/* jQuery Calendar v2.8
   Written by Marc Grabanski (m@marcgrabanski.com) and Keith Wood (kbwood@iprimus.com.au).

   Copyright (c) 2007 Marc Grabanski (http://marcgrabanski.com/code/jquery-calendar)
   Dual licensed under the GPL (http://www.gnu.org/licenses/gpl-3.0.txt) and 
   CC (http://creativecommons.org/licenses/by/3.0/) licenses. "Share or Remix it but please Attribute the authors."
   Date: 09-03-2007  */

/* PopUp Calendar manager.
   Use the singleton instance of this class, popUpCal, to interact with the calendar.
   Settings for (groups of) calendars are maintained in an instance object
   (PopUpCalInstance), allowing multiple different settings on the same page. */
   
(function($) { // hide the namespace

function PopUpCal() {
    this.debug = false; // Change this to true to start debugging
    this._nextId = 0; // Next ID for a calendar instance
    this._inst = []; // List of instances indexed by ID
    this._curInst = null; // The current instance in use
    this._disabledInputs = []; // List of calendar inputs that have been disabled
    this._popUpShowing = false; // True if the popup calendar is showing , false if not
    this._inDialog = false; // True if showing within a "dialog", false if not
    this._buttons = {};
    this.regional = []; // Available regional settings, indexed by language code
    this.regional[''] = { // Default regional settings
        clearText: '', // Display text for clear link
        closeText: '<img src="/images/calendar/cal-close.png" alt="[ X ]" />', // Display text for close link
        prevText: '<img src="/images/calendar/cal-left.png" alt="&larr;" />', // Display text for previous month link
        nextText: '<img src="/images/calendar/cal-right.png" alt="&rarr;" />', // Display text for next month link
        currentText: 'Ñåãîäíÿ', // Display text for current month link
        dayNames: ['Âñ','Ïí','Âò','Ñð','×ò','Ïò','Ñá'], // Names of days starting at Sunday
        monthNames: ['ßíâàðü','Ôåâðàëü','Ìàðò','Àïðåëü','Ìàé','Èþíü',
            'Èþëü','Àâãóñò','Ñåíòÿáðü','Îêòÿáðü','Íîÿáðü','Äåêàáðü'], // Names of months
        dateFormat: 'DMY.', // First three are day, month, year in the required order,
            // fourth (optional) is the separator, e.g. US would be 'MDY/', ISO would be 'YMD-'
        firstDay: 1 // The first day of the week, Sun = 0, Mon = 1, ...
    };
    this._defaults = { // Global defaults for all the calendar instances
        autoPopUp: 'button', // 'focus' for popup on focus,
            // 'button' for trigger button, or 'both' for either
        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
        button: null,
        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
        hideIfNoPrevNext: false, // True to hide next/previous month links
            // if not applicable, false to just disable them
        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: '-3:+3', // 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
        showOtherMonths: false, // True to show dates in other months, false to leave blank
        minDate: null, // The earliest selectable date, or null for no limit
        maxDate: null, // The latest selectable date, or null for no limit
        speed: 'fast', // Speed of display/closure
        customDate: 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 '', e.g. popUpCal.noWeekends
        fieldSettings: null, // Function that takes an input field and
            // returns a set of custom settings for the calendar
        onSelect: null, // Define a callback function when a date is selected
        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 calendar
        rangeSeparator: ' - ' // Text between two dates in a range
    };
    $.extend(this._defaults, this.regional['']);
    this._calendarDiv = $('<div id="calendar_div"></div>');
    $(document.body).append(this._calendarDiv).mousedown(this._checkExternalClick);
}

$.extend(PopUpCal.prototype, {
    /* Class name added to elements to indicate already configured with a calendar. */
    markerClassName: 'hasCalendar',

    /* Debug logging (if enabled). */
    log: function () {
        if (this.debug) {
            console.log.apply('', arguments);
        }
    },
    
    /* Register a new calendar instance - with custom settings. */
    _register: function(inst) {
        var id = this._nextId++;
        this._inst[id] = inst;
        return id;
    },

    /* Retrieve a particular calendar instance based on its ID. */
    _getInst: function(id) {
        return this._inst[id] || id;
    },

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

    /* Handle keystrokes. */
    _doKeyDown: function(e) {
        var inst = popUpCal._getInst(this._calId);
        if (popUpCal._popUpShowing) {
            switch (e.keyCode) {
                case 9:  popUpCal.hideCalendar(inst, '');
                        break; // hide on tab out
                case 13: popUpCal._selectDay(inst, inst._selectedMonth, inst._selectedYear,
                            $('td.calendar_daysCellOver', inst._calendarDiv)[0]);
                        break; // select the value on enter
                case 27: popUpCal.hideCalendar(inst, inst._get('speed'));
                        break; // hide on escape
                case 33: popUpCal._adjustDate(inst,
                            (e.ctrlKey ? -1 : -inst._get('stepMonths')), (e.ctrlKey ? 'Y' : 'M'));
                        break; // previous month/year on page up/+ ctrl
                case 34: popUpCal._adjustDate(inst,
                            (e.ctrlKey ? +1 : +inst._get('stepMonths')), (e.ctrlKey ? 'Y' : 'M'));
                        break; // next month/year on page down/+ ctrl
                case 35: if (e.ctrlKey) popUpCal._clearDate(inst);
                        break; // clear on ctrl+end
                case 36: if (e.ctrlKey) popUpCal._gotoToday(inst);
                        break; // current on ctrl+home
                case 37: if (e.ctrlKey) popUpCal._adjustDate(inst, -1, 'D');
                        break; // -1 day on ctrl+left
                case 38: if (e.ctrlKey) popUpCal._adjustDate(inst, -7, 'D');
                        break; // -1 week on ctrl+up
                case 39: if (e.ctrlKey) popUpCal._adjustDate(inst, +1, 'D');
                        break; // +1 day on ctrl+right
                case 40: if (e.ctrlKey) popUpCal._adjustDate(inst, +7, 'D');
                        break; // +1 week on ctrl+down
            }
        }
        else if (e.keyCode == 36 && e.ctrlKey) { // display the calendar on ctrl+home
            popUpCal.showFor(this);
        }
    },

    /* Filter entered characters. */
    _doKeyPress: function(e) {
        var inst = popUpCal._getInst(this._calId);
        var chr = String.fromCharCode(e.charCode == undefined ? e.keyCode : e.charCode);
        return (chr < ' ' || chr == inst._get('dateFormat').charAt(3) ||
            (chr >= '0' && chr <= '9')
			|| (chr == ' ' || chr == ':')); // only allow numbers and separator
    },

    /* Attach the calendar to an input field. */
    _connectCalendar: function(target, inst) {
        var input = $(target);
        if (this._hasClass(input, this.markerClassName)) {
            return;
        }
        var appendText = inst._get('appendText');
        if (appendText) {
            input.after('<span class="calendar_append">' + appendText + '</span>');
        }
        var autoPopUp = inst._get('autoPopUp');
        if (autoPopUp == 'focus' || autoPopUp == 'both') { // pop-up calendar when in the marked field
            input.focus(this.showFor);
        }
        if (autoPopUp == 'button' || autoPopUp == 'both') { // pop-up calendar when button clicked
            var buttonText = inst._get('buttonText');
            var buttonImage = inst._get('buttonImage');
            var buttonImageOnly = inst._get('buttonImageOnly');
            var trigger = $(buttonImageOnly ? '<img class="calendar_trigger" src="' +
                buttonImage + '" alt="' + buttonText + '" title="' + buttonText + '"/>' :
                '<button type="button" class="calendar_trigger">' + (buttonImage != '' ?
                '<img src="' + buttonImage + '" alt="' + buttonText + '" title="' + buttonText + '"/>' :
                buttonText) + '</button>');
            input.wrap('<span class="calendar_wrap"></span>').after(inst._get('button') ? '' : trigger);
            if (inst._get('button'))
            {
                this._buttons[inst._get('button').attr('id')] = input.attr('id');
                inst._get('button').click(this.showFor);
            }
            else
            {
                trigger.click(this.showFor);
            }
        }
        input.addClass(this.markerClassName).keydown(this._doKeyDown).keypress(this._doKeyPress);
        input[0]._calId = inst._id;
    },

    /* Attach an inline calendar to a div. */
    _inlineCalendar: function(target, inst) {
        var input = $(target);
        if (this._hasClass(input, this.markerClassName)) {
            return;
        }
        input.addClass(this.markerClassName).append(inst._calendarDiv);
        input[0]._calId = inst._id;
        this._updateCalendar(inst);
        inst._calendarDiv.resize(function() { popUpCal._inlineShow(inst); });
    },

    /* Tidy up after displaying the calendar. */
    _inlineShow: function(inst) {
        var numMonths = inst._get('numberOfMonths'); // fix width for dynamic number of calendars
        numMonths = (numMonths == null ? 1 : (typeof numMonths == 'number' ? numMonths : numMonths[1]));
        inst._calendarDiv.width(numMonths * $('.calendar', inst._calendarDiv[0]).width());
    },

    /* Does this element have a particular class? */
    _hasClass: function(element, className) {
        var classes = element.attr('class');
        return (classes && classes.indexOf(className) > -1);
    },

    /* Pop-up the calendar in a "dialog" box.
       @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 calendar instance's settings (anonymous object)
       @param  pos       int[2] - coordinates for the dialog's position within the screen
            leave empty for default (screen centre)
       @return void */
    dialogCalendar: function(dateText, onSelect, settings, pos) {
        var inst = this._dialogInst; // internal instance
        if (!inst) {
            inst = this._dialogInst = new PopUpCalInstance({}, false);
            this._dialogInput = $('<input type="text" size="1" style="position: absolute; top: -100px;"/>');
            this._dialogInput.keydown(this._doKeyDown);
            $('body').append(this._dialogInput);
            this._dialogInput[0]._calId = inst._id;
        }
        extendRemove(inst._settings, settings || {});
        this._dialogInput.val(dateText);
        
        this._pos = pos || // should use actual width/height below
            [($(window).width() / 2) - 100, ($(window).height() / 2) - 150];
        
        // Get position of window
        if ( document.documentElement && (document.documentElement.scrollTop)) {
            browserTopY = document.documentElement.scrollTop;
        }
        else {
            browserTopY = document.body.scrollTop;
        }   
        this._pos[1] = this._pos[1] + browserTopY; // add the browser position to the height

        // 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._calendarDiv.addClass('calendar_dialog');
        this.showFor(this._dialogInput[0]);
        if ($.blockUI) {
            $.blockUI(this._calendarDiv);
        }
    },

    /* Enable the input field(s) for entry.
       @param  inputs  element - single input field or
                       string - the ID or other jQuery selector of the input field(s) or
                       object - jQuery collection of input fields
       @return void */
    enableFor: function(inputs) {
        inputs = (inputs.jquery ? inputs : $(inputs));
        inputs.each(function() {
            this.disabled = false;
            $('../button.calendar_trigger', this).each(function() { this.disabled = false; });
            $('../img.calendar_trigger', this).css({opacity:'1.0',cursor:''});
            var $this = this;
            popUpCal._disabledInputs = $.map(popUpCal._disabledInputs,
                function(value) { return (value == $this ? null : value); }); // delete entry
        });
    },

    /* Disable the input field(s) from entry.
       @param  inputs  element - single input field or
                       string - the ID or other jQuery selector of the input field(s) or
                       object - jQuery collection of input fields
       @return void */
    disableFor: function(inputs) {
        inputs = (inputs.jquery ? inputs : $(inputs));
        inputs.each(function() {
            this.disabled = true;
            $('../button.calendar_trigger', this).each(function() { this.disabled = true; });
            $('../img.calendar_trigger', this).css({opacity:'0.5',cursor:'default'});
            var $this = this;
            popUpCal._disabledInputs = $.map(popUpCal._disabledInputs,
                function(value) { return (value == $this ? null : value); }); // delete entry
            popUpCal._disabledInputs[popUpCal._disabledInputs.length] = this;
        });
    },

    /* Update the settings for a calendar attached to an input field or division.
       @param  control   element - the input field or div/span attached to the calendar or
                         string - the ID or other jQuery selector of the input field
       @param  settings  object - the new settings to update
       @return void */
    reconfigureFor: function(control, settings) {
        control = (typeof control == 'string' ? $(control)[0] : control);
        var inst = this._getInst(control._calId);
        if (inst) {
            extendRemove(inst._settings, settings || {});
            this._updateCalendar(inst);
        }
    },

    /* Set the date for a calendar attached to an input field or division.
       @param  control  element - the input field or div/span attached to the calendar or
                        string - the ID or other jQuery selector of the input field
       @param  date     Date - the new date
       @return void */
    setDateFor: function(control, date) {
        control = (typeof control == 'string' ? $(control)[0] : control);
        var inst = this._getInst($(control)[0]._calId);
        if (inst) {
            inst._setDate(date);
            this._updateCalendar(inst);
        }
    },

    /* Retrieve the date for a calendar attached to an input field or division.
       @param  control  element - the input field or div/span attached to the calendar or
                        string - the ID or other jQuery selector of the input field
       @return Date - the current date */
    getDateFor: function(control) {
        control = (typeof control == 'string' ? $(control)[0] : control);
        var inst = this._getInst(control._calId);
        return (inst ? inst._getDate() : null);
    },

    /* Pop-up the calendar for a given input field.
       @param  target  element - the input field attached to the calendar or
                       string - the ID or other jQuery selector of the input field
       @return void */
    showFor: function(target) {
        target = (typeof target == 'string' ? $(target)[0] : target);
        var input = ((target.nodeName && target.nodeName.toLowerCase() == 'input' || $(target).hasClass('calendar_trigger')) ? target : this);
        if (input.nodeName.toLowerCase() != 'input') { // find from button/image trigger
            if (popUpCal._buttons[input.id]) {
                input = $('#'+popUpCal._buttons[input.id])[0];
            }
            else {
                input = $('input', input.parentNode)[0];
            }
        }
        if (popUpCal._lastInput == input) { // already here
            return false;
        }
        for (var i = 0; i < popUpCal._disabledInputs.length; i++) {  // check not disabled
            if (popUpCal._disabledInputs[i] == input) {
                return false;
            }
        }
        var inst = popUpCal._getInst(input._calId);
        var fieldSettings = inst._get('fieldSettings');
        extendRemove(inst._settings, (fieldSettings ? fieldSettings(input) : {}));
        popUpCal.hideCalendar(inst, '');
        popUpCal._lastInput = input;
        inst._setDateFromField(input);
        if (popUpCal._inDialog) { // hide cursor
            input.value = '';
        }
        if (!popUpCal._pos) { // position below input
            popUpCal._pos = popUpCal._findPos(input);
            popUpCal._pos[1] += input.offsetHeight; // add the height
        }
        inst._calendarDiv.css('position', (popUpCal._inDialog && $.blockUI ? 'static' : 'absolute')).
            css('left', popUpCal._pos[0] + 'px').css('top', popUpCal._pos[1] + 'px');
        popUpCal._pos = null;
        popUpCal._showCalendar(inst);
        return false;
    },

    /* Construct and display the calendar. */
    _showCalendar: function(id) {
        var inst = this._getInst(id);
        inst._rangeStart = null;
        this._updateCalendar(inst);
        if (!inst._inline) {
            var speed = inst._get('speed');
            var postProcess = function() {
                popUpCal._popUpShowing = true;
                popUpCal._afterShow(inst);
            };
            inst._calendarDiv.show(speed, postProcess);
            if (speed == '') {
                postProcess();
            }
            if (inst._input[0].type != 'hidden') {
                inst._input[0].focus();
            }
            this._curInst = inst;
        }
    },

    /* Generate the calendar content. */
    _updateCalendar: function(inst) {
        inst._calendarDiv.empty().append(inst._generateCalendar());
        if (inst._get('numberOfMonths') != 1) {
            inst._calendarDiv.addClass('calendar_multi');
        } 
        else {
            inst._calendarDiv.removeClass('calendar_multi');
        }
        if (inst._input && inst._input[0].type != 'hidden') {
            inst._input[0].focus();
        }
    },

    /* Tidy up after displaying the calendar. */
    _afterShow: function(inst) {
        var numMonths = inst._get('numberOfMonths'); // fix width for dynamic number of calendars
        numMonths = (numMonths == null ? 1 : (typeof numMonths == 'number' ? numMonths : numMonths[1]));
        inst._calendarDiv.width(numMonths * $('.calendar', inst._calendarDiv[0]).width()+7);
        if ($.browser.msie) { // fix IE < 7 select problems
            $('#calendar_cover').css({width: inst._calendarDiv.width() + 4,
                height: inst._calendarDiv.height() + 4});
        }
        // re-position on screen if necessary
        var pos = popUpCal._findPos(inst._input[0]);
        browserWidth = $(window).width();
        if (document.documentElement && (document.documentElement.scrollLeft)) {
            browserX = document.documentElement.scrollLeft; 
        }
        else {
            browserX = document.body.scrollLeft;
        }
        // reposition calendar if outside the browser window
        if ((inst._calendarDiv.offset().left + inst._calendarDiv.width()) > (browserWidth + browserX)) {
            inst._calendarDiv.css('left', (pos[0] + $(inst._input[0]).width() - inst._calendarDiv.width()) + 'px');
        }
        browserHeight = $(window).height();
        if (document.documentElement && (document.documentElement.scrollTop)) {
            browserTopY = document.documentElement.scrollTop;
        } 
        else {
            browserTopY = document.body.scrollTop;
        }
        // reposition calendar if outside the browser window
        if ((inst._calendarDiv.offset().top + inst._calendarDiv.height()) > (browserTopY + browserHeight) ) {
            inst._calendarDiv.css('top', (pos[1] - inst._calendarDiv.height()) + 'px');
        }
    },

    /* Hide the calendar from view.
       @param  id     string/object - the ID of the current calendar instance,
            or the instance itself
       @param  speed  string - the speed at which to close the calendar
       @return void */
    hideCalendar: function(id, speed) {
        var inst = this._getInst(id);
        var rangeSelect = inst._get('rangeSelect');
        if (rangeSelect && this._stayOpen) {
            this._appendDate = true;
            this._selectDate(id, inst._formatDate());
        }
        this._stayOpen = false;
        if (this._popUpShowing) {
            speed = (speed != null ? speed : inst._get('speed'));
            inst._calendarDiv.hide(speed, function() {
                popUpCal._tidyDialog(inst);
            });
            if (speed == '') {
                this._tidyDialog(inst);
            }
            this._popUpShowing = false;
            this._lastInput = null;
            inst._settings.prompt = null;
            if (this._inDialog) {
                this._dialogInput.css('position', 'absolute').
                    css('left', '0px').css('top', '-100px');
                if ($.blockUI) {
                    $.unblockUI();
                    $('body').append(this._calendarDiv);
                }
            }
            this._inDialog = false;
        }
        this._curInst = null;
    },

    /* Tidy up after a dialog display. */
    _tidyDialog: function(inst) {
        inst._calendarDiv.removeClass('calendar_dialog');
        $('.calendar_prompt', inst._calendarDiv).remove();
    },

    /* Close calendar if clicked elsewhere. */
    _checkExternalClick: function(event) {
        if (!popUpCal._curInst) {
            return;
        }
        var target = $(event.target);
        if( (target.parents("#calendar_div").length == 0)
            && (target.attr('class') != 'calendar_trigger')
            && popUpCal._popUpShowing 
            && !(popUpCal._inDialog && $.blockUI) )
        {
            popUpCal.hideCalendar(popUpCal._curInst, '');
        }
    },

    /* Adjust one of the date sub-fields. */
    _adjustDate: function(id, offset, period) {
        var inst = this._getInst(id);
        inst._adjustDate(offset, period);
        this._updateCalendar(inst);
    },

    /* Action for current link. */
    _gotoToday: function(id) {
        var date = new Date();
        var inst = this._getInst(id);
        inst._selectedDay = date.getDate();
        inst._selectedMonth = date.getMonth();
        inst._selectedYear = date.getFullYear();
        this._adjustDate(inst);
    },

    /* Action for selecting a new month/year. */
    _selectMonthYear: function(id, select, period) {
        var inst = this._getInst(id);
        inst._selectingMonthYear = false;
        inst[period == 'M' ? '_selectedMonth' : '_selectedYear'] =
            select.options[select.selectedIndex].value - 0;
        this._adjustDate(inst);
    },

    /* Restore input focus after not changing month/year. */
    _clickMonthYear: function(id) {
        var inst = this._getInst(id);
        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, a) {
        var inst = this._getInst(id);
        var dayNames = inst._get('dayNames');
        var value = a.firstChild.nodeValue;
        for (var i = 0; i < 7; i++) {
            if (dayNames[i] == value) {
                inst._settings.firstDay = i;
                break;
            }
        }
        this._updateCalendar(inst);
    },

    /* Action for selecting a day. */
    _selectDay: function(id, month, year, td) {
        var inst = this._getInst(id);
        var rangeSelect = inst._get('rangeSelect');
        if (rangeSelect) {
            if (!this._stayOpen) {
                this._stayOpen = true;
                $('.calendar td').removeClass('calendar_currentDay');
                $(td).addClass('calendar_currentDay');
            } 
            else {
                this._appendDate = true;
                this._stayOpen = false;
            }
        }
        inst._selectedDay = $("a", td).html();
        inst._selectedMonth = month;
        inst._selectedYear = year;
        this._selectDate(id);
        if (this._stayOpen) {
            inst._endDay = inst._endMonth = inst._endYear = null;
            inst._rangeStart = new Date(inst._selectedYear, inst._selectedMonth, inst._selectedDay);
            this._updateCalendar(inst);
        }
        else if (rangeSelect) {
            if (inst._inline) {
                inst._endDay = inst._currentDay;
                inst._endMonth = inst._currentMonth;
                inst._endYear = inst._currentYear;
                inst._selectedDay = inst._currentDay = inst._rangeStart.getDate();
                inst._selectedMonth = inst._currentMonth = inst._rangeStart.getMonth();
                inst._selectedYear = inst._currentYear = inst._rangeStart.getFullYear();
                inst._rangeStart = null;
                this._updateCalendar(inst);
            }
            else {
                inst._rangeStart = null;
            }
        }
    },

    /* Erase the input field and hide the calendar. */
    _clearDate: function(id) {
        this._selectDate(id, '');
    },

    /* Update the input field with the selected date. */
    _selectDate: function(id, dateStr) {
        var inst = this._getInst(id);
        dateStr = (dateStr != null ? dateStr : inst._formatDate());
        if (this._appendDate) {
            dateStr = inst._formatDate(inst._rangeStart) + inst._get('rangeSeparator') + dateStr;
            this._appendDate = false;
        }
        if (inst._input) {
            inst._input.val(dateStr);
        }
        var onSelect = inst._get('onSelect');
        if (onSelect) {
            onSelect(dateStr, inst);  // trigger custom callback
        }
        else {
            inst._input.trigger('change'); // fire the change event
        }
        if (inst._inline) {
            this._updateCalendar(inst);
        }
        else {
            if (!this._stayOpen) {
                this.hideCalendar(inst, inst._get('speed'));
            }
        }
    },

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

/* Individualised settings for calendars applied to one or more related inputs.
   Instances are managed and manipulated through the PopUpCal manager. */
function PopUpCalInstance(settings, inline) {
    this._id = popUpCal._register(this);
    this._selectedDay = 0;
    this._selectedMonth = 0; // 0-11
    this._selectedYear = 0; // 4-digit year
    this._input = null; // The attached input field
    this._inline = inline; // True if showing inline, false if used in a popup
    this._calendarDiv = (!inline ? popUpCal._calendarDiv :
        $('<div id="calendar_div_' + this._id + '" class="calendar_inline"></div>'));
    // customise the calendar object - uses manager defaults if not overridden
    this._settings = extendRemove({}, settings || {}); // clone
    if (inline) {
        this._setDate(this._getDefaultDate());
    }
}

$.extend(PopUpCalInstance.prototype, {
    /* Get a setting value, defaulting if necessary. */
    _get: function(name) {
        return (this._settings[name] != null ? this._settings[name] : popUpCal._defaults[name]);
    },

    /* Parse existing date and initialise calendar. */
    _setDateFromField: function(input) {
        this._input = $(input);
        var dateFormat = this._get('dateFormat');
        var currentDate = this._input.val().split(dateFormat.charAt(3));
        this._endDay = this._endMonth = this._endYear = null;
        if (currentDate.length == 3) {
            this._currentDay = parseInt(currentDate[dateFormat.indexOf('D')], 10);
            this._currentMonth = parseInt(currentDate[dateFormat.indexOf('M')], 10) - 1;
            this._currentYear = parseInt(currentDate[dateFormat.indexOf('Y')], 10);
        } 
        else if (currentDate.length == 5) { // if it's a date range
            currentDateArray = this._input.val().split(this._get('rangeSeparator'));
            currentDate = currentDateArray[0].split(dateFormat.charAt(3));
            this._currentDay = parseInt(currentDate[dateFormat.indexOf('D')], 10);
            this._currentMonth = parseInt(currentDate[dateFormat.indexOf('M')], 10) - 1;
            this._currentYear = parseInt(currentDate[dateFormat.indexOf('Y')], 10);
            currentDate = currentDateArray[1].split(dateFormat.charAt(3));
            this._endDay = parseInt(currentDate[dateFormat.indexOf('D')], 10);
            this._endMonth = parseInt(currentDate[dateFormat.indexOf('M')], 10) - 1;
            this._endYear = parseInt(currentDate[dateFormat.indexOf('Y')], 10);
        }
        else {
            var date = this._getDefaultDate();
            this._currentDay = date.getDate();
            this._currentMonth = date.getMonth();
            this._currentYear = date.getFullYear();
        }
        this._selectedDay = this._currentDay;
        this._selectedMonth = this._currentMonth;
        this._selectedYear = this._currentYear;
        this._adjustDate();
    },
    
    /* Retrieve the default date shown on opening. */
    _getDefaultDate: function() {
        var offsetDate = function(offset) {
            var date = new Date();
            date.setDate(date.getDate() + offset);
            return date;
        };
        var defaultDate = this._get('defaultDate');
        return (defaultDate == null ? new Date() :
            (typeof defaultDate == 'number' ? offsetDate(defaultDate) : defaultDate));
    },

    /* Set the date directly. */
    _setDate: function(date) {
        this._selectedDay = this._currentDay = date.getDate();
        this._selectedMonth = this._currentMonth = date.getMonth();
        this._selectedYear = this._currentYear = date.getFullYear();
        this._adjustDate();
    },

    /* Retrieve the date directly. */
    _getDate: function() {
        return new Date(this._currentYear, this._currentMonth, this._currentDay);
    },

    /* Generate the HTML for the current state of the calendar. */
    _generateCalendar: function() {
        var today = new Date();
        today = new Date(today.getFullYear(), today.getMonth(), today.getDate()); // clear time
        // build the calendar HTML
        var prompt = this._get('prompt');
        var closeAtTop = this._get('closeAtTop');
        var hideIfNoPrevNext = this._get('hideIfNoPrevNext');
        var numMonths = this._get('numberOfMonths');
        var stepMonths = this._get('stepMonths');
        var isMultiMonth = (numMonths != 1);
        var minDate = this._getMinDate();
        var maxDate = this._get('maxDate');
        var drawMonth = this._selectedMonth;
        var drawYear = this._selectedYear;
        var controls = '<div class="calendar_control">' +
            '<div class="calendar_clear"><a href="javascript:void(0);" onclick="popUpCal._clearDate(' + this._id + ');">' +
            this._get('clearText') + '</a></div>' +
            '<div class="calendar_close"><a href="javascript:void(0);" onclick="popUpCal.hideCalendar(' + this._id + ');">' +
            this._get('closeText') + '</a></div></div>'+this._generateMonthYearHeader(drawMonth, drawYear, minDate, maxDate, 0, 0);
        numMonths = (numMonths == null ? [1, 1] : (typeof numMonths == 'number' ? [1, numMonths] : numMonths));
        // controls and links
        var html = (prompt ? '<div class="calendar_prompt">' + prompt + '</div>' : '') +
            (closeAtTop && !this._inline ? controls : '') +
            '<div class="calendar_links"><div class="calendar_prev">' +
            (this._canAdjustMonth(-1) ? '<a href="javascript:void(0);" onclick="popUpCal._adjustDate(' + this._id +
            ', -' + stepMonths + ', \'M\');">' + this._get('prevText') + '</a>' :
            (hideIfNoPrevNext ? '' : '<label>' + this._get('prevText') + '</label>')) + '</div>' +
            (this._isInRange(today) ? '<div class="calendar_current"><a href="javascript:void(0);" ' +
            'onclick="popUpCal._gotoToday(' + this._id + ');">' + this._get('currentText') + '</a></div>' : '') +
            '<div class="calendar_next">' +
            (this._canAdjustMonth(+1) ? '<a href="javascript:void(0);" onclick="popUpCal._adjustDate(' + this._id +
            ', +' + stepMonths + ', \'M\');">' + this._get('nextText') + '</a>' :
            (hideIfNoPrevNext ? '' : '<label>' + this._get('nextText') + '</label>')) + '</div></div>';
        for (var row = 0; row < numMonths[0]; row++) {
        for (var col = 0; col < numMonths[1]; col++) {
            html += '<div class="calendar_oneMonth' + (col == 0 ? ' calendar_newRow' : '') + '" id="cal-wrapper">' +
                 // draw month headers
                '<table class="calendar" cellpadding="0" cellspacing="0"><thead>' + 
                '<tr class="calendar_titleRow">';
            var firstDay = this._get('firstDay');
            var changeFirstDay = this._get('changeFirstDay');
            var dayNames = this._get('dayNames');
            for (var dow = 0; dow < 7; dow++) { // days of the week
                html += '<td>' + (!changeFirstDay ? '' :
                    '<a href="javascript:void(0);" onclick="popUpCal._changeFirstDay(' + this._id + ', this);">') +
                    dayNames[(dow + firstDay) % 7] + (changeFirstDay ? '</a>' : '') + '</td>';
            }
            html += '</tr></thead><tbody>';
            var daysInMonth = this._getDaysInMonth(drawYear, drawMonth);
            this._selectedDay = Math.min(this._selectedDay, daysInMonth);
            var leadDays = (this._getFirstDayOfMonth(drawYear, drawMonth) - firstDay + 7) % 7;
            var currentDate = new Date(this._currentYear, this._currentMonth, this._currentDay);
            var endDate = this._endDay ? new Date(this._endYear, this._endMonth, this._endDay) : currentDate;
            var selectedDate = new Date(drawYear, drawMonth, this._selectedDay);
            var printDate = new Date(drawYear, drawMonth, 1 - leadDays);
            var numRows = (isMultiMonth ? 6 : Math.ceil((leadDays + daysInMonth) / 7)); // calculate the number of rows to generate
            var customDate = this._get('customDate');
            var showOtherMonths = this._get('showOtherMonths');
            var count = 0;
            for (var dRow = 0; dRow < numRows; dRow++) { // create calendar rows
                html += '<tr class="calendar_daysRow">';
                for (var dow = 0; dow < 7; dow++) { // create calendar days
                    var customSettings = (customDate ? customDate(printDate) : [true, '']);
                    var otherMonth = (printDate.getMonth() != drawMonth);
                    var unselectable = otherMonth || !customSettings[0] ||
                        (minDate && printDate < minDate) || (maxDate && printDate > maxDate);
                    html += '<td class="calendar_daysCell' +
                        ((dow + firstDay + 6) % 7 >= 5 ? ' calendar_weekEndCell' : '') + // highlight weekends
                        (otherMonth ? ' calendar_otherMonth' : '') + // highlight days from other months
                        (printDate.getTime() == selectedDate.getTime() && drawMonth == this._selectedMonth ? ' calendar_daysCellOver' : '') + // highlight selected day
                        (unselectable ? ' calendar_unselectable' : '') +  // highlight unselectable days
                        (otherMonth && !showOtherMonths ? '' : ' ' + customSettings[1] + // highlight custom dates
                        (printDate.getTime() >= currentDate.getTime() && printDate.getTime() <= endDate.getTime() ?  // in current range
                        ' calendar_currentDay' : // highlight selected day
                        (printDate.getTime() == today.getTime() ? ' calendar_today' : ''))) + '"' + // highlight today (if different)
                        (unselectable ? '' : ' onmouseover="$(this).addClass(\'calendar_daysCellOver\');"' +
                        ' onmouseout="$(this).removeClass(\'calendar_daysCellOver\');"' +
                        ' onclick="popUpCal._selectDay(' + this._id + ',' + drawMonth + ',' + drawYear + ', this);"') + '>' + // actions
                        (otherMonth ? (showOtherMonths ? printDate.getDate() : '&nbsp;') : // display for other months
                        (unselectable ? printDate.getDate() : '<a href="javascript:void(0);">' + printDate.getDate() + '</a>')) + '</td>'; // display for this month
                    printDate.setDate(printDate.getDate() + 1);
                }
                html += '</tr>';
            }
            drawMonth++;
            if (drawMonth > 11) {
                drawMonth = 0;
                drawYear++;
            }
            html += '</tbody></table></div>';
        }
        }
        html += (!closeAtTop && !this._inline ? controls : '') +
            '<div id="cal-bottom"></div><div style="clear: both;"></div>' + (!$.browser.msie ? '' :
            '<!--[if lte IE 6.5]><iframe src="javascript:false;" class="calendar_cover"></iframe><![endif]-->');
        return html;
    },
    
    /* Generate the month and year header. */
    _generateMonthYearHeader: function(drawMonth, drawYear, minDate, maxDate, secondary) {
        var html = '<div class="calendar_header">';
        // month selection
        var monthNames = this._get('monthNames');
        if (secondary || !this._get('changeMonth')) {
            html += monthNames[drawMonth] + '&nbsp;';
        }
        else {
            var inMinYear = (minDate && minDate.getFullYear() == drawYear);
            var inMaxYear = (maxDate && maxDate.getFullYear() == drawYear);
            html += '<select class="calendar_newMonth" ' +
                'onchange="popUpCal._selectMonthYear(' + this._id + ', this, \'M\');" ' +
                'onclick="popUpCal._clickMonthYear(' + this._id + ');">';
            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('changeYear')) {
            html += drawYear;
        }
        else {
            // determine range of years to display
            var years = this._get('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 = drawYear + parseInt(years[0], 10);
                endYear = drawYear + 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="calendar_newYear" ' +
                'onchange="popUpCal._selectMonthYear(' + this._id + ', this, \'Y\');" ' +
                'onclick="popUpCal._clickMonthYear(' + this._id + ');">';
            for (; year <= endYear; year++) {
                html += '<option value="' + year + '"' +
                    (year == drawYear ? ' selected="selected"' : '') +
                    '>' + year + '</option>';
            }
            html += '</select>';
        }
        html += '</div>'; // Close calendar_header
        return html;
    },

    /* Adjust one of the date sub-fields. */
    _adjustDate: function(offset, period) {
        var date = new Date(this._selectedYear + (period == 'Y' ? offset : 0),
            this._selectedMonth + (period == 'M' ? offset : 0),
            this._selectedDay + (period == 'D' ? offset : 0));
        // ensure it is within the bounds set
        var minDate = this._getMinDate();
        var maxDate = this._get('maxDate');
        date = (minDate && date < minDate ? minDate : date);
        date = (maxDate && date > maxDate ? maxDate : date);
        this._selectedDay = date.getDate();
        this._selectedMonth = date.getMonth();
        this._selectedYear = date.getFullYear();
    },

    /* Determine the current minimum date - may be overridden for a range. */
    _getMinDate: function() {
        var minDate = this._get('minDate');
        return (!this._rangeStart ? minDate :
            (!minDate || this._rangeStart > minDate ? this._rangeStart : minDate));
    },

    /* 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(offset) {
        var date = new Date(this._selectedYear, this._selectedMonth + offset, 1);
        if (offset < 0) {
            date.setDate(this._getDaysInMonth(date.getFullYear(), date.getMonth()));
        }
        return this._isInRange(date);
    },

    /* Is the given date in the accepted range? */
    _isInRange: function(date) {
        var minDate = this._get('minDate');
        var maxDate = this._get('maxDate');
        return ((!minDate || date >= minDate) && (!maxDate || date <= maxDate));
    },

    /* Format the given date for display. */
    _formatDate: function(day, month, year) {
        if (!day) {
            day = this._currentDay = this._selectedDay;
            month = this._currentMonth = this._selectedMonth;
            year = this._currentYear = this._selectedYear;
        }
        else if (typeof day == 'object') {
            year = day.getFullYear();
            month = day.getMonth();
            day = day.getDate();
        }
        month++; // adjust javascript month
        var dateFormat = this._get('dateFormat');
        var dateString = '';
        for (var i = 0; i < 3; i++) {
            dateString += dateFormat.charAt(3) +
                (dateFormat.charAt(i) == 'D' ? (day < 10 ? '0' : '') + day :
                (dateFormat.charAt(i) == 'M' ? (month < 10 ? '0' : '') + month :
                (dateFormat.charAt(i) == 'Y' ? year : '?')));
        }
        return dateString.substring(dateFormat.charAt(3) ? 1 : 0);
    }
});

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

/* Attach the calendar to a jQuery selection.
   @param  settings  object - the new settings to use for this calendar instance (anonymous)
   @return jQuery object - for chaining further calls */
$.fn.calendar = function(settings) {
    return this.each(function() {
        // check for settings on the control itself - in namespace 'cal:'
        var inlineSettings = null;
        for (attrName in popUpCal._defaults) {
            var attrValue = this.getAttribute('cal:' + attrName);
            if (attrValue) {
                inlineSettings = inlineSettings || {};
                try {
                    inlineSettings[attrName] = eval(attrValue);
                }
                catch (err) {
                    inlineSettings[attrName] = attrValue;
                }
            }
        }
        var nodeName = this.nodeName.toLowerCase();
        if (nodeName == 'input') {
            var instSettings = (inlineSettings ? $.extend($.extend({}, settings || {}),
                inlineSettings || {}) : settings); // clone and customise
            var inst = (inst && !inlineSettings ? inst :
                new PopUpCalInstance(instSettings, false));
            popUpCal._connectCalendar(this, inst);
        } 
        else if (nodeName == 'div' || nodeName == 'span') {
            var instSettings = $.extend($.extend({}, settings || {}),
                inlineSettings || {}); // clone and customise
            var inst = new PopUpCalInstance(instSettings, true);
            popUpCal._inlineCalendar(this, inst);
        }
    });
};

/* Initialise the calendar. */
$(document).ready(function() {
    popUpCal = new PopUpCal(); // singleton instance
});

})(jQuery);