNode(project, target, frame) {
    if (!this._groupByFrame || !frame) {
      return this._targetNode(project, target);
    }

    let frameNode = this._frameNodes.get(frame);
    if (frameNode) {
      return frameNode;
    }

    frameNode = new Sources.NavigatorGroupTreeNode(
        this, project, target.id() + ':' + frame.id, Sources.NavigatorView.Types.Frame, frame.displayName());
    frameNode.setHoverCallback(hoverCallback);
    this._frameNodes.set(frame, frameNode);

    const parentFrame = frame.parentFrame || frame.crossTargetParentFrame();
    this._frameNode(project, parentFrame ? parentFrame.resourceTreeModel().target() : target, parentFrame)
        .appendChild(frameNode);
    if (!parentFrame) {
      frameNode.treeNode()._boostOrder = true;
      frameNode.treeNode().expand();
    }

    /**
     * @param {boolean} hovered
     */
    function hoverCallback(hovered) {
      if (hovered) {
        const overlayModel = target.model(SDK.OverlayModel);
        if (overlayModel) {
          overlayModel.highlightFrame(frame.id);
        }
      } else {
        SDK.OverlayModel.hideDOMNodeHighlight();
      }
    }
    return frameNode;
  }

  /**
   * @param {!Workspace.Project} project
   * @param {!SDK.Target} target
   * @return {!Sources.NavigatorTreeNode}
   */
  _targetNode(project, target) {
    if (target === SDK.targetManager.mainTarget()) {
      return this._rootNode;
    }

    let targetNode = this._rootNode.child('target:' + target.id());
    if (!targetNode) {
      targetNode = new Sources.NavigatorGroupTreeNode(
          this, project, 'target:' + target.id(),
          target.type() === SDK.Target.Type.Frame ? Sources.NavigatorView.Types.Frame :
                                                    Sources.NavigatorView.Types.Worker,
          target.name());
      this._rootNode.appendChild(targetNode);
    }
    return targetNode;
  }

  /**
   * @param {!SDK.Target} target
   * @param {string} projectOrigin
   * @return {string}
   */
  _computeProjectDisplayName(target, projectOrigin) {
    const runtimeModel = target.model(SDK.RuntimeModel);
    const executionContexts = runtimeModel ? runtimeModel.executionContexts() : [];
    for (const context of executionContexts) {
      if (context.name && context.origin && projectOrigin.startsWith(context.origin)) {
        return context.name;
      }
    }

    if (!projectOrigin) {
      return Common.UIString('(no domain)');
    }

    const parsedURL = new Common.ParsedURL(projectOrigin);
    const prettyURL = parsedURL.isValid ? parsedURL.host + (parsedURL.port ? (':' + parsedURL.port) : '') : '';

    return (prettyURL || projectOrigin);
  }

  /**
   * @param {!Workspace.UISourceCode} uiSourceCode
   * @param {boolean=} select
   * @return {?Sources.NavigatorUISourceCodeTreeNode}
   */
  revealUISourceCode(uiSourceCode, select) {
    const nodes = this._uiSourceCodeNodes.get(uiSourceCode);
    const node = nodes.firstValue();
    if (!node) {
      return null;
    }
    if (this._scriptsTree.selectedTreeElement) {
      this._scriptsTree.selectedTreeElement.deselect();
    }
    this._lastSelectedUISourceCode = uiSourceCode;
    // TODO(dgozman): figure out revealing multiple.
    node.reveal(select);
    return node;
  }

  /**
   * @param {!Workspace.UISourceCode} uiSourceCode
   * @param {boolean} focusSource
   */
  _sourceSelected(uiSourceCode, focusSource) {
    this._lastSelectedUISourceCode = uiSourceCode;
    Common.Revealer.reveal(uiSourceCode, !focusSource);
  }

  /**
   * @param {!Workspace.UISourceCode} uiSourceCode
   */
  _removeUISourceCode(uiSourceCode) {
    const nodes = this._uiSourceCodeNodes.get(uiSourceCode);
    for (const node of nodes) {
      this._removeUISourceCodeNode(node);
    }
  }

  /**
   * @param {!Sources.NavigatorUISourceCodeTreeNode} node
   */
  _removeUISourceCodeNode(node) {
    const uiSourceCode = node.uiSourceCode();
    this._uiSourceCodeNodes.delete(uiSourceCode, node);
    const project = uiSourceCode.project();
    const target = Bindings.NetworkProject.targetForUISourceCode(uiSourceCode);
    const frame = node.frame();

    let parentNode = node.parent;
    parentNode.removeChild(node);
    node = parentNode;

    while (node) {
      parentNode = node.parent;
      if (!parentNode || !node.isEmpty()) {
        break;
      }
      if (parentNode === this._rootNode && project.type() === Workspace.projectTypes.FileSystem) {
        break;
      }
      if (!(node instanceof Sources.NavigatorGroupTreeNode || node instanceof Sources.NavigatorFolderTreeNode)) {
        break;
      }
      if (node._type === Sources.NavigatorView.Types.Frame) {
        this._discardFrame(/** @type {!SDK.ResourceTreeFrame} */ (frame));
        break;
      }

      const folderId = this._folderNodeId(project, target, frame, uiSourceCode.origin(), node._folderPath);
      this._subfolderNodes.delete(folderId);
      parentNode.removeChild(node);
      node = parentNode;
    }
  }

  reset() {
    for (const node of this._uiSourceCodeNodes.valuesArray()) {
      node.dispose();
    }

    this._scriptsTree.removeChildren();
    this._uiSourceCodeNodes.clear();
    this._subfolderNodes.clear();
    this._frameNodes.clear();
    this._rootNode.reset();
  }

  /**
   * @param {!Event} event
   */
  handleContextMenu(event) {
  }

  /**
   * @return {boolean}
   */
  _renameShortcut() {
    const node = this._scriptsTree.selectedTreeElement && this._scriptsTree.selectedTreeElement._node;
    if (!node || !node._uiSourceCode || !node._uiSourceCode.canRename()) {
      return false;
    }
    this.rename(node, false);
    return true;
  }

  /**
   * @param {!Workspace.Project} project
   * @param {string} path
   * @param {!Workspace.UISourceCode=} uiSourceCode
   */
  _handleContextMenuCreate(project, path, uiSourceCode) {
    if (uiSourceCode) {
      const relativePath = Persistence.FileSystemWorkspaceBinding.relativePath(uiSourceCode);
      relativePath.pop();
      path = relativePath.join('/');
    }
    this.create(project, path, uiSourceCode);
  }

  /**
   * @param {!Sources.NavigatorUISourceCodeTreeNode} node
   */
  _handleContextMenuRename(node) {
    this.rename(node, false);
  }

  /**
   * @param {!Workspace.Project} project
   * @param {string} path
   */
  _handleContextMenuExclude(project, path) {
    const shouldExclude = window.confirm(Common.UIString('Are you sure you want to exclude this folder?'));
    if (shouldExclude) {
      UI.startBatchUpdate();
      project.excludeFolder(Persistence.FileSystemWorkspaceBinding.completeURL(project, path));
      UI.endBatchUpdate();
    }
  }

  /**
   * @param {!Workspace.UISourceCode} uiSourceCode
   */
  _handleContextMenuDelete(uiSourceCode) {
    const shouldDelete = window.confirm(Common.UIString('Are you sure you want to delete this file?'));
    if (shouldDelete) {
      uiSourceCode.project().deleteFile(uiSourceCode);
    }
  }

  /**
   * @param {!Event} event
   * @param {!Sources.NavigatorUISourceCodeTreeNode} node
   */
  handleFileContextMenu(event, node) {
    const uiSourceCode = node.uiSourceCode();
    const contextMenu = new UI.ContextMenu(event);
    contextMenu.appendApplicableItems(uiSourceCode);

    const project = uiSourceCode.project();
    if (project.type() === Workspace.projectTypes.FileSystem) {
      contextMenu.editSection().appendItem(
          Common.UIString('Rename\u2026'), this._handleContextMenuRename.bind(this, node));
      contextMenu.editSection().appendItem(
          Common.UIString('Make a copy\u2026'), this._handleContextMenuCreate.bind(this, project, '', uiSourceCode));
      contextMenu.editSection().appendItem(
          Common.UIString('Delete'), this._handleContextMenuDelete.bind(this, uiSourceCode));
    }

    contextMenu.show();
  }

  /**
   * @param {!Event} event
   * @param {!Sources.NavigatorTreeNode} node
   */
  handleFolderContextMenu(event, node) {
    const path = node._folderPath || '';
    const project = node._project;

    const contextMenu = new UI.ContextMenu(event);

    if (project.type() === Workspace.projectTypes.FileSystem) {
      Sources.NavigatorView.appendSearchItem(contextMenu, path);

      const folderPath = Common.ParsedURL.urlToPlatformPath(
          Persistence.FileSystemWorkspaceBinding.completeURL(project, path), Host.isWin());
      contextMenu.revealSection().appendItem(
          Common.UIString('Open folder'), () => Host.InspectorFrontendHost.showItemInFolder(folderPath));
      if (project.canCreateFile()) {
        contextMenu.defaultSection().appendItem(
            Common.UIString('New file'), this._handleContextMenuCreate.bind(this, project, path));
      }
    }

    if (project.canExcludeFolder(path)) {
      contextMenu.defaultSection().appendItem(
          Common.UIString('Exclude folder'), this._handleContextMenuExclude.bind(this, project, path));
    }

    function removeFolder() {
      const shouldRemove = window.confirm(Common.UIString('Are you sure you want to remove this folder?'));
      if (shouldRemove) {
        project.remove();
      }
    }

    if (project.type() === Workspace.projectTypes.FileSystem) {
      contextMenu.defaultSection().appendAction('sources.add-folder-to-workspace', undefined, true);
      if (node instanceof Sources.NavigatorGroupTreeNode) {
        contextMenu.defaultSection().appendItem(Common.UIString('Remove folder from workspace'), removeFolder);
      }
    }

    contextMenu.show();
  }

  /**
   * @param {!Sources.NavigatorUISourceCodeTreeNode} node
   * @param {boolean} creatingNewUISourceCode
   * @protected
   */
  rename(node, creatingNewUISourceCode) {
    const uiSourceCode = node.uiSourceCode();
    node.rename(callback.bind(this));

    /**
     * @this {Sources.NavigatorView}
     * @param {boolean} committed
     */
    function callback(committed) {
      if (!creatingNewUISourceCode) {
        return;
      }
      if (!committed) {
        uiSourceCode.remove();
      } else if (node._treeElement.listItemElement.hasFocus()) {
        this._sourceSelected(uiSourceCode, true);
      }
    }
  }

  /**
   * @param {!Workspace.Project} project
   * @param {string} path
   * @param {!Workspace.UISourceCode=} uiSourceCodeToCopy
   */
  async create(project, path, uiSourceCodeToCopy) {
    let content = '';
    if (uiSourceCodeToCopy) {
      content = (await uiSourceCodeToCopy.requestContent()).content || '';
    }
    const uiSourceCode = await project.createFile(path, null, content);
    if (!uiSourceCode) {
      return;
    }
    this._sourceSelected(uiSourceCode, false);
    const node = this.revealUISourceCode(uiSourceCode, true);
    if (node) {
      this.rename(node, true);
    }
  }

  _groupingChanged() {
    this.reset();
    this._initGrouping();
    this._workspace.uiSourceCodes().forEach(this._addUISourceCode.bind(this));
  }

  _initGrouping() {
    this._groupByFrame = true;
    this._groupByDomain = this._navigatorGroupByFolderSetting.get();
    this._groupByFolder = this._groupByDomain;
  }

  _resetForTest() {
    this.reset();
    this._workspace.uiSourceCodes().forEach(this._addUISourceCode.bind(this));
  }

  /**
   * @param {!SDK.ResourceTreeFrame} frame
   */
  _discardFrame(frame) {
    const node = this._frameNodes.get(frame);
    if (!node) {
      return;
    }

    if (node.parent) {
      node.parent.removeChild(node);
    }
    this._frameNodes.delete(frame);
    for (const child of frame.childFrames) {
      this._discardFrame(child);
    }
  }

  /**
   * @override
   * @param {!SDK.Target} target
   */
  targetAdded(target) {
  }

  /**
   * @override
   * @param {!SDK.Target} target
   */
  targetRemoved(target) {
    const targetNode = this._rootNode.child('target:' + target.id());
    if (targetNode) {
      this._rootNode.removeChild(targetNode);
    }
  }

  /**
   * @param {!Common.Event} event
   */
  _targetNameChanged(event) {
    const target = /** @type {!SDK.Target} */ (event.data);
    const targetNode = this._rootNode.child('target:' + target.id());
    if (targetNode) {
      targetNode.setTitle(target.name());
    }
  }
};

Sources.NavigatorView.Types = {
  Domain: 'domain',
  File: 'file',
  FileSystem: 'fs',
  FileSystemFolder: 'fs-folder',
  Frame: 'frame',
  NetworkFolder: 'nw-folder',
  Root: 'root',
  SourceMapFolder: 'sm-folder',
  Worker: 'worker'
};

/**
 * @unrestricted
 */
Sources.NavigatorFolderTreeElement = class extends UI.TreeElement {
  /**
   * @param {!Sources.NavigatorView} navigatorView
   * @param {string} type
   * @param {string} title
   * @param {function(boolean)=} hoverCallback
   */
  constructor(navigatorView, type, title, hoverCallback) {
    super('', true);
    this.listItemElement.classList.add('navigator-' + type + '-tree-item', 'navigator-folder-tree-item');
    this._nodeType = type;
    this.title = title;
    this.tooltip = title;
    this._navigatorView = navigatorView;
    this._hoverCallback = hoverCallback;
    let iconType = 'largeicon-navigator-folder';
    if (type === Sources.NavigatorView.Types.Domain) {
      iconType = 'largeicon-navigator-domain';
    } else if (type === Sources.NavigatorView.Types.Frame) {
      iconType = 'largeicon-navigator-frame';
    } else if (type === Sources.NavigatorView.Types.Worker) {
      iconType = 'largeicon-navigator-worker';
    }
    this.setLeadingIcons([UI.Icon.create(iconType, 'icon')]);
  }

  /**
   * @override
   * @returns {!Promise}
   */
  async onpopulate() {
    this._node.populate();
  }

  /**
   * @override
   */
  onattach() {
    this.collapse();
    this._node.onattach();
    this.listItemElement.addEventListener('contextmenu', this._handleContextMenuEvent.bind(this), false);
    this.listItemElement.addEventListener('mousemove', this._mouseMove.bind(this), false);
    this.listItemElement.addEventListener('mouseleave', this._mouseLeave.bind(this), false);
  }

  /**
   * @param {!Sources.NavigatorTreeNode} node
   */
  setNode(node) {
    this._node = node;
    const paths = [];
    while (node && !node.isRoot()) {
      paths.push(node._title);
      node = node.parent;
    }
    paths.reverse();
    this.tooltip = paths.join('/');
  }

  /**
   * @param {!Event} event
   */
  _handleContextMenuEvent(event) {
    if (!this._node) {
      return;
    }
    this.select();
    this._navigatorView.handleFolderContextMenu(event, this._node);
  }

  /**
   * @param {!Event} event
   */
  _mouseMove(event) {
    if (this._hovered || !this._hoverCallback) {
      return;
    }
    this._hovered = true;
    this._hoverCallback(true);
  }

  /**
   * @param {!Event} event
   */
  _mouseLeave(event) {
    if (!this._hoverCallback) {
      return;
    }
    this._hovered = false;
    this._hoverCallback(false);
  }
};

/**
 * @unrestricted
 */
Sources.NavigatorSourceTreeElement = class extends UI.TreeElement {
  /**
   * @param {!Sources.NavigatorView} navigatorView
   * @param {!Workspace.UISourceCode} uiSourceCode
   * @param {string} title
   * @param {!Sources.NavigatorUISourceCodeTreeNode} node
   */
  constructor(navigatorView, uiSourceCode, title, node) {
    super('', false);
    this._nodeType = Sources.NavigatorView.Types.File;
    this._node = node;
    this.title = title;
    this.listItemElement.classList.add(
        'navigator-' + uiSourceCode.contentType().name() + '-tree-item', 'navigator-file-tree-item');
    this.tooltip = uiSourceCode.url();
    this._navigatorView = navigatorView;
    this._uiSourceCode = uiSourceCode;
    this.updateIcon();
  }

  updateIcon() {
    const binding = Persistence.persistence.binding(this._uiSourceCode);
    if (binding) {
      const container = createElementWithClass('span', 'icon-stack');
      let iconType = 'largeicon-navigator-file-sync';
      if (Snippets.isSnippetsUISourceCode(binding.fileSystem)) {
        iconType = 'largeicon-navigator-snippet';
      }
      const icon = UI.Icon.create(iconType, 'icon');
      const badge = UI.Icon.create('badge-navigator-file-sync', 'icon-badge');
      // TODO(allada) This does not play well with dark theme. Add an actual icon and use it.
      if (Persistence.networkPersistenceManager.project() === binding.fileSystem.project()) {
        badge.style.filter = 'hue-rotate(160deg)';
      }
      container.appendChild(icon);
      container.appendChild(badge);
      container.title = Persistence.PersistenceUtils.tooltipForUISourceCode(this._uiSourceCode);
      this.setLeadingIcons([container]);
    } else {
      let iconType = 'largeicon-navigator-file';
      if (Snippets.isSnippetsUISourceCode(this._uiSourceCode)) {
        iconType = 'largeicon-navigator-snippet';
      }
      const defaultIcon = UI.Icon.create(iconType, 'icon');
      this.setLeadingIcons([defaultIcon]);
    }
  }

  /**
   * @return {!Workspace.UISourceCode}
   */
  get uiSourceCode() {
    return this._uiSourceCode;
  }

  /**
   * @override
   */
  onattach() {
    this.listItemElement.draggable = true;
    this.listItemElement.addEventListener('click', this._onclick.bind(this), false);
    this.listItemElement.addEventListener('contextmenu', this._handleContextMenuEvent.bind(this), false);
    this.listItemElement.addEventListener('dragstart', this._ondragstart.bind(this), false);
  }

  _shouldRenameOnMouseDown() {
    if (!this._uiSourceCode.canRename()) {
      return false;
    }
    const isSelected = this === this.treeOutline.selectedTreeElement;
    return isSelected && this.treeOutline.element.hasFocus() && !UI.isBeingEdited(this.treeOutline.element);
  }

  /**
   * @override
   */
  selectOnMouseDown(event) {
    if (event.which !== 1 || !this._shouldRenameOnMouseDown()) {
      super.selectOnMouseDown(event);
      return;
    }
    setTimeout(rename.bind(this), 300);

    /**
     * @this {Sources.NavigatorSourceTreeElement}
     */
    function rename() {
      if (this._shouldRenameOnMouseDown()) {
        this._navigatorView.rename(this._node, false);
      }
    }
  }

  /**
   * @param {!DragEvent} event
   */
  _ondragstart(event) {
    event.dataTransfer.setData('text/plain', this._uiSourceCode.url());
    event.dataTransfer.effectAllowed = 'copy';
  }

  /**
   * @override
   * @return {boolean}
   */
  onspace() {
    this._navigatorView._sourceSelected(this.uiSourceCode, true);
    return true;
  }

  /**
   * @param {!Event} event
   */
  _onclick(event) {
    this._navigatorView._sourceSelected(this.uiSourceCode, false);
  }

  /**
   * @override
   * @return {boolean}
   */
  ondblclick(event) {
    const middleClick = event.button === 1;
    this._navigatorView._sourceSelected(this.uiSourceCode, !middleClick);
    return false;
  }

  /**
   * @override
   * @return {boolean}
   */
  onenter() {
    this._navigatorView._sourceSelected(this.uiSourceCode, true);
    return true;
  }

  /**
   * @override
   * @return {boolean}
   */
  ondelete() {
    return true;
  }

  /**
   * @param {!Event} event
   */
  _handleContextMenuEvent(event) {
    this.select();
    this._navigatorView.handleFileContextMenu(event, this._node);
  }
};

/**
 * @unrestricted
 */
Sources.NavigatorTreeNode = class {
  /**
   * @param {string} id
   * @param {string} type
   */
  constructor(id, type) {
    this.id = id;
    this._type = type;
    /** @type {!Map.<string, !Sources.NavigatorTreeNode>} */
    this._children = new Map();
  }

  /**
   * @return {!UI.TreeElement}
   */
  treeNode() {
    throw 'Not implemented';
  }

  dispose() {
  }

  /**
   * @return {boolean}
   */
  isRoot() {
    return false;
  }

  /**
   * @return {boolean}
   */
  hasChildren() {
    return true;
  }

  onattach() {
  }

  /**
   * @param {string} title
   */
  setTitle(title) {
    throw 'Not implemented';
  }

  populate() {
    if (this.isPopulated()) {
      return;
    }
    if (this.parent) {
      this.parent.populate();
    }
    this._populated = true;
    this.wasPopulated();
  }

  wasPopulated() {
    const children = this.children();
    for (let i = 0; i < children.length; ++i) {
      this.treeNode().appendChild(/** @type {!UI.TreeElement} */ (children[i].treeNode()));
    }
  }

  /**
   * @param {!Sources.NavigatorTreeNode} node
   */
  didAddChild(node) {
    if (this.isPopulated()) {
      this.treeNode().appendChild(/** @type {!UI.TreeElement} */ (node.treeNode()));
    }
  }

  /**
   * @param {!Sources.NavigatorTreeNode} node
   */
  willRemoveChild(node) {
    if (this.isPopulated()) {
      this.treeNode().removeChild(/** @type {!UI.TreeElement} */ (node.treeNode()));
    }
  }

  /**
   * @return {boolean}
   */
  isPopulated() {
    return this._populated;
  }

  /**
   * @return {boolean}
   */
  isEmpty() {
    return !this._children.size;
  }

  /**
   * @return {!Array.<!Sources.NavigatorTreeNode>}
   */
  children() {
    return this._children.valuesArray();
  }

  /**
   * @param {string} id
   * @return {?Sources.NavigatorTreeNode}
   */
  child(id) {
    return this._children.get(id) || null;
  }

  /**
   * @param {!Sources.NavigatorTreeNode} node
   */
  appendChild(node) {
    this._children.set(node.id, node);
    node.parent = this;
    this.didAddChild(node);
  }

  /**
   * @param {!Sources.NavigatorTreeNode} node
   */
  removeChild(node) {
    this.willRemoveChild(node);
    this._children.remove(node.id);
    delete node.parent;
    node.dispose();
  }

  reset() {
    this._children.clear();
  }
};

/**
 * @unrestricted
 */
Sources.NavigatorRootTreeNode = class extends Sources.NavigatorTreeNode {
  /**
   * @param {!Sources.NavigatorView} navigatorView
   */
  constructor(navigatorView) {
    super('', Sources.NavigatorView.Types.Root);
    this._navigatorView = navigatorView;
  }

  /**
   * @override
   * @return {boolean}
   */
  isRoot() {
    return true;
  }

  /**
   * @override
   * @return {!UI.TreeElement}
   */
  treeNode() {
    return this._navigatorView._scriptsTree.rootElement();
  }
};

/**
 * @unrestricted
 */
Sources.NavigatorUISourceCodeTreeNode = class extends Sources.NavigatorTreeNode {
  /**
   * @param {!Sources.NavigatorView} navigatorView
   * @param {!Workspace.UISourceCode} uiSourceCode
   * @param {?SDK.ResourceTreeFrame} frame
   */
  constructor(navigatorView, uiSourceCode, frame) {
    super(uiSourceCode.project().id() + ':' + uiSourceCode.url(), Sources.NavigatorView.Types.File);
    this._navigatorView = navigatorView;
    this._uiSourceCode = uiSourceCode;
    this._treeElement = null;
    this._eventListeners = [];
    this._frame = frame;
  }

  /**
   * @return {?SDK.ResourceTreeFrame}
   */
  frame() {
    return this._frame;
  }

  /**
   * @return {!Workspace.UISourceCode}
   */
  uiSourceCode() {
    return this._uiSourceCode;
  }

  /**
   * @override
   * @return {!UI.TreeElement}
   */
  treeNode() {
    if (this._treeElement) {
      return this._treeElement;
    }

    this._treeElement = new Sources.NavigatorSourceTreeElement(this._navigatorView, this._uiSourceCode, '', this);
    this.updateTitle();

    const updateTitleBound = this.updateTitle.bind(this, undefined);
    this._eventListeners = [
      this._uiSourceCode.addEventListener(Workspace.UISourceCode.Events.TitleChanged, updateTitleBound),
      this._uiSourceCode.addEventListener(Workspace.UISourceCode.Events.WorkingCopyChanged, updateTitleBound),
      this._uiSourceCode.addEventListener(Workspace.UISourceCode.Events.WorkingCopyCommitted, updateTitleBound)
    ];
    return this._treeElement;
  }

  /**
   * @param {boolean=} ignoreIsDirty
   */
  updateTitle(ignoreIsDirty) {
    if (!this._treeElement) {
      return;
    }

    let titleText = this._uiSourceCode.displayName();
    if (!ignoreIsDirty && this._uiSourceCode.isDirty()) {
      titleText = '*' + titleText;
    }

    this._treeElement.title = titleText;
    this._treeElement.updateIcon();

    let tooltip = this._uiSourceCode.url();
    if (this._uiSourceCode.contentType().isFromSourceMap()) {
      tooltip = Common.UIString('%s (from source map)', this._uiSourceCode.displayName());
    }
    this._treeElement.tooltip = tooltip;
  }

  /**
   * @override
   * @return {boolean}
   */
  hasChildren() {
    return false;
  }

  /**
   * @override
   */
  dispose() {
    Common.EventTarget.removeEventListeners(this._eventListeners);
  }

  /**
   * @param {boolean=} select
   */
  reveal(select) {
    this.parent.populate();
    this.parent.treeNode().expand();
    this._treeElement.reveal(true);
    if (select) {
      this._treeElement.select(true);
    }
  }

  /**
   * @param {function(boolean)=} callback
   */
  rename(callback) {
    if (!this._treeElement) {
      return;
    }

    this._treeElement.listItemElement.focus();

    // Tree outline should be marked as edited as well as the tree element to prevent search from starting.
    const treeOutlineElement = this._treeElement.treeOutline.element;
    UI.markBeingEdited(treeOutlineElement, true);

    /**
     * @param {!Element} element
     * @param {string} newTitle
     * @param {string} oldTitle
     * @this {Sources.NavigatorUISourceCodeTreeNode}
     */
    function commitHandler(element, newTitle, oldTitle) {
      if (newTitle !== oldTitle) {
        this._treeElement.title = newTitle;
        this._uiSourceCode.rename(newTitle).then(renameCallback.bind(this));
        return;
      }
      afterEditing.call(this, true);
    }

    /**
     * @param {boolean} success
     * @this {Sources.NavigatorUISourceCodeTreeNode}
     */
    function renameCallback(success) {
      if (!success) {
        UI.markBeingEdited(treeOutlineElement, false);
        this.updateTitle();
        this.rename(callback);
        return;
      }
      afterEditing.call(this, true);
    }

    /**
     * @param {boolean} committed
     * @this {Sources.NavigatorUISourceCodeTreeNode}
     */
    function afterEditing(committed) {
      UI.markBeingEdited(treeOutlineElement, false);
      this.updateTitle();
      if (callback) {
        callback(committed);
      }
    }

    this.updateTitle(true);
    this._treeElement.startEditingTitle(
        new UI.InplaceEditor.Config(commitHandler.bind(this), afterEditing.bind(this, false)));
  }
};

/**
 * @unrestricted
 */
Sources.NavigatorFolderTreeNode = class extends Sources.NavigatorTreeNode {
  /**
   * @param {!Sources.NavigatorView} navigatorView
   * @param {?Workspace.Project} project
   * @param {string} id
   * @param {string} type
   * @param {string} folderPath
   * @param {string} title
   */
  constructor(navigatorView, project, id, type, folderPath, title) {
    super(id, type);
    this._navigatorView = navigatorView;
    this._project = project;
    this._folderPath = folderPath;
    this._title = title;
  }

  /**
   * @override
   * @return {!UI.TreeElement}
   */
  treeNode() {
    if (this._treeElement) {
      return this._treeElement;
    }
    this._treeElement = this._createTreeElement(this._title, this);
    this.updateTitle();
    return this._treeElement;
  }

  updateTitle() {
    if (!this._treeElement || this._project.type() !== Workspace.projectTypes.FileSystem) {
      return;
    }
    const absoluteFileSystemPath =
        Persistence.FileSystemWorkspaceBinding.fileSystemPath(this._project.id()) + '/' + this._folderPath;
    const hasMappedFiles = Persistence.persistence.filePathHasBindings(absoluteFileSystemPath);
    this._treeElement.listItemElement.classList.toggle('has-mapped-files', hasMappedFiles);
  }

  /**
   * @return {!UI.TreeElement}
   */
  _createTreeElement(title, node) {
    if (this._project.type() !== Workspace.projectTypes.FileSystem) {
      try {
        title = decodeURI(title);
      } catch (e) {
      }
    }
    const treeElement = new Sources.NavigatorFolderTreeElement(this._navigatorView, this._type, title);
    treeElement.setNode(node);
    return treeElement;
  }

  /**
   * @override
   */
  wasPopulated() {
    if (!this._treeElement || this._treeElement._node !== this) {
      return;
    }
    this._addChildrenRecursive();
  }

  _addChildrenRecursive() {
    const children = this.children();
    for (let i = 0; i < children.length; ++i) {
      const child = children[i];
      this.didAddChild(child);
      if (child instanceof Sources.NavigatorFolderTreeNode) {
        child._addChildrenRecursive();
      }
    }
  }

  _shouldMerge(node) {
    return this._type !== Sources.NavigatorView.Types.Domain && node instanceof Sources.NavigatorFolderTreeNode;
  }

  /**
   * @param {!Sources.NavigatorTreeNode} node
   * @override
   */
  didAddChild(node) {
    function titleForNode(node) {
      return node._title;
    }

    if (!this._treeElement) {
      return;
    }

    let children = this.children();

    if (children.length === 1 && this._shouldMerge(node)) {
      node._isMerged = true;
      this._treeElement.title = this._treeElement.title + '/' + node._title;
      node._treeElement = this._treeElement;
      this._treeElement.setNode(node);
      return;
    }

    let oldNode;
    if (children.length === 2) {
      oldNode = children[0] !== node ? children[0] : children[1];
    }
    if (oldNode && oldNode._isMerged) {
      delete oldNode._isMerged;
      const mergedToNodes = [];
      mergedToNodes.push(this);
      let treeNode = this;
      while (treeNode._isMerged) {
        treeNode = treeNode.parent;
        mergedToNodes.push(treeNode);
      }
      mergedToNodes.reverse();
      const titleText = mergedToNodes.map(titleForNode).join('/');

      const nodes = [];
      treeNode = oldNode;
      do {
        nodes.push(treeNode);
        children = treeNode.children();
        treeNode = children.length === 1 ? children[0] : null;
      } while (treeNode && treeNode._isMerged);

      if (!this.isPopulated()) {
        this._treeElement.title = titleText;
        this._treeElement.setNode(this);
        for (let i = 0; i < nodes.length; ++i) {
          delete nodes[i]._treeElement;
          delete nodes[i]._isMerged;
        }
        return;
      }
      const oldTreeElement = this._treeElement;
      const treeElement = this._createTreeElement(titleText, this);
      for (let i = 0; i < mergedToNodes.length; ++i) {
        mergedToNodes[i]._treeElement = treeElement;
      }
      oldTreeElement.parent.appendChild(treeElement);

      oldTreeElement.setNode(nodes[nodes.length - 1]);
      oldTreeElement.title = nodes.map(titleForNode).join('/');
      oldTreeElement.parent.removeChild(oldTreeElement);
      this._treeElement.appendChild(oldTreeElement);
      if (oldTreeElement.expanded) {
        treeElement.expand();
      }
    }
    if (this.isPopulated()) {
      this._treeElement.appendChild(node.treeNode());
    }
  }

  /**
   * @override
   * @param {!Sources.NavigatorTreeNode} node
   */
  willRemoveChild(node) {
    if (node._isMerged || !this.isPopulated()) {
      return;
    }
    this._treeElement.removeChild(node._treeElement);
  }
};

/**
 * @unrestricted
 */
Sources.NavigatorGroupTreeNode = class extends Sources.NavigatorTreeNode {
  /**
   * @param {!Sources.NavigatorView} navigatorView
   * @param {!Workspace.Project} project
   * @param {string} id
   * @param {string} type
   * @param {string} title
   */
  constructor(navigatorView, project, id, type, title) {
    super(id, type);
    this._project = project;
    this._navigatorView = navigatorView;
    this._title = title;
    this.populate();
  }

  /**
   * @param {function(boolean)} hoverCallback
   */
  setHoverCallback(hoverCallback) {
    this._hoverCallback = hoverCallback;
  }

  /**
   * @override
   * @return {!UI.TreeElement}
   */
  treeNode() {
    if (this._treeElement) {
      return this._treeElement;
    }
    this._treeElement =
        new Sources.NavigatorFolderTreeElement(this._navigatorView, this._type, this._title, this._hoverCallback);
    this._treeElement.setNode(this);
    return this._treeElement;
  }

  /**
   * @override
   */
  onattach() {
    this.updateTitle();
  }

  updateTitle() {
    if (!this._treeElement || this._project.type() !== Workspace.projectTypes.FileSystem) {
      return;
    }
    const fileSystemPath = Persistence.FileSystemWorkspaceBinding.fileSystemPath(this._project.id());
    const wasActive = this._treeElement.listItemElement.classList.contains('has-mapped-files');
    const isActive = Persistence.persistence.filePathHasBindings(fileSystemPath);
    if (wasActive === isActive) {
      return;
    }
    this._treeElement.listItemElement.classList.toggle('has-mapped-files', isActive);
    if (this._treeElement.childrenListElement.hasFocus()) {
      return;
    }
    if (isActive) {
      this._treeElement.expand();
    } else {
      this._treeElement.collapse();
    }
  }

  /**
   * @param {string} title
   * @override
   */
  setTitle(title) {
    this._title = title;
    if (this._treeElement) {
      this._treeElement.title = this._title;
    }
  }
};