/*
 * jQuery UI Datepicker @VERSION
 *
 * Copyright (c) 2008 AUTHORS.txt (http://ui.jquery.com/about)
 * Dual licensed under the MIT (MIT-LICENSE.txt)
 * and GPL (GPL-LICENSE.txt) licenses.
 *
 * http://docs.jquery.com/UI/Datepicker
 *
 * Depends:
 * ui.core.js
 */

(function($) { // hide the namespace

$.extend($.ui, { datepicker: { version: "@VERSION" } });

var PROP_NAME = 'datepicker';

/* Date picker manager.
   Use the singleton instance of this class, $.datepicker, to interact with the date picker.
   Settings for (groups of) date pickers are maintained in an instance object,
   allowing multiple different settings on the same page. */

function Datepicker() {
   this.debug = false; // Change this to true to start debugging
   this._curInst = null; // The current instance in use
   this._keyEvent = false; // If the last event was a key event
   this._disabledInputs = []; // List of date picker inputs that have been disabled
   this._datepickerShowing = false; // True if the popup picker is showing , false if not
   this._inDialog = false; // True if showing within a "dialog", false if not
   this._mainDivId = 'ui-datepicker-div'; // The ID of the main datepicker division
   this._inlineClass = 'ui-datepicker-inline'; // The name of the inline marker class
   this._appendClass = 'ui-datepicker-append'; // The name of the append marker class
   this._triggerClass = 'ui-datepicker-trigger'; // The name of the trigger marker class
   this._dialogClass = 'ui-datepicker-dialog'; // The name of the dialog marker class
   this._promptClass = 'ui-datepicker-prompt'; // The name of the dialog prompt marker class
   this._disableClass = 'ui-datepicker-disabled'; // The name of the disabled covering marker class
   this._unselectableClass = 'ui-datepicker-unselectable'; // The name of the unselectable cell marker class
   this._currentClass = 'ui-datepicker-current-day'; // The name of the current day marker class
   this._dayOverClass = 'ui-datepicker-days-cell-over'; // The name of the day hover marker class
   this._weekOverClass = 'ui-datepicker-week-over'; // The name of the week hover marker class
   this.regional = []; // Available regional settings, indexed by language code
   this.regional[''] = { // Default regional settings
      clearText: 'Clear', // Display text for clear link
      clearStatus: 'Erase the current date', // Status text for clear link
      closeText: 'Close', // Display text for close link
      closeStatus: 'Close without change', // Status text for close link
      prevText: '&#x3c;Prev', // Display text for previous month link
      prevStatus: 'Show the previous month', // Status text for previous month link
      prevBigText: '&#x3c;&#x3c;', // Display text for previous year link
      prevBigStatus: 'Show the previous year', // Status text for previous year link
      nextText: 'Next&#x3e;', // Display text for next month link
      nextStatus: 'Show the next month', // Status text for next month link
      nextBigText: '&#x3e;&#x3e;', // Display text for next year link
      nextBigStatus: 'Show the next year', // Status text for next year link
      currentText: 'Today', // Display text for current month link
      currentStatus: 'Show the current month', // Status text for current month link
      monthNames: ['January','February','March','April','May','June',
         'July','August','September','October','November','December'], // Names of months for drop-down and formatting
      monthNamesShort: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'], // For formatting
      monthStatus: 'Show a different month', // Status text for selecting a month
      yearStatus: 'Show a different year', // Status text for selecting a year
      weekHeader: 'Wk', // Header for the week of the year column
      weekStatus: 'Week of the year', // Status text for the week of the year column
      dayNames: ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'], // For formatting
      dayNamesShort: ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'], // For formatting
      dayNamesMin: ['Su','Mo','Tu','We','Th','Fr','Sa'], // Column headings for days starting at Sunday
      dayStatus: 'Set DD as first week day', // Status text for the day of the week selection
      dateStatus: 'Select DD, M d', // Status text for the date selection
      dateFormat: 'mm/dd/yy', // See format options on parseDate
      firstDay: 0, // The first day of the week, Sun = 0, Mon = 1, ...
      initStatus: 'Select a date', // Initial Status text on opening
      isRTL: false // True if right-to-left language, false if left-to-right
   };
   this._defaults = { // Global defaults for all the date picker instances
      showOn: 'focus', // 'focus' for popup on focus,
         // 'button' for trigger button, or 'both' for either
      showAnim: 'show', // Name of jQuery animation for popup
      showOptions: {}, // Options for enhanced animations
      defaultDate: null, // Used when field is blank: actual date,
         // +/-number for offset from today, null for today
      appendText: '', // Display text following the input box, e.g. showing the format
      buttonText: '...', // Text for trigger button
      buttonImage: '', // URL for trigger button image
      buttonImageOnly: false, // True if the image appears alone, false if it appears on a button
      closeAtTop: true, // True to have the clear/close at the top,
         // false to have them at the bottom
      mandatory: false, // True to hide the Clear link, false to include it
      hideIfNoPrevNext: false, // True to hide next/previous month links
         // if not applicable, false to just disable them
      navigationAsDateFormat: false, // True if date formatting applied to prev/today/next links
      showBigPrevNext: false, // True to show big prev/next links
      gotoCurrent: false, // True if today link goes back to current selection instead
      changeMonth: true, // True if month can be selected directly, false if only prev/next
      changeYear: true, // True if year can be selected directly, false if only prev/next
      showMonthAfterYear: false, // True if the year select precedes month, false for month then year
      yearRange: '-10:+10', // Range of years to display in drop-down,
         // either relative to current year (-nn:+nn) or absolute (nnnn:nnnn)
      changeFirstDay: true, // True to click on day name to change, false to remain as set
      highlightWeek: false, // True to highlight the selected week
      showOtherMonths: false, // True to show dates in other months, false to leave blank
      showWeeks: false, // True to show week of the year, false to omit
      calculateWeek: this.iso8601Week, // How to calculate the week of the year,
         // takes a Date and returns the number of the week for it
      shortYearCutoff: '+10', // Short year values < this are in the current century,
         // > this are in the previous century,
         // string value starting with '+' for current year + value
      showStatus: false, // True to show status bar at bottom, false to not show it
      statusForDate: this.dateStatus, // Function to provide status text for a date -
         // takes date and instance as parameters, returns display text
      minDate: null, // The earliest selectable date, or null for no limit
      maxDate: null, // The latest selectable date, or null for no limit
      duration: 'normal', // Duration of display/closure
      beforeShowDay: null, // Function that takes a date and returns an array with
         // [0] = true if selectable, false if not, [1] = custom CSS class name(s) or '',
         // [2] = cell title (optional), e.g. $.datepicker.noWeekends
      beforeShow: null, // Function that takes an input field and
         // returns a set of custom settings for the date picker
      onSelect: null, // Define a callback function when a date is selected
      onChangeMonthYear: null, // Define a callback function when the month or year is changed
      onClose: null, // Define a callback function when the datepicker is closed
      numberOfMonths: 1, // Number of months to show at a time
      showCurrentAtPos: 0, // The position in multipe months at which to show the current month (starting at 0)
      stepMonths: 1, // Number of months to step back/forward
      stepBigMonths: 12, // Number of months to step back/forward for the big links
      rangeSelect: false, // Allows for selecting a date range on one date picker
      rangeSeparator: ' - ', // Text between two dates in a range
      altField: '', // Selector for an alternate field to store selected dates into
      altFormat: '', // The date format to use for the alternate field
      constrainInput: true // The input is constrained by the current date format
   };
   $.extend(this._defaults, this.regional['']);
   this.dpDiv = $('<div id="' + this._mainDivId + '" style="display: none;"></div>');
}

$.extend(Datepicker.prototype, {
   /* Class name added to elements to indicate already configured with a date picker. */
   markerClassName: 'hasDatepicker',

   /* Debug logging (if enabled). */
   log: function () {
      if (this.debug)
         console.log.apply('', arguments);
   },

   /* Override the default settings for all instances of the date picker.
      @param  settings  object - the new settings to use as defaults (anonymous object)
      @return the manager object */
   setDefaults: function(settings) {
      extendRemove(this._defaults, settings || {});
      return this;
   },

   /* Attach the date picker to a jQuery selection.
      @param  target    element - the target input field or division or span
      @param  settings  object - the new settings to use for this date picker instance (anonymous) */
   _attachDatepicker: function(target, settings) {
      // check for settings on the control itself - in namespace 'date:'
      var inlineSettings = null;
      for (var attrName in this._defaults) {
         var attrValue = target.getAttribute('date:' + attrName);
         if (attrValue) {
            inlineSettings = inlineSettings || {};
            try {
               inlineSettings[attrName] = eval(attrValue);
            } catch (err) {
               inlineSettings[attrName] = attrValue;
            }
         }
      }
      var nodeName = target.nodeName.toLowerCase();
      var inline = (nodeName == 'div' || nodeName == 'span');
      if (!target.id)
         target.id = 'dp' + (++this.uuid);
      var inst = this._newInst($(target), inline);
      inst.settings = $.extend({}, settings || {}, inlineSettings || {});
      if (nodeName == 'input') {
         this._connectDatepicker(target, inst);
      } else if (inline) {
         this._inlineDatepicker(target, inst);
      }
   },

   /* Create a new instance object. */
   _newInst: function(target, inline) {
      var id = target[0].id.replace(/([:\[\]\.])/g, '\\\\$1'); // escape jQuery meta chars
      return {id: id, input: target, // associated target
         selectedDay: 0, selectedMonth: 0, selectedYear: 0, // current selection
         drawMonth: 0, drawYear: 0, // month being drawn
         inline: inline, // is datepicker inline or not
         dpDiv: (!inline ? this.dpDiv : // presentation div
         $('<div class="' + this._inlineClass + '"></div>'))};
   },

   /* Attach the date picker to an input field. */
   _connectDatepicker: function(target, inst) {
      var input = $(target);
      if (input.hasClass(this.markerClassName))
         return;
      var appendText = this._get(inst, 'appendText');
      var isRTL = this._get(inst, 'isRTL');
      if (appendText)
         input[isRTL ? 'before' : 'after']('<span class="' + this._appendClass + '">' + appendText + '</span>');
      var showOn = this._get(inst, 'showOn');
      if (showOn == 'focus' || showOn == 'both') // pop-up date picker when in the marked field
         input.focus(this._showDatepicker);
      if (showOn == 'button' || showOn == 'both') { // pop-up date picker when button clicked
         var buttonText = this._get(inst, 'buttonText');
         var buttonImage = this._get(inst, 'buttonImage');
         var trigger = $(this._get(inst, 'buttonImageOnly') ?
            $('<img/>').addClass(this._triggerClass).
               attr({ src: buttonImage, alt: buttonText, title: buttonText }) :
            $('<button type="button"></button>').addClass(this._triggerClass).
               html(buttonImage == '' ? buttonText : $('<img/>').attr(
               { src:buttonImage, alt:buttonText, title:buttonText })));
         input[isRTL ? 'before' : 'after'](trigger);
         trigger.click(function() {
            if ($.datepicker._datepickerShowing && $.datepicker._lastInput == target)
               $.datepicker._hideDatepicker();
            else
               $.datepicker._showDatepicker(target);
            return false;
         });
      }
      input.addClass(this.markerClassName).keydown(this._doKeyDown).keypress(this._doKeyPress).
         bind("setData.datepicker", function(event, key, value) {
            inst.settings[key] = value;
         }).bind("getData.datepicker", function(event, key) {
            return this._get(inst, key);
         });
      $.data(target, PROP_NAME, inst);
   },

   /* Attach an inline date picker to a div. */
   _inlineDatepicker: function(target, inst) {
      var divSpan = $(target);
      if (divSpan.hasClass(this.markerClassName))
         return;
      divSpan.addClass(this.markerClassName).append(inst.dpDiv).
         bind("setData.datepicker", function(event, key, value){
            inst.settings[key] = value;
         }).bind("getData.datepicker", function(event, key){
            return this._get(inst, key);
         });
      $.data(target, PROP_NAME, inst);
      this._setDate(inst, this._getDefaultDate(inst));
      this._updateDatepicker(inst);
      this._updateAlternate(inst);
   },

   /* Pop-up the date picker in a "dialog" box.
      @param  input     element - ignored
      @param  dateText  string - the initial date to display (in the current format)
      @param  onSelect  function - the function(dateText) to call when a date is selected
      @param  settings  object - update the dialog date picker instance's settings (anonymous object)
      @param  pos       int[2] - coordinates for the dialog's position within the screen or
                        event - with x/y coordinates or
                        leave empty for default (screen centre)
      @return the manager object */
   _dialogDatepicker: function(input, dateText, onSelect, settings, pos) {
      var inst = this._dialogInst; // internal instance
      if (!inst) {
         var id = 'dp' + (++this.uuid);
         this._dialogInput = $('<input type="text" id="' + id +
            '" size="1" style="position: absolute; top: -100px;"/>');
         this._dialogInput.keydown(this._doKeyDown);
         $('body').append(this._dialogInput);
         inst = this._dialogInst = this._newInst(this._dialogInput, false);
         inst.settings = {};
         $.data(this._dialogInput[0], PROP_NAME, inst);
      }
      extendRemove(inst.settings, settings || {});
      this._dialogInput.val(dateText);

      this._pos = (pos ? (pos.length ? pos : [pos.pageX, pos.pageY]) : null);
      if (!this._pos) {
         var browserWidth = window.innerWidth || document.documentElement.clientWidth ||  document.body.clientWidth;
         var browserHeight = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight;
         var scrollX = document.documentElement.scrollLeft || document.body.scrollLeft;
         var scrollY = document.documentElement.scrollTop || document.body.scrollTop;
         this._pos = // should use actual width/height below
            [(browserWidth / 2) - 100 + scrollX, (browserHeight / 2) - 150 + scrollY];
      }

      // move input on screen for focus, but hidden behind dialog
      this._dialogInput.css('left', this._pos[0] + 'px').css('top', this._pos[1] + 'px');
      inst.settings.onSelect = onSelect;
      this._inDialog = true;
      this.dpDiv.addClass(this._dialogClass);
      this._showDatepicker(this._dialogInput[0]);
      if ($.blockUI)
         $.blockUI(this.dpDiv);
      $.data(this._dialogInput[0], PROP_NAME, inst);
      return this;
   },

   /* Detach a datepicker from its control.
      @param  target    element - the target input field or division or span */
   _destroyDatepicker: function(target) {
      var $target = $(target);
      if (!$target.hasClass(this.markerClassName)) {
         return;
      }
      var nodeName = target.nodeName.toLowerCase();
      $.removeData(target, PROP_NAME);
      if (nodeName == 'input') {
         $target.siblings('.' + this._appendClass).remove().end().
            siblings('.' + this._triggerClass).remove().end().
            removeClass(this.markerClassName).
            unbind('focus', this._showDatepicker).
            unbind('keydown', this._doKeyDown).
            unbind('keypress', this._doKeyPress);
      } else if (nodeName == 'div' || nodeName == 'span')
         $target.removeClass(this.markerClassName).empty();
   },

   /* Enable the date picker to a jQuery selection.
      @param  target    element - the target input field or division or span */
   _enableDatepicker: function(target) {
      var $target = $(target);
      if (!$target.hasClass(this.markerClassName)) {
         return;
      }
      var nodeName = target.nodeName.toLowerCase();
      if (nodeName == 'input') {
      target.disabled = false;
         $target.siblings('button.' + this._triggerClass).
         each(function() { this.disabled = false; }).end().
            siblings('img.' + this._triggerClass).
            css({opacity: '1.0', cursor: ''});
      }
      else if (nodeName == 'div' || nodeName == 'span') {
         $target.children('.' + this._disableClass).remove();
      }
      this._disabledInputs = $.map(this._disabledInputs,
         function(value) { return (value == target ? null : value); }); // delete entry
   },

   /* Disable the date picker to a jQuery selection.
      @param  target    element - the target input field or division or span */
   _disableDatepicker: function(target) {
      var $target = $(target);
      if (!$target.hasClass(this.markerClassName)) {
         return;
      }
      var nodeName = target.nodeName.toLowerCase();
      if (nodeName == 'input') {
      target.disabled = true;
         $target.siblings('button.' + this._triggerClass).
         each(function() { this.disabled = true; }).end().
            siblings('img.' + this._triggerClass).
            css({opacity: '0.5', cursor: 'default'});
      }
      else if (nodeName == 'div' || nodeName == 'span') {
         var inline = $target.children('.' + this._inlineClass);
         var offset = inline.offset();
         var relOffset = {left: 0, top: 0};
         inline.parents().each(function() {
            if ($(this).css('position') == 'relative') {
               relOffset = $(this).offset();
               return false;
            }
         });
         $target.prepend('<div class="' + this._disableClass + '" style="' +
            ($.browser.msie ? 'background-color: transparent; ' : '') +
            'width: ' + inline.width() + 'px; height: ' + inline.height() +
            'px; left: ' + (offset.left - relOffset.left) +
            'px; top: ' + (offset.top - relOffset.top) + 'px;"></div>');
      }
      this._disabledInputs = $.map(this._disabledInputs,
         function(value) { return (value == target ? null : value); }); // delete entry
      this._disabledInputs[this._disabledInputs.length] = target;
   },

   /* Is the first field in a jQuery collection disabled as a datepicker?
      @param  target    element - the target input field or division or span
      @return boolean - true if disabled, false if enabled */
   _isDisabledDatepicker: function(target) {
      if (!target)
         return false;
      for (var i = 0; i < this._disabledInputs.length; i++) {
         if (this._disabledInputs[i] == target)
            return true;
      }
      return false;
   },

   /* Retrieve the instance data for the target control.
      @param  target  element - the target input field or division or span
      @return  object - the associated instance data
      @throws  error if a jQuery problem getting data */
   _getInst: function(target) {
      try {
         return $.data(target, PROP_NAME);
      }
      catch (err) {
         throw 'Missing instance data for this datepicker';
      }
   },

   /* Update the settings for a date picker attached to an input field or division.
      @param  target  element - the target input field or division or span
      @param  name    object - the new settings to update or
                      string - the name of the setting to change or
      @param  value   any - the new value for the setting (omit if above is an object) */
   _optionDatepicker: function(target, name, value) {
      var settings = name || {};
      if (typeof name == 'string') {
         settings = {};
         settings[name] = value;
      }
      var inst = this._getInst(target);
      if (inst) {
         if (this._curInst == inst) {
            this._hideDatepicker(null);
         }
         extendRemove(inst.settings, settings);
         var date = new Date();
         extendRemove(inst, {rangeStart: null, // start of range
            endDay: null, endMonth: null, endYear: null, // end of range
            selectedDay: date.getDate(), selectedMonth: date.getMonth(),
            selectedYear: date.getFullYear(), // starting point
            currentDay: date.getDate(), currentMonth: date.getMonth(),
            currentYear: date.getFullYear(), // current selection
            drawMonth: date.getMonth(), drawYear: date.getFullYear()}); // month being drawn
         this._updateDatepicker(inst);
      }
   },

   // change method deprecated
   _changeDatepicker: function(target, name, value) {
      this._optionDatepicker(target, name, value);
   },

   /* Redraw the date picker attached to an input field or division.
      @param  target  element - the target input field or division or span */
   _refreshDatepicker: function(target) {
      var inst = this._getInst(target);
      if (inst) {
         this._updateDatepicker(inst);
      }
   },

   /* Set the dates for a jQuery selection.
      @param  target   element - the target input field or division or span
      @param  date     Date - the new date
      @param  endDate  Date - the new end date for a range (optional) */
   _setDateDatepicker: function(target, date, endDate) {
      var inst = this._getInst(target);
      if (inst) {
         this._setDate(inst, date, endDate);
         this._updateDatepicker(inst);
         this._updateAlternate(inst);
      }
   },

   /* Get the date(s) for the first entry in a jQuery selection.
      @param  target  element - the target input field or division or span
      @return Date - the current date or
              Date[2] - the current dates for a range */
   _getDateDatepicker: function(target) {
      var inst = this._getInst(target);
      if (inst && !inst.inline)
         this._setDateFromField(inst);
      return (inst ? this._getDate(inst) : null);
   },

   /* Handle keystrokes. */
   _doKeyDown: function(event) {
      var inst = $.datepicker._getInst(event.target);
      var handled = true;
      inst._keyEvent = true;
      if ($.datepicker._datepickerShowing)
         switch (event.keyCode) {
            case 9:  $.datepicker._hideDatepicker(null, '');
                  break; // hide on tab out
            case 13: var sel = $('td.' + $.datepicker._dayOverClass +
                     ', td.' + $.datepicker._currentClass, inst.dpDiv);
                  if (sel[0])
                     $.datepicker._selectDay(event.target, inst.selectedMonth, inst.selectedYear, sel[0]);
                  else
                     $.datepicker._hideDatepicker(null, $.datepicker._get(inst, 'duration'));
                  return false; // don't submit the form
                  break; // select the value on enter
            case 27: $.datepicker._hideDatepicker(null, $.datepicker._get(inst, 'duration'));
                  break; // hide on escape
            case 33: $.datepicker._adjustDate(event.target, (event.ctrlKey ?
                     -$.datepicker._get(inst, 'stepBigMonths') :
                     -$.datepicker._get(inst, 'stepMonths')), 'M');
                  break; // previous month/year on page up/+ ctrl
            case 34: $.datepicker._adjustDate(event.target, (event.ctrlKey ?
                     +$.datepicker._get(inst, 'stepBigMonths') :
                     +$.datepicker._get(inst, 'stepMonths')), 'M');
                  break; // next month/year on page down/+ ctrl
            case 35: if (event.ctrlKey || event.metaKey) $.datepicker._clearDate(event.target);
                  handled = event.ctrlKey || event.metaKey;
                  break; // clear on ctrl or command +end
            case 36: if (event.ctrlKey || event.metaKey) $.datepicker._gotoToday(event.target);
                  handled = event.ctrlKey || event.metaKey;
                  break; // current on ctrl or command +home
            case 37: if (event.ctrlKey || event.metaKey) $.datepicker._adjustDate(event.target, -1, 'D');
                  handled = event.ctrlKey || event.metaKey;
                  // -1 day on ctrl or command +left
                  if (event.originalEvent.altKey) $.datepicker._adjustDate(event.target, (event.ctrlKey ?
                           -$.datepicker._get(inst, 'stepBigMonths') :
                           -$.datepicker._get(inst, 'stepMonths')), 'M');
                  // next month/year on alt +left on Mac
                  break;
            case 38: if (event.ctrlKey || event.metaKey) $.datepicker._adjustDate(event.target, -7, 'D');
                  handled = event.ctrlKey || event.metaKey;
                  break; // -1 week on ctrl or command +up
            case 39: if (event.ctrlKey || event.metaKey) $.datepicker._adjustDate(event.target, +1, 'D');
                  handled = event.ctrlKey || event.metaKey;
                  // +1 day on ctrl or command +right
                  if (event.originalEvent.altKey) $.datepicker._adjustDate(event.target, (event.ctrlKey ?
                           +$.datepicker._get(inst, 'stepBigMonths') :
                           +$.datepicker._get(inst, 'stepMonths')), 'M');
                  // next month/year on alt +right
                  break;
            case 40: if (event.ctrlKey || event.metaKey) $.datepicker._adjustDate(event.target, +7, 'D');
                  handled = event.ctrlKey || event.metaKey;
                  break; // +1 week on ctrl or command +down
            default: handled = false;
         }
      else if (event.keyCode == 36 && event.ctrlKey) // display the date picker on ctrl+home
         $.datepicker._showDatepicker(this);
      else {
         handled = false;
      }
      if (handled) {
         event.preventDefault();
         event.stopPropagation();
      }
   },

   /* Filter entered characters - based on date format. */
   _doKeyPress: function(event) {
      var inst = $.datepicker._getInst(event.target);
      if ($.datepicker._get(inst, 'constrainInput')) {
         var chars = $.datepicker._possibleChars($.datepicker._get(inst, 'dateFormat'));
         var chr = String.fromCharCode(event.charCode == undefined ? event.keyCode : event.charCode);
         return event.ctrlKey || (chr < ' ' || !chars || chars.indexOf(chr) > -1);
      }
   },

   /* Pop-up the date picker for a given input field.
      @param  input  element - the input field attached to the date picker or
                     event - if triggered by focus */
   _showDatepicker: function(input) {
      input = input.target || input;
      if (input.nodeName.toLowerCase() != 'input') // find from button/image trigger
         input = $('input', input.parentNode)[0];
      if ($.datepicker._isDisabledDatepicker(input) || $.datepicker._lastInput == input) // already here
         return;
      var inst = $.datepicker._getInst(input);
      var beforeShow = $.datepicker._get(inst, 'beforeShow');
      extendRemove(inst.settings, (beforeShow ? beforeShow.apply(input, [input, inst]) : {}));
      $.datepicker._hideDatepicker(null, '');
      $.datepicker._lastInput = input;
      $.datepicker._setDateFromField(inst);
      if ($.datepicker._inDialog) // hide cursor
         input.value = '';
      if (!$.datepicker._pos) { // position below input
         $.datepicker._pos = $.datepicker._findPos(input);
         $.datepicker._pos[1] += input.offsetHeight; // add the height
      }
      var isFixed = false;
      $(input).parents().each(function() {
         isFixed |= $(this).css('position') == 'fixed';
         return !isFixed;
      });
      if (isFixed && $.browser.opera) { // correction for Opera when fixed and scrolled
         $.datepicker._pos[0] -= document.documentElement.scrollLeft;
         $.datepicker._pos[1] -= document.documentElement.scrollTop;
      }
      var offset = {left: $.datepicker._pos[0], top: $.datepicker._pos[1]};
      $.datepicker._pos = null;
      inst.rangeStart = null;
      // determine sizing offscreen
      inst.dpDiv.css({position: 'absolute', display: 'block', top: '-1000px'});
      $.datepicker._updateDatepicker(inst);
      // fix width for dynamic number of date pickers
      inst.dpDiv.width($.datepicker._getNumberOfMonths(inst)[1] *
         $('.ui-datepicker', inst.dpDiv[0])[0].offsetWidth);
      // and adjust position before showing
      offset = $.datepicker._checkOffset(inst, offset, isFixed);
      inst.dpDiv.css({position: ($.datepicker._inDialog && $.blockUI ?
         'static' : (isFixed ? 'fixed' : 'absolute')), display: 'none',
         left: offset.left + 'px', top: offset.top + 'px'});
      if (!inst.inline) {
         var showAnim = $.datepicker._get(inst, 'showAnim') || 'show';
         var duration = $.datepicker._get(inst, 'duration');
         var postProcess = function() {
            $.datepicker._datepickerShowing = true;
            if ($.browser.msie && parseInt($.browser.version,10) < 7) // fix IE < 7 select problems
               $('iframe.ui-datepicker-cover').css({width: inst.dpDiv.width() + 4,
                  height: inst.dpDiv.height() + 4});
         };
         if ($.effects && $.effects[showAnim])
            inst.dpDiv.show(showAnim, $.datepicker._get(inst, 'showOptions'), duration, postProcess);
         else
            inst.dpDiv[showAnim](duration, postProcess);
         if (duration == '')
            postProcess();
         if (inst.input[0].type != 'hidden')
            inst.input[0].focus();
         $.datepicker._curInst = inst;
      }
   },

   /* Generate the date picker content. */
   _updateDatepicker: function(inst) {
      var dims = {width: inst.dpDiv.width() + 4,
         height: inst.dpDiv.height() + 4};
      inst.dpDiv.empty().append(this._generateHTML(inst)).
         find('iframe.ui-datepicker-cover').
         css({width: dims.width, height: dims.height});
      var numMonths = this._getNumberOfMonths(inst);
      inst.dpDiv[(numMonths[0] != 1 || numMonths[1] != 1 ? 'add' : 'remove') +
         'Class']('ui-datepicker-multi');
      inst.dpDiv[(this._get(inst, 'isRTL') ? 'add' : 'remove') +
         'Class']('ui-datepicker-rtl');
      if (inst.input && inst.input[0].type != 'hidden' && inst == $.datepicker._curInst)
         $(inst.input[0]).focus();
   },

   /* Check positioning to remain on screen. */
   _checkOffset: function(inst, offset, isFixed) {
      var pos = inst.input ? this._findPos(inst.input[0]) : null;
      var browserWidth = window.innerWidth || (document.documentElement ?
         document.documentElement.clientWidth : document.body.clientWidth);
      var browserHeight = window.innerHeight || (document.documentElement ?
         document.documentElement.clientHeight : document.body.clientHeight);
      var scrollX = document.documentElement.scrollLeft || document.body.scrollLeft;
      var scrollY = document.documentElement.scrollTop || document.body.scrollTop;
      // reposition date picker horizontally if outside the browser window
      if (this._get(inst, 'isRTL') || (offset.left + inst.dpDiv.width() - scrollX) > browserWidth)
         offset.left = Math.max((isFixed ? 0 : scrollX),
            pos[0] + (inst.input ? inst.input.width() : 0) - (isFixed ? scrollX : 0) - inst.dpDiv.width() -
            (isFixed && $.browser.opera ? document.documentElement.scrollLeft : 0));
      else
         offset.left -= (isFixed ? scrollX : 0);
      // reposition date picker vertically if outside the browser window
      if ((offset.top + inst.dpDiv.height() - scrollY) > browserHeight)
         offset.top = Math.max((isFixed ? 0 : scrollY),
            pos[1] - (isFixed ? scrollY : 0) - (this._inDialog ? 0 : inst.dpDiv.height()) -
            (isFixed && $.browser.opera ? document.documentElement.scrollTop : 0));
      else
         offset.top -= (isFixed ? scrollY : 0);
      return offset;
   },

   /* Find an object's position on the screen. */
   _findPos: function(obj) {
        while (obj && (obj.type == 'hidden' || obj.nodeType != 1)) {
            obj = obj.nextSibling;
        }
        var position = $(obj).offset();
       return [position.left, position.top];
   },

   /* Hide the date picker from view.
      @param  input  element - the input field attached to the date picker
      @param  duration  string - the duration over which to close the date picker */
   _hideDatepicker: function(input, duration) {
      var inst = this._curInst;
      if (!inst || (input && inst != $.data(input, PROP_NAME)))
         return;
      var rangeSelect = this._get(inst, 'rangeSelect');
      if (rangeSelect && inst.stayOpen)
         this._selectDate('#' + inst.id, this._formatDate(inst,
            inst.currentDay, inst.currentMonth, inst.currentYear));
      inst.stayOpen = false;
      if (this._datepickerShowing) {
         duration = (duration != null ? duration : this._get(inst, 'duration'));
         var showAnim = this._get(inst, 'showAnim');
         var postProcess = function() {
            $.datepicker._tidyDialog(inst);
         };
         if (duration != '' && $.effects && $.effects[showAnim])
            inst.dpDiv.hide(showAnim, $.datepicker._get(inst, 'showOptions'),
               duration, postProcess);
         else
            inst.dpDiv[(duration == '' ? 'hide' : (showAnim == 'slideDown' ? 'slideUp' :
               (showAnim == 'fadeIn' ? 'fadeOut' : 'hide')))](duration, postProcess);
         if (duration == '')
            this._tidyDialog(inst);
         var onClose = this._get(inst, 'onClose');
         if (onClose)
            onClose.apply((inst.input ? inst.input[0] : null),
               [(inst.input ? inst.input.val() : ''), inst]);  // trigger custom callback
         this._datepickerShowing = false;
         this._lastInput = null;
         inst.settings.prompt = null;
         if (this._inDialog) {
            this._dialogInput.css({ position: 'absolute', left: '0', top: '-100px' });
            if ($.blockUI) {
               $.unblockUI();
               $('body').append(this.dpDiv);
            }
         }
         this._inDialog = false;
      }
      this._curInst = null;
   },

   /* Tidy up after a dialog display. */
   _tidyDialog: function(inst) {
      inst.dpDiv.removeClass(this._dialogClass).unbind('.ui-datepicker');
      $('.' + this._promptClass, inst.dpDiv).remove();
   },

   /* Close date picker if clicked elsewhere. */
   _checkExternalClick: function(event) {
      if (!$.datepicker._curInst)
         return;
      var $target = $(event.target);
      if (($target.parents('#' + $.datepicker._mainDivId).length == 0) &&
            !$target.hasClass($.datepicker.markerClassName) &&
            !$target.hasClass($.datepicker._triggerClass) &&
            $.datepicker._datepickerShowing && !($.datepicker._inDialog && $.blockUI))
         $.datepicker._hideDatepicker(null, '');
   },

   /* Adjust one of the date sub-fields. */
   _adjustDate: function(id, offset, period) {
      var target = $(id);
      var inst = this._getInst(target[0]);
      this._adjustInstDate(inst, offset, period);
      this._updateDatepicker(inst);
   },

   /* Action for current link. */
   _gotoToday: function(id) {
      var target = $(id);
      var inst = this._getInst(target[0]);
      if (this._get(inst, 'gotoCurrent') && inst.currentDay) {
         inst.selectedDay = inst.currentDay;
         inst.drawMonth = inst.selectedMonth = inst.currentMonth;
         inst.drawYear = inst.selectedYear = inst.currentYear;
      }
      else {
      var date = new Date();
      inst.selectedDay = date.getDate();
      inst.drawMonth = inst.selectedMonth = date.getMonth();
      inst.drawYear = inst.selectedYear = date.getFullYear();
      }
      this._notifyChange(inst);
      this._adjustDate(target);
   },

   /* Action for selecting a new month/year. */
   _selectMonthYear: function(id, select, period) {
      var target = $(id);
      var inst = this._getInst(target[0]);
      inst._selectingMonthYear = false;
      inst['selected' + (period == 'M' ? 'Month' : 'Year')] =
      inst['draw' + (period == 'M' ? 'Month' : 'Year')] =
         parseInt(select.options[select.selectedIndex].value,10);
      this._notifyChange(inst);
      this._adjustDate(target);
   },

   /* Restore input focus after not changing month/year. */
   _clickMonthYear: function(id) {
      var target = $(id);
      var inst = this._getInst(target[0]);
      if (inst.input && inst._selectingMonthYear && !$.browser.msie)
         inst.input[0].focus();
      inst._selectingMonthYear = !inst._selectingMonthYear;
   },

   /* Action for changing the first week day. */
   _changeFirstDay: function(id, day) {
      var target = $(id);
      var inst = this._getInst(target[0]);
      inst.settings.firstDay = day;
      this._updateDatepicker(inst);
   },

   /* Action for selecting a day. */
   _selectDay: function(id, month, year, td) {
      if ($(td).hasClass(this._unselectableClass))
         return;
      var target = $(id);
      var inst = this._getInst(target[0]);
      var rangeSelect = this._get(inst, 'rangeSelect');
      if (rangeSelect) {
         inst.stayOpen = !inst.stayOpen;
         if (inst.stayOpen) {
            $('.ui-datepicker td', inst.dpDiv).removeClass(this._currentClass);
            $(td).addClass(this._currentClass);
         }
      }
      inst.selectedDay = inst.currentDay = $('a', td).html();
      inst.selectedMonth = inst.currentMonth = month;
      inst.selectedYear = inst.currentYear = year;
      if (inst.stayOpen) {
         inst.endDay = inst.endMonth = inst.endYear = null;
      }
      else if (rangeSelect) {
         inst.endDay = inst.currentDay;
         inst.endMonth = inst.currentMonth;
         inst.endYear = inst.currentYear;
      }
      this._selectDate(id, this._formatDate(inst,
         inst.currentDay, inst.currentMonth, inst.currentYear));
      if (inst.stayOpen) {
         inst.rangeStart = this._daylightSavingAdjust(
            new Date(inst.currentYear, inst.currentMonth, inst.currentDay));
         this._updateDatepicker(inst);
      }
      else if (rangeSelect) {
         inst.selectedDay = inst.currentDay = inst.rangeStart.getDate();
         inst.selectedMonth = inst.currentMonth = inst.rangeStart.getMonth();
         inst.selectedYear = inst.currentYear = inst.rangeStart.getFullYear();
         inst.rangeStart = null;
         if (inst.inline)
            this._updateDatepicker(inst);
      }
   },

   /* Erase the input field and hide the date picker. */
   _clearDate: function(id) {
      var target = $(id);
      var inst = this._getInst(target[0]);
      if (this._get(inst, 'mandatory'))
         return;
      inst.stayOpen = false;
      inst.endDay = inst.endMonth = inst.endYear = inst.rangeStart = null;
      this._selectDate(target, '');
   },

   /* Update the input field with the selected date. */
   _selectDate: function(id, dateStr) {
      var target = $(id);
      var inst = this._getInst(target[0]);
      dateStr = (dateStr != null ? dateStr : this._formatDate(inst));
      if (this._get(inst, 'rangeSelect') && dateStr)
         dateStr = (inst.rangeStart ? this._formatDate(inst, inst.rangeStart) :
            dateStr) + this._get(inst, 'rangeSeparator') + dateStr;
      if (inst.input)
         inst.input.val(dateStr);
      this._updateAlternate(inst);
      var onSelect = this._get(inst, 'onSelect');
      if (onSelect)
         onSelect.apply((inst.input ? inst.input[0] : null), [dateStr, inst]);  // trigger custom callback
      else if (inst.input)
         inst.input.trigger('change'); // fire the change event
      if (inst.inline)
         this._updateDatepicker(inst);
      else if (!inst.stayOpen) {
         this._hideDatepicker(null, this._get(inst, 'duration'));
         this._lastInput = inst.input[0];
         if (typeof(inst.input[0]) != 'object')
            inst.input[0].focus(); // restore focus
         this._lastInput = null;
      }
   },

   /* Update any alternate field to synchronise with the main field. */
   _updateAlternate: function(inst) {
      var altField = this._get(inst, 'altField');
      if (altField) { // update alternate field too
         var altFormat = this._get(inst, 'altFormat') || this._get(inst, 'dateFormat');
         var date = this._getDate(inst);
         dateStr = (isArray(date) ? (!date[0] && !date[1] ? '' :
            this.formatDate(altFormat, date[0], this._getFormatConfig(inst)) +
            this._get(inst, 'rangeSeparator') + this.formatDate(
            altFormat, date[1] || date[0], this._getFormatConfig(inst))) :
            this.formatDate(altFormat, date, this._getFormatConfig(inst)));
         $(altField).each(function() { $(this).val(dateStr); });
      }
   },

   /* Set as beforeShowDay function to prevent selection of weekends.
      @param  date  Date - the date to customise
      @return [boolean, string] - is this date selectable?, what is its CSS class? */
   noWeekends: function(date) {
      var day = date.getDay();
      return [(day > 0 && day < 6), ''];
   },

   /* Set as calculateWeek to determine the week of the year based on the ISO 8601 definition.
      @param  date  Date - the date to get the week for
      @return  number - the number of the week within the year that contains this date */
   iso8601Week: function(date) {
      var checkDate = new Date(date.getFullYear(), date.getMonth(), date.getDate());
      var firstMon = new Date(checkDate.getFullYear(), 1 - 1, 4); // First week always contains 4 Jan
      var firstDay = firstMon.getDay() || 7; // Day of week: Mon = 1, ..., Sun = 7
      firstMon.setDate(firstMon.getDate() + 1 - firstDay); // Preceding Monday
      if (firstDay < 4 && checkDate < firstMon) { // Adjust first three days in year if necessary
         checkDate.setDate(checkDate.getDate() - 3); // Generate for previous year
         return $.datepicker.iso8601Week(checkDate);
      } else if (checkDate > new Date(checkDate.getFullYear(), 12 - 1, 28)) { // Check last three days in year
         firstDay = new Date(checkDate.getFullYear() + 1, 1 - 1, 4).getDay() || 7;
         if (firstDay > 4 && (checkDate.getDay() || 7) < firstDay - 3) { // Adjust if necessary
            return 1;
         }
      }
      return Math.floor(((checkDate - firstMon) / 86400000) / 7) + 1; // Weeks to given date
   },

   /* Provide status text for a particular date.
      @param  date  the date to get the status for
      @param  inst  the current datepicker instance
      @return  the status display text for this date */
   dateStatus: function(date, inst) {
      return $.datepicker.formatDate($.datepicker._get(inst, 'dateStatus'),
         date, $.datepicker._getFormatConfig(inst));
   },

   /* Parse a string value into a date object.
      See formatDate below for the possible formats.

      @param  format    string - the expected format of the date
      @param  value     string - the date in the above format
      @param  settings  Object - attributes include:
                        shortYearCutoff  number - the cutoff year for determining the century (optional)
                        dayNamesShort    string[7] - abbreviated names of the days from Sunday (optional)
                        dayNames         string[7] - names of the days from Sunday (optional)
                        monthNamesShort  string[12] - abbreviated names of the months (optional)
                        monthNames       string[12] - names of the months (optional)
      @return  Date - the extracted date value or null if value is blank */
   parseDate: function (format, value, settings) {
      if (format == null || value == null)
         throw 'Invalid arguments';
      value = (typeof value == 'object' ? value.toString() : value + '');
      if (value == '')
         return null;
      var shortYearCutoff = (settings ? settings.shortYearCutoff : null) || this._defaults.shortYearCutoff;
      var dayNamesShort = (settings ? settings.dayNamesShort : null) || this._defaults.dayNamesShort;
      var dayNames = (settings ? settings.dayNames : null) || this._defaults.dayNames;
      var monthNamesShort = (settings ? settings.monthNamesShort : null) || this._defaults.monthNamesShort;
      var monthNames = (settings ? settings.monthNames : null) || this._defaults.monthNames;
      var year = -1;
      var month = -1;
      var day = -1;
      var doy = -1;
      var literal = false;
      // Check whether a format character is doubled
      var lookAhead = function(match) {
         var matches = (iFormat + 1 < format.length && format.charAt(iFormat + 1) == match);
         if (matches)
            iFormat++;
         return matches;
      };
      // Extract a number from the string value
      var getNumber = function(match) {
         lookAhead(match);
         var origSize = (match == '@' ? 14 : (match == 'y' ? 4 : (match == 'o' ? 3 : 2)));
         var size = origSize;
         var num = 0;
         while (size > 0 && iValue < value.length &&
               value.charAt(iValue) >= '0' && value.charAt(iValue) <= '9') {
            num = num * 10 + parseInt(value.charAt(iValue++),10);
            size--;
         }
         if (size == origSize)
            throw 'Missing number at position ' + iValue;
         return num;
      };
      // Extract a name from the string value and convert to an index
      var getName = function(match, shortNames, longNames) {
         var names = (lookAhead(match) ? longNames : shortNames);
         var size = 0;
         for (var j = 0; j < names.length; j++)
            size = Math.max(size, names[j].length);
         var name = '';
         var iInit = iValue;
         while (size > 0 && iValue < value.length) {
            name += value.charAt(iValue++);
            for (var i = 0; i < names.length; i++)
               if (name == names[i])
                  return i + 1;
            size--;
         }
         throw 'Unknown name at position ' + iInit;
      };
      // Confirm that a literal character matches the string value
      var checkLiteral = function() {
         if (value.charAt(iValue) != format.charAt(iFormat))
            throw 'Unexpected literal at position ' + iValue;
         iValue++;
      };
      var iValue = 0;
      for (var iFormat = 0; iFormat < format.length; iFormat++) {
         if (literal)
            if (format.charAt(iFormat) == "'" && !lookAhead("'"))
               literal = false;
            else
               checkLiteral();
         else
            switch (format.charAt(iFormat)) {
               case 'd':
                  day = getNumber('d');
                  break;
               case 'D':
                  getName('D', dayNamesShort, dayNames);
                  break;
               case 'o':
                  doy = getNumber('o');
                  break;
               case 'm':
                  month = getNumber('m');
                  break;
               case 'M':
                  month = getName('M', monthNamesShort, monthNames);
                  break;
               case 'y':
                  year = getNumber('y');
                  break;
               case '@':
                  var date = new Date(getNumber('@'));
                  year = date.getFullYear();
                  month = date.getMonth() + 1;
                  day = date.getDate();
                  break;
               case "'":
                  if (lookAhead("'"))
                     checkLiteral();
                  else
                     literal = true;
                  break;
               default:
                  checkLiteral();
            }
      }
      if (year == -1)
         year = new Date().getFullYear();
      else if (year < 100)
         year += new Date().getFullYear() - new Date().getFullYear() % 100 +
            (year <= shortYearCutoff ? 0 : -100);
      if (doy > -1) {
         month = 1;
         day = doy;
         do {
            var dim = this._getDaysInMonth(year, month - 1);
            if (day <= dim)
               break;
            month++;
            day -= dim;
         } while (true);
      }
      var date = this._daylightSavingAdjust(new Date(year, month - 1, day));
      if (date.getFullYear() != year || date.getMonth() + 1 != month || date.getDate() != day)
         throw 'Invalid date'; // E.g. 31/02/*
      return date;
   },

   /* Standard date formats. */
   ATOM: 'yy-mm-dd', // RFC 3339 (ISO 8601)
   COOKIE: 'D, dd M yy',
   ISO_8601: 'yy-mm-dd',
   RFC_822: 'D, d M y',
   RFC_850: 'DD, dd-M-y',
   RFC_1036: 'D, d M y',
   RFC_1123: 'D, d M yy',
   RFC_2822: 'D, d M yy',
   RSS: 'D, d M y', // RFC 822
   TIMESTAMP: '@',
   W3C: 'yy-mm-dd', // ISO 8601

   /* Format a date object into a string value.
      The format can be combinations of the following:
      d  - day of month (no leading zero)
      dd - day of month (two digit)
      o  - day of year (no leading zeros)
      oo - day of year (three digit)
      D  - day name short
      DD - day name long
      m  - month of year (no leading zero)
      mm - month of year (two digit)
      M  - month name short
      MM - month name long
      y  - year (two digit)
      yy - year (four digit)
      @ - Unix timestamp (ms since 01/01/1970)
      '...' - literal text
      '' - single quote

      @param  format    string - the desired format of the date
      @param  date      Date - the date value to format
      @param  settings  Object - attributes include:
                        dayNamesShort    string[7] - abbreviated names of the days from Sunday (optional)
                        dayNames         string[7] - names of the days from Sunday (optional)
                        monthNamesShort  string[12] - abbreviated names of the months (optional)
                        monthNames       string[12] - names of the months (optional)
      @return  string - the date in the above format */
   formatDate: function (format, date, settings) {
      if (!date)
         return '';
      var dayNamesShort = (settings ? settings.dayNamesShort : null) || this._defaults.dayNamesShort;
      var dayNames = (settings ? settings.dayNames : null) || this._defaults.dayNames;
      var monthNamesShort = (settings ? settings.monthNamesShort : null) || this._defaults.monthNamesShort;
      var monthNames = (settings ? settings.monthNames : null) || this._defaults.monthNames;
      // Check whether a format character is doubled
      var lookAhead = function(match) {
         var matches = (iFormat + 1 < format.length && format.charAt(iFormat + 1) == match);
         if (matches)
            iFormat++;
         return matches;
      };
      // Format a number, with leading zero if necessary
      var formatNumber = function(match, value, len) {
         var num = '' + value;
         if (lookAhead(match))
            while (num.length < len)
               num = '0' + num;
         return num;
      };
      // Format a name, short or long as requested
      var formatName = function(match, value, shortNames, longNames) {
         return (lookAhead(match) ? longNames[value] : shortNames[value]);
      };
      var output = '';
      var literal = false;
      if (date)
         for (var iFormat = 0; iFormat < format.length; iFormat++) {
            if (literal)
               if (format.charAt(iFormat) == "'" && !lookAhead("'"))
                  literal = false;
               else
                  output += format.charAt(iFormat);
            else
               switch (format.charAt(iFormat)) {
                  case 'd':
                     output += formatNumber('d', date.getDate(), 2);
                     break;
                  case 'D':
                     output += formatName('D', date.getDay(), dayNamesShort, dayNames);
                     break;
                  case 'o':
                     var doy = date.getDate();
                     for (var m = date.getMonth() - 1; m >= 0; m--)
                        doy += this._getDaysInMonth(date.getFullYear(), m);
                     output += formatNumber('o', doy, 3);
                     break;
                  case 'm':
                     output += formatNumber('m', date.getMonth() + 1, 2);
                     break;
                  case 'M':
                     output += formatName('M', date.getMonth(), monthNamesShort, monthNames);
                     break;
                  case 'y':
                     output += (lookAhead('y') ? date.getFullYear() :
                        (date.getYear() % 100 < 10 ? '0' : '') + date.getYear() % 100);
                     break;
                  case '@':
                     output += date.getTime();
                     break;
                  case "'":
                     if (lookAhead("'"))
                        output += "'";
                     else
                        literal = true;
                     break;
                  default:
                     output += format.charAt(iFormat);
               }
         }
      return output;
   },

   /* Extract all possible characters from the date format. */
   _possibleChars: function (format) {
      var chars = '';
      var literal = false;
      for (var iFormat = 0; iFormat < format.length; iFormat++)
         if (literal)
            if (format.charAt(iFormat) == "'" && !lookAhead("'"))
               literal = false;
            else
               chars += format.charAt(iFormat);
         else
            switch (format.charAt(iFormat)) {
               case 'd': case 'm': case 'y': case '@':
                  chars += '0123456789';
                  break;
               case 'D': case 'M':
                  return null; // Accept anything
               case "'":
                  if (lookAhead("'"))
                     chars += "'";
                  else
                     literal = true;
                  break;
               default:
                  chars += format.charAt(iFormat);
            }
      return chars;
   },

   /* Get a setting value, defaulting if necessary. */
   _get: function(inst, name) {
      return inst.settings[name] !== undefined ?
         inst.settings[name] : this._defaults[name];
   },

   /* Parse existing date and initialise date picker. */
   _setDateFromField: function(inst) {
      var dateFormat = this._get(inst, 'dateFormat');
      var dates = inst.input ? inst.input.val().split(this._get(inst, 'rangeSeparator')) : null;
      inst.endDay = inst.endMonth = inst.endYear = null;
      var date = defaultDate = this._getDefaultDate(inst);
      if (dates.length > 0) {
         var settings = this._getFormatConfig(inst);
         if (dates.length > 1) {
            date = this.parseDate(dateFormat, dates[1], settings) || defaultDate;
            inst.endDay = date.getDate();
            inst.endMonth = date.getMonth();
            inst.endYear = date.getFullYear();
         }
         try {
            date = this.parseDate(dateFormat, dates[0], settings) || defaultDate;
         } catch (event) {
            this.log(event);
            date = defaultDate;
         }
      }
      inst.selectedDay = date.getDate();
      inst.drawMonth = inst.selectedMonth = date.getMonth();
      inst.drawYear = inst.selectedYear = date.getFullYear();
      inst.currentDay = (dates[0] ? date.getDate() : 0);
      inst.currentMonth = (dates[0] ? date.getMonth() : 0);
      inst.currentYear = (dates[0] ? date.getFullYear() : 0);
      this._adjustInstDate(inst);
   },

   /* Retrieve the default date shown on opening. */
   _getDefaultDate: function(inst) {
      var date = this._determineDate(this._get(inst, 'defaultDate'), new Date());
      var minDate = this._getMinMaxDate(inst, 'min', true);
      var maxDate = this._getMinMaxDate(inst, 'max');
      date = (minDate && date < minDate ? minDate : date);
      date = (maxDate && date > maxDate ? maxDate : date);
      return date;
   },

   /* A date may be specified as an exact value or a relative one. */
   _determineDate: function(date, defaultDate) {
      var offsetNumeric = function(offset) {
         var date = new Date();
         date.setDate(date.getDate() + offset);
         return date;
      };
      var offsetString = function(offset, getDaysInMonth) {
         var date = new Date();
         var year = date.getFullYear();
         var month = date.getMonth();
         var day = date.getDate();
         var pattern = /([+-]?[0-9]+)\s*(d|D|w|W|m|M|y|Y)?/g;
         var matches = pattern.exec(offset);
         while (matches) {
            switch (matches[2] || 'd') {
               case 'd' : case 'D' :
                  day += parseInt(matches[1],10); break;
               case 'w' : case 'W' :
                  day += parseInt(matches[1],10) * 7; break;
               case 'm' : case 'M' :
                  month += parseInt(matches[1],10);
                  day = Math.min(day, getDaysInMonth(year, month));
                  break;
               case 'y': case 'Y' :
                  year += parseInt(matches[1],10);
                  day = Math.min(day, getDaysInMonth(year, month));
                  break;
            }
            matches = pattern.exec(offset);
         }
         return new Date(year, month, day);
      };
      date = (date == null ? defaultDate :
         (typeof date == 'string' ? offsetString(date, this._getDaysInMonth) :
         (typeof date == 'number' ? (isNaN(date) ? defaultDate : offsetNumeric(date)) : date)));
      date = (date && date.toString() == 'Invalid Date' ? defaultDate : date);
      if (date) {
         date.setHours(0);
         date.setMinutes(0);
         date.setSeconds(0);
         date.setMilliseconds(0);
      }
      return this._daylightSavingAdjust(date);
   },

   /* Handle switch to/from daylight saving.
      Hours may be non-zero on daylight saving cut-over:
      > 12 when midnight changeover, but then cannot generate
      midnight datetime, so jump to 1AM, otherwise reset.
      @param  date  (Date) the date to check
      @return  (Date) the corrected date */
   _daylightSavingAdjust: function(date) {
      if (!date) return null;
      date.setHours(date.getHours() > 12 ? date.getHours() + 2 : 0);
      return date;
   },

   /* Set the date(s) directly. */
   _setDate: function(inst, date, endDate) {
      var clear = !(date);
      var origMonth = inst.selectedMonth;
      var origYear = inst.selectedYear;
      date = this._determineDate(date, new Date());
      inst.selectedDay = inst.currentDay = date.getDate();
      inst.drawMonth = inst.selectedMonth = inst.currentMonth = date.getMonth();
      inst.drawYear = inst.selectedYear = inst.currentYear = date.getFullYear();
      if (this._get(inst, 'rangeSelect')) {
         if (endDate) {
            endDate = this._determineDate(endDate, null);
            inst.endDay = endDate.getDate();
            inst.endMonth = endDate.getMonth();
            inst.endYear = endDate.getFullYear();
         } else {
            inst.endDay = inst.currentDay;
            inst.endMonth = inst.currentMonth;
            inst.endYear = inst.currentYear;
         }
      }
      if (origMonth != inst.selectedMonth || origYear != inst.selectedYear)
         this._notifyChange(inst);
      this._adjustInstDate(inst);
      if (inst.input)
         inst.input.val(clear ? '' : this._formatDate(inst) +
            (!this._get(inst, 'rangeSelect') ? '' : this._get(inst, 'rangeSeparator') +
            this._formatDate(inst, inst.endDay, inst.endMonth, inst.endYear)));
   },

   /* Retrieve the date(s) directly. */
   _getDate: function(inst) {
      var startDate = (!inst.currentYear || (inst.input && inst.input.val() == '') ? null :
         this._daylightSavingAdjust(new Date(
         inst.currentYear, inst.currentMonth, inst.currentDay)));
      if (this._get(inst, 'rangeSelect')) {
         return [inst.rangeStart || startDate,
            (!inst.endYear ? inst.rangeStart || startDate :
            this._daylightSavingAdjust(new Date(inst.endYear, inst.endMonth, inst.endDay)))];
      } else
         return startDate;
   },

   /* Generate the HTML for the current state of the date picker. */
   _generateHTML: function(inst) {
      var today = new Date();
      today = this._daylightSavingAdjust(
         new Date(today.getFullYear(), today.getMonth(), today.getDate())); // clear time
      var showStatus = this._get(inst, 'showStatus');
      var initStatus = this._get(inst, 'initStatus') || '&#xa0;';
      var isRTL = this._get(inst, 'isRTL');
      // build the date picker HTML
      var clear = (this._get(inst, 'mandatory') ? '' :
         '<div class="ui-datepicker-clear"><a onclick="jQuery.datepicker._clearDate(\'#' + inst.id + '\');"' +
         this._addStatus(showStatus, inst.id, this._get(inst, 'clearStatus'), initStatus) + '>' +
         this._get(inst, 'clearText') + '</a></div>');
      var controls = '<div class="ui-datepicker-control">' + (isRTL ? '' : clear) +
         '<div class="ui-datepicker-close"><a onclick="jQuery.datepicker._hideDatepicker();"' +
         this._addStatus(showStatus, inst.id, this._get(inst, 'closeStatus'), initStatus) + '>' +
         this._get(inst, 'closeText') + '</a></div>' + (isRTL ? clear : '')  + '</div>';
      var prompt = this._get(inst, 'prompt');
      var closeAtTop = this._get(inst, 'closeAtTop');
      var hideIfNoPrevNext = this._get(inst, 'hideIfNoPrevNext');
      var navigationAsDateFormat = this._get(inst, 'navigationAsDateFormat');
      var showBigPrevNext = this._get(inst, 'showBigPrevNext');
      var numMonths = this._getNumberOfMonths(inst);
      var showCurrentAtPos = this._get(inst, 'showCurrentAtPos');
      var stepMonths = this._get(inst, 'stepMonths');
      var stepBigMonths = this._get(inst, 'stepBigMonths');
      var isMultiMonth = (numMonths[0] != 1 || numMonths[1] != 1);
      var currentDate = this._daylightSavingAdjust((!inst.currentDay ? new Date(9999, 9, 9) :
         new Date(inst.currentYear, inst.currentMonth, inst.currentDay)));
      var minDate = this._getMinMaxDate(inst, 'min', true);
      var maxDate = this._getMinMaxDate(inst, 'max');
      var drawMonth = inst.drawMonth - showCurrentAtPos;
      var drawYear = inst.drawYear;
      if (drawMonth < 0) {
         drawMonth += 12;
         drawYear--;
      }
      if (maxDate) {
         var maxDraw = this._daylightSavingAdjust(new Date(maxDate.getFullYear(),
            maxDate.getMonth() - numMonths[1] + 1, maxDate.getDate()));
         maxDraw = (minDate && maxDraw < minDate ? minDate : maxDraw);
         while (this._daylightSavingAdjust(new Date(drawYear, drawMonth, 1)) > maxDraw) {
            drawMonth--;
            if (drawMonth < 0) {
               drawMonth = 11;
               drawYear--;
            }
         }
      }
      // controls and links
      var prevText = this._get(inst, 'prevText');
      prevText = (!navigationAsDateFormat ? prevText : this.formatDate(prevText,
         this._daylightSavingAdjust(new Date(drawYear, drawMonth - stepMonths, 1)),
         this._getFormatConfig(inst)));
      var prevBigText = (showBigPrevNext ? this._get(inst, 'prevBigText') : '');
      prevBigText = (!navigationAsDateFormat ? prevBigText : this.formatDate(prevBigText,
         this._daylightSavingAdjust(new Date(drawYear, drawMonth - stepBigMonths, 1)),
         this._getFormatConfig(inst)));
      var prev = '<div class="ui-datepicker-prev">' + (this._canAdjustMonth(inst, -1, drawYear, drawMonth) ?
         (showBigPrevNext ? '<a onclick="jQuery.datepicker._adjustDate(\'#' + inst.id + '\', -' + stepBigMonths + ', \'M\');"' +
         this._addStatus(showStatus, inst.id, this._get(inst, 'prevBigStatus'), initStatus) + '>' + prevBigText + '</a>' : '') +
         '<a onclick="jQuery.datepicker._adjustDate(\'#' + inst.id + '\', -' + stepMonths + ', \'M\');"' +
         this._addStatus(showStatus, inst.id, this._get(inst, 'prevStatus'), initStatus) + '>' + prevText + '</a>' :
         (hideIfNoPrevNext ? '' : (showBigPrevNext ? '<label>' + prevBigText + '</label>' : '') +
         '<label>' + prevText + '</label>')) + '</div>';
      var nextText = this._get(inst, 'nextText');
      nextText = (!navigationAsDateFormat ? nextText : this.formatDate(nextText,
         this._daylightSavingAdjust(new Date(drawYear, drawMonth + stepMonths, 1)),
         this._getFormatConfig(inst)));
      var nextBigText = (showBigPrevNext ? this._get(inst, 'nextBigText') : '');
      nextBigText = (!navigationAsDateFormat ? nextBigText : this.formatDate(nextBigText,
         this._daylightSavingAdjust(new Date(drawYear, drawMonth + stepBigMonths, 1)),
         this._getFormatConfig(inst)));
      var next = '<div class="ui-datepicker-next">' + (this._canAdjustMonth(inst, +1, drawYear, drawMonth) ?
         '<a onclick="jQuery.datepicker._adjustDate(\'#' + inst.id + '\', +' + stepMonths + ', \'M\');"' +
         this._addStatus(showStatus, inst.id, this._get(inst, 'nextStatus'), initStatus) + '>' + nextText + '</a>' +
         (showBigPrevNext ? '<a onclick="jQuery.datepicker._adjustDate(\'#' + inst.id + '\', +' + stepBigMonths + ', \'M\');"' +
         this._addStatus(showStatus, inst.id, this._get(inst, 'nextBigStatus'), initStatus) + '>' + nextBigText + '</a>' : '') :
         (hideIfNoPrevNext ? '' : '<label>' + nextText + '</label>' +
         (showBigPrevNext ? '<label>' + nextBigText + '</label>' : ''))) + '</div>';
      var currentText = this._get(inst, 'currentText');
      var gotoDate = (this._get(inst, 'gotoCurrent') && inst.currentDay ? currentDate : today);
      currentText = (!navigationAsDateFormat ? currentText :
         this.formatDate(currentText, gotoDate, this._getFormatConfig(inst)));
      var html = (closeAtTop && !inst.inline ? controls : '') +
         '<div class="ui-datepicker-links">' + (isRTL ? next : prev) +
         (this._isInRange(inst, gotoDate) ? '<div class="ui-datepicker-current">' +
         '<a onclick="jQuery.datepicker._gotoToday(\'#' + inst.id + '\');"' +
         this._addStatus(showStatus, inst.id, this._get(inst, 'currentStatus'), initStatus) + '>' +
         currentText + '</a></div>' : '') + (isRTL ? prev : next) + '</div>' +
         (prompt ? '<div class="' + this._promptClass + '"><span>' + prompt + '</span></div>' : '');
      var firstDay = parseInt(this._get(inst, 'firstDay'));
      firstDay = (isNaN(firstDay) ? 0 : firstDay);
      var changeFirstDay = this._get(inst, 'changeFirstDay');
      var dayNames = this._get(inst, 'dayNames');
      var dayNamesShort = this._get(inst, 'dayNamesShort');
      var dayNamesMin = this._get(inst, 'dayNamesMin');
      var monthNames = this._get(inst, 'monthNames');
      var beforeShowDay = this._get(inst, 'beforeShowDay');
      var highlightWeek = this._get(inst, 'highlightWeek');
      var showOtherMonths = this._get(inst, 'showOtherMonths');
      var showWeeks = this._get(inst, 'showWeeks');
      var calculateWeek = this._get(inst, 'calculateWeek') || this.iso8601Week;
      var weekStatus = this._get(inst, 'weekStatus');
      var status = (showStatus ? this._get(inst, 'dayStatus') || initStatus : '');
      var dateStatus = this._get(inst, 'statusForDate') || this.dateStatus;
      var endDate = inst.endDay ? this._daylightSavingAdjust(
         new Date(inst.endYear, inst.endMonth, inst.endDay)) : currentDate;
      var defaultDate = this._getDefaultDate(inst);
      for (var row = 0; row < numMonths[0]; row++)
         for (var col = 0; col < numMonths[1]; col++) {
            var selectedDate = this._daylightSavingAdjust(new Date(drawYear, drawMonth, inst.selectedDay));
            html += '<div class="ui-datepicker-one-month' + (col == 0 ? ' ui-datepicker-new-row' : '') + '">' +
               this._generateMonthYearHeader(inst, drawMonth, drawYear, minDate, maxDate,
               selectedDate, row > 0 || col > 0, showStatus, initStatus, monthNames) + // draw month headers
               '<table class="ui-datepicker" cellpadding="0" cellspacing="0"><thead>' +
               '<tr class="ui-datepicker-title-row">' +
               (showWeeks ? '<td' + this._addStatus(showStatus, inst.id, weekStatus, initStatus) + '>' +
               this._get(inst, 'weekHeader') + '</td>' : '');
            for (var dow = 0; dow < 7; dow++) { // days of the week
               var day = (dow + firstDay) % 7;
               var dayStatus = (status.indexOf('DD') > -1 ? status.replace(/DD/, dayNames[day]) :
                  status.replace(/D/, dayNamesShort[day]));
               html += '<td' + ((dow + firstDay + 6) % 7 >= 5 ? ' class="ui-datepicker-week-end-cell"' : '') + '>' +
                  (!changeFirstDay ? '<span' :
                  '<a onclick="jQuery.datepicker._changeFirstDay(\'#' + inst.id + '\', ' + day + ');"') +
                  this._addStatus(showStatus, inst.id, dayStatus, initStatus) + ' title="' + dayNames[day] + '">' +
                  dayNamesMin[day] + (changeFirstDay ? '</a>' : '</span>') + '</td>';
            }
            html += '</tr></thead><tbody>';
            var daysInMonth = this._getDaysInMonth(drawYear, drawMonth);
            if (drawYear == inst.selectedYear && drawMonth == inst.selectedMonth)
               inst.selectedDay = Math.min(inst.selectedDay, daysInMonth);
            var leadDays = (this._getFirstDayOfMonth(drawYear, drawMonth) - firstDay + 7) % 7;
            var numRows = (isMultiMonth ? 6 : Math.ceil((leadDays + daysInMonth) / 7)); // calculate the number of rows to generate
            var printDate = this._daylightSavingAdjust(new Date(drawYear, drawMonth, 1 - leadDays));
            for (var dRow = 0; dRow < numRows; dRow++) { // create date picker rows
               html += '<tr class="ui-datepicker-days-row">' +
                  (showWeeks ? '<td class="ui-datepicker-week-col"' +
                  this._addStatus(showStatus, inst.id, weekStatus, initStatus) + '>' +
                  calculateWeek(printDate) + '</td>' : '');
               for (var dow = 0; dow < 7; dow++) { // create date picker days
                  var daySettings = (beforeShowDay ?
                     beforeShowDay.apply((inst.input ? inst.input[0] : null), [printDate]) : [true, '']);
                  var otherMonth = (printDate.getMonth() != drawMonth);
                  var unselectable = otherMonth || !daySettings[0] ||
                     (minDate && printDate < minDate) || (maxDate && printDate > maxDate);
                  html += '<td class="ui-datepicker-days-cell' +
                     ((dow + firstDay + 6) % 7 >= 5 ? ' ui-datepicker-week-end-cell' : '') + // highlight weekends
                     (otherMonth ? ' ui-datepicker-other-month' : '') + // highlight days from other months
                     ((printDate.getTime() == selectedDate.getTime() && drawMonth == inst.selectedMonth && inst._keyEvent) || // user pressed key
                     (defaultDate.getTime() == printDate.getTime() && defaultDate.getTime() == selectedDate.getTime()) ?
                     // or defaultDate is current printedDate and defaultDate is selectedDate
                     ' ' + $.datepicker._dayOverClass : '') + // highlight selected day
                     (unselectable ? ' ' + this._unselectableClass : '') +  // highlight unselectable days
                     (otherMonth && !showOtherMonths ? '' : ' ' + daySettings[1] + // highlight custom dates
                     (printDate.getTime() >= currentDate.getTime() && printDate.getTime() <= endDate.getTime() ? // in current range
                     ' ' + this._currentClass : '') + // highlight selected day
                     (printDate.getTime() == today.getTime() ? ' ui-datepicker-today' : '')) + '"' + // highlight today (if different)
                     ((!otherMonth || showOtherMonths) && daySettings[2] ? ' title="' + daySettings[2] + '"' : '') + // cell title
                     (unselectable ? (highlightWeek ? ' onmouseover="jQuery(this).parent().addClass(\'' + this._weekOverClass + '\');"' + // highlight selection week
                     ' onmouseout="jQuery(this).parent().removeClass(\'' + this._weekOverClass + '\');"' : '') : // unhighlight selection week
                     ' onmouseover="jQuery(this).addClass(\'' + this._dayOverClass + '\')' + // highlight selection
                     (highlightWeek ? '.parent().addClass(\'' + this._weekOverClass + '\')' : '') + ';' + // highlight selection week
                     (!showStatus || (otherMonth && !showOtherMonths) ? '' : 'jQuery(\'#ui-datepicker-status-' +
                     inst.id + '\').html(\'' + (dateStatus.apply((inst.input ? inst.input[0] : null),
                     [printDate, inst]) || initStatus) +'\');') + '"' +
                     ' onmouseout="jQuery(this).removeClass(\'' + this._dayOverClass + '\')' + // unhighlight selection
                     (highlightWeek ? '.parent().removeClass(\'' + this._weekOverClass + '\')' : '') + ';' + // unhighlight selection week
                     (!showStatus || (otherMonth && !showOtherMonths) ? '' : 'jQuery(\'#ui-datepicker-status-' +
                     inst.id + '\').html(\'' + initStatus + '\');') + '" onclick="jQuery.datepicker._selectDay(\'#' +
                     inst.id + '\',' + drawMonth + ',' + drawYear + ', this);"') + '>' + // actions
                     (otherMonth ? (showOtherMonths ? printDate.getDate() : '&#xa0;') : // display for other months
                     (unselectable ? printDate.getDate() : '<a>' + printDate.getDate() + '</a>')) + '</td>'; // display for this month
                  printDate.setDate(printDate.getDate() + 1);
                  printDate = this._daylightSavingAdjust(printDate);
               }
               html += '</tr>';
            }
            drawMonth++;
            if (drawMonth > 11) {
               drawMonth = 0;
               drawYear++;
            }
            html += '</tbody></table></div>';
         }
      html += (showStatus ? '<div style="clear: both;"></div><div id="ui-datepicker-status-' + inst.id +
         '" class="ui-datepicker-status">' + initStatus + '</div>' : '') +
         (!closeAtTop && !inst.inline ? controls : '') +
         '<div style="clear: both;"></div>' +
         ($.browser.msie && parseInt($.browser.version,10) < 7 && !inst.inline ?
         '<iframe src="javascript:false;" class="ui-datepicker-cover"></iframe>' : '');
      inst._keyEvent = false;
      return html;
   },

   /* Generate the month and year header. */
   _generateMonthYearHeader: function(inst, drawMonth, drawYear, minDate, maxDate,
         selectedDate, secondary, showStatus, initStatus, monthNames) {
      minDate = (inst.rangeStart && minDate && selectedDate < minDate ? selectedDate : minDate);
      var changeMonth = this._get(inst, 'changeMonth');
      var changeYear = this._get(inst, 'changeYear');
      var showMonthAfterYear = this._get(inst, 'showMonthAfterYear');
      var html = '<div class="ui-datepicker-header">';
      var monthHtml = '';
      // month selection
      if (secondary || !changeMonth)
         monthHtml += monthNames[drawMonth];
      else {
         var inMinYear = (minDate && minDate.getFullYear() == drawYear);
         var inMaxYear = (maxDate && maxDate.getFullYear() == drawYear);
         monthHtml += '<select class="ui-datepicker-new-month" ' +
            'onchange="jQuery.datepicker._selectMonthYear(\'#' + inst.id + '\', this, \'M\');" ' +
            'onclick="jQuery.datepicker._clickMonthYear(\'#' + inst.id + '\');"' +
            this._addStatus(showStatus, inst.id, this._get(inst, 'monthStatus'), initStatus) + '>';
         for (var month = 0; month < 12; month++) {
            if ((!inMinYear || month >= minDate.getMonth()) &&
                  (!inMaxYear || month <= maxDate.getMonth()))
               monthHtml += '<option value="' + month + '"' +
                  (month == drawMonth ? ' selected="selected"' : '') +
                  '>' + monthNames[month] + '</option>';
         }
         monthHtml += '</select>';
      }
      if (!showMonthAfterYear)
         html += monthHtml + (secondary || changeMonth || changeYear ? '&#xa0;' : '');
      // year selection
      if (secondary || !changeYear)
         html += drawYear;
      else {
         // determine range of years to display
         var years = this._get(inst, 'yearRange').split(':');
         var year = 0;
         var endYear = 0;
         if (years.length != 2) {
            year = drawYear - 10;
            endYear = drawYear + 10;
         } else if (years[0].charAt(0) == '+' || years[0].charAt(0) == '-') {
            year = endYear = new Date().getFullYear();
            year += parseInt(years[0], 10);
            endYear += parseInt(years[1], 10);
         } else {
            year = parseInt(years[0], 10);
            endYear = parseInt(years[1], 10);
         }
         year = (minDate ? Math.max(year, minDate.getFullYear()) : year);
         endYear = (maxDate ? Math.min(endYear, maxDate.getFullYear()) : endYear);
         html += '<select class="ui-datepicker-new-year" ' +
            'onchange="jQuery.datepicker._selectMonthYear(\'#' + inst.id + '\', this, \'Y\');" ' +
            'onclick="jQuery.datepicker._clickMonthYear(\'#' + inst.id + '\');"' +
            this._addStatus(showStatus, inst.id, this._get(inst, 'yearStatus'), initStatus) + '>';
         for (; year <= endYear; year++) {
            html += '<option value="' + year + '"' +
               (year == drawYear ? ' selected="selected"' : '') +
               '>' + year + '</option>';
         }
         html += '</select>';
      }
      if (showMonthAfterYear)
         html += (secondary || changeMonth || changeYear ? '&#xa0;' : '') + monthHtml;
      html += '</div>'; // Close datepicker_header
      return html;
   },

   /* Provide code to set and clear the status panel. */
   _addStatus: function(showStatus, id, text, initStatus) {
      return (showStatus ? ' onmouseover="jQuery(\'#ui-datepicker-status-' + id +
         '\').html(\'' + (text || initStatus) + '\');" ' +
         'onmouseout="jQuery(\'#ui-datepicker-status-' + id +
         '\').html(\'' + initStatus + '\');"' : '');
   },

   /* Adjust one of the date sub-fields. */
   _adjustInstDate: function(inst, offset, period) {
      var year = inst.drawYear + (period == 'Y' ? offset : 0);
      var month = inst.drawMonth + (period == 'M' ? offset : 0);
      var day = Math.min(inst.selectedDay, this._getDaysInMonth(year, month)) +
         (period == 'D' ? offset : 0);
      var date = this._daylightSavingAdjust(new Date(year, month, day));
      // ensure it is within the bounds set
      var minDate = this._getMinMaxDate(inst, 'min', true);
      var maxDate = this._getMinMaxDate(inst, 'max');
      date = (minDate && date < minDate ? minDate : date);
      date = (maxDate && date > maxDate ? maxDate : date);
      inst.selectedDay = date.getDate();
      inst.drawMonth = inst.selectedMonth = date.getMonth();
      inst.drawYear = inst.selectedYear = date.getFullYear();
      if (period == 'M' || period == 'Y')
         this._notifyChange(inst);
   },

   /* Notify change of month/year. */
   _notifyChange: function(inst) {
      var onChange = this._get(inst, 'onChangeMonthYear');
      if (onChange)
         onChange.apply((inst.input ? inst.input[0] : null),
            [inst.selectedYear, inst.selectedMonth + 1, inst]);
   },

   /* Determine the number of months to show. */
   _getNumberOfMonths: function(inst) {
      var numMonths = this._get(inst, 'numberOfMonths');
      return (numMonths == null ? [1, 1] : (typeof numMonths == 'number' ? [1, numMonths] : numMonths));
   },

   /* Determine the current maximum date - ensure no time components are set - may be overridden for a range. */
   _getMinMaxDate: function(inst, minMax, checkRange) {
      var date = this._determineDate(this._get(inst, minMax + 'Date'), null);
      return (!checkRange || !inst.rangeStart ? date :
         (!date || inst.rangeStart > date ? inst.rangeStart : date));
   },

   /* Find the number of days in a given month. */
   _getDaysInMonth: function(year, month) {
      return 32 - new Date(year, month, 32).getDate();
   },

   /* Find the day of the week of the first of a month. */
   _getFirstDayOfMonth: function(year, month) {
      return new Date(year, month, 1).getDay();
   },

   /* Determines if we should allow a "next/prev" month display change. */
   _canAdjustMonth: function(inst, offset, curYear, curMonth) {
      var numMonths = this._getNumberOfMonths(inst);
      var date = this._daylightSavingAdjust(new Date(
         curYear, curMonth + (offset < 0 ? offset : numMonths[1]), 1));
      if (offset < 0)
         date.setDate(this._getDaysInMonth(date.getFullYear(), date.getMonth()));
      return this._isInRange(inst, date);
   },

   /* Is the given date in the accepted range? */
   _isInRange: function(inst, date) {
      // during range selection, use minimum of selected date and range start
      var newMinDate = (!inst.rangeStart ? null : this._daylightSavingAdjust(
         new Date(inst.selectedYear, inst.selectedMonth, inst.selectedDay)));
      newMinDate = (newMinDate && inst.rangeStart < newMinDate ? inst.rangeStart : newMinDate);
      var minDate = newMinDate || this._getMinMaxDate(inst, 'min');
      var maxDate = this._getMinMaxDate(inst, 'max');
      return ((!minDate || date >= minDate) && (!maxDate || date <= maxDate));
   },

   /* Provide the configuration settings for formatting/parsing. */
   _getFormatConfig: function(inst) {
      var shortYearCutoff = this._get(inst, 'shortYearCutoff');
      shortYearCutoff = (typeof shortYearCutoff != 'string' ? shortYearCutoff :
         new Date().getFullYear() % 100 + parseInt(shortYearCutoff, 10));
      return {shortYearCutoff: shortYearCutoff,
         dayNamesShort: this._get(inst, 'dayNamesShort'), dayNames: this._get(inst, 'dayNames'),
         monthNamesShort: this._get(inst, 'monthNamesShort'), monthNames: this._get(inst, 'monthNames')};
   },

   /* Format the given date for display. */
   _formatDate: function(inst, day, month, year) {
      if (!day) {
         inst.currentDay = inst.selectedDay;
         inst.currentMonth = inst.selectedMonth;
         inst.currentYear = inst.selectedYear;
      }
      var date = (day ? (typeof day == 'object' ? day :
         this._daylightSavingAdjust(new Date(year, month, day))) :
         this._daylightSavingAdjust(new Date(inst.currentYear, inst.currentMonth, inst.currentDay)));
      return this.formatDate(this._get(inst, 'dateFormat'), date, this._getFormatConfig(inst));
   }
});

/* jQuery extend now ignores nulls! */
function extendRemove(target, props) {
   $.extend(target, props);
   for (var name in props)
      if (props[name] == null || props[name] == undefined)
         target[name] = props[name];
   return target;
};

/* Determine whether an object is an array. */
function isArray(a) {
   return (a && (($.browser.safari && typeof a == 'object' && a.length) ||
      (a.constructor && a.constructor.toString().match(/\Array\(\)/))));
};

/* Invoke the datepicker functionality.
   @param  options  string - a command, optionally followed by additional parameters or
                    Object - settings for attaching new datepicker functionality
   @return  jQuery object */
$.fn.datepicker = function(options){

   /* Initialise the date picker. */
   if (!$.datepicker.initialized) {
      $(document.body).append($.datepicker.dpDiv).
         mousedown($.datepicker._checkExternalClick);
      $.datepicker.initialized = true;
   }

   var otherArgs = Array.prototype.slice.call(arguments, 1);
   if (typeof options == 'string' && (options == 'isDisabled' || options == 'getDate'))
      return $.datepicker['_' + options + 'Datepicker'].
         apply($.datepicker, [this[0]].concat(otherArgs));
   return this.each(function() {
      typeof options == 'string' ?
         $.datepicker['_' + options + 'Datepicker'].
            apply($.datepicker, [this].concat(otherArgs)) :
         $.datepicker._attachDatepicker(this, options);
   });
};

$.datepicker = new Datepicker(); // singleton instance
$.datepicker.initialized = false;
$.datepicker.uuid = new Date().getTime();
$.datepicker.version = "@VERSION";

})(jQuery);

