/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla History System
 *
 * The Initial Developer of the Original Code is
 * Google Inc.
 * Portions created by the Initial Developer are Copyright (C) 2005
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Brett Wilson <brettw@gmail.com> (Original author)
 *   Asaf Romano <mano@mozilla.com> (JavaScript version)
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

function PlacesTreeView(aFlatList, aOnOpenFlatContainer) {
  this._tree = null;
  this._result = null;
  this._selection = null;
  this._rootNode = null;
  this._rows = [];
  this._flatList = aFlatList;
  this._openContainerCallback = aOnOpenFlatContainer;
}

PlacesTreeView.prototype = {
  _makeAtom: function PTV__makeAtom(aString) {
    return Components.classes["@mozilla.org/atom-service;1"]
                     .getService(Components.interfaces.nsIAtomService)
                     .getAtom(aString);
  },

  _atoms: [],
  _getAtomFor: function PTV__getAtomFor(aName) {
    if (!this._atoms[aName])
      this._atoms[aName] = this._makeAtom(aName);

    return this._atoms[aName];
  },

  __dateService: null,
  get _dateService() {
    if (!this.__dateService) {
      this.__dateService = Components.classes["@mozilla.org/intl/scriptabledateformat;1"]
                                     .getService(Components.interfaces.nsIScriptableDateFormat);
    }
    return this.__dateService;
  },

  QueryInterface: function PTV_QueryInterface(aIID) {
    if (aIID.equals(Components.interfaces.nsITreeView) ||
        aIID.equals(Components.interfaces.nsINavHistoryResultObserver) ||
        aIID.equals(Components.interfaces.nsINavHistoryResultTreeViewer) ||
        aIID.equals(Components.interfaces.nsISupportsWeakReference) ||
        aIID.equals(Components.interfaces.nsISupports))
      return this;

    throw Components.results.NS_ERROR_NO_INTERFACE;
  },

  /**
   * This is called once both the result and the tree are set.
   */
  _finishInit: function PTV__finishInit() {
    let selection = this.selection;
    if (selection)
      selection.selectEventsSuppressed = true;

    if (!this._rootNode.containerOpen) {
      // This triggers containerStateChanged which then builds the visible section.
      this._rootNode.containerOpen = true;
    }
    else
      this.invalidateContainer(this._rootNode);

    // "Activate" the sorting column and update commands.
    this.sortingChanged(this._result.sortingMode);

    if (selection)
      selection.selectEventsSuppressed = false;
  },

  /**
   * Plain Container: container result nodes which may never include sub
   * hierarchies.
   *
   * When the rows array is constructed, we don't set the children of plain
   * containers.  Instead, we keep placeholders for these children.  We then
   * build these children lazily as the tree asks us for information about each
   * row.  Luckily, the tree doesn't ask about rows outside the visible area.
   *
   * @see _getNodeForRow and _getRowForNode for the actual magic.
   *
   * @note It's guaranteed that all containers are listed in the rows
   * elements array.  It's also guaranteed that separators (if they're not
   * filtered, see below) are listed in the visible elements array, because
   * bookmark folders are never built lazily, as described above.
   *
   * @param aContainer
   *        A container result node.
   *
   * @return true if aContainer is a plain container, false otherwise.
   */
  _isPlainContainer: function PTV__isPlainContainer(aContainer) {
    if (aContainer._plainContainer !== undefined)
      return aContainer._plainContainer;

    // We don't know enough about non-query containers.
    if (!(aContainer instanceof Components.interfaces.nsINavHistoryQueryResultNode))
      return aContainer._plainContainer = false;

    switch (aContainer.queryOptions.resultType) {
      case Components.interfaces.nsINavHistoryQueryOptions.RESULTS_AS_DATE_QUERY:
      case Components.interfaces.nsINavHistoryQueryOptions.RESULTS_AS_SITE_QUERY:
      case Components.interfaces.nsINavHistoryQueryOptions.RESULTS_AS_DATE_SITE_QUERY:
      case Components.interfaces.nsINavHistoryQueryOptions.RESULTS_AS_TAG_QUERY:
        return aContainer._plainContainer = false;
    }

    // If it's a folder, it's not a plain container.
    let nodeType = aContainer.type;
    return aContainer._plainContainer =
           (nodeType != Components.interfaces.nsINavHistoryResultNode.RESULT_TYPE_FOLDER &&
            nodeType != Components.interfaces.nsINavHistoryResultNode.RESULT_TYPE_FOLDER_SHORTCUT);
  },

  /**
   * Gets the row number for a given node.  Assumes that the given node is
   * visible (i.e. it's not an obsolete node).
   *
   * @param aNode
   *        A result node.  Do not pass an obsolete node, or any
   *        node which isn't supposed to be in the tree (e.g. separators in
   *        sorted trees).
   * @param [optional] aForceBuild
   *        @see _isPlainContainer.
   *        If true, the row will be computed even if the node still isn't set
   *        in our rows array.
   * @param [optional] aParentRow
   *        The row of aNode's parent. Ignored for the root node.
   * @param [optional] aNodeIndex
   *        The index of aNode in its parent.  Only used if aParentRow is
   *        set too.
   *
   * @throws if aNode is invisible.
   * @note If aParentRow and aNodeIndex are passed and parent is a plain
   * container, this method will just return a calculated row value, without
   * making assumptions on existence of the node at that position.
   * @return aNode's row if it's in the rows list or if aForceBuild is set, -1
   *         otherwise.
   */
  _getRowForNode:
  function PTV__getRowForNode(aNode, aForceBuild, aParentRow, aNodeIndex) {
    if (aNode == this._rootNode)
      throw "The root node is never visible";

    let ancestors = PlacesUtils.nodeAncestors(aNode);
    for (let ancestor in ancestors) {
      if (!ancestor.containerOpen)
        throw "Invisible node passed to _getRowForNode";
    }

    // Non-plain containers are initially built with their contents.
    let parent = aNode.parent;
    let parentIsPlain = this._isPlainContainer(parent);
    if (!parentIsPlain) {
      if (parent == this._rootNode)
        return this._rows.indexOf(aNode);

      return this._rows.indexOf(aNode, aParentRow);
    }

    let row = -1;
    let useNodeIndex = typeof(aNodeIndex) == "number";
    if (parent == this._rootNode)
      row = useNodeIndex ? aNodeIndex : this._rootNode.getChildIndex(aNode);
    else if (useNodeIndex && typeof(aParentRow) == "number") {
      // If we have both the row of the parent node, and the node's index, we
      // can avoid searching the rows array if the parent is a plain container.
      row = aParentRow + aNodeIndex + 1;
    }
    else {
      // Look for the node in the nodes array.  Start the search at the parent
      // row.  If the parent row isn't passed, we'll pass undefined to indexOf,
      // which is fine.
      row = this._rows.indexOf(aNode, aParentRow);
      if (row == -1 && aForceBuild) {
        let parentRow = typeof(aParentRow) == "number" ? aParentRow
                                                       : this._getRowForNode(parent);
        row = parentRow + parent.getChildIndex(aNode) + 1;
      }
    }

    if (row != -1)
      this._rows[row] = aNode;

    return row;
  },

  /**
   * Given a row, finds and returns the parent details of the associated node.
   *
   * @param aChildRow
   *        Row number.
   * @return [parentNode, parentRow]
   */
  _getParentByChildRow: function PTV__getParentByChildRow(aChildRow) {
    let parent = this._getNodeForRow(aChildRow).parent;

    // The root node is never visible
    if (parent == this._rootNode)
      return [this._rootNode, -1];

    let parentRow = this._rows.lastIndexOf(parent, aChildRow - 1);
    return [parent, parentRow];
  },

  /**
   * Gets the node at a given row.
   */
  _getNodeForRow: function PTV__getNodeForRow(aRow) {
    let node = this._rows[aRow];
    if (node !== undefined)
      return node;

    // Find the nearest node.
    let rowNode, row;
    for (let i = aRow - 1; i >= 0 && rowNode === undefined; i--) {
      rowNode = this._rows[i];
      row = i;
    }

    // If there's no container prior to the given row, it's a child of
    // the root node (remember: all containers are listed in the rows array).
    if (!rowNode)
      return this._rows[aRow] = this._rootNode.getChild(aRow);

    // Unset elements may exist only in plain containers.  Thus, if the nearest
    // node is a container, it's the row's parent, otherwise, it's a sibling.
    if (rowNode instanceof Components.interfaces.nsINavHistoryContainerResultNode)
      return this._rows[aRow] = rowNode.getChild(aRow - row - 1);

    let [parent, parentRow] = this._getParentByChildRow(row);
    return this._rows[aRow] = parent.getChild(aRow - parentRow - 1);
  },

  /**
   * This takes a container and recursively appends our rows array per its
   * contents.  Assumes that the rows arrays has no rows for the given
   * container.
   *
   * @param [in] aContainer
   *        A container result node.
   * @param [in] aFirstChildRow
   *        The first row at which nodes may be inserted to the row array.
   *        In other words, that's aContainer's row + 1.
   * @param [out] aToOpen
   *        An array of containers to open once the build is done.
   *
   * @return the number of rows which were inserted.
   */
  _buildVisibleSection:
  function PTV__buildVisibleSection(aContainer, aFirstChildRow, aToOpen)
  {
    // There's nothing to do if the container is closed.
    if (!aContainer.containerOpen)
      return;

    // Inserting the new elements into the rows array in one shot (by
    // Array.concat) is faster than resizing the array (by splice) on each loop
    // iteration.
    let cc = aContainer.childCount;
    let newElements = new Array(cc);
    this._rows = this._rows.splice(0, aFirstChildRow)
                     .concat(newElements, this._rows);

    if (this._isPlainContainer(aContainer))
      return cc;

    const openLiteral = PlacesUIUtils.RDF.GetResource("http://home.netscape.com/NC-rdf#open");
    const trueLiteral = PlacesUIUtils.RDF.GetLiteral("true");
    let sortingMode = this._result.sortingMode;

    let rowsInserted = 0;
    for (let i = 0; i < cc; i++) {
      let curChild = aContainer.getChild(i);
      let curChildType = curChild.type;

      let row = aFirstChildRow + rowsInserted;

      // Don't display separators when sorted.
      if (curChildType == Components.interfaces.nsINavHistoryResultNode.RESULT_TYPE_SEPARATOR) {
        if (sortingMode != Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_NONE) {
          // Remove the element for the filtered separator.
          // Notice that the rows array was initially resized to include all
          // children.
          this._rows.splice(row, 1);
          continue;
        }
      }

      this._rows[row] = curChild;
      rowsInserted++;

      // Recursively do containers.
      if (!this._flatList &&
          curChild instanceof Components.interfaces.nsINavHistoryContainerResultNode) {
        let resource = this._getResourceForNode(curChild);
        let isopen = resource != null &&
                     PlacesUIUtils.localStore.HasAssertion(resource,
                                                           openLiteral,
                                                           trueLiteral, true);
        if (isopen != curChild.containerOpen)
          aToOpen.push(curChild);
        else if (curChild.containerOpen && curChild.childCount > 0)
          rowsInserted += this._buildVisibleSection(curChild, row + 1, aToOpen);
      }
    }

    return rowsInserted;
  },

  /**
   * This counts how many rows a node takes in the tree.  For containers it
   * will count the node itself plus any child node following it.
   */
  _countVisibleRowsForNodeAtRow:
  function PTV__countVisibleRowsForNodeAtRow(aNodeRow) {
    let node = this._rows[aNodeRow];

    // If it's not listed yet, we know that it's a leaf node (instanceof also
    // null-checks).
    if (!(node instanceof Components.interfaces.nsINavHistoryContainerResultNode))
      return 1;

    let outerLevel = node.indentLevel;
    for (let i = aNodeRow + 1; i < this._rows.length; i++) {
      let rowNode = this._rows[i];
      if (rowNode && rowNode.indentLevel <= outerLevel)
        return i - aNodeRow;
    }

    // This node plus its children take up the bottom of the list.
    return this._rows.length - aNodeRow;
  },

  _getSelectedNodesInRange:
  function PTV__getSelectedNodesInRange(aFirstRow, aLastRow) {
    let selection = this.selection;
    let rc = selection.getRangeCount();
    if (rc == 0)
      return [];

    // The visible-area borders are needed for checking whether a
    // selected row is also visible.
    let firstVisibleRow = this._tree.getFirstVisibleRow();
    let lastVisibleRow = this._tree.getLastVisibleRow();

    let nodesInfo = [];
    for (let rangeIndex = 0; rangeIndex < rc; rangeIndex++) {
      let min = { }, max = { };
      selection.getRangeAt(rangeIndex, min, max);

      // If this range does not overlap the replaced chunk, we don't need to
      // persist the selection.
      if (max.value < aFirstRow || min.value > aLastRow)
        continue;

      let firstRow = Math.max(min.value, aFirstRow);
      let lastRow = Math.min(max.value, aLastRow);
      for (let i = firstRow; i <= lastRow; i++) {
        nodesInfo.push({
          node: this._rows[i],
          oldRow: i,
          wasVisible: i >= firstVisibleRow && i <= lastVisibleRow
        });
      }
    }

    return nodesInfo;
  },

  /**
   * Tries to find an equivalent node for a node which was removed.  We first
   * look for the original node, in case it was just relocated.  Then, if we
   * that node was not found, we look for a node that has the same itemId, uri
   * and time values.
   *
   * @param aUpdatedContainer
   *        An ancestor of the node which was removed.  It does not have to be
   *        its direct parent.
   * @param aOldNode
   *        The node which was removed.
   *
   * @return the row number of an equivalent node for aOldOne, if one was
   *         found, -1 otherwise.
   */
  _getNewRowForRemovedNode:
  function PTV__getNewRowForRemovedNode(aUpdatedContainer, aOldNode) {
    let parent = aOldNode.parent;
    if (parent) {
      // If the node's parent is still set, the node is not obsolete
      // and we should just find out its new position.
      // However, if any of the node's ancestor is closed, the node is
      // invisible.
      let ancestors = PlacesUtils.nodeAncestors(aOldNode);
      for (let ancestor in ancestors) {
        if (!ancestor.containerOpen)
          return -1;
      }

      return this._getRowForNode(aOldNode, true);
    }

    // There's a broken edge case here.
    // If a visit appears in two queries, and the second one was
    // the old node, we'll select the first one after refresh.  There's
    // nothing we could do about that, because aOldNode.parent is
    // gone by the time invalidateContainer is called.
    let newNode = aUpdatedContainer.findNodeByDetails(aOldNode.uri,
                                                      aOldNode.time,
                                                      aOldNode.itemId,
                                                      true);
    if (!newNode)
      return -1;

    return this._getRowForNode(newNode, true);
  },

  /**
   * Restores a given selection state as near as possible to the original
   * selection state.
   *
   * @param aNodesInfo
   *        The persisted selection state as returned by
   *        _getSelectedNodesInRange.
   * @param aUpdatedContainer
   *        The container which was updated.
   */
  _restoreSelection:
  function PTV__restoreSelection(aNodesInfo, aUpdatedContainer) {
    if (aNodesInfo.length == 0)
      return;

    let selection = this.selection;

    // Attempt to ensure that previously-visible selection will be visible
    // if it's re-selected.  However, we can only ensure that for one row.
    let scrollToRow = -1;
    for (let i = 0; i < aNodesInfo.length; i++) {
      let nodeInfo = aNodesInfo[i];
      let row = this._getNewRowForRemovedNode(aUpdatedContainer,
                                              aNodesInfo[i].node);
      // Select the found node, if any.
      if (row != -1) {
        selection.rangedSelect(row, row, true);
        if (nodeInfo.wasVisible && scrollToRow == -1)
          scrollToRow = row;
      }
    }

    // If only one node was previously selected and there's no selection now,
    // select the node at its old row, if any.
    if (aNodesInfo.length == 1 && selection.count == 0) {
      let row = Math.min(aNodesInfo[0].oldRow, this._rows.length - 1);
      selection.rangedSelect(row, row, true);
      if (aNodesInfo[0].wasVisible && scrollToRow == -1)
        scrollToRow = aNodesInfo[0].oldRow;
    }

    if (scrollToRow != -1)
      this._tree.ensureRowIsVisible(scrollToRow);
  },

  _convertPRTimeToString: function PTV__convertPRTimeToString(aTime) {
    const MS_PER_MINUTE = 60000;
    const MS_PER_DAY = 86400000;
    let timeMs = aTime / 1000; // PRTime is in microseconds

    // Date is calculated starting from midnight, so the modulo with a day are
    // milliseconds from today's midnight.
    // getTimezoneOffset corrects that based on local time, notice midnight
    // can have a different offset during DST-change days.
    let dateObj = new Date();
    let now = dateObj.getTime() - dateObj.getTimezoneOffset() * MS_PER_MINUTE;
    let midnight = now - (now % MS_PER_DAY);
    midnight += new Date(midnight).getTimezoneOffset() * MS_PER_MINUTE;

    const nsIScriptableDateFormat = Components.interfaces.nsIScriptableDateFormat;
    let dateFormat = timeMs >= midnight ?
                      nsIScriptableDateFormat.dateFormatNone :
                      nsIScriptableDateFormat.dateFormatShort;

    let timeObj = new Date(timeMs);
    return (this._dateService.FormatDateTime("", dateFormat,
      nsIScriptableDateFormat.timeFormatNoSeconds,
      timeObj.getFullYear(), timeObj.getMonth() + 1,
      timeObj.getDate(), timeObj.getHours(),
      timeObj.getMinutes(), timeObj.getSeconds()));
  },

  COLUMN_TYPE_UNKNOWN: 0,
  COLUMN_TYPE_TITLE: 1,
  COLUMN_TYPE_URI: 2,
  COLUMN_TYPE_DATE: 3,
  COLUMN_TYPE_VISITCOUNT: 4,
  COLUMN_TYPE_KEYWORD: 5,
  COLUMN_TYPE_DESCRIPTION: 6,
  COLUMN_TYPE_DATEADDED: 7,
  COLUMN_TYPE_LASTMODIFIED: 8,
  COLUMN_TYPE_TAGS: 9,

  _getColumnType: function PTV__getColumnType(aColumn) {
    let columnType = aColumn.element.getAttribute("anonid") || aColumn.id;

    switch (columnType) {
      case "title":
        return this.COLUMN_TYPE_TITLE;
      case "url":
        return this.COLUMN_TYPE_URI;
      case "date":
        return this.COLUMN_TYPE_DATE;
      case "visitCount":
        return this.COLUMN_TYPE_VISITCOUNT;
      case "keyword":
        return this.COLUMN_TYPE_KEYWORD;
      case "description":
        return this.COLUMN_TYPE_DESCRIPTION;
      case "dateAdded":
        return this.COLUMN_TYPE_DATEADDED;
      case "lastModified":
        return this.COLUMN_TYPE_LASTMODIFIED;
      case "tags":
        return this.COLUMN_TYPE_TAGS;
    }
    return this.COLUMN_TYPE_UNKNOWN;
  },

  _sortTypeToColumnType: function PTV__sortTypeToColumnType(aSortType) {
    switch (aSortType) {
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_TITLE_ASCENDING:
        return [this.COLUMN_TYPE_TITLE, false];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_TITLE_DESCENDING:
        return [this.COLUMN_TYPE_TITLE, true];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_DATE_ASCENDING:
        return [this.COLUMN_TYPE_DATE, false];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_DATE_DESCENDING:
        return [this.COLUMN_TYPE_DATE, true];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_URI_ASCENDING:
        return [this.COLUMN_TYPE_URI, false];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_URI_DESCENDING:
        return [this.COLUMN_TYPE_URI, true];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_VISITCOUNT_ASCENDING:
        return [this.COLUMN_TYPE_VISITCOUNT, false];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_VISITCOUNT_DESCENDING:
        return [this.COLUMN_TYPE_VISITCOUNT, true];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_KEYWORD_ASCENDING:
        return [this.COLUMN_TYPE_KEYWORD, false];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_KEYWORD_DESCENDING:
        return [this.COLUMN_TYPE_KEYWORD, true];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_ANNOTATION_ASCENDING:
        if (this._result.sortingAnnotation == PlacesUIUtils.DESCRIPTION_ANNO)
          return [this.COLUMN_TYPE_DESCRIPTION, false];
        break;
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_ANNOTATION_DESCENDING:
        if (this._result.sortingAnnotation == PlacesUIUtils.DESCRIPTION_ANNO)
          return [this.COLUMN_TYPE_DESCRIPTION, true];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_DATEADDED_ASCENDING:
        return [this.COLUMN_TYPE_DATEADDED, false];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_DATEADDED_DESCENDING:
        return [this.COLUMN_TYPE_DATEADDED, true];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_LASTMODIFIED_ASCENDING:
        return [this.COLUMN_TYPE_LASTMODIFIED, false];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_LASTMODIFIED_DESCENDING:
        return [this.COLUMN_TYPE_LASTMODIFIED, true];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_TAGS_ASCENDING:
        return [this.COLUMN_TYPE_TAGS, false];
      case Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_TAGS_DESCENDING:
        return [this.COLUMN_TYPE_TAGS, true];
    }
    return [this.COLUMN_TYPE_UNKNOWN, false];
  },

  // nsINavHistoryResultObserver
  nodeInserted: function PTV_nodeInserted(aParentNode, aNode, aNewIndex) {
    NS_ASSERT(this._result, "Got a notification but have no result!");
    if (!this._tree || !this._result)
      return;

    // Bail out for hidden separators.
    if (PlacesUtils.nodeIsSeparator(aNode) && this.isSorted())
      return;

    let parentRow;
    if (aParentNode != this._rootNode) {
      parentRow = this._getRowForNode(aParentNode);

      // Update parent when inserting the first item, since twisty has changed.
      if (aParentNode.childCount == 1)
        this._tree.invalidateRow(parentRow);
    }

    // Compute the new row number of the node.
    let row = -1;
    if (aNewIndex == 0 || this._isPlainContainer(aParentNode)) {
      // We don't need to worry about sub hierarchies of the parent node
      // if it's a plain container, or if the new node is its first child.
      if (aParentNode == this._rootNode)
        row = aNewIndex;
      else
        row = parentRow + aNewIndex + 1;
    }
    else {
      // Here, we try to find the next visible element in the child list so we
      // can set the new visible index to be right before that.  Note that we
      // have to search down instead of up, because some siblings could have
      // children themselves that would be in the way.
      let cc = aParentNode.childCount;
      let separatorsAreHidden = PlacesUtils.nodeIsSeparator(aNode) &&
                                this.isSorted();
      for (let i = aNewIndex + 1; i < cc; i++) {
        let node = aParentNode.getChild(i);
        if (!separatorsAreHidden || PlacesUtils.nodeIsSeparator(node)) {
          // The children have not been shifted so the next item will have what
          // should be our index.
          row = this._getRowForNode(node, false, parentRow, i);
          break;
        }
      }
      if (row < 0) {
        // At the end of the child list without finding a visible sibling. This
        // is a little harder because we don't know how many rows the last item
        // in our list takes up (it could be a container with many children).
        let prevChild = aParentNode.getChild(aNewIndex - 1);
        let prevIndex = this._getRowForNode(prevChild, false, parentRow,
                                            aNewIndex - 1);
        row = prevIndex + this._countVisibleRowsForNodeAtRow(prevIndex);
      }
    }

    this._rows.splice(row, 0, aNode);
    this._tree.rowCountChanged(row, 1);

    if (PlacesUtils.nodeIsContainer(aNode) && PlacesUtils.asContainer(aNode).containerOpen)
      this.invalidateContainer(aNode);
  },

  /**
   * THIS FUNCTION DOES NOT HANDLE cases where a collapsed node is being
   * removed but the node it is collapsed with is not being removed (this then
   * just swap out the removee with its collapsing partner). The only time
   * when we really remove things is when deleting URIs, which will apply to
   * all collapsees. This function is called sometimes when resorting items.
   * However, we won't do this when sorted by date because dates will never
   * change for visits, and date sorting is the only time things are collapsed.
   */
  nodeRemoved: function PTV_nodeRemoved(aParentNode, aNode, aOldIndex) {
    NS_ASSERT(this._result, "Got a notification but have no result!");
    if (!this._tree || !this._result)
      return;

    // XXX bug 517701: We don't know what to do when the root node is removed.
    if (aNode == this._rootNode)
      throw Components.results.NS_ERROR_NOT_IMPLEMENTED;

    // Bail out for hidden separators.
    if (PlacesUtils.nodeIsSeparator(aNode) && this.isSorted())
      return;

    let parentRow = aParentNode == this._rootNode ?
                    undefined : this._getRowForNode(aParentNode, true);
    let oldRow = this._getRowForNode(aNode, true, parentRow, aOldIndex);
    if (oldRow < 0)
      throw Components.results.NS_ERROR_UNEXPECTED;

    // If the node was exclusively selected, the node next to it will be
    // selected.
    let selectNext = false;
    let selection = this.selection;
    if (selection.getRangeCount() == 1) {
      let min = { }, max = { };
      selection.getRangeAt(0, min, max);
      if (min.value == max.value &&
          this.nodeForTreeIndex(min.value) == aNode)
        selectNext = true;
    }

    // Remove the node and its children, if any.
    let count = this._countVisibleRowsForNodeAtRow(oldRow);
    this._rows.splice(oldRow, count);
    this._tree.rowCountChanged(oldRow, -count);

    // Redraw the parent if its twisty state has changed.
    if (aParentNode != this._rootNode && !aParentNode.hasChildren) {
      let parentRow = oldRow - 1;
      this._tree.invalidateRow(parentRow);
    }

    // Restore selection if the node was exclusively selected.
    if (!selectNext)
      return;

    // Restore selection.
    let rowToSelect = Math.min(oldRow, this._rows.length - 1);
    this.selection.rangedSelect(rowToSelect, rowToSelect, true);
  },

  nodeMoved:
  function PTV_nodeMoved(aNode, aOldParent, aOldIndex, aNewParent, aNewIndex) {
    NS_ASSERT(this._result, "Got a notification but have no result!");
    if (!this._tree || !this._result)
      return;

    // Bail out for hidden separators.
    if (PlacesUtils.nodeIsSeparator(aNode) && this.isSorted())
      return;

    let oldRow = this._getRowForNode(aNode, true);

    // If this node is a container it could take up more than one row.
    let count = this._countVisibleRowsForNodeAtRow(oldRow);

    // Persist selection state.
    let nodesToReselect =
      this._getSelectedNodesInRange(oldRow, oldRow + count);
    if (nodesToReselect.length > 0)
      this.selection.selectEventsSuppressed = true;

    // Redraw the parent if its twisty state has changed.
    if (aOldParent != this._rootNode && !aOldParent.hasChildren) {
      let parentRow = oldRow - 1;
      this._tree.invalidateRow(parentRow);
    }

    // Remove node and its children, if any, from the old position.
    this._rows.splice(oldRow, count);
    this._tree.rowCountChanged(oldRow, -count);

    // Insert the node into the new position.
    this.nodeInserted(aNewParent, aNode, aNewIndex);

    // Restore selection.
    if (nodesToReselect.length > 0) {
      this._restoreSelection(nodesToReselect, aNewParent);
      this.selection.selectEventsSuppressed = false;
    }
  },

  /**
   * Be careful, the parameter 'aIndex' here specifies the node's index in the
   * parent node, not the visible index.
   */
  nodeReplaced:
  function PTV_nodeReplaced(aParentNode, aOldNode, aNewNode, aIndexDoNotUse) {
    NS_ASSERT(this._result, "Got a notification but have no result!");
    if (!this._tree || !this._result)
      return;

    // Nothing to do if the replaced node was not set.
    var row = this._getRowForNode(aOldNode);
    if (row != -1) {
      this._rows[row] = aNewNode;
      this._tree.invalidateRow(row);
    }
  },

  _invalidateCellValue: function PTV__invalidateCellValue(aNode,
                                                          aColumnType) {
    NS_ASSERT(this._result, "Got a notification but have no result!");
    if (!this._tree || !this._result)
      return;

    // Nothing to do for the root node.
    if (aNode == this._rootNode)
      return;

    let row = this._getRowForNode(aNode);
    if (row == -1)
      return;

    let column = this._findColumnByType(aColumnType);
    if (column && !column.element.hidden)
      this._tree.invalidateCell(row, column);

    // Last modified time is altered for almost all node changes.
    if (aColumnType != this.COLUMN_TYPE_LASTMODIFIED) {
      let lastModifiedColumn =
        this._findColumnByType(this.COLUMN_TYPE_LASTMODIFIED);
      if (lastModifiedColumn && !lastModifiedColumn.hidden)
        this._tree.invalidateCell(row, lastModifiedColumn);
    }
  },

  nodeTitleChanged: function PTV_nodeTitleChanged(aNode, aNewTitle) {
    this._invalidateCellValue(aNode, this.COLUMN_TYPE_TITLE);
  },

  nodeURIChanged: function PTV_nodeURIChanged(aNode, aNewURI) {
    this._invalidateCellValue(aNode, this.COLUMN_TYPE_URI);
  },

  nodeIconChanged: function PTV_nodeIconChanged(aNode) {
    this._invalidateCellValue(aNode, this.COLUMN_TYPE_TITLE);
  },

  nodeHistoryDetailsChanged:
  function PTV_nodeHistoryDetailsChanged(aNode, aUpdatedVisitDate,
                                         aUpdatedVisitCount) {
    this._invalidateCellValue(aNode, this.COLUMN_TYPE_DATE);
    this._invalidateCellValue(aNode, this.COLUMN_TYPE_VISITCOUNT);
  },

  nodeTagsChanged: function PTV_nodeTagsChanged(aNode) {
    this._invalidateCellValue(aNode, this.COLUMN_TYPE_TAGS);
  },

  nodeKeywordChanged: function PTV_nodeKeywordChanged(aNode, aNewKeyword) {
    this._invalidateCellValue(aNode, this.COLUMN_TYPE_KEYWORD);
  },

  nodeAnnotationChanged: function PTV_nodeAnnotationChanged(aNode, aAnno) {
    if (aAnno == PlacesUIUtils.DESCRIPTION_ANNO) {
      this._invalidateCellValue(aNode, this.COLUMN_TYPE_DESCRIPTION);
    } else if (aAnno == PlacesUtils.LMANNO_FEEDURI) {
      // The livemark attribute is set as a cell property on the title cell.
      this._invalidateCellValue(aNode, this.COLUMN_TYPE_TITLE);
    }
  },

  nodeDateAddedChanged: function PTV_nodeDateAddedChanged(aNode, aNewValue) {
    this._invalidateCellValue(aNode, this.COLUMN_TYPE_DATEADDED);
  },

  nodeLastModifiedChanged:
  function PTV_nodeLastModifiedChanged(aNode, aNewValue) {
    this._invalidateCellValue(aNode, this.COLUMN_TYPE_LASTMODIFIED);
  },

  containerStateChanged:
  function PTV_containerStateChanged(aNode, aOldState, aNewState) {
    this.invalidateContainer(aNode);
  },

  invalidateContainer: function PTV_invalidateContainer(aContainer) {
    NS_ASSERT(this._result, "Need to have a result to update");
    if (!this._tree)
      return;

    let startReplacement, replaceCount;
    if (aContainer == this._rootNode) {
      startReplacement = 0;
      replaceCount = this._rows.length;

      // If the root node is now closed, the tree is empty.
      if (!this._rootNode.containerOpen) {
        this._rows = [];
        if (replaceCount)
          this._tree.rowCountChanged(startReplacement, -replaceCount);

        return;
      }
    }
    else {
      // Update the twisty state.
      let row = this._getRowForNode(aContainer);
      this._tree.invalidateRow(row);

      // We don't replace the container node itself, so we should decrease the
      // replaceCount by 1.
      startReplacement = row + 1;
      replaceCount = this._countVisibleRowsForNodeAtRow(row) - 1;
    }

    // Persist selection state.
    let nodesToReselect =
      this._getSelectedNodesInRange(startReplacement,
                                    startReplacement + replaceCount);

    // Now update the number of elements.
    this.selection.selectEventsSuppressed = true;

    // First remove the old elements
    this._rows.splice(startReplacement, replaceCount);

    // If the container is now closed, we're done.
    if (!aContainer.containerOpen) {
      let oldSelectionCount = this.selection.count;
      if (replaceCount)
        this._tree.rowCountChanged(startReplacement, -replaceCount);

      // Select the row next to the closed container if any of its
      // children were selected, and nothing else is selected.
      if (nodesToReselect.length > 0 &&
          nodesToReselect.length == oldSelectionCount) {
        this.selection.rangedSelect(startReplacement, startReplacement, true);
        this._tree.ensureRowIsVisible(startReplacement);
      }

      this.selection.selectEventsSuppressed = false;
      return;
    }

    // Otherwise, start a batch first.
    this._tree.beginUpdateBatch();
    if (replaceCount)
      this._tree.rowCountChanged(startReplacement, -replaceCount);

    let toOpenElements = [];
    let elementsAddedCount = this._buildVisibleSection(aContainer,
                                                       startReplacement,
                                                       toOpenElements);
    if (elementsAddedCount)
      this._tree.rowCountChanged(startReplacement, elementsAddedCount);

    if (!this._flatList) {
      // Now, open any containers that were persisted.
      for (let i = 0; i < toOpenElements.length; i++) {
        let item = toOpenElements[i];
        let parent = item.parent;

        // Avoid recursively opening containers.
        while (parent) {
          if (parent.uri == item.uri)
            break;
          parent = parent.parent;
        }

        // If we don't have a parent, we made it all the way to the root
        // and didn't find a match, so we can open our item.
        if (!parent && !item.containerOpen)
          item.containerOpen = true;
      }
    }

    this._tree.endUpdateBatch();

    // Restore selection.
    this._restoreSelection(nodesToReselect, aContainer);
    this.selection.selectEventsSuppressed = false;
  },

  _columns: [],
  _findColumnByType: function PTV__findColumnByType(aColumnType) {
    if (this._columns[aColumnType])
      return this._columns[aColumnType];

    let columns = this._tree.columns;
    let colCount = columns.count;
    for (let i = 0; i < colCount; i++) {
      let column = columns.getColumnAt(i);
      let columnType = this._getColumnType(column);
      this._columns[columnType] = column;
      if (columnType == aColumnType)
        return column;
    }

    // That's completely valid.  Most of our trees actually include just the
    // title column.
    return null;
  },

  sortingChanged: function PTV__sortingChanged(aSortingMode) {
    if (!this._tree || !this._result)
      return;

    // Depending on the sort mode, certain commands may be disabled.
    window.updateCommands("sort");

    let columns = this._tree.columns;

    // Clear old sorting indicator.
    let sortedColumn = columns.getSortedColumn();
    if (sortedColumn)
      sortedColumn.element.removeAttribute("sortDirection");

    // Set new sorting indicator by looking through all columns for ours.
    if (aSortingMode == Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_NONE)
      return;

    let [desiredColumn, desiredIsDescending] =
      this._sortTypeToColumnType(aSortingMode);
    let colCount = columns.count;
    let column = this._findColumnByType(desiredColumn);
    if (column) {
      let sortDir = desiredIsDescending ? "descending" : "ascending";
      column.element.setAttribute("sortDirection", sortDir);
    }
  },

  _inBatchMode: false,
  batching: function PTV_batching(aBatching) {
    if (aBatching == this._inBatchMode)
      return;
    this._inBatchMode = this.selection.selectEventsSuppressed = aBatching;
    if (aBatching)
      this._tree.beginUpdateBatch();
    else
      this._tree.endUpdateBatch();
  },

  get result() {
    return this._result;
  },

  set result(val) {
    if (this._result) {
      this._result.removeObserver(this);
      this._rootNode.containerOpen = false;
    }

    this._result = val;
    this._rootNode = val ? val.root : null;

    // If the tree is not set yet, setTree will call finishInit.
    if (this._tree && val)
      this._finishInit();

    return val;
  },

  nodeForTreeIndex: function PTV_nodeForTreeIndex(aIndex) {
    if (aIndex > this._rows.length)
      throw Components.results.NS_ERROR_INVALID_ARG;

    return this._getNodeForRow(aIndex);
  },

  treeIndexForNode: function PTV_treeNodeForIndex(aNode) {
    // The API allows passing invisible nodes.
    try {
      return this._getRowForNode(aNode, true);
    }
    catch(ex) { }

    return Components.interfaces.nsINavHistoryResultTreeViewer.INDEX_INVISIBLE;
  },

  _getResourceForNode: function PTV_getResourceForNode(aNode)
  {
    let uri = aNode.uri;
    NS_ASSERT(uri, "if there is no uri, we can't persist the open state");
    return uri ? PlacesUIUtils.RDF.GetResource(uri) : null;
  },

  // nsITreeView
  get rowCount() {
    return this._rows.length;
  },

  get selection() {
    return this._selection;
  },

  set selection(val) {
    return this._selection = val;
  },

  getRowProperties: function PTV_getRowProperties(aRow, aProperties) { },

  getCellProperties: function PTV_getCellProperties(aRow, aColumn, aProperties) {
    // for anonid-trees, we need to add the column-type manually
    let columnType = aColumn.element.getAttribute("anonid");
    if (columnType)
      aProperties.AppendElement(this._getAtomFor(columnType));
    else
      columnType = aColumn.id;

    // Set the "ltr" property on url cells
    if (columnType == "url")
      aProperties.AppendElement(this._getAtomFor("ltr"));

    if (columnType != "title")
      return;

    let node = this._getNodeForRow(aRow);
    if (!node._cellProperties) {
      let properties = new Array();
      let itemId = node.itemId;
      let nodeType = node.type;
      if (PlacesUtils.containerTypes.indexOf(nodeType) != -1) {
        if (nodeType == Components.interfaces.nsINavHistoryResultNode.RESULT_TYPE_QUERY) {
          properties.push(this._getAtomFor("query"));
          if (PlacesUtils.nodeIsTagQuery(node))
            properties.push(this._getAtomFor("tagContainer"));
          else if (PlacesUtils.nodeIsDay(node))
            properties.push(this._getAtomFor("dayContainer"));
          else if (PlacesUtils.nodeIsHost(node))
            properties.push(this._getAtomFor("hostContainer"));
        }
        else if (nodeType == Components.interfaces.nsINavHistoryResultNode.RESULT_TYPE_FOLDER ||
                 nodeType == Components.interfaces.nsINavHistoryResultNode.RESULT_TYPE_FOLDER_SHORTCUT) {
          if (PlacesUtils.nodeIsLivemarkContainer(node))
            properties.push(this._getAtomFor("livemark"));
        }

        if (itemId != -1) {
          let queryName = PlacesUIUtils.getLeftPaneQueryNameFromId(itemId);
          if (queryName)
            properties.push(this._getAtomFor("OrganizerQuery_" + queryName));
        }
      }
      else if (nodeType == Components.interfaces.nsINavHistoryResultNode.RESULT_TYPE_SEPARATOR)
        properties.push(this._getAtomFor("separator"));
      else if (PlacesUtils.nodeIsURI(node)) {
        properties.push(this._getAtomFor(PlacesUIUtils.guessUrlSchemeForUI(node.uri)));
        if (itemId != -1) {
          if (PlacesUtils.nodeIsLivemarkContainer(node.parent))
            properties.push(this._getAtomFor("livemarkItem"));
        }
      }

      node._cellProperties = properties;
    }
    for (let i = 0; i < node._cellProperties.length; i++)
      aProperties.AppendElement(node._cellProperties[i]);
  },

  getColumnProperties: function(aColumn, aProperties) { },

  isContainer: function PTV_isContainer(aRow) {
    // Only leaf nodes aren't listed in the rows array.
    let node = this._rows[aRow];
    if (node === undefined)
      return false;

    if (PlacesUtils.nodeIsContainer(node)) {
      // Flat-lists may ignore expandQueries and other query options when
      // they are asked to open a container.
      if (this._flatList)
        return true;

      // treat non-expandable childless queries as non-containers
      if (PlacesUtils.nodeIsQuery(node)) {
        let parent = node.parent;
        if ((PlacesUtils.nodeIsQuery(parent) ||
             PlacesUtils.nodeIsFolder(parent)) &&
            !node.hasChildren)
          return PlacesUtils.asQuery(parent).queryOptions.expandQueries;
      }
      return true;
    }
    return false;
  },

  isContainerOpen: function PTV_isContainerOpen(aRow) {
    if (this._flatList)
      return false;

    // All containers are listed in the rows array.
    return this._rows[aRow].containerOpen;
  },

  isContainerEmpty: function PTV_isContainerEmpty(aRow) {
    if (this._flatList)
      return true;

    // All containers are listed in the rows array.
    return !this._rows[aRow].hasChildren;
  },

  isSeparator: function PTV_isSeparator(aRow) {
    // All separators are listed in the rows array.
    let node = this._rows[aRow];
    return node && PlacesUtils.nodeIsSeparator(node);
  },

  isSorted: function PTV_isSorted() {
    return this._result.sortingMode !=
           Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_NONE;
  },

  canDrop: function PTV_canDrop(aRow, aOrientation, aDataTransfer) {
    if (!this._result)
      throw Components.results.NS_ERROR_UNEXPECTED;

    // Drop position into a sorted treeview would be wrong.
    if (this.isSorted())
      return false;

    let ip = this._getInsertionPoint(aRow, aOrientation);
    return ip && PlacesControllerDragHelper.canDrop(ip, aDataTransfer);
  },

  _getInsertionPoint: function PTV__getInsertionPoint(index, orientation) {
    let container = this._result.root;
    let dropNearItemId = -1;
    // When there's no selection, assume the container is the container
    // the view is populated from (i.e. the result's itemId).
    if (index != -1) {
      let lastSelected = this.nodeForTreeIndex(index);
      if (this.isContainer(index) && orientation == Components.interfaces.nsITreeView.DROP_ON) {
        // If the last selected item is an open container, append _into_
        // it, rather than insert adjacent to it.
        container = lastSelected;
        index = -1;
      }
      else if (lastSelected.containerOpen &&
               orientation == Components.interfaces.nsITreeView.DROP_AFTER &&
               lastSelected.hasChildren) {
        // If the last selected node is an open container and the user is
        // trying to drag into it as a first node, really insert into it.
        container = lastSelected;
        orientation = Components.interfaces.nsITreeView.DROP_ON;
        index = 0;
      }
      else {
        // Use the last-selected node's container.
        container = lastSelected.parent;

        // During its Drag & Drop operation, the tree code closes-and-opens
        // containers very often (part of the XUL "spring-loaded folders"
        // implementation).  And in certain cases, we may reach a closed
        // container here.  However, we can simply bail out when this happens,
        // because we would then be back here in less than a millisecond, when
        // the container had been reopened.
        if (!container || !container.containerOpen)
          return null;

        // Avoid the potentially expensive call to getChildIndex
        // if we know this container doesn't allow insertion.
        if (PlacesControllerDragHelper.disallowInsertion(container))
          return null;

        let queryOptions = PlacesUtils.asQuery(this._result.root).queryOptions;
        if (queryOptions.sortingMode !=
              Components.interfaces.nsINavHistoryQueryOptions.SORT_BY_NONE) {
          // If we are within a sorted view, insert at the end.
          index = -1;
        }
        else if (queryOptions.excludeItems ||
                 queryOptions.excludeQueries ||
                 queryOptions.excludeReadOnlyFolders) {
          // Some item may be invisible, insert near last selected one.
          // We don't replace index here to avoid requests to the db,
          // instead it will be calculated later by the controller.
          index = -1;
          dropNearItemId = lastSelected.itemId;
        }
        else {
          let lsi = container.getChildIndex(lastSelected);
          index = orientation == Components.interfaces.nsITreeView.DROP_BEFORE ? lsi : lsi + 1;
        }
      }
    }

    if (PlacesControllerDragHelper.disallowInsertion(container))
      return null;

    return new InsertionPoint(PlacesUtils.getConcreteItemId(container),
                              index, orientation,
                              PlacesUtils.nodeIsTagQuery(container),
                              dropNearItemId);
  },

  drop: function PTV_drop(aRow, aOrientation, aDataTransfer) {
    // We are responsible for translating the |index| and |orientation|
    // parameters into a container id and index within the container,
    // since this information is specific to the tree view.
    let ip = this._getInsertionPoint(aRow, aOrientation);
    if (ip)
      PlacesControllerDragHelper.onDrop(ip, aDataTransfer);

    PlacesControllerDragHelper.currentDropTarget = null;
  },

  getParentIndex: function PTV_getParentIndex(aRow) {
    let [parentNode, parentRow] = this._getParentByChildRow(aRow);
    return parentRow;
  },

  hasNextSibling: function PTV_hasNextSibling(aRow, aAfterIndex) {
    if (aRow == this._rows.length - 1) {
      // The last row has no sibling.
      return false;
    }

    let node = this._rows[aRow];
    if (node === undefined || this._isPlainContainer(node.parent)) {
      // The node is a child of a plain container.
      // If the next row is either unset or has the same parent,
      // it's a sibling.
      let nextNode = this._rows[aRow + 1];
      return (nextNode == undefined || nextNode.parent == node.parent);
    }

    let thisLevel = node.indentLevel;
    for (let i = aAfterIndex + 1; i < this._rows.length; ++i) {
      let rowNode = this._getNodeForRow(i);
      let nextLevel = rowNode.indentLevel;
      if (nextLevel == thisLevel)
        return true;
      if (nextLevel < thisLevel)
        break;
    }

    return false;
  },

  getLevel: function(aRow) this._getNodeForRow(aRow).indentLevel,

  getImageSrc: function PTV_getImageSrc(aRow, aColumn) {
    // Only the title column has an image.
    if (this._getColumnType(aColumn) != this.COLUMN_TYPE_TITLE)
      return "";

    return this._getNodeForRow(aRow).icon;
  },

  getProgressMode: function(aRow, aColumn) { },
  getCellValue: function(aRow, aColumn) { },

  getCellText: function PTV_getCellText(aRow, aColumn) {
    let node = this._getNodeForRow(aRow);
    switch (this._getColumnType(aColumn)) {
      case this.COLUMN_TYPE_TITLE:
        // normally, this is just the title, but we don't want empty items in
        // the tree view so return a special string if the title is empty.
        // Do it here so that callers can still get at the 0 length title
        // if they go through the "result" API.
        if (PlacesUtils.nodeIsSeparator(node))
          return "";
        return PlacesUIUtils.getBestTitle(node);
      case this.COLUMN_TYPE_TAGS:
        return node.tags;
      case this.COLUMN_TYPE_URI:
        if (PlacesUtils.nodeIsURI(node))
          return node.uri;
        return "";
      case this.COLUMN_TYPE_DATE:
        let nodeTime = node.time;
        if (nodeTime == 0 || !PlacesUtils.nodeIsURI(node)) {
          // hosts and days shouldn't have a value for the date column.
          // Actually, you could argue this point, but looking at the
          // results, seeing the most recently visited date is not what
          // I expect, and gives me no information I know how to use.
          // Only show this for URI-based items.
          return "";
        }

        return this._convertPRTimeToString(nodeTime);
      case this.COLUMN_TYPE_VISITCOUNT:
        return node.accessCount;
      case this.COLUMN_TYPE_KEYWORD:
        if (PlacesUtils.nodeIsBookmark(node))
          return PlacesUtils.bookmarks.getKeywordForBookmark(node.itemId);
        return "";
      case this.COLUMN_TYPE_DESCRIPTION:
        if (node.itemId != -1) {
          try {
            return PlacesUtils.annotations
                              .getItemAnnotation(node.itemId, PlacesUIUtils.DESCRIPTION_ANNO);
          }
          catch (ex) { /* has no description */ }
        }
        return "";
      case this.COLUMN_TYPE_DATEADDED:
        if (node.dateAdded)
          return this._convertPRTimeToString(node.dateAdded);
        return "";
      case this.COLUMN_TYPE_LASTMODIFIED:
        if (node.lastModified)
          return this._convertPRTimeToString(node.lastModified);
        return "";
    }
    return "";
  },

  setTree: function PTV_setTree(aTree) {
    // If we are replacing the tree during a batch, there is a concrete risk
    // that the treeView goes out of sync, thus it's safer to end the batch now.
    // This is a no-op if we are not batching.
    this.batching(false);

    let hasOldTree = this._tree != null;
    this._tree = aTree;

    if (this._result) {
      if (hasOldTree) {
        // detach from result when we are detaching from the tree.
        // This breaks the reference cycle between us and the result.
        if (!aTree) {
          this._result.removeObserver(this);
          this._rootNode.containerOpen = false;
        }
      }
      if (aTree)
        this._finishInit();
    }
  },

  toggleOpenState: function PTV_toggleOpenState(aRow) {
    if (!this._result)
      throw Components.results.NS_ERROR_UNEXPECTED;

    let node = this._rows[aRow];
    if (this._flatList && this._openContainerCallback) {
      this._openContainerCallback(node);
      return;
    }

    let resource = this._getResourceForNode(node);
    if (resource) {
      const openLiteral = PlacesUIUtils.RDF.GetResource("http://home.netscape.com/NC-rdf#open");
      const trueLiteral = PlacesUIUtils.RDF.GetLiteral("true");

      if (node.containerOpen)
        PlacesUIUtils.localStore.Unassert(resource, openLiteral, trueLiteral);
      else
        PlacesUIUtils.localStore.Assert(resource, openLiteral, trueLiteral, true);
    }

    node.containerOpen = !node.containerOpen;
  },

  cycleHeader: function PTV_cycleHeader(aColumn) {
    if (!this._result)
      throw Components.results.NS_ERROR_UNEXPECTED;

    // Sometimes you want a tri-state sorting, and sometimes you don't. This
    // rule allows tri-state sorting when the root node is a folder. This will
    // catch the most common cases. When you are looking at folders, you want
    // the third state to reset the sorting to the natural bookmark order. When
    // you are looking at history, that third state has no meaning so we try
    // to disallow it.
    //
    // The problem occurs when you have a query that results in bookmark
    // folders. One example of this is the subscriptions view. In these cases,
    // this rule doesn't allow you to sort those sub-folders by their natural
    // order.
    let allowTriState = PlacesUtils.nodeIsFolder(this._result.root);

    let oldSort = this._result.sortingMode;
    let oldSortingAnnotation = this._result.sortingAnnotation;
    let newSort;
    let newSortingAnnotation = "";
    const NHQO = Components.interfaces.nsINavHistoryQueryOptions;
    switch (this._getColumnType(aColumn)) {
      case this.COLUMN_TYPE_TITLE:
        if (oldSort == NHQO.SORT_BY_TITLE_ASCENDING)
          newSort = NHQO.SORT_BY_TITLE_DESCENDING;
        else if (allowTriState && oldSort == NHQO.SORT_BY_TITLE_DESCENDING)
          newSort = NHQO.SORT_BY_NONE;
        else
          newSort = NHQO.SORT_BY_TITLE_ASCENDING;

        break;
      case this.COLUMN_TYPE_URI:
        if (oldSort == NHQO.SORT_BY_URI_ASCENDING)
          newSort = NHQO.SORT_BY_URI_DESCENDING;
        else if (allowTriState && oldSort == NHQO.SORT_BY_URI_DESCENDING)
          newSort = NHQO.SORT_BY_NONE;
        else
          newSort = NHQO.SORT_BY_URI_ASCENDING;

        break;
      case this.COLUMN_TYPE_DATE:
        if (oldSort == NHQO.SORT_BY_DATE_ASCENDING)
          newSort = NHQO.SORT_BY_DATE_DESCENDING;
        else if (allowTriState &&
                 oldSort == NHQO.SORT_BY_DATE_DESCENDING)
          newSort = NHQO.SORT_BY_NONE;
        else
          newSort = NHQO.SORT_BY_DATE_ASCENDING;

        break;
      case this.COLUMN_TYPE_VISITCOUNT:
        // visit count default is unusual because we sort by descending
        // by default because you are most likely to be looking for
        // highly visited sites when you click it
        if (oldSort == NHQO.SORT_BY_VISITCOUNT_DESCENDING)
          newSort = NHQO.SORT_BY_VISITCOUNT_ASCENDING;
        else if (allowTriState && oldSort == NHQO.SORT_BY_VISITCOUNT_ASCENDING)
          newSort = NHQO.SORT_BY_NONE;
        else
          newSort = NHQO.SORT_BY_VISITCOUNT_DESCENDING;

        break;
      case this.COLUMN_TYPE_KEYWORD:
        if (oldSort == NHQO.SORT_BY_KEYWORD_ASCENDING)
          newSort = NHQO.SORT_BY_KEYWORD_DESCENDING;
        else if (allowTriState && oldSort == NHQO.SORT_BY_KEYWORD_DESCENDING)
          newSort = NHQO.SORT_BY_NONE;
        else
          newSort = NHQO.SORT_BY_KEYWORD_ASCENDING;

        break;
      case this.COLUMN_TYPE_DESCRIPTION:
        if (oldSort == NHQO.SORT_BY_ANNOTATION_ASCENDING &&
            oldSortingAnnotation == PlacesUIUtils.DESCRIPTION_ANNO) {
          newSort = NHQO.SORT_BY_ANNOTATION_DESCENDING;
          newSortingAnnotation = PlacesUIUtils.DESCRIPTION_ANNO;
        }
        else if (allowTriState &&
                 oldSort == NHQO.SORT_BY_ANNOTATION_DESCENDING &&
                 oldSortingAnnotation == PlacesUIUtils.DESCRIPTION_ANNO)
          newSort = NHQO.SORT_BY_NONE;
        else {
          newSort = NHQO.SORT_BY_ANNOTATION_ASCENDING;
          newSortingAnnotation = PlacesUIUtils.DESCRIPTION_ANNO;
        }

        break;
      case this.COLUMN_TYPE_DATEADDED:
        if (oldSort == NHQO.SORT_BY_DATEADDED_ASCENDING)
          newSort = NHQO.SORT_BY_DATEADDED_DESCENDING;
        else if (allowTriState &&
                 oldSort == NHQO.SORT_BY_DATEADDED_DESCENDING)
          newSort = NHQO.SORT_BY_NONE;
        else
          newSort = NHQO.SORT_BY_DATEADDED_ASCENDING;

        break;
      case this.COLUMN_TYPE_LASTMODIFIED:
        if (oldSort == NHQO.SORT_BY_LASTMODIFIED_ASCENDING)
          newSort = NHQO.SORT_BY_LASTMODIFIED_DESCENDING;
        else if (allowTriState &&
                 oldSort == NHQO.SORT_BY_LASTMODIFIED_DESCENDING)
          newSort = NHQO.SORT_BY_NONE;
        else
          newSort = NHQO.SORT_BY_LASTMODIFIED_ASCENDING;

        break;
      case this.COLUMN_TYPE_TAGS:
        if (oldSort == NHQO.SORT_BY_TAGS_ASCENDING)
          newSort = NHQO.SORT_BY_TAGS_DESCENDING;
        else if (allowTriState && oldSort == NHQO.SORT_BY_TAGS_DESCENDING)
          newSort = NHQO.SORT_BY_NONE;
        else
          newSort = NHQO.SORT_BY_TAGS_ASCENDING;

        break;
      default:
        throw Components.results.NS_ERROR_INVALID_ARG;
    }
    this._result.sortingAnnotation = newSortingAnnotation;
    this._result.sortingMode = newSort;
  },

  isEditable: function PTV_isEditable(aRow, aColumn) {
    // At this point we only support editing the title field.
    if (aColumn.index != 0)
      return false;

    // Only bookmark-nodes are editable, and those are never built lazily
    let node = this._rows[aRow];
    if (!node || node.itemId == -1)
      return false;

    // The following items are never editable:
    // * Read-only items.
    // * places-roots
    // * livemark items
    // * separators
    if (PlacesUtils.nodeIsReadOnly(node) ||
        PlacesUtils.nodeIsLivemarkItem(node) ||
        PlacesUtils.nodeIsSeparator(node))
      return false;

    if (PlacesUtils.nodeIsFolder(node)) {
      let itemId = PlacesUtils.getConcreteItemId(node);
      if (PlacesUtils.isRootItem(itemId))
        return false;
    }

    return true;
  },

  setCellText: function PTV_setCellText(aRow, aColumn, aText) {
    // We may only get here if the cell is editable.
    let node = this._rows[aRow];
    if (node.title != aText) {
      let txn = PlacesUIUtils.ptm.editItemTitle(node.itemId, aText);
      PlacesUIUtils.ptm.doTransaction(txn);
    }
  },

  selectionChanged: function() { },
  cycleCell: function(aRow, aColumn) { },
  isSelectable: function(aRow, aColumn) { return false; },
  performAction: function(aAction) { },
  performActionOnRow: function(aAction, aRow) { },
  performActionOnCell: function(aAction, aRow, aColumn) { }
};
