path: root/template-common/lib/ui/ui.datepicker.js

/*
 * jQuery UI Datepicker
 *
 * Copyright (c) 2006, 2007, 2008 Marc Grabanski
 * Dual licensed under the MIT (MIT-LICENSE.txt)
 * and GPL (GPL-LICENSE.txt) licenses.
 * 
 * http://docs.jquery.com/UI/Datepicker
 *
 * Depends:
 *	ui.core.js
 *
 * Marc Grabanski (m@marcgrabanski.com) and Keith Wood (kbwood@virginbroadband.com.au).
 */
   
(function($) { // hide the namespace

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._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._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._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.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: '<Prev', // Display text for previous month link
		prevStatus: 'Show the previous month', // Status text for previous month link
		nextText: 'Next>', // Display text for next month link
		nextStatus: 'Show the next month', // Status text for next month 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
		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
		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
		stepMonths: 1, // Number of months to step back/forward
		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
	};
	$.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 (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' + new Date().getTime();
		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) {
		return {id: target[0].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="ui-datepicker-inline"></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 input = $(target);
		if (input.hasClass(this.markerClassName))
			return;
		input.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);
	},

	/* 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' + new Date().getTime();
			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 nodeName = target.nodeName.toLowerCase();
		var $target = $(target);
		$.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) {
		target.disabled = false;
		$(target).siblings('button.' + this._triggerClass).each(function() { this.disabled = false; }).end().
			siblings('img.' + this._triggerClass).css({opacity: '1.0', cursor: ''});
		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) {
		target.disabled = true;
		$(target).siblings('button.' + this._triggerClass).each(function() { this.disabled = true; }).end().
			siblings('img.' + this._triggerClass).css({opacity: '0.5', cursor: 'default'});
		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;
	},

	/* 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) */
	_changeDatepicker: function(target, name, value) {
		var settings = name || {};
		if (typeof name == 'string') {
			settings = {};
			settings[name] = value;
		}
		if (inst = $.data(target, PROP_NAME)) {
			extendRemove(inst.settings, settings);
			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 = $.data(target, PROP_NAME);
		if (inst) {
			this._setDate(inst, date, endDate);
			this._updateDatepicker(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 = $.data(target, PROP_NAME);
		if (inst)
			this._setDateFromField(inst); 
		return (inst ? this._getDate(inst) : null);
	},

	/* Handle keystrokes. */
	_doKeyDown: function(e) {
		var inst = $.data(e.target, PROP_NAME);
		var handled = true;
		if ($.datepicker._datepickerShowing)
			switch (e.keyCode) {
				case 9:  $.datepicker._hideDatepicker(null, '');
						break; // hide on tab out
				case 13: $.datepicker._selectDay(e.target, inst.selectedMonth, inst.selectedYear,
							$('td.ui-datepicker-days-cell-over', inst.dpDiv)[0]);
						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: $.datepicker._adjustDate(e.target, (e.ctrlKey ? -1 :
							-$.datepicker._get(inst, 'stepMonths')), (e.ctrlKey ? 'Y' : 'M'));
						break; // previous month/year on page up/+ ctrl
				case 34: $.datepicker._adjustDate(e.target, (e.ctrlKey ? +1 :
							+$.datepicker._get(inst, 'stepMonths')), (e.ctrlKey ? 'Y' : 'M'));
						break; // next month/year on page down/+ ctrl
				case 35: if (e.ctrlKey) $.datepicker._clearDate(e.target);
						break; // clear on ctrl+end
				case 36: if (e.ctrlKey) $.datepicker._gotoToday(e.target);
						break; // current on ctrl+home
				case 37: if (e.ctrlKey) $.datepicker._adjustDate(e.target, -1, 'D');
						break; // -1 day on ctrl+left
				case 38: if (e.ctrlKey) $.datepicker._adjustDate(e.target, -7, 'D');
						break; // -1 week on ctrl+up
				case 39: if (e.ctrlKey) $.datepicker._adjustDate(e.target, +1, 'D');
						break; // +1 day on ctrl+right
				case 40: if (e.ctrlKey) $.datepicker._adjustDate(e.target, +7, 'D');
						break; // +1 week on ctrl+down
				default: handled = false;
			}
		else if (e.keyCode == 36 && e.ctrlKey) // display the date picker on ctrl+home
			$.datepicker._showDatepicker(this);
		else
			handled = false;
		if (handled) {
			e.preventDefault();
			e.stopPropagation();
		}
	},

	/* Filter entered characters - based on date format. */
	_doKeyPress: function(e) {
		var inst = $.data(e.target, PROP_NAME);
		var chars = $.datepicker._possibleChars($.datepicker._get(inst, 'dateFormat'));
		var chr = String.fromCharCode(e.charCode == undefined ? e.keyCode : e.charCode);
		return e.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 = $.data(input, PROP_NAME);
		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) < 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._generateDatepicker(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.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.clientWidth;
		var browserHeight = window.innerHeight || document.documentElement.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)
			return;
		var rangeSelect = this._get(inst, 'rangeSelect');
		if (rangeSelect && this._stayOpen)
			this._selectDate('#' + inst.id, this._formatDate(inst,
				inst.currentDay, inst.currentMonth, inst.currentYear));
		this._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, $.datepicker._get(inst, 'showOptions'),
					duration, postProcess);
			else
				inst.dpDiv[(duration == '' ? 'hide' : (showAnim == 'slideDown' ? 'slideUp' :
					(showAnim == 'fadeIn' ? 'fadeOut' : 'hide')))](duration, postProcess);
			if (duration == '')
				this._tidyDialog(inst);
			var onClose = this._get(inst, 'onClose');
			if (onClose)
				onClose.apply((inst.input ? inst.input[0] : null),
					[this._getDate(inst), inst]);  // trigger custom callback
			this._datepickerShowing = false;
			this._lastInput = null;
			inst.settings.prompt = null;
			if (this._inDialog) {
				this._dialogInput.css({ position: 'absolute', left: '0', top: '-100px' });
				if ($.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 = $.data(target[0], PROP_NAME);
		this._adjustInstDate(inst, offset, period);
		this._updateDatepicker(inst);
	},

	/* Action for current link. */
	_gotoToday: function(id) {
		var target = $(id);
		var inst = $.data(target[0], PROP_NAME);
		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._adjustDate(target);
		this._notifyChange(inst);
	},

	/* Action for selecting a new month/year. */
	_selectMonthYear: function(id, select, period) {
		var target = $(id);
		var inst = $.data(target[0], PROP_NAME);
		inst._selectingMonthYear = false;
		inst[period == 'M' ? 'drawMonth' : 'drawYear'] =
			select.options[select.selectedIndex].value - 0;
		this._adjustDate(target);
		this._notifyChange(inst);
	},

	/* Restore input focus after not changing month/year. */
	_clickMonthYear: function(id) {
		var target = $(id);
		var inst = $.data(target[0], PROP_NAME);
		if (inst.input && inst._selectingMonthYear && !$.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 = $.data(target[0], PROP_NAME);
		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 = $.data(target[0], PROP_NAME);
		var rangeSelect = this._get(inst, 'rangeSelect');
		if (rangeSelect) {
			this._stayOpen = !this._stayOpen;
			if (this._stayOpen) {
				$('.ui-datepicker td').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 (this._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 (this._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 = $.data(target[0], PROP_NAME);
		if (this._get(inst, 'mandatory'))
			return;
		this._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 = $.data(target[0], PROP_NAME);
		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 (!this._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');
			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
				checkDate.setDate(checkDate.getDate() + 3); // Generate for next year
				return $.datepicker.iso8601Week(checkDate);
			}
		}
		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 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 : 2));
			var size = origSize;
			var num = 0;
			while (size > 0 && iValue < value.length &&
					value.charAt(iValue) >= '0' && value.charAt(iValue) <= '9') {
				num = num * 10 + (value.charAt(iValue++) - 0);
				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 '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 < 100)
			year += new Date().getFullYear() - new Date().getFullYear() % 100 +
				(year <= shortYearCutoff ? 0 : -100);
		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)
	   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) {
			return (lookAhead(match) && value < 10 ? '0' : '') + value;
		};
		// 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()); 
							break;
						case 'D': 
							output += formatName('D', date.getDay(), dayNamesShort, dayNames);
							break;
						case 'm': 
							output += formatNumber('m', date.getMonth() + 1); 
							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 (e) {
				this.log(e);
				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 += (matches[1] - 0); break;
					case 'w' : case 'W' :
						day += (matches[1] * 7); break;
					case 'm' : case 'M' :
						month += (matches[1] - 0); 
						day = Math.min(day, getDaysInMonth(year, month));
						break;
					case 'y': case 'Y' :
						year += (matches[1] - 0);
						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);
		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;
			}
		}
		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. */
	_generateDatepicker: 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 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 + '\');"' +
			(showStatus ? this._addStatus(inst, this._get(inst, 'clearStatus') || '&#xa0;') : '') + '>' +
			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();"' +
			(showStatus ? this._addStatus(inst, this._get(inst, 'closeStatus') || '&#xa0;') : '') + '>' +
			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 numMonths = this._getNumberOfMonths(inst);
		var stepMonths = this._get(inst, 'stepMonths');
		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;
		var drawYear = inst.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 prev = '<div class="ui-datepicker-prev">' + (this._canAdjustMonth(inst, -1, drawYear, drawMonth) ? 
			'<a onclick="jQuery.datepicker._adjustDate(\'#' + inst.id + '\', -' + stepMonths + ', \'M\');"' +
			(showStatus ? this._addStatus(inst, this._get(inst, 'prevStatus') || '&#xa0;') : '') + '>' + prevText + '</a>' :
			(hideIfNoPrevNext ? '' : '<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 next = '<div class="ui-datepicker-next">' + (this._canAdjustMonth(inst, +1, drawYear, drawMonth) ?
			'<a onclick="jQuery.datepicker._adjustDate(\'#' + inst.id + '\', +' + stepMonths + ', \'M\');"' +
			(showStatus ? this._addStatus(inst, this._get(inst, 'nextStatus') || '&#xa0;') : '') + '>' + nextText + '</a>' :
			(hideIfNoPrevNext ? '' : '<label>' + nextText + '</label>')) + '</div>';
		var currentText = this._get(inst, 'currentText');
		currentText = (!navigationAsDateFormat ? currentText: this.formatDate(
			currentText, today, this._getFormatConfig(inst)));
		var html = (prompt ? '<div class="' + this._promptClass + '">' + prompt + '</div>' : '') +
			(closeAtTop && !inst.inline ? controls : '') +
			'<div class="ui-datepicker-links">' + (isRTL ? next : prev) +
			(this._isInRange(inst, (this._get(inst, 'gotoCurrent') && inst.currentDay ?
			currentDate : today)) ? '<div class="ui-datepicker-current">' +
			'<a onclick="jQuery.datepicker._gotoToday(\'#' + inst.id + '\');"' +
			(showStatus ? this._addStatus(inst, this._get(inst, 'currentStatus') || '&#xa0;') : '') + '>' +
			currentText + '</a></div>' : '') + (isRTL ? prev : next) + '</div>';
		var firstDay = this._get(inst, '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 status = (showStatus ? this._get(inst, 'dayStatus') || '&#xa0;' : '');
		var dateStatus = this._get(inst, 'statusForDate') || this.dateStatus;
		var endDate = inst.endDay ? this._daylightSavingAdjust(
			new Date(inst.endYear, inst.endMonth, inst.endDay)) : currentDate;
		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, monthNames) + // draw month headers
					'<table class="ui-datepicker" cellpadding="0" cellspacing="0"><thead>' + 
					'<tr class="ui-datepicker-title-row">' +
					(showWeeks ? '<td>' + 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 + ');"') + 
						(showStatus ? this._addStatus(inst, dayStatus) : '') + ' 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">' + 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-otherMonth' : '') + // highlight days from other months
							(printDate.getTime() == selectedDate.getTime() && drawMonth == inst.selectedMonth ?
							' ui-datepicker-days-cell-over' : '') + // 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(\'ui-datepicker-week-over\');"' + // highlight selection week
							' onmouseout="jQuery(this).parent().removeClass(\'ui-datepicker-week-over\');"' : '') : // unhighlight selection week
							' onmouseover="jQuery(this).addClass(\'ui-datepicker-days-cell-over\')' + // highlight selection
							(highlightWeek ? '.parent().addClass(\'ui-datepicker-week-over\')' : '') + ';' + // highlight selection week
							(!showStatus || (otherMonth && !showOtherMonths) ? '' : 'jQuery(\'#ui-datepicker-status-' +
							inst.id + '\').html(\'' + (dateStatus.apply((inst.input ? inst.input[0] : null),
							[printDate, inst]) || '&#xa0;') +'\');') + '"' +
							' onmouseout="jQuery(this).removeClass(\'ui-datepicker-days-cell-over\')' + // unhighlight selection
							(highlightWeek ? '.parent().removeClass(\'ui-datepicker-week-over\')' : '') + ';' + // unhighlight selection week
							(!showStatus || (otherMonth && !showOtherMonths) ? '' : 'jQuery(\'#ui-datepicker-status-' +
							inst.id + '\').html(\'&#xa0;\');') + '" 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">' + (this._get(inst, 'initStatus') || '&#xa0;') + '</div>' : '') +
			(!closeAtTop && !inst.inline ? controls : '') +
			'<div style="clear: both;"></div>' + 
			($.browser.msie && parseInt($.browser.version) < 7 && !inst.inline ? 
			'<iframe src="javascript:false;" class="ui-datepicker-cover"></iframe>' : '');
		return html;
	},
	
	/* Generate the month and year header. */
	_generateMonthYearHeader: function(inst, drawMonth, drawYear, minDate, maxDate,
			selectedDate, secondary, showStatus, monthNames) {
		minDate = (inst.rangeStart && minDate && selectedDate < minDate ? selectedDate : minDate);
		var html = '<div class="ui-datepicker-header">';
		// month selection
		if (secondary || !this._get(inst, 'changeMonth'))
			html += monthNames[drawMonth] + '&#xa0;';
		else {
			var inMinYear = (minDate && minDate.getFullYear() == drawYear);
			var inMaxYear = (maxDate && maxDate.getFullYear() == drawYear);
			html += '<select class="ui-datepicker-new-month" ' +
				'onchange="jQuery.datepicker._selectMonthYear(\'#' + inst.id + '\', this, \'M\');" ' +
				'onclick="jQuery.datepicker._clickMonthYear(\'#' + inst.id + '\');"' +
				(showStatus ? this._addStatus(inst, this._get(inst, 'monthStatus') || '&#xa0;') : '') + '>';
			for (var month = 0; month < 12; month++) {
				if ((!inMinYear || month >= minDate.getMonth()) &&
						(!inMaxYear || month <= maxDate.getMonth()))
					html += '<option value="' + month + '"' +
						(month == drawMonth ? ' selected="selected"' : '') +
						'>' + monthNames[month] + '</option>';
			}
			html += '</select>';
		}
		// year selection
		if (secondary || !this._get(inst, '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 + '\');"' +
				(showStatus ? this._addStatus(inst, this._get(inst, 'yearStatus') || '&#xa0;') : '') + '>';
			for (; year <= endYear; year++) {
				html += '<option value="' + year + '"' +
					(year == drawYear ? ' selected="selected"' : '') +
					'>' + year + '</option>';
			}
			html += '</select>';
		}
		html += '</div>'; // Close datepicker_header
		return html;
	},

	/* Provide code to set and clear the status panel. */
	_addStatus: function(inst, text) {
		return ' onmouseover="jQuery(\'#ui-datepicker-status-' + inst.id + '\').html(\'' + text + '\');" ' +
			'onmouseout="jQuery(\'#ui-datepicker-status-' + inst.id + '\').html(\'&#xa0;\');"';
	},

	/* 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),
				[new Date(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){
	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
	
/* Initialise the date picker. */
$(document).ready(function() {
	$(document.body).append($.datepicker.dpDiv).
		mousedown($.datepicker._checkExternalClick);
});

})(jQuery);