MD Bookmarks: Make CommandManager available as a singleton

chrome/browser/resources/md_bookmarks/command_manager.js

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-Polymer({
-  is: 'bookmarks-command-manager',
-
-  behaviors: [
-    bookmarks.StoreClient,
-  ],
-
-  properties: {
-    /** @private {!Array<Command>} */
-    menuCommands_: {
-      type: Array,
-      value: function() {
-        return [
-          Command.EDIT,
-          Command.COPY,
-          Command.DELETE,
-          // <hr>
-          Command.OPEN_NEW_TAB,
-          Command.OPEN_NEW_WINDOW,
-          Command.OPEN_INCOGNITO,
-        ];
+/**
+ * @fileoverview Element which shows context menus and handles keyboard
+ * shortcuts.
+ */
+cr.define('bookmarks', function() {
+
+  var CommandManager = Polymer({
+    is: 'bookmarks-command-manager',
+
+    behaviors: [
+      bookmarks.StoreClient,
+    ],
+
+    properties: {
+      /** @private {!Array<Command>} */
+      menuCommands_: {
+        type: Array,
+        value: function() {
+          return [
+            Command.EDIT,
+            Command.COPY,
+            Command.DELETE,
+            // <hr>
+            Command.OPEN_NEW_TAB,
+            Command.OPEN_NEW_WINDOW,
+            Command.OPEN_INCOGNITO,
+          ];
+        },
       },
-    },
-
-    /** @type {Set<string>} */
-    menuIds_: Object,
-  },
-
-  attached: function() {
-    /** @private {function(!Event)} */
-    this.boundOnOpenItemMenu_ = this.onOpenItemMenu_.bind(this);
-    document.addEventListener('open-item-menu', this.boundOnOpenItemMenu_);
-
-    /** @private {function(!Event)} */
-    this.boundOnKeydown_ = this.onKeydown_.bind(this);
-    document.addEventListener('keydown', this.boundOnKeydown_);
-
-    /** @private {Object<Command, string>} */
-    this.shortcuts_ = {};
-    this.shortcuts_[Command.EDIT] = cr.isMac ? 'enter' : 'f2';
-    this.shortcuts_[Command.COPY] = cr.isMac ? 'meta+c' : 'ctrl+c';
-    this.shortcuts_[Command.DELETE] = cr.isMac ? 'delete backspace' : 'delete';
-    this.shortcuts_[Command.OPEN_NEW_TAB] =
-        cr.isMac ? 'meta+enter' : 'ctrl+enter';
-    this.shortcuts_[Command.OPEN_NEW_WINDOW] = 'shift+enter';
-  },
-
-  detached: function() {
-    document.removeEventListener('open-item-menu', this.boundOnOpenItemMenu_);
-    document.removeEventListener('keydown', this.boundOnKeydown_);
-  },
-
-  /**
-   * Display the command context menu at (|x|, |y|) in window co-ordinates.
-   * Commands will execute on the currently selected items.
-   * @param {number} x
-   * @param {number} y
-   */
-  openCommandMenuAtPosition: function(x, y) {
-    this.menuIds_ = this.getState().selection.items;
-    /** @type {!CrActionMenuElement} */ (this.$.dropdown)
-        .showAtPosition({top: y, left: x});
-  },
-
-  /**
-   * Display the command context menu positioned to cover the |target|
-   * element. Commands will execute on the currently selected items.
-   * @param {!Element} target
-   */
-  openCommandMenuAtElement: function(target) {
-    this.menuIds_ = this.getState().selection.items;
-    /** @type {!CrActionMenuElement} */ (this.$.dropdown).showAt(target);
-  },
-
-  closeCommandMenu: function() {
-    /** @type {!CrActionMenuElement} */ (this.$.dropdown).close();
-  },
-
-  ////////////////////////////////////////////////////////////////////////////
-  // Command handlers:
-
-  /**
-   * Determine if the |command| can be executed with the given |itemIds|.
-   * Commands which appear in the context menu should be implemented separately
-   * using `isCommandVisible_` and `isCommandEnabled_`.
-   * @param {Command} command
-   * @param {!Set<string>} itemIds
-   * @return {boolean}
-   */
-  canExecute: function(command, itemIds) {
-    return this.isCommandVisible_(command, itemIds) &&
-        this.isCommandEnabled_(command, itemIds);
-  },
-
-  /**
-   * @param {Command} command
-   * @param {!Set<string>} itemIds
-   * @return {boolean} True if the command should be visible in the context
-   *     menu.
-   */
-  isCommandVisible_: function(command, itemIds) {
-    switch (command) {
-      case Command.EDIT:
-        return itemIds.size == 1;
-      case Command.COPY:
-        return itemIds.size == 1 &&
-            this.containsMatchingNode_(itemIds, function(node) {
-              return !!node.url;
-            });
-      case Command.DELETE:
-      case Command.OPEN_NEW_TAB:
-      case Command.OPEN_NEW_WINDOW:
-      case Command.OPEN_INCOGNITO:
-        return itemIds.size > 0;
-      default:
-        return false;
-    }
-  },
-
-  /**
-   * @param {Command} command
-   * @param {!Set<string>} itemIds
-   * @return {boolean} True if the command should be clickable in the context
-   *     menu.
-   */
-  isCommandEnabled_: function(command, itemIds) {
-    switch (command) {
-      case Command.OPEN_NEW_TAB:
-      case Command.OPEN_NEW_WINDOW:
-      case Command.OPEN_INCOGNITO:
-        return this.expandUrls_(itemIds).length > 0;
-      default:
-        return true;
-    }
-  },
-
-  /**
-   * @param {Command} command
-   * @param {!Set<string>} itemIds
-   */
-  handle: function(command, itemIds) {
-    switch (command) {
-      case Command.EDIT:
-        var id = Array.from(itemIds)[0];
-        /** @type {!BookmarksEditDialogElement} */ (this.$.editDialog.get())
-            .showEditDialog(this.getState().nodes[id]);
-        break;
-      case Command.COPY:
-        var idList = Array.from(itemIds);
-        chrome.bookmarkManagerPrivate.copy(idList, function() {
-          // TODO(jiaxi): Add toast later.
+
+      /** @type {Set<string>} */
+      menuIds_: Object,
+    },
+
+    attached: function() {
+      assert(CommandManager.instance_ == null);
+      CommandManager.instance_ = this;
+
+      /** @private {function(!Event)} */
+      this.boundOnOpenItemMenu_ = this.onOpenItemMenu_.bind(this);
+      document.addEventListener('open-item-menu', this.boundOnOpenItemMenu_);
+
+      /** @private {function(!Event)} */
+      this.boundOnKeydown_ = this.onKeydown_.bind(this);
+      document.addEventListener('keydown', this.boundOnKeydown_);
+
+      /** @private {Object<Command, string>} */
+      this.shortcuts_ = {};
+      this.shortcuts_[Command.EDIT] = cr.isMac ? 'enter' : 'f2';
+      this.shortcuts_[Command.COPY] = cr.isMac ? 'meta+c' : 'ctrl+c';
+      this.shortcuts_[Command.DELETE] =
+          cr.isMac ? 'delete backspace' : 'delete';
+      this.shortcuts_[Command.OPEN_NEW_TAB] =
+          cr.isMac ? 'meta+enter' : 'ctrl+enter';
+      this.shortcuts_[Command.OPEN_NEW_WINDOW] = 'shift+enter';
+    },
+
+    detached: function() {
+      CommandManager.instance_ = null;
+      document.removeEventListener('open-item-menu', this.boundOnOpenItemMenu_);
+      document.removeEventListener('keydown', this.boundOnKeydown_);
+    },
+
+    /**
+     * Display the command context menu at (|x|, |y|) in window co-ordinates.
+     * Commands will execute on the currently selected items.
+     * @param {number} x
+     * @param {number} y
+     */
+    openCommandMenuAtPosition: function(x, y) {
+      this.menuIds_ = this.getState().selection.items;
+      /** @type {!CrActionMenuElement} */ (this.$.dropdown)
+          .showAtPosition({top: y, left: x});
+    },
+
+    /**
+     * Display the command context menu positioned to cover the |target|
+     * element. Commands will execute on the currently selected items.
+     * @param {!Element} target
+     */
+    openCommandMenuAtElement: function(target) {
+      this.menuIds_ = this.getState().selection.items;
+      /** @type {!CrActionMenuElement} */ (this.$.dropdown).showAt(target);
+    },
+
+    closeCommandMenu: function() {
+      /** @type {!CrActionMenuElement} */ (this.$.dropdown).close();
+    },
+
+    ////////////////////////////////////////////////////////////////////////////
+    // Command handlers:
+
+    /**
+     * Determine if the |command| can be executed with the given |itemIds|.
+     * Commands which appear in the context menu should be implemented
+     * separately using `isCommandVisible_` and `isCommandEnabled_`.
+     * @param {Command} command
+     * @param {!Set<string>} itemIds
+     * @return {boolean}
+     */
+    canExecute: function(command, itemIds) {
+      return this.isCommandVisible_(command, itemIds) &&
+          this.isCommandEnabled_(command, itemIds);
+    },
+
+    /**
+     * @param {Command} command
+     * @param {!Set<string>} itemIds
+     * @return {boolean} True if the command should be visible in the context
+     *     menu.
+     */
+    isCommandVisible_: function(command, itemIds) {
+      switch (command) {
+        case Command.EDIT:
+          return itemIds.size == 1;
+        case Command.COPY:
+          return itemIds.size == 1 &&
+              this.containsMatchingNode_(itemIds, function(node) {
+                return !!node.url;
+              });
+        case Command.DELETE:
+        case Command.OPEN_NEW_TAB:
+        case Command.OPEN_NEW_WINDOW:
+        case Command.OPEN_INCOGNITO:
+          return itemIds.size > 0;
+        default:
+          return false;
+      }
+    },
+
+    /**
+     * @param {Command} command
+     * @param {!Set<string>} itemIds
+     * @return {boolean} True if the command should be clickable in the context
+     *     menu.
+     */
+    isCommandEnabled_: function(command, itemIds) {
+      switch (command) {
+        case Command.OPEN_NEW_TAB:
+        case Command.OPEN_NEW_WINDOW:
+        case Command.OPEN_INCOGNITO:
+          return this.expandUrls_(itemIds).length > 0;
+        default:
+          return true;
+      }
+    },
+
+    /**
+     * @param {Command} command
+     * @param {!Set<string>} itemIds
+     */
+    handle: function(command, itemIds) {
+      switch (command) {
+        case Command.EDIT:
+          var id = Array.from(itemIds)[0];
+          /** @type {!BookmarksEditDialogElement} */ (this.$.editDialog.get())
+              .showEditDialog(this.getState().nodes[id]);
+          break;
+        case Command.COPY:
+          var idList = Array.from(itemIds);
+          chrome.bookmarkManagerPrivate.copy(idList, function() {
+            // TODO(jiaxi): Add toast later.
+          });
+          break;
+        case Command.DELETE:
+          chrome.bookmarkManagerPrivate.removeTrees(
+              Array.from(this.minimizeDeletionSet_(itemIds)), function() {
+                // TODO(jiaxi): Add toast later.
+              });
+          break;
+        case Command.OPEN_NEW_TAB:
+        case Command.OPEN_NEW_WINDOW:
+        case Command.OPEN_INCOGNITO:
+          this.openUrls_(this.expandUrls_(itemIds), command);
+          break;
+      }
+    },
+
+    ////////////////////////////////////////////////////////////////////////////
+    // Private functions:
+
+    /**
+     * Minimize the set of |itemIds| by removing any node which has an ancestor
+     * node already in the set. This ensures that instead of trying to delete
+     * both a node and its descendant, we will only try to delete the topmost
+     * node, preventing an error in the bookmarkManagerPrivate.removeTrees API
+     * call.
+     * @param {!Set<string>} itemIds
+     * @return {!Set<string>}
+     */
+    minimizeDeletionSet_: function(itemIds) {
+      var minimizedSet = new Set();
+      var nodes = this.getState().nodes;
+      itemIds.forEach(function(itemId) {
+        var currentId = itemId;
+        while (currentId != ROOT_NODE_ID) {
+          currentId = assert(nodes[currentId].parentId);
+          if (itemIds.has(currentId))
+            return;
+        }
+        minimizedSet.add(itemId);
+      });
+      return minimizedSet;
+    },
+
+    /**
+     * @param {!Array<string>} urls
+     * @param {Command} command
+     * @private
+     */
+    openUrls_: function(urls, command) {
+      assert(
+          command == Command.OPEN_NEW_TAB ||
+          command == Command.OPEN_NEW_WINDOW ||
+          command == Command.OPEN_INCOGNITO);
+
+      if (urls.length == 0)
+        return;
+
+      var incognito = command == Command.OPEN_INCOGNITO;
+      if (command == Command.OPEN_NEW_WINDOW || incognito) {
+        chrome.windows.create({url: urls, incognito: incognito});
+      } else {
+        urls.forEach(function(url) {
+          chrome.tabs.create({url: url, active: false});
         });
-        break;
-      case Command.DELETE:
-        chrome.bookmarkManagerPrivate.removeTrees(
-            Array.from(this.minimizeDeletionSet_(itemIds)), function() {
-              // TODO(jiaxi): Add toast later.
-            });
-        break;
-      case Command.OPEN_NEW_TAB:
-      case Command.OPEN_NEW_WINDOW:
-      case Command.OPEN_INCOGNITO:
-        this.openUrls_(this.expandUrls_(itemIds), command);
-        break;
-    }
-  },
-
-  ////////////////////////////////////////////////////////////////////////////
-  // Private functions:
-
-  /**
-   * Minimize the set of |itemIds| by removing any node which has an ancestor
-   * node already in the set. This ensures that instead of trying to delete both
-   * a node and its descendant, we will only try to delete the topmost node,
-   * preventing an error in the bookmarkManagerPrivate.removeTrees API call.
-   * @param {!Set<string>} itemIds
-   * @return {!Set<string>}
-   */
-  minimizeDeletionSet_: function(itemIds) {
-    var minimizedSet = new Set();
-    var nodes = this.getState().nodes;
-    itemIds.forEach(function(itemId) {
-      var currentId = itemId;
-      while (currentId != ROOT_NODE_ID) {
-        currentId = assert(nodes[currentId].parentId);
-        if (itemIds.has(currentId))
+      }
+    },
+
+    /**
+     * Returns all URLs in the given set of nodes and their immediate children.
+     * Note that these will be ordered by insertion order into the |itemIds|
+     * set, and that it is possible to duplicate a URL by passing in both the
+     * parent ID and child ID.
+     * @param {!Set<string>} itemIds
+     * @return {!Array<string>}
+     * @private
+     */
+    expandUrls_: function(itemIds) {
+      var urls = [];
+      var nodes = this.getState().nodes;
+
+      itemIds.forEach(function(id) {
+        var node = nodes[id];
+        if (node.url) {
+          urls.push(node.url);
+        } else {
+          node.children.forEach(function(childId) {
+            var childNode = nodes[childId];
+            if (childNode.url)
+              urls.push(childNode.url);
+          });
+        }
+      });
+
+      return urls;
+    },
+
+    /**
+     * @param {!Set<string>} itemIds
+     * @param {function(BookmarkNode):boolean} predicate
+     * @return {boolean} True if any node in |itemIds| returns true for
+     *     |predicate|.
+     */
+    containsMatchingNode_: function(itemIds, predicate) {
+      var nodes = this.getState().nodes;
+
+      return Array.from(itemIds).some(function(id) {
+        return predicate(nodes[id]);
+      });
+    },
+
+    /**
+     * @param {Event} e
+     * @private
+     */
+    onOpenItemMenu_: function(e) {
+      if (e.detail.targetElement) {
+        this.openCommandMenuAtElement(e.detail.targetElement);
+      } else {
+        this.openCommandMenuAtPosition(e.detail.x, e.detail.y);
+      }
+    },
+
+    /**
+     * @param {Event} e
+     * @private
+     */
+    onCommandClick_: function(e) {
+      this.closeCommandMenu();
+      this.handle(e.target.getAttribute('command'), assert(this.menuIds_));
+    },
+
+    /**
+     * @param {!Event} e
+     * @private
+     */
+    onKeydown_: function(e) {
+      var selection = this.getState().selection.items;
+      // TODO(tsergeant): Prevent keyboard shortcuts when a dialog is open or
+      // text field is focused.
+      for (var commandName in this.shortcuts_) {
+        var shortcut = this.shortcuts_[commandName];
+        if (Polymer.IronA11yKeysBehavior.keyboardEventMatchesKeys(
+                e, shortcut) &&
+            this.canExecute(commandName, selection)) {
+          this.handle(commandName, selection);
+
+          e.stopPropagation();
+          e.preventDefault();
           return;
-      }
-      minimizedSet.add(itemId);
-    });
-    return minimizedSet;
-  },
-
-  /**
-   * @param {!Array<string>} urls
-   * @param {Command} command
-   * @private
-   */
-  openUrls_: function(urls, command) {
-    assert(
-        command == Command.OPEN_NEW_TAB || command == Command.OPEN_NEW_WINDOW ||
-        command == Command.OPEN_INCOGNITO);
-
-    if (urls.length == 0)
-      return;
-
-    var incognito = command == Command.OPEN_INCOGNITO;
-    if (command == Command.OPEN_NEW_WINDOW || incognito) {
-      chrome.windows.create({url: urls, incognito: incognito});
-    } else {
-      urls.forEach(function(url) {
-        chrome.tabs.create({url: url, active: false});
-      });
-    }
-  },
-
-  /**
-   * Returns all URLs in the given set of nodes and their immediate children.
-   * Note that these will be ordered by insertion order into the |itemIds| set,
-   * and that it is possible to duplicate a URL by passing in both the parent ID
-   * and child ID.
-   * @param {!Set<string>} itemIds
-   * @return {!Array<string>}
-   * @private
-   */
-  expandUrls_: function(itemIds) {
-    var urls = [];
-    var nodes = this.getState().nodes;
-
-    itemIds.forEach(function(id) {
-      var node = nodes[id];
-      if (node.url) {
-        urls.push(node.url);
-      } else {
-        node.children.forEach(function(childId) {
-          var childNode = nodes[childId];
-          if (childNode.url)
-            urls.push(childNode.url);
-        });
-      }
-    });
-
-    return urls;
-  },
-
-  /**
-   * @param {!Set<string>} itemIds
-   * @param {function(BookmarkNode):boolean} predicate
-   * @return {boolean} True if any node in |itemIds| returns true for
-   *     |predicate|.
-   */
-  containsMatchingNode_: function(itemIds, predicate) {
-    var nodes = this.getState().nodes;
-
-    return Array.from(itemIds).some(function(id) {
-      return predicate(nodes[id]);
-    });
-  },
-
-  /**
-   * @param {Event} e
-   * @private
-   */
-  onOpenItemMenu_: function(e) {
-    if (e.detail.targetElement) {
-      this.openCommandMenuAtElement(e.detail.targetElement);
-    } else {
-      this.openCommandMenuAtPosition(e.detail.x, e.detail.y);
-    }
-  },
-
-  /**
-   * @param {Event} e
-   * @private
-   */
-  onCommandClick_: function(e) {
-    this.closeCommandMenu();
-    this.handle(e.target.getAttribute('command'), assert(this.menuIds_));
-  },
-
-  /**
-   * @param {!Event} e
-   * @private
-   */
-  onKeydown_: function(e) {
-    var selection = this.getState().selection.items;
-    // TODO(tsergeant): Prevent keyboard shortcuts when a dialog is open or text
-    // field is focused.
-    for (var commandName in this.shortcuts_) {
-      var shortcut = this.shortcuts_[commandName];
-      if (Polymer.IronA11yKeysBehavior.keyboardEventMatchesKeys(e, shortcut) &&
-          this.canExecute(commandName, selection)) {
-        this.handle(commandName, selection);
-
-        e.stopPropagation();
-        e.preventDefault();
+        }
+      }
+    },
+
+    /**
+     * Close the menu on mousedown so clicks can propagate to the underlying UI.
+     * This allows the user to right click the list while a context menu is
+     * showing and get another context menu.
+     * @param {Event} e
+     * @private
+     */
+    onMenuMousedown_: function(e) {
+      if (e.path[0] != this.$.dropdown)
         return;
-      }
-    }
-  },
-
-  /**
-   * Close the menu on mousedown so clicks can propagate to the underlying UI.
-   * This allows the user to right click the list while a context menu is
-   * showing and get another context menu.
-   * @param {Event} e
-   * @private
-   */
-  onMenuMousedown_: function(e) {
-    if (e.path[0] != this.$.dropdown)
-      return;
-
-    this.$.dropdown.close();
-  },
-
-  /**
-   * @param {Command} command
-   * @return {string}
-   * @private
-   */
-  getCommandLabel_: function(command) {
-    var multipleNodes = this.menuIds_.size > 1 ||
-        this.containsMatchingNode_(this.menuIds_, function(node) {
-          return !node.url;
-        });
-    var label;
-    switch (command) {
-      case Command.EDIT:
-        if (this.menuIds_.size > 1)
-          return '';
-
-        var id = Array.from(this.menuIds_)[0];
-        var itemUrl = this.getState().nodes[id].url;
-        label = itemUrl ? 'menuEdit' : 'menuRename';
-        break;
-      case Command.COPY:
-        label = 'menuCopyURL';
-        break;
-      case Command.DELETE:
-        label = 'menuDelete';
-        break;
-      case Command.OPEN_NEW_TAB:
-        label = multipleNodes ? 'menuOpenAllNewTab' : 'menuOpenNewTab';
-        break;
-      case Command.OPEN_NEW_WINDOW:
-        label = multipleNodes ? 'menuOpenAllNewWindow' : 'menuOpenNewWindow';
-        break;
-      case Command.OPEN_INCOGNITO:
-        label = multipleNodes ? 'menuOpenAllIncognito' : 'menuOpenIncognito';
-        break;
-    }
-
-    return loadTimeData.getString(assert(label));
-  },
-
-  /**
-   * @param {Command} command
-   * @return {boolean}
-   * @private
-   */
-  showDividerAfter_: function(command) {
-    return command == Command.DELETE;
-  },
+
+      this.$.dropdown.close();
+    },
+
+    /**
+     * @param {Command} command
+     * @return {string}
+     * @private
+     */
+    getCommandLabel_: function(command) {
+      var multipleNodes = this.menuIds_.size > 1 ||
+          this.containsMatchingNode_(this.menuIds_, function(node) {
+            return !node.url;
+          });
+      var label;
+      switch (command) {
+        case Command.EDIT:
+          if (this.menuIds_.size > 1)
+            return '';
+
+          var id = Array.from(this.menuIds_)[0];
+          var itemUrl = this.getState().nodes[id].url;
+          label = itemUrl ? 'menuEdit' : 'menuRename';
+          break;
+        case Command.COPY:
+          label = 'menuCopyURL';
+          break;
+        case Command.DELETE:
+          label = 'menuDelete';
+          break;
+        case Command.OPEN_NEW_TAB:
+          label = multipleNodes ? 'menuOpenAllNewTab' : 'menuOpenNewTab';
+          break;
+        case Command.OPEN_NEW_WINDOW:
+          label = multipleNodes ? 'menuOpenAllNewWindow' : 'menuOpenNewWindow';
+          break;
+        case Command.OPEN_INCOGNITO:
+          label = multipleNodes ? 'menuOpenAllIncognito' : 'menuOpenIncognito';
+          break;
+      }
+
+      return loadTimeData.getString(assert(label));
+    },
+
+    /**
+     * @param {Command} command
+     * @return {boolean}
+     * @private
+     */
+    showDividerAfter_: function(command) {
+      return command == Command.DELETE;
+    },
+  });
+
+  /** @private {bookmarks.CommandManager} */
+  CommandManager.instance_ = null;
+
+  /** @return {!bookmarks.CommandManager} */
+  CommandManager.getInstance = function() {
+    return assert(CommandManager.instance_);
+  };
+
+  return {
+    CommandManager: CommandManager,
+  };
 });