text: // Copyright 2006 The Closure Library Authors. All Rights Reserved.
  //
  // Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS-IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  /**
   * @fileoverview Date picker implementation.
   *
   * @see ../demos/datepicker.html
   */
  
  goog.provide('goog.ui.DatePicker');
  goog.provide('goog.ui.DatePicker.Events');
  goog.provide('goog.ui.DatePickerEvent');
  
  goog.require('goog.date');
  goog.require('goog.date.Date');
  goog.require('goog.date.Interval');
  goog.require('goog.dom');
  goog.require('goog.dom.a11y');
  goog.require('goog.dom.classes');
  goog.require('goog.events');
  goog.require('goog.events.Event');
  goog.require('goog.events.EventType');
  goog.require('goog.events.KeyHandler');
  goog.require('goog.events.KeyHandler.EventType');
  goog.require('goog.i18n.DateTimeFormat');
  goog.require('goog.i18n.DateTimeSymbols');
  goog.require('goog.style');
  goog.require('goog.ui.Component');
  
  
  
  /**
   * DatePicker widget. Allows a single date to be selected from a calendar like
   * view.
   *
   * @param {goog.date.Date|Date=} opt_date Date to initialize the date picker
   *     with, defaults to the current date.
   * @param {Object=} opt_dateTimeSymbols Date and time symbols to use.
   *     Defaults to goog.i18n.DateTimeSymbols if not set.
   * @param {goog.dom.DomHelper=} opt_domHelper Optional DOM helper.
   * @constructor
   * @extends {goog.ui.Component}
   */
  goog.ui.DatePicker = function(opt_date, opt_dateTimeSymbols, opt_domHelper) {
    goog.ui.Component.call(this, opt_domHelper);
  
    /**
     * Date and time symbols to use.
     * @type {Object}
     * @private
     */
    this.symbols_ = opt_dateTimeSymbols || goog.i18n.DateTimeSymbols;
  
    this.wdayNames_ = this.symbols_.SHORTWEEKDAYS;
  
    /**
     * Selected date.
     * @type {goog.date.Date}
     * @private
     */
    this.date_ = new goog.date.Date(opt_date);
    this.date_.setFirstWeekCutOffDay(this.symbols_.FIRSTWEEKCUTOFFDAY);
    this.date_.setFirstDayOfWeek(this.symbols_.FIRSTDAYOFWEEK);
  
    /**
     * Active month.
     * @type {goog.date.Date}
     * @private
     */
    this.activeMonth_ = this.date_.clone();
    this.activeMonth_.setDate(1);
  
    /**
     * Class names to apply to the weekday columns.
     * @type {Array.<string>}
     * @private
     */
    this.wdayStyles_ = ['', '', '', '', '', '', ''];
    this.wdayStyles_[this.symbols_.WEEKENDRANGE[0]] =
        goog.getCssName(this.getBaseCssClass(), 'wkend-start');
    this.wdayStyles_[this.symbols_.WEEKENDRANGE[1]] =
        goog.getCssName(this.getBaseCssClass(), 'wkend-end');
  
    /**
     * Object that is being used to cache key handlers.
     * @type {Object}
     * @private
     */
    this.keyHandlers_ = {};
  
    /**
     * Dom helper.
     * @type {goog.dom.DomHelper}
     * @private
     */
    this.dom_ = opt_domHelper || goog.dom.getDomHelper();
  };
  goog.inherits(goog.ui.DatePicker, goog.ui.Component);
  
  
  /**
   * Flag indicating if the number of weeks shown should be fixed.
   * @type {boolean}
   * @private
   */
  goog.ui.DatePicker.prototype.showFixedNumWeeks_ = true;
  
  
  /**
   * Flag indicating if days from other months should be shown.
   * @type {boolean}
   * @private
   */
  goog.ui.DatePicker.prototype.showOtherMonths_ = true;
  
  
  /**
   * Flag indicating if extra week(s) always should be added at the end. If not
   * set the extra week is added at the beginning if the number of days shown
   * from the previous month is less then the number from the next month.
   * @type {boolean}
   * @private
   */
  goog.ui.DatePicker.prototype.extraWeekAtEnd_ = true;
  
  
  /**
   * Flag indicating if week numbers should be shown.
   * @type {boolean}
   * @private
   */
  goog.ui.DatePicker.prototype.showWeekNum_ = true;
  
  
  /**
   * Flag indicating if weekday names should be shown.
   * @type {boolean}
   * @private
   */
  goog.ui.DatePicker.prototype.showWeekdays_ = true;
  
  
  /**
   * Flag indicating if none is a valid selection. Also controls if the none
   * button should be shown or not.
   * @type {boolean}
   * @private
   */
  goog.ui.DatePicker.prototype.allowNone_ = true;
  
  
  /**
   * Flag indicating if the today button should be shown.
   * @type {boolean}
   * @private
   */
  goog.ui.DatePicker.prototype.showToday_ = true;
  
  
  /**
   * Flag indicating if the picker should use a simple navigation menu that only
   * contains controls for navigating to the next and previous month. The default
   * navigation menu contains controls for navigating to the next/previous month,
   * next/previous year, and menus for jumping to specific months and years.
   * @type {boolean}
   * @private
   */
  goog.ui.DatePicker.prototype.simpleNavigation_ = false;
  
  
  /**
   * Custom decorator function. Takes a goog.date.Date object, returns a String
   * representing a CSS class or null if no special styling applies
   * @type {Function}
   * @private
   */
  goog.ui.DatePicker.prototype.decoratorFunction_ = null;
  
  
  /**
   * Element for navigation row on a datepicker.
   * @type {Element}
   * @private
   */
  goog.ui.DatePicker.prototype.elNavRow_ = null;
  
  
  /**
   * Element for footer row on a datepicker.
   * @type {Element}
   * @private
   */
  goog.ui.DatePicker.prototype.elFootRow_ = null;
  
  
  /**
   * Next unique instance ID of a datepicker cell.
   * @type {number}
   * @private
   */
  goog.ui.DatePicker.nextId_ = 0;
  
  
  /**
   * Name of base CSS clase of datepicker.
   * @type {string}
   * @private
   */
  goog.ui.DatePicker.BASE_CSS_CLASS_ = goog.getCssName('goog-date-picker');
  
  
  /**
   * Constants for event names
   *
   * @type {Object}
   */
  goog.ui.DatePicker.Events = {
    CHANGE: 'change',
    SELECT: 'select'
  };
  
  
  /**
   * @deprecated Use isInDocument.
   */
  goog.ui.DatePicker.prototype.isCreated =
      goog.ui.DatePicker.prototype.isInDocument;
  
  
  /**
   * @return {number} The first day of week, 0 = Monday, 6 = Sunday.
   */
  goog.ui.DatePicker.prototype.getFirstWeekday = function() {
    return this.activeMonth_.getFirstDayOfWeek();
  };
  
  
  /**
   * Returns the class name associated with specified weekday.
   * @param {number} wday The week day number to get the class name for.
   * @return {string} The class name associated with specified weekday.
   */
  goog.ui.DatePicker.prototype.getWeekdayClass = function(wday) {
    return this.wdayStyles_[wday];
  };
  
  
  /**
   * @return {boolean} Whether a fixed number of weeks should be showed. If not
   *     only weeks for the current month will be shown.
   */
  goog.ui.DatePicker.prototype.getShowFixedNumWeeks = function() {
    return this.showFixedNumWeeks_;
  };
  
  
  /**
   * @return {boolean} Whether a days from the previous and/or next month should
   *     be shown.
   */
  goog.ui.DatePicker.prototype.getShowOtherMonths = function() {
    return this.showOtherMonths_;
  };
  
  
  /**
   * @return {boolean} Whether a the extra week(s) added always should be at the
   *     end. Only applicable if a fixed number of weeks are shown.
   */
  goog.ui.DatePicker.prototype.getExtraWeekAtEnd = function() {
    return this.extraWeekAtEnd_;
  };
  
  
  /**
   * @return {boolean} Whether week numbers should be shown.
   */
  goog.ui.DatePicker.prototype.getShowWeekNum = function() {
    return this.showWeekNum_;
  };
  
  
  /**
   * @return {boolean} Whether weekday names should be shown.
   */
  goog.ui.DatePicker.prototype.getShowWeekdayNames = function() {
    return this.showWeekdays_;
  };
  
  
  /**
   * @return {boolean} Whether none is a valid selection.
   */
  goog.ui.DatePicker.prototype.getAllowNone = function() {
    return this.allowNone_;
  };
  
  
  /**
   * @return {boolean} Whether the today button should be shown.
   */
  goog.ui.DatePicker.prototype.getShowToday = function() {
    return this.showToday_;
  };
  
  
  /**
   * Returns base CSS class. This getter is used to get base CSS class part.
   * All CSS class names in component are created as:
   *   goog.getCssName(this.getBaseCssClass(), 'CLASS_NAME')
   * @return {string} Base CSS class.
   */
  goog.ui.DatePicker.prototype.getBaseCssClass = function() {
    return goog.ui.DatePicker.BASE_CSS_CLASS_;
  };
  
  
  /**
   * Sets the first day of week
   *
   * @param {number} wday Week day, 0 = Monday, 6 = Sunday.
   */
  goog.ui.DatePicker.prototype.setFirstWeekday = function(wday) {
    this.activeMonth_.setFirstDayOfWeek(wday);
    this.updateCalendarGrid_();
    this.redrawWeekdays_();
  };
  
  
  /**
   * Sets class name associated with specified weekday.
   *
   * @param {number} wday Week day, 0 = Monday, 6 = Sunday.
   * @param {string} className Class name.
   */
  goog.ui.DatePicker.prototype.setWeekdayClass = function(wday, className) {
    this.wdayStyles_[wday] = className;
    this.redrawCalendarGrid_();
  };
  
  
  /**
   * Sets whether a fixed number of weeks should be showed. If not only weeks
   * for the current month will be showed.
   *
   * @param {boolean} b Whether a fixed number of weeks should be showed.
   */
  goog.ui.DatePicker.prototype.setShowFixedNumWeeks = function(b) {
    this.showFixedNumWeeks_ = b;
    this.updateCalendarGrid_();
  };
  
  
  /**
   * Sets whether a days from the previous and/or next month should be shown.
   *
   * @param {boolean} b Whether a days from the previous and/or next month should
   *     be shown.
   */
  goog.ui.DatePicker.prototype.setShowOtherMonths = function(b) {
    this.showOtherMonths_ = b;
    this.redrawCalendarGrid_();
  };
  
  
  /**
   * Sets whether the picker should use a simple navigation menu that only
   * contains controls for navigating to the next and previous month. The default
   * navigation menu contains controls for navigating to the next/previous month,
   * next/previous year, and menus for jumping to specific months and years.
   *
   * @param {boolean} b Whether to use a simple navigation menu.
   */
  goog.ui.DatePicker.prototype.setUseSimpleNavigationMenu = function(b) {
    this.simpleNavigation_ = b;
    this.updateNavigationRow_();
    this.updateCalendarGrid_();
  };
  
  
  /**
   * Sets whether a the extra week(s) added always should be at the end. Only
   * applicable if a fixed number of weeks are shown.
   *
   * @param {boolean} b Whether a the extra week(s) added always should be at the
   *     end.
   */
  goog.ui.DatePicker.prototype.setExtraWeekAtEnd = function(b) {
    this.extraWeekAtEnd_ = b;
    this.updateCalendarGrid_();
  };
  
  
  /**
   * Sets whether week numbers should be shown.
   *
   * @param {boolean} b Whether week numbers should be shown.
   */
  goog.ui.DatePicker.prototype.setShowWeekNum = function(b) {
    this.showWeekNum_ = b;
    // The navigation row may rely on the number of visible columns,
    // so we update it when adding/removing the weeknum column.
    this.updateNavigationRow_();
    this.updateCalendarGrid_();
  };
  
  
  /**
   * Sets whether weekday names should be shown.
   *
   * @param {boolean} b Whether weekday names should be shown.
   */
  goog.ui.DatePicker.prototype.setShowWeekdayNames = function(b) {
    this.showWeekdays_ = b;
    this.redrawCalendarGrid_();
  };
  
  
  /**
   * Sets whether the picker uses narrow weekday names ('M', 'T', 'W', ...).
   *
   * The default behavior is to use short names ('Mon', 'Tue', 'Wed', ...).
   *
   * @param {boolean} b Whether to use narrow weekday names.
   */
  goog.ui.DatePicker.prototype.setUseNarrowWeekdayNames = function(b) {
    this.wdayNames_ = b ? this.symbols_.NARROWWEEKDAYS :
        this.symbols_.SHORTWEEKDAYS;
    this.redrawWeekdays_();
  };
  
  
  /**
   * Sets whether none is a valid selection.
   *
   * @param {boolean} b Whether none is a valid selection.
   */
  goog.ui.DatePicker.prototype.setAllowNone = function(b) {
    this.allowNone_ = b;
    if (this.elNone_) {
      this.updateTodayAndNone_();
    }
  };
  
  
  /**
   * Sets whether the today button should be shown.
   *
   * @param {boolean} b Whether the today button should be shown.
   */
  goog.ui.DatePicker.prototype.setShowToday = function(b) {
    this.showToday_ = b;
    if (this.elToday_) {
      this.updateTodayAndNone_();
    }
  };
  
  
  /**
   * Updates the display style of the None and Today buttons as well as hides the
   * table foot if both are hidden.
   * @private
   */
  goog.ui.DatePicker.prototype.updateTodayAndNone_ = function() {
    goog.style.showElement(this.elToday_, this.showToday_);
    goog.style.showElement(this.elNone_, this.allowNone_);
    goog.style.showElement(this.tableFoot_, this.showToday_ || this.allowNone_);
  };
  
  
  /**
   * Sets the decorator function. The function should have the interface of
   *   {string} f({goog.date.Date});
   * and return a String representing a CSS class to decorate the cell
   * corresponding to the date specified.
   *
   * @param {Function} f The decorator function.
   */
  goog.ui.DatePicker.prototype.setDecorator = function(f) {
    this.decoratorFunction_ = f;
  };
  
  
  /**
   * Changes the active month to the previous one.
   */
  goog.ui.DatePicker.prototype.previousMonth = function() {
    this.activeMonth_.add(new goog.date.Interval(goog.date.Interval.MONTHS, -1));
    this.updateCalendarGrid_();
  };
  
  
  /**
   * Changes the active month to the next one.
   */
  goog.ui.DatePicker.prototype.nextMonth = function() {
    this.activeMonth_.add(new goog.date.Interval(goog.date.Interval.MONTHS, 1));
    this.updateCalendarGrid_();
  };
  
  
  /**
   * Changes the active year to the previous one.
   */
  goog.ui.DatePicker.prototype.previousYear = function() {
    this.activeMonth_.add(new goog.date.Interval(goog.date.Interval.YEARS, -1));
    this.updateCalendarGrid_();
  };
  
  
  /**
   * Changes the active year to the next one.
   */
  goog.ui.DatePicker.prototype.nextYear = function() {
    this.activeMonth_.add(new goog.date.Interval(goog.date.Interval.YEARS, 1));
    this.updateCalendarGrid_();
  };
  
  
  /**
   * Selects the current date.
   */
  goog.ui.DatePicker.prototype.selectToday = function() {
    this.setDate(new goog.date.Date());
  };
  
  
  /**
   * Clears the selection.
   */
  goog.ui.DatePicker.prototype.selectNone = function() {
    if (this.allowNone_) {
      this.setDate(null);
    }
  };
  
  
  /**
   * @return {goog.date.Date} The selected date.
   */
  goog.ui.DatePicker.prototype.getDate = function() {
    return this.date_;
  };
  
  
  /**
   * Sets the selected date.
   *
   * @param {goog.date.Date|Date} date Date to select or null to select nothing.
   */
  goog.ui.DatePicker.prototype.setDate = function(date) {
    // Check if date has been changed
    var changed = date != this.date_ &&
        !(date && this.date_ &&
          date.getFullYear() == this.date_.getFullYear() &&
          date.getMonth() == this.date_.getMonth() &&
          date.getDate() == this.date_.getDate());
  
    // Set current date to clone of supplied goog.date.Date or Date.
    this.date_ = date && new goog.date.Date(date);
  
    // Set current month
    if (date) {
      this.activeMonth_.set(this.date_);
      this.activeMonth_.setDate(1);
    }
  
    // Update calendar grid even if the date has not changed as even if today is
    // selected another month can be displayed.
    this.updateCalendarGrid_();
  
    // TODO(user): Standardize selection and change events with other components.
    // Fire select event.
    var selectEvent = new goog.ui.DatePickerEvent(
        goog.ui.DatePicker.Events.SELECT, this, this.date_);
    this.dispatchEvent(selectEvent);
  
    // Fire change event.
    var changeEvent = new goog.ui.DatePickerEvent(
        goog.ui.DatePicker.Events.CHANGE, this, this.date_);
    this.dispatchEvent(changeEvent);
  };
  
  
  /**
   * Updates the navigation row (navigating months and maybe years) in the navRow_
   * element of a created picker.
   * @private
   */
  goog.ui.DatePicker.prototype.updateNavigationRow_ = function() {
    if (!this.elNavRow_) {
      return;
    }
    var row = this.elNavRow_;
  
    // Clear the navigation row.
    while (row.firstChild) {
      row.removeChild(row.firstChild);
    }
    // Populate the navigation row according to the configured navigation mode.
    var cell, monthCell, yearCell;
  
    if (this.simpleNavigation_) {
      cell = this.dom_.createElement('td');
      cell.colSpan = this.showWeekNum_ ? 1 : 2;
      this.createButton_(cell, '\u00AB', this.previousMonth);  // <<
      row.appendChild(cell);
  
      cell = this.dom_.createElement('td');
      cell.colSpan = this.showWeekNum_ ? 6 : 5;
      cell.className = goog.getCssName(this.getBaseCssClass(), 'monthyear');
      row.appendChild(cell);
      this.elMonthYear_ = cell;
  
      cell = this.dom_.createElement('td');
      this.createButton_(cell, '\u00BB', this.nextMonth);  // >>
      row.appendChild(cell);
  
    } else {
      var fullDateFormat = this.symbols_.DATEFORMATS[
          goog.i18n.DateTimeFormat.Format.FULL_DATE].toLowerCase();
  
      monthCell = this.dom_.createElement('td');
      monthCell.colSpan = 5;
      this.createButton_(monthCell, '\u00AB', this.previousMonth);  // <<
      this.elMonth_ = this.createButton_(
          monthCell, '', this.showMonthMenu_,
          goog.getCssName(this.getBaseCssClass(), 'month'));
      this.createButton_(monthCell, '\u00BB', this.nextMonth);  // >>
  
      yearCell = this.dom_.createElement('td');
      yearCell.colSpan = 3;
      this.createButton_(yearCell, '\u00AB', this.previousYear);  // <<
      this.elYear_ = this.createButton_(yearCell, '', this.showYearMenu_,
                                        goog.getCssName(this.getBaseCssClass(),
                                                        'year'));
      this.createButton_(yearCell, '\u00BB', this.nextYear);  // >>
  
      // If the date format has year ('y') appearing first before month ('m'),
      // show the year on the left hand side of the datepicker popup.  Otherwise,
      // show the month on the left side.  This check assumes the data to be
      // valid, and that all date formats contain month and year.
      if (fullDateFormat.indexOf('y') < fullDateFormat.indexOf('m')) {
        row.appendChild(yearCell);
        row.appendChild(monthCell);
      } else {
        row.appendChild(monthCell);
        row.appendChild(yearCell);
      }
    }
  };
  
  
  /**
   * Updates the footer row (with select buttons) in the footRow_ element of a
   * created picker.
   * @private
   */
  goog.ui.DatePicker.prototype.updateFooterRow_ = function() {
    var row = this.elFootRow_;
  
    // Clear the footer row.
    goog.dom.removeChildren(row);
  
    // Populate the footer row with buttons for Today and None.
    var cell = this.dom_.createElement('td');
    cell.colSpan = 2;
    cell.className = goog.getCssName(this.getBaseCssClass(), 'today-cont');
  
    /** @desc Label for button that selects the current date. */
    var MSG_DATEPICKER_TODAY_BUTTON_LABEL = goog.getMsg('Today');
    this.elToday_ = this.createButton_(cell, MSG_DATEPICKER_TODAY_BUTTON_LABEL,
                                       this.selectToday);
    row.appendChild(cell);
  
    cell = this.dom_.createElement('td');
    cell.colSpan = 4;
    row.appendChild(cell);
  
    cell = this.dom_.createElement('td');
    cell.colSpan = 2;
    cell.className = goog.getCssName(this.getBaseCssClass(), 'none-cont');
  
    /** @desc Label for button that clears the selection. */
    var MSG_DATEPICKER_NONE = goog.getMsg('None');
    this.elNone_ = this.createButton_(cell, MSG_DATEPICKER_NONE, this.selectNone);
    row.appendChild(cell);
    this.updateTodayAndNone_();
  };
  
  
  /** @inheritDoc */
  goog.ui.DatePicker.prototype.decorateInternal = function(el) {
    goog.ui.DatePicker.superClass_.decorateInternal.call(this, el);
  
    el.className = this.getBaseCssClass();
  
    var table = this.dom_.createElement('table');
    var thead = this.dom_.createElement('thead');
    var tbody = this.dom_.createElement('tbody');
    var tfoot = this.dom_.createElement('tfoot');
  
    goog.dom.a11y.setRole(tbody, 'grid');
    tbody.tabIndex = '0';
  
    // As per comment in colorpicker: table.tBodies and table.tFoot should not be
    // used because of a bug in Safari, hence using an instance variable
    this.tableBody_ = tbody;
    this.tableFoot_ = tfoot;
  
    var row = this.dom_.createElement('tr');
    row.className = goog.getCssName(this.getBaseCssClass(), 'head');
    this.elNavRow_ = row;
    this.updateNavigationRow_();
  
    thead.appendChild(row);
  
    var cell;
    this.elTable_ = [];
    for (var i = 0; i < 7; i++) {
      row = this.dom_.createElement('tr');
      this.elTable_[i] = [];
      for (var j = 0; j < 8; j++) {
        cell = this.dom_.createElement(j == 0 || i == 0 ? 'th' : 'td');
        if ((j == 0 || i == 0) && j != i) {
          cell.className = (j == 0) ?
              goog.getCssName(this.getBaseCssClass(), 'week') :
              goog.getCssName(this.getBaseCssClass(), 'wday');
          goog.dom.a11y.setRole(cell, j == 0 ? 'rowheader' : 'columnheader');
        }
        row.appendChild(cell);
        this.elTable_[i][j] = cell;
      }
      tbody.appendChild(row);
    }
  
    row = this.dom_.createElement('tr');
    row.className = goog.getCssName(this.getBaseCssClass(), 'foot');
    this.elFootRow_ = row;
    this.updateFooterRow_();
    tfoot.appendChild(row);
  
  
    table.cellSpacing = '0';
    table.cellPadding = '0';
    table.appendChild(thead);
    table.appendChild(tbody);
    table.appendChild(tfoot);
    el.appendChild(table);
  
    this.redrawWeekdays_();
    this.updateCalendarGrid_();
  
    el.tabIndex = 0;
  };
  
  
  /** @inheritDoc */
  goog.ui.DatePicker.prototype.createDom = function() {
    goog.ui.DatePicker.superClass_.createDom.call(this);
    this.decorateInternal(this.getElement());
  };
  
  
  /** @inheritDoc */
  goog.ui.DatePicker.prototype.enterDocument = function() {
    goog.ui.DatePicker.superClass_.enterDocument.call(this);
  
    var eh = this.getHandler();
    eh.listen(this.tableBody_, goog.events.EventType.CLICK,
        this.handleGridClick_);
    eh.listen(this.getKeyHandlerForElement_(this.getElement()),
        goog.events.KeyHandler.EventType.KEY, this.handleGridKeyPress_);
  };
  
  
  /** @inheritDoc */
  goog.ui.DatePicker.prototype.exitDocument = function() {
    goog.ui.DatePicker.superClass_.exitDocument.call(this);
    this.destroyMenu_();
    for (var uid in this.keyHandlers_) {
      this.keyHandlers_[uid].dispose();
    }
    this.keyHandlers_ = {};
  };
  
  
  /**
   * @deprecated Use decorate instead.
   */
  goog.ui.DatePicker.prototype.create =
      goog.ui.DatePicker.prototype.decorate;
  
  
  /** @inheritDoc */
  goog.ui.DatePicker.prototype.disposeInternal = function() {
    goog.ui.DatePicker.superClass_.disposeInternal.call(this);
  
    this.elTable_ = null;
    this.tableBody_ = null;
    this.tableFoot_ = null;
    this.elNavRow_ = null;
    this.elFootRow_ = null;
    this.elMonth_ = null;
    this.elMonthYear_ = null;
    this.elYear_ = null;
    this.elToday_ = null;
    this.elNone_ = null;
  };
  
  
  /**
   * Click handler for date grid.
   *
   * @param {goog.events.BrowserEvent} event Click event.
   * @private
   */
  goog.ui.DatePicker.prototype.handleGridClick_ = function(event) {
    if (event.target.tagName == 'TD') {
      // colIndex/rowIndex is broken in Safari, find position by looping
      var el, x = -2, y = -2; // first col/row is for weekday/weeknum
      for (el = event.target; el; el = el.previousSibling, x++) {}
      for (el = event.target.parentNode; el; el = el.previousSibling, y++) {}
      var obj = this.grid_[y][x];
      this.setDate(obj.clone());
    }
  };
  
  
  /**
   * Keypress handler for date grid.
   *
   * @param {goog.events.BrowserEvent} event Keypress event.
   * @private
   */
  goog.ui.DatePicker.prototype.handleGridKeyPress_ = function(event) {
    var months, days;
    switch (event.keyCode) {
      case 33: // Page up
        event.preventDefault();
        months = -1;
        break;
      case 34: // Page down
        event.preventDefault();
        months = 1;
        break;
      case 37: // Left
        event.preventDefault();
        days = -1;
        break;
      case 39: // Right
        event.preventDefault();
        days = 1;
        break;
      case 38: // Down
        event.preventDefault();
        days = -7;
        break;
      case 40: // Up
        event.preventDefault();
        days = 7;
        break;
      case 36: // Home
        event.preventDefault();
        this.selectToday();
      case 46: // Delete
        event.preventDefault();
        this.selectNone();
      default:
        return;
    }
    var date;
    if (this.date_) {
      date = this.date_.clone();
      date.add(new goog.date.Interval(0, months, days));
    } else {
      date = this.activeMonth_.clone();
      date.setDate(1);
    }
    this.setDate(date);
  };
  
  
  /**
   * Click handler for month button. Opens month selection menu.
   *
   * @param {goog.events.BrowserEvent} event Click event.
   * @private
   */
  goog.ui.DatePicker.prototype.showMonthMenu_ = function(event) {
    event.stopPropagation();
  
    var list = [];
    for (var i = 0; i < 12; i++) {
      list.push(this.symbols_.MONTHS[i]);
    }
    this.createMenu_(this.elMonth_, list, this.handleMonthMenuClick_,
        this.symbols_.MONTHS[this.activeMonth_.getMonth()]);
  };
  
  
  /**
   * Click handler for year button. Opens year selection menu.
   *
   * @param {goog.events.BrowserEvent} event Click event.
   * @private
   */
  goog.ui.DatePicker.prototype.showYearMenu_ = function(event) {
    event.stopPropagation();
  
    var list = [];
    var year = this.activeMonth_.getFullYear() - 5;
    for (var i = 0; i < 11; i++) {
      list.push(String(year + i));
    }
    this.createMenu_(this.elYear_, list, this.handleYearMenuClick_,
                     String(this.activeMonth_.getFullYear()));
  };
  
  
  /**
   * Call back function for month menu.
   *
   * @param {Element} target Selected item.
   * @private
   */
  goog.ui.DatePicker.prototype.handleMonthMenuClick_ = function(target) {
    var el = target;
    for (var i = -1; el; el = goog.dom.getPreviousElementSibling(el), i++) {}
  
    this.activeMonth_.setMonth(i);
    this.updateCalendarGrid_();
  
    if (this.elMonth_.focus) {
      this.elMonth_.focus();
    }
  };
  
  
  /**
   * Call back function for year menu.
   *
   * @param {Element} target Selected item.
   * @private
   */
  goog.ui.DatePicker.prototype.handleYearMenuClick_ = function(target) {
    if (target.firstChild.nodeType == goog.dom.NodeType.TEXT) {
      this.activeMonth_.setFullYear(Number(target.firstChild.nodeValue));
      this.updateCalendarGrid_();
    }
  
    this.elYear_.focus();
  };
  
  
  /**
   * Support function for menu creation.
   *
   * @param {Element} srcEl Button to create menu for.
   * @param {Array.<string>} items List of items to populate menu with.
   * @param {Function} method Call back method.
   * @param {string} selected Item to mark as selected in menu.
   * @private
   */
  goog.ui.DatePicker.prototype.createMenu_ = function(srcEl, items, method,
                                                      selected) {
    this.destroyMenu_();
  
    var el = this.dom_.createElement('div');
    el.className = goog.getCssName(this.getBaseCssClass(), 'menu');
  
    this.menuSelected_ = null;
  
    var ul = this.dom_.createElement('ul');
    for (var i = 0; i < items.length; i++) {
      var li = this.dom_.createDom('li', null, items[i]);
      if (items[i] == selected) {
        this.menuSelected_ = li;
      }
      ul.appendChild(li);
    }
    el.appendChild(ul);
    el.style.left = srcEl.offsetLeft + srcEl.parentNode.offsetLeft + 'px';
    el.style.top = srcEl.offsetTop + 'px';
    el.style.width = srcEl.clientWidth + 'px';
    this.elMonth_.parentNode.appendChild(el);
  
    this.menu_ = el;
    if (!this.menuSelected_) {
      this.menuSelected_ = ul.firstChild;
    }
    this.menuSelected_.className =
        goog.getCssName(this.getBaseCssClass(), 'menu-selected');
    this.menuCallback_ = method;
  
    var eh = this.getHandler();
    eh.listen(this.menu_, goog.events.EventType.CLICK, this.handleMenuClick_);
    eh.listen(this.getKeyHandlerForElement_(this.menu_),
        goog.events.KeyHandler.EventType.KEY, this.handleMenuKeyPress_);
    eh.listen(this.dom_.getDocument(), goog.events.EventType.CLICK,
        this.destroyMenu_);
    el.tabIndex = 0;
    el.focus();
  };
  
  
  /**
   * Click handler for menu.
   *
   * @param {goog.events.BrowserEvent} event Click event.
   * @private
   */
  goog.ui.DatePicker.prototype.handleMenuClick_ = function(event) {
    event.stopPropagation();
  
    this.destroyMenu_();
    if (this.menuCallback_) {
      this.menuCallback_(event.target);
    }
  };
  
  
  /**
   * Keypress handler for menu.
   *
   * @param {goog.events.BrowserEvent} event Keypress event.
   * @private
   */
  goog.ui.DatePicker.prototype.handleMenuKeyPress_ = function(event) {
    // Prevent the grid keypress handler from catching the keypress event.
    event.stopPropagation();
  
    var el;
    var menuSelected = this.menuSelected_;
    switch (event.keyCode) {
      case 35: // End
        event.preventDefault();
        el = menuSelected.parentNode.lastChild;
        break;
      case 36: // Home
        event.preventDefault();
        el = menuSelected.parentNode.firstChild;
        break;
      case 38: // Up
        event.preventDefault();
        el = menuSelected.previousSibling;
        break;
      case 40: // Down
        event.preventDefault();
        el = menuSelected.nextSibling;
        break;
      case 13: // Enter
      case 9: // Tab
      case 0: // Space
        event.preventDefault();
        this.destroyMenu_();
        this.menuCallback_(menuSelected);
        break;
    }
    if (el && el != menuSelected) {
      menuSelected.className = '';
      el.className = goog.getCssName(this.getBaseCssClass(), 'menu-selected');
      this.menuSelected_ = el;
    }
  };
  
  
  /**
   * Support function for menu destruction.
   * @private
   */
  goog.ui.DatePicker.prototype.destroyMenu_ = function() {
    if (this.menu_) {
      var eh = this.getHandler();
      eh.unlisten(this.menu_, goog.events.EventType.CLICK, this.handleMenuClick_);
      eh.unlisten(this.getKeyHandlerForElement_(this.menu_),
          goog.events.KeyHandler.EventType.KEY, this.handleMenuKeyPress_);
      eh.unlisten(this.dom_.getDocument(), goog.events.EventType.CLICK,
          this.destroyMenu_);
      goog.dom.removeNode(this.menu_);
      delete this.menu_;
    }
  };
  
  
  /**
   * Support function for button creation.
   *
   * @param {Element} parentNode Container the button should be added to.
   * @param {string} label Button label.
   * @param {Function} method Event handler.
   * @param {string=} opt_className Class name for button, which will be used
   *    in addition to "goog-date-picker-btn".
   * @private
   * @return {Element} The created button element.
   */
  goog.ui.DatePicker.prototype.createButton_ = function(parentNode, label,
                                                        method, opt_className) {
    var classes = [goog.getCssName(this.getBaseCssClass(), 'btn')];
    if (opt_className) {
      classes.push(opt_className);
    }
    var el = this.dom_.createElement('button');
    el.className = classes.join(' ');
    el.appendChild(this.dom_.createTextNode(label));
    parentNode.appendChild(el);
    this.getHandler().listen(el, goog.events.EventType.CLICK, function(e) {
      // Since this is a button, the default action is to submit a form if the
      // node is added inside a form.  Prevent this.
      e.preventDefault();
      method.call(this, e);
    });
  
    return el;
  };
  
  
  /**
   * Determines the dates/weekdays for the current month and builds an in memory
   * representation of the calendar.
   *
   * @private
   */
  goog.ui.DatePicker.prototype.updateCalendarGrid_ = function() {
    if (!this.getElement()) {
      return;
    }
  
    var date = this.activeMonth_.clone();
    date.setDate(1);
  
    // Show year name of select month
    if (this.elMonthYear_) {
      goog.dom.setTextContent(this.elMonthYear_,
          goog.date.formatMonthAndYear(
              this.symbols_.MONTHS[date.getMonth()],
              date.getFullYear()));
    }
    if (this.elMonth_) {
      goog.dom.setTextContent(this.elMonth_,
          this.symbols_.MONTHS[date.getMonth()]);
    }
    if (this.elYear_) {
      goog.dom.setTextContent(this.elYear_, String(date.getFullYear()));
    }
  
    var wday = date.getWeekday();
    var days = date.getNumberOfDaysInMonth();
  
    // Determine how many days to show for previous month
    date.add(new goog.date.Interval(goog.date.Interval.MONTHS, -1));
    date.setDate(date.getNumberOfDaysInMonth() - (wday - 1));
  
    if (this.showFixedNumWeeks_ && !this.extraWeekAtEnd_ && days + wday < 33) {
      date.add(new goog.date.Interval(goog.date.Interval.DAYS, -7));
    }
  
    // Create weekday/day grid
    var dayInterval = new goog.date.Interval(goog.date.Interval.DAYS, 1);
    this.grid_ = [];
    for (var y = 0; y < 6; y++) { // Weeks
      this.grid_[y] = [];
      for (var x = 0; x < 7; x++) { // Weekdays
        this.grid_[y][x] = date.clone();
        date.add(dayInterval);
      }
    }
  
    this.redrawCalendarGrid_();
  };
  
  
  /**
   * Draws calendar view from in memory representation and applies class names
   * depending on the selection, weekday and whatever the day belongs to the
   * active month or not.
   * @private
   */
  goog.ui.DatePicker.prototype.redrawCalendarGrid_ = function() {
    if (!this.getElement()) {
      return;
    }
  
    var month = this.activeMonth_.getMonth();
    var today = new goog.date.Date();
    var todayYear = today.getFullYear();
    var todayMonth = today.getMonth();
    var todayDate = today.getDate();
  
    // Draw calendar week by week, a worst case month has six weeks.
    for (var y = 0; y < 6; y++) {
  
      // Draw week number, if enabled
      if (this.showWeekNum_) {
        goog.dom.setTextContent(this.elTable_[y + 1][0],
                                this.grid_[y][0].getWeekNumber());
        goog.dom.classes.set(this.elTable_[y + 1][0],
                             goog.getCssName(this.getBaseCssClass(), 'week'));
      } else {
        goog.dom.setTextContent(this.elTable_[y + 1][0], '');
        goog.dom.classes.set(this.elTable_[y + 1][0], '');
      }
  
      for (var x = 0; x < 7; x++) {
        var o = this.grid_[y][x];
        var el = this.elTable_[y + 1][x + 1];
  
        // Assign a unique element id (required for setting the active descendant
        // ARIA role) unless already set.
        if (!el.id) {
          el.id = 'goog-dp-' + goog.ui.DatePicker.nextId_++;
        }
        goog.dom.a11y.setRole(el, 'gridcell');
        var classes = [goog.getCssName(this.getBaseCssClass(), 'date')];
        if (this.showOtherMonths_ || o.getMonth() == month) {
          // Date belongs to previous or next month
          if (o.getMonth() != month) {
            classes.push(goog.getCssName(this.getBaseCssClass(), 'other-month'));
          }
  
          // Apply styles set by setWeekdayClass
          var wday = (x + this.activeMonth_.getFirstDayOfWeek() + 7) % 7;
          if (this.wdayStyles_[wday]) {
            classes.push(this.wdayStyles_[wday]);
          }
  
          // Current date
          if (o.getDate() == todayDate && o.getMonth() == todayMonth &&
              o.getFullYear() == todayYear) {
            classes.push(goog.getCssName(this.getBaseCssClass(), 'today'));
          }
  
          // Selected date
          if (this.date_ && o.getDate() == this.date_.getDate() &&
              o.getMonth() == this.date_.getMonth() &&
              o.getFullYear() == this.date_.getFullYear()) {
            classes.push(goog.getCssName(this.getBaseCssClass(), 'selected'));
            goog.dom.a11y.setState(this.tableBody_, 'activedescendant', el.id);
          }
  
          // Custom decorator
          if (this.decoratorFunction_) {
            var customClass = this.decoratorFunction_(o);
            if (customClass) {
              classes.push(customClass);
            }
          }
  
          // Set cell text to the date and apply classes.
          goog.dom.setTextContent(el, o.getDate());
          // Date belongs to previous or next month and showOtherMonths is false,
          // clear text and classes.
        } else {
          goog.dom.setTextContent(el, '');
        }
        goog.dom.classes.set(el, classes.join(' '));
      }
  
      // Hide the either the last one or last two weeks if they contain no days
      // from the active month and the showFixedNumWeeks is false. The first four
      // weeks are always shown as no month has less than 28 days).
      if (y >= 4) {
        goog.style.showElement(this.elTable_[y + 1][0].parentNode,
                               this.grid_[y][0].getMonth() == month ||
                                   this.showFixedNumWeeks_);
      }
    }
  };
  
  
  /**
   * Draw weekday names, if enabled. Start with whatever day has been set as the
   * first day of week.
   * @private
   */
  goog.ui.DatePicker.prototype.redrawWeekdays_ = function() {
    if (!this.getElement()) {
      return;
    }
    if (this.showWeekdays_) {
      for (var x = 0; x < 7; x++) {
        var el = this.elTable_[0][x + 1];
        var wday = (x + this.activeMonth_.getFirstDayOfWeek() + 7) % 7;
        goog.dom.setTextContent(el, this.wdayNames_[(wday + 1) % 7]);
      }
    }
    goog.style.showElement(this.elTable_[0][0].parentNode, this.showWeekdays_);
  };
  
  
  /**
   * Returns the key handler for an element and caches it so that it can be
   * retrieved at a later point.
   * @param {Element} el The element to get the key handler for.
   * @return {goog.events.KeyHandler} The key handler for the element.
   * @private
   */
  goog.ui.DatePicker.prototype.getKeyHandlerForElement_ = function(el) {
    var uid = goog.getUid(el);
    if (!(uid in this.keyHandlers_)) {
      this.keyHandlers_[uid] = new goog.events.KeyHandler(el);
    }
    return this.keyHandlers_[uid];
  };
  
  
  
  /**
   * Object representing a date picker event.
   *
   * @param {string} type Event type.
   * @param {goog.ui.DatePicker} target Date picker initiating event.
   * @param {goog.date.Date} date Selected date.
   * @constructor
   * @extends {goog.events.Event}
   */
  goog.ui.DatePickerEvent = function(type, target, date) {
    goog.events.Event.call(this, type, target);
  
    /**
     * The selected date
     * @type {goog.date.Date}
     */
    this.date = date;
  };
  goog.inherits(goog.ui.DatePickerEvent, goog.events.Event);
  