// Calendar: a Javascript class for Mootools that adds accessible and unobtrusive date pickers to your form elements <http://electricprism.com/aeron/calendar>
// Calendar RC4, Copyright (c) 2007 Aeron Glemann <http://electricprism.com/aeron>, MIT Style License.
// Mootools 1.2 compatibility by Davorin Å ego

var Calendar = new Class({

    options: {
        blocked: [], // blocked dates 
        classes: [], // ['calendar', 'prev', 'next', 'month', 'year', 'today', 'invalid', 'valid', 'inactive', 'active', 'hover', 'hilite']
        days: ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'], // days of the week starting at sunday
        direction: 0, // -1 past, 0 past + future, 1 future
        draggable: true,
        months: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
        navigation: 1, // 0 = no nav; 1 = single nav for month; 2 = dual nav for month and year
        offset: 0, // first day of the week: 0 = sunday, 1 = monday, etc..
        onHideStart: Class.empty,
        onHideComplete: Class.empty,
        onShowStart: Class.empty,
        onShowComplete: Class.empty,
        pad: 1, // padding between multiple calendars
        tweak: {
            x: 0,
            y: 0
        } // tweak calendar positioning
    },
    
    // initialize: calendar constructor
    // @param obj (obj) a js object containing the form elements and format strings { id: 'format', id: 'format' etc }
    // @param props (obj) optional properties
    
    initialize: function(obj, options){
        // basic error checking
        if (!obj) {
            return false;
        }
        
        this.setOptions(options);
        
        // create our classes array
        var keys = ['calendar', 'prev', 'next', 'month', 'year', 'today', 'invalid', 'valid', 'inactive', 'active', 'hover', 'hilite'];
        
        var values = keys.map(function(key, i){
            if (this.options.classes[i]) {
                if (this.options.classes[i].length) {
                    key = this.options.classes[i];
                }
            }
            return key;
        }, this);
        
        this.classes = values.associate(keys);
        
        // create cal element with css styles required for proper cal functioning
        this.calendar = new Element('div', {
            'styles': {
                left: '-1000px',
                opacity: 0,
                position: 'absolute',
                top: '-1000px',
                zIndex: 1000
            }
        }).addClass(this.classes.calendar).injectInside(document.body);
        
        // iex 6 needs a transparent iframe underneath the calendar in order to not allow select elements to render through
        if (window.ie6) {
            this.iframe = new Element('iframe', {
                'styles': {
                    left: '-1000px',
                    position: 'absolute',
                    top: '-1000px',
                    zIndex: 999
                }
            }).injectInside(document.body);
            this.iframe.style.filter = 'progid:DXImageTransform.Microsoft.Alpha(style=0,opacity=0)';
        }
        
        // initialize fade method
        this.fx = new Fx.Tween(this.calendar, {
            onStart: function(){
                if (this.calendar.getStyle('opacity') == 0) { // show
                    if (window.ie6) {
                        this.iframe.setStyle('display', 'block');
                    }
                    this.calendar.setStyle('display', 'block');
                    this.fireEvent('onShowStart', this.element);
                }
                else { // hide
                    this.fireEvent('onHideStart', this.element);
                }
            }
.bind(this)            ,
            onComplete: function(){
                if (this.calendar.getStyle('opacity') == 0) { // hidden
                    this.calendar.setStyle('display', 'none');
                    if (window.ie6) {
                        this.iframe.setStyle('display', 'none');
                    }
                    this.fireEvent('onHideComplete', this.element);
                }
                else { // shown
                    this.fireEvent('onShowComplete', this.element);
                }
            }
.bind(this)
        });
        
        // initialize drag method
        if (window.Drag && this.options.draggable) {
            this.drag = new Drag.Move(this.calendar, {
                onDrag: function(){
                    if (window.ie6) {
                        this.iframe.setStyles({
                            left: this.calendar.style.left,
                            top: this.calendar.style.top
                        });
                    }
                }
.bind(this)
            });
        }
        
        // create calendars array
        this.calendars = [];
        
        var id = 0;
        var d = new Date(); // today
        d.setDate(d.getDate() + this.options.direction.toInt()); // correct today for directional offset
        for (var i in obj) {
            var cal = {
                button: new Element('button', {
                    'type': 'button'
                }),
                el: $(i),
                els: [],
                id: id++,
                month: d.getMonth(),
                visible: false,
                year: d.getFullYear()
            };
            
            // fix for bad element (naughty, naughty element!)
            if (!this.element(i, obj[i], cal)) {
                continue;
            }
            
            cal.el.addClass(this.classes.calendar);
            
            // create cal button
            cal.button.addClass(this.classes.calendar).addEvent('click', function(cal){
                this.toggle(cal);
            }
.pass(cal, this)).injectAfter(cal.el);
            
            // read in default value
            cal.val = this.read(cal);
            
            $extend(cal, this.bounds(cal)); // abs bounds of calendar
            $extend(cal, this.values(cal)); // valid days, months, years
            this.rebuild(cal);
            
            this.calendars.push(cal); // add to cals array		
        }
    },
    
    
    // blocked: returns an array of blocked days for the month / year
    // @param cal (obj)
    // @returns blocked days (array)
    
    blocked: function(cal){
        var blocked = [];
        var offset = new Date(cal.year, cal.month, 1).getDay(); // day of the week (offset)
        var last = new Date(cal.year, cal.month + 1, 0).getDate(); // last day of this month
        this.options.blocked.each(function(date){
            var values = date.split(' ');
            
            // preparation
            for (var i = 0; i <= 3; i++) {
                if (!values[i]) {
                    values[i] = (i == 3) ? '' : '*';
                } // make sure blocked date contains values for at least d, m and y
                values[i] = values[i].contains(',') ? values[i].split(',') : new Array(values[i]); // split multiple values
                var count = values[i].length - 1;
                for (var j = count; j >= 0; j--) {
                    if (values[i][j].contains('-')) { // a range
                        var val = values[i][j].split('-');
                        for (var k = val[0]; k <= val[1]; k++) {
                            if (!values[i].contains(k)) {
                                values[i].push(k + '');
                            }
                        }
                        values[i].splice(j, 1);
                    }
                }
            }
            
            // execution
            if (values[2].contains(cal.year + '') || values[2].contains('*')) {
                if (values[1].contains(cal.month + 1 + '') || values[1].contains('*')) {
                    values[0].each(function(val){ // if blocked value indicates this month / year
                        if (val > 0) {
                            blocked.push(val.toInt());
                        } // add date to blocked array
                    });
                    
                    if (values[3]) { // optional value for day of week
                        for (var i = 0; i < last; i++) {
                            var day = (i + offset) % 7;
                            
                            if (values[3].contains(day + '')) {
                                blocked.push(i + 1); // add every date that corresponds to the blocked day of the week to the blocked array
                            }
                        }
                    }
                }
            }
        }, this);
        
        return blocked;
    },
    
    
    // bounds: returns the start / end bounds of the calendar
    // @param cal (obj)
    // @returns obj	
    
    bounds: function(cal){
        // 1. first we assume the calendar has no bounds (or a thousand years in either direction)
        
        // by default the calendar will accept a millennium in either direction
        var start = new Date(1000, 0, 1); // jan 1, 1000
        var end = new Date(2999, 11, 31); // dec 31, 2999
        // 2. but if the cal is one directional we adjust accordingly
        var date = new Date().getDate() + this.options.direction.toInt();
        
        if (this.options.direction > 0) {
            start = new Date();
            start.setDate(date + this.options.pad * cal.id);
        }
        
        if (this.options.direction < 0) {
            end = new Date();
            end.setDate(date - this.options.pad * (this.calendars.length - cal.id - 1));
        }
        
        // 3. then we can further filter the limits by using the pre-existing values in the selects
        cal.els.each(function(el){
            if (el.get('tag') == 'select') {
                if (el.format.test('(y|Y)')) { // search for a year select
                    var years = [];
                    
                    el.getChildren().each(function(option){ // get options
                        var values = this.unformat(option.value, el.format);
                        
                        if (!years.contains(values[0])) {
                            years.push(values[0]);
                        } // add to years array
                    }, this);
                    
                    years.sort(this.sort);
                    
                    if (years[0] > start.getFullYear()) {
                        d = new Date(years[0], start.getMonth() + 1, 0); // last day of new month
                        if (start.getDate() > d.getDate()) {
                            start.setDate(d.getDate());
                        }
                        
                        start.setYear(years[0]);
                    }
                    
                    if (years.getLast() < end.getFullYear()) {
                        d = new Date(years.getLast(), end.getMonth() + 1, 0); // last day of new month
                        if (end.getDate() > d.getDate()) {
                            end.setDate(d.getDate());
                        }
                        
                        end.setYear(years.getLast());
                    }
                }
                
                if (el.format.test('(F|m|M|n)')) { // search for a month select
                    var months_start = [];
                    var months_end = [];
                    
                    el.getChildren().each(function(option){ // get options
                        var values = this.unformat(option.value, el.format);
                        
                        if ($type(values[0]) != 'number' || values[0] == years[0]) { // if it's a year / month combo for curr year, or simply a month select
                            if (!months_start.contains(values[1])) {
                                months_start.push(values[1]);
                            } // add to months array
                        }
                        
                        if ($type(values[0]) != 'number' || values[0] == years.getLast()) { // if it's a year / month combo for curr year, or simply a month select
                            if (!months_end.contains(values[1])) {
                                months_end.push(values[1]);
                            } // add to months array
                        }
                    }, this);
                    
                    months_start.sort(this.sort);
                    months_end.sort(this.sort);
                    
                    if (months_start[0] > start.getMonth()) {
                        d = new Date(start.getFullYear(), months_start[0] + 1, 0); // last day of new month
                        if (start.getDate() > d.getDate()) {
                            start.setDate(d.getDate());
                        }
                        
                        start.setMonth(months_start[0]);
                    }
                    
                    if (months_end.getLast() < end.getMonth()) {
                        d = new Date(start.getFullYear(), months_end.getLast() + 1, 0); // last day of new month
                        if (end.getDate() > d.getDate()) {
                            end.setDate(d.getDate());
                        }
                        
                        end.setMonth(months_end.getLast());
                    }
                }
            }
        }, this);
        
        return {
            'start': start,
            'end': end
        };
    },
    
    
    // caption: returns the caption element with header and navigation
    // @param cal (obj)
    // @returns caption (element)
    
    caption: function(cal){
        // start by assuming navigation is allowed
        var navigation = {
            prev: {
                'month': true,
                'year': true
            },
            next: {
                'month': true,
                'year': true
            }
        };
        
        // if we're in an out of bounds year
        if (cal.year == cal.start.getFullYear()) {
            navigation.prev.year = false;
            if (cal.month == cal.start.getMonth() && this.options.navigation == 1) {
                navigation.prev.month = false;
            }
        }
        if (cal.year == cal.end.getFullYear()) {
            navigation.next.year = false;
            if (cal.month == cal.end.getMonth() && this.options.navigation == 1) {
                navigation.next.month = false;
            }
        }
        
        // special case of improved navigation but months array with only 1 month we can disable all month navigation
        if ($type(cal.months) == 'array') {
            if (cal.months.length == 1 && this.options.navigation == 2) {
                navigation.prev.month = navigation.next.month = false;
            }
        }
        
        var caption = new Element('caption');
        
        var prev = new Element('a').addClass(this.classes.prev).appendText('\x3c'); // <		
        var next = new Element('a').addClass(this.classes.next).appendText('\x3e'); // >
        if (this.options.navigation == 2) {
            var month = new Element('span').addClass(this.classes.month).injectInside(caption);
            
            if (navigation.prev.month) {
                prev.clone().addEvent('click', function(cal){
                    this.navigate(cal, 'm', -1);
                }
.pass(cal, this)).injectInside(month);
            }
            
            month.adopt(new Element('span').appendText(this.options.months[cal.month]));
            
            if (navigation.next.month) {
                next.clone().addEvent('click', function(cal){
                    this.navigate(cal, 'm', 1);
                }
.pass(cal, this)).injectInside(month);
            }
            
            var year = new Element('span').addClass(this.classes.year).injectInside(caption);
            
            if (navigation.prev.year) {
                prev.clone().addEvent('click', function(cal){
                    this.navigate(cal, 'y', -1);
                }
.pass(cal, this)).injectInside(year);
            }
            
            year.adopt(new Element('span').appendText(cal.year));
            
            if (navigation.next.year) {
                next.clone().addEvent('click', function(cal){
                    this.navigate(cal, 'y', 1);
                }
.pass(cal, this)).injectInside(year);
            }
        }
        else { // 1 or 0
            if (navigation.prev.month && this.options.navigation) {
                prev.clone().addEvent('click', function(cal){
                    this.navigate(cal, 'm', -1);
                }
.pass(cal, this)).injectInside(caption);
            }
            
            caption.adopt(new Element('span').addClass(this.classes.month).appendText(this.options.months[cal.month]));
            
            caption.adopt(new Element('span').addClass(this.classes.year).appendText(cal.year));
            
            if (navigation.next.month && this.options.navigation) {
                next.clone().addEvent('click', function(cal){
                    this.navigate(cal, 'm', 1);
                }
.pass(cal, this)).injectInside(caption);
            }
            
        }
        
        return caption;
    },
    
    
    // changed: run when a select value is changed
    // @param cal (obj)
    
    changed: function(cal){
        cal.val = this.read(cal); // update calendar val from inputs	
        $extend(cal, this.values(cal)); // update bounds - based on curr month
        this.rebuild(cal); // rebuild days select
        if (!cal.val) {
            return;
        } // in case the same date was clicked the cal has no set date we should exit		
        if (cal.val.getDate() < cal.days[0]) {
            cal.val.setDate(cal.days[0]);
        }
        if (cal.val.getDate() > cal.days.getLast()) {
            cal.val.setDate(cal.days.getLast());
        }
        
        cal.els.each(function(el){ // then we can set the value to the field
            el.value = this.format(cal.val, el.format);
        }, this);
        
        this.check(cal); // checks other cals
        this.calendars.each(function(kal){ // update cal graphic if visible
            if (kal.visible) {
                this.display(kal);
            }
        }, this);
    },
    
    
    // check: checks other calendars to make sure no overlapping values
    // @param cal (obj)
    
    check: function(cal){
        this.calendars.each(function(kal, i){
            if (kal.val) { // if calendar has value set
                var change = false;
                
                if (i < cal.id) { // preceding calendar
                    var bound = new Date(Date.parse(cal.val));
                    
                    bound.setDate(bound.getDate() - (this.options.pad * (cal.id - i)));
                    
                    if (bound < kal.val) {
                        change = true;
                    }
                }
                if (i > cal.id) { // following calendar
                    var bound = new Date(Date.parse(cal.val));
                    
                    bound.setDate(bound.getDate() + (this.options.pad * (i - cal.id)));
                    
                    if (bound > kal.val) {
                        change = true;
                    }
                }
                
                if (change) {
                    if (kal.start > bound) {
                        bound = kal.start;
                    }
                    if (kal.end < bound) {
                        bound = kal.end;
                    }
                    
                    kal.month = bound.getMonth();
                    kal.year = bound.getFullYear();
                    
                    $extend(kal, this.values(kal));
                    
                    // TODO - IN THE CASE OF SELECT MOVE TO NEAREST VALID VALUE
                    // IN THE CASE OF INPUT DISABLE
                    
                    // if new date is not valid better unset cal value
                    // otherwise it would mean incrementally checking to find the nearest valid date which could be months / years away
                    kal.val = kal.days.contains(bound.getDate()) ? bound : null;
                    
                    this.write(kal);
                    
                    if (kal.visible) {
                        this.display(kal);
                    } // update cal graphic if visible
                }
            }
            else {
                kal.month = cal.month;
                kal.year = cal.year;
            }
        }, this);
    },
    
    
    // clicked: run when a valid day is clicked in the calendar
    // @param cal (obj)
    
    clicked: function(td, day, cal){
        cal.val = (this.value(cal) == day) ? null : new Date(cal.year, cal.month, day); // set new value - if same then disable
        this.write(cal);
        
        // ok - in the special case that it's all selects and there's always a date no matter what (at least as far as the form is concerned)
        // we can't let the calendar undo a date selection - it's just not possible!!
        if (!cal.val) {
            cal.val = this.read(cal);
        }
        
        if (cal.val) {
            this.check(cal); // checks other cals						
            this.toggle(cal); // hide cal
        }
        else { // remove active class and replace with valid
            td.addClass(this.classes.valid);
            td.removeClass(this.classes.active);
        }
    },
    
    
    // display: create calendar element
    // @param cal (obj)
    
    display: function(cal){
        // 1. header and navigation
        this.calendar.empty(); // init div
        this.calendar.className = this.classes.calendar + ' ' + this.options.months[cal.month].toLowerCase();
        
        var div = new Element('div').injectInside(this.calendar); // a wrapper div to help correct browser css problems with the caption element
        var table = new Element('table').injectInside(div).adopt(this.caption(cal));
        
        // 2. day names		
        var thead = new Element('thead').injectInside(table);
        
        var tr = new Element('tr').injectInside(thead);
        
        for (var i = 0; i <= 6; i++) {
            var th = this.options.days[(i + this.options.offset) % 7];
            
            tr.adopt(new Element('th', {
                'title': th
            }).appendText(th.substr(0, 1)));
        }
        
        // 3. day numbers
        var tbody = new Element('tbody').injectInside(table);
        var tr = new Element('tr').injectInside(tbody);
        
        var d = new Date(cal.year, cal.month, 1);
        var offset = ((d.getDay() - this.options.offset) + 7) % 7; // day of the week (offset)
        var last = new Date(cal.year, cal.month + 1, 0).getDate(); // last day of this month
        var prev = new Date(cal.year, cal.month, 0).getDate(); // last day of previous month
        var active = this.value(cal); // active date (if set and within curr month)
        var valid = cal.days; // valid days for curr month
        var inactive = []; // active dates set by other calendars
        var hilited = [];
        this.calendars.each(function(kal, i){
            if (kal != cal && kal.val) {
                if (cal.year == kal.val.getFullYear() && cal.month == kal.val.getMonth()) {
                    inactive.push(kal.val.getDate());
                }
                
                if (cal.val) {
                    for (var day = 1; day <= last; day++) {
                        d.setDate(day);
                        
                        if ((i < cal.id && d > kal.val && d < cal.val) || (i > cal.id && d > cal.val && d < kal.val)) {
                            if (!hilited.contains(day)) {
                                hilited.push(day);
                            }
                        }
                    }
                }
            }
        }, this);
        var d = new Date();
        var today = new Date(d.getFullYear(), d.getMonth(), d.getDate()).getTime(); // today obv 
        for (var i = 1; i < 43; i++) { // 1 to 42 (6 x 7 or 6 weeks)
            if ((i - 1) % 7 == 0) {
                tr = new Element('tr').injectInside(tbody);
            } // each week is it's own table row
            var td = new Element('td').injectInside(tr);
            
            var day = i - offset;
            var date = new Date(cal.year, cal.month, day);
            
            var cls = '';
            
            if (day === active) {
                cls = this.classes.active;
            } // active
            else 
                if (inactive.contains(day)) {
                    cls = this.classes.inactive;
                } // inactive
                else 
                    if (valid.contains(day)) {
                        cls = this.classes.valid;
                    } // valid
                    else 
                        if (day >= 1 && day <= last) {
                            cls = this.classes.invalid;
                        } // invalid
            if (date.getTime() == today) {
                cls = cls + ' ' + this.classes.today;
            } // adds class for today
            if (hilited.contains(day)) {
                cls = cls + ' ' + this.classes.hilite;
            } // adds class if hilited
            td.addClass(cls);
            
            if (valid.contains(day)) { // if it's a valid - clickable - day we add interaction
                td.setProperty('title', this.format(date, 'D M jS Y'));
                
                td.addEvents({
                    'click': function(td, day, cal){
                        this.clicked(td, day, cal);
                    }
.pass([td, day, cal], this)                    ,
                    'mouseover': function(td, cls){
                        td.addClass(cls);
                    }
.pass([td, this.classes.hover])                    ,
                    'mouseout': function(td, cls){
                        td.removeClass(cls);
                    }
.pass([td, this.classes.hover])
                });
            }
            
            // pad calendar with last days of prev month and first days of next month
            if (day < 1) {
                day = prev + day;
            }
            else 
                if (day > last) {
                    day = day - last;
                }
            
            td.appendText(day);
        }
    },
    
    
    // element: helper function
    // @param el (string) element id
    // @param f (string) format string
    // @param cal (obj)
    
    element: function(el, f, cal){
        if ($type(f) == 'object') { // in the case of multiple inputs per calendar
            for (var i in f) {
                if (!this.element(i, f[i], cal)) {
                    return false;
                }
            }
            
            return true;
        }
        
        el = $(el);
        
        if (!el) {
            return false;
        }
        
        el.format = f;
        
        if (el.get('tag') == 'select') { // select elements allow the user to manually set the date via select option
            el.addEvent('change', function(cal){
                this.changed(cal);
            }
.pass(cal, this));
        }
        else { // input (type text) elements restrict the user to only setting the date via the calendar
            el.readOnly = false;
            el.addEvent('focus', function(cal){
                this.toggle(cal);
            }
.pass(cal, this));
        }
        
        cal.els.push(el);
        
        return true;
    },
    
    
    // format: formats a date object according to passed in instructions
    // @param date (obj)
    // @param f (string) any combination of punctuation / separators and d, j, D, l, S, m, n, F, M, y, Y
    // @returns string
    
    format: function(date, format){
        var str = '';
        
        if (date) {
            var j = date.getDate(); // 1 - 31
            var w = date.getDay(); // 0 - 6
            var l = this.options.days[w]; // Sunday - Saturday
            var n = date.getMonth() + 1; // 1 - 12
            var f = this.options.months[n - 1]; // January - December
            var y = date.getFullYear() + ''; // 19xx - 20xx
            for (var i = 0, len = format.length; i < len; i++) {
                var cha = format.charAt(i); // format char
                switch (cha) {
                    // year cases
                    case 'y': // xx - xx
                        y = y.substr(2);
                    case 'Y': // 19xx - 20xx
                        str += y;
                        break;
                        
                    // month cases
                    case 'm': // 01 - 12
                        if (n < 10) {
                            n = '0' + n;
                        }
                    case 'n': // 1 - 12
                        str += n;
                        break;
                        
                    case 'M': // Jan - Dec
                        f = f.substr(0, 3);
                    case 'F': // January - December
                        str += f;
                        break;
                        
                    // day cases
                    case 'd': // 01 - 31
                        if (j < 10) {
                            j = '0' + j;
                        }
                    case 'j': // 1 - 31
                        str += j;
                        break;
                        
                    case 'D': // Sun - Sat
                        l = l.substr(0, 3);
                    case 'l': // Sunday - Saturday
                        str += l;
                        break;
                        
                    case 'N': // 1 - 7
                        w += 1;
                    case 'w': // 0 - 6
                        str += w;
                        break;
                        
                    case 'S': // st, nd, rd or th (works well with j)
                        if (j % 10 == 1 && j != '11') {
                            str += 'st';
                        }
                        else 
                            if (j % 10 == 2 && j != '12') {
                                str += 'nd';
                            }
                            else 
                                if (j % 10 == 3 && j != '13') {
                                    str += 'rd';
                                }
                                else {
                                    str += 'th';
                                }
                        break;
                        
                    default:
                        str += cha;
                }
            }
        }
        
        return str; //  return format with values replaced
    },
    
    
    // navigate: calendar navigation
    // @param cal (obj)
    // @param type (str) m or y for month or year
    // @param n (int) + or - for next or prev
    
    navigate: function(cal, type, n){
        switch (type) {
            case 'm': // month
                if ($type(cal.months) == 'array') {
                    var i = cal.months.indexOf(cal.month) + n; // index of current month
                    if (i < 0 || i == cal.months.length) { // out of range
                        if (this.options.navigation == 1) { // if type 1 nav we'll need to increment the year
                            this.navigate(cal, 'y', n);
                        }
                        
                        i = (i < 0) ? cal.months.length - 1 : 0;
                    }
                    
                    cal.month = cal.months[i];
                }
                else {
                    var i = cal.month + n;
                    
                    if (i < 0 || i == 12) {
                        if (this.options.navigation == 1) {
                            this.navigate(cal, 'y', n);
                        }
                        
                        i = (i < 0) ? 11 : 0;
                    }
                    
                    cal.month = i;
                }
                break;
                
            case 'y': // year
                if ($type(cal.years) == 'array') {
                    var i = cal.years.indexOf(cal.year) + n;
                    
                    cal.year = cal.years[i];
                }
                else {
                    cal.year += n;
                }
                break;
        }
        
        $extend(cal, this.values(cal));
        
        if ($type(cal.months) == 'array') { // if the calendar has a months select
            var i = cal.months.indexOf(cal.month); // and make sure the curr months exists for the new year
            if (i < 0) {
                cal.month = cal.months[0];
            } // otherwise we'll reset the month
        }
        
        
        this.display(cal);
    },
    
    
    // read: compiles cal value based on array of inputs passed in
    // @param cal (obj)
    // @returns date (obj) or (null)
    
    read: function(cal){
        var arr = [null, null, null];
        
        cal.els.each(function(el){
            // returns an array which may contain empty values
            var values = this.unformat(el.value, el.format);
            
            values.each(function(val, i){
                if ($type(val) == 'number') {
                    arr[i] = val;
                }
            });
        }, this);
        
        // we can update the cals month and year values
        if ($type(arr[0]) == 'number') {
            cal.year = arr[0];
        }
        if ($type(arr[1]) == 'number') {
            cal.month = arr[1];
        }
        
        var val = null;
        
        if (arr.every(function(i){
            return $type(i) == 'number';
        })) { // if valid date
            var last = new Date(arr[0], arr[1] + 1, 0).getDate(); // last day of month
            if (arr[2] > last) {
                arr[2] = last;
            } // make sure we stay within the month (ex in case default day of select is 31 and month is feb)
            val = new Date(arr[0], arr[1], arr[2]);
        }
        
        return (cal.val == val) ? null : val; // if new date matches old return null (same date clicked twice = disable)
    },
    
    
    // rebuild: rebuilds days + months selects
    // @param cal (obj)
    
    rebuild: function(cal){
        cal.els.each(function(el){
            /*
             if (el.get('tag') == 'select' && el.format.test('^(F|m|M|n)$')) { // special case for months-only select
             if (!cal.options) { cal.options = el.clone(); } // clone a copy of months select
             
             var val = (cal.val) ? cal.val.getMonth() : el.value.toInt();
             el.empty(); // initialize select
             cal.months.each(function(month) {
             // create an option element
             var option = new Element('option', {
             'selected': (val == month),
             'value': this.format(new Date(1, month, 1), el.format);
             }).appendText(day).injectInside(el);
             }, this);
             }
             */
            if (el.get('tag') == 'select' && el.format.test('^(d|j)$')) { // special case for days-only select
                var d = this.value(cal);
                
                if (!d) {
                    d = el.value.toInt();
                } // if the calendar doesn't have a set value, try to use value from select
                el.empty(); // initialize select
                cal.days.each(function(day){
                    // create an option element
                    var option = new Element('option', {
                        'selected': (d == day),
                        'value': ((el.format == 'd' && day < 10) ? '0' + day : day)
                    }).appendText(day).injectInside(el);
                }, this);
            }
        }, this);
    },
    
    
    // sort: helper function for numerical sorting
    
    sort: function(a, b){
        return a - b;
    },
    
    
    // toggle: show / hide calendar 
    // @param cal (obj)
    
    toggle: function(cal){
        document.removeEvent('mousedown', this.fn); // always remove the current mousedown script first
        if (cal.visible) { // simply hide curr cal						
            cal.visible = false;
            cal.button.removeClass(this.classes.active); // active
            this.fx.start('opacity', 1, 0);
        }
        else { // otherwise show (may have to hide others)
            // hide cal on out-of-bounds click
            this.fn = function(e, cal){
                var e = new Event(e);
                
                var el = e.target;
                
                var stop = false;
                
                while (el != document.body && el.nodeType == 1) {
                    if (el == this.calendar) {
                        stop = true;
                    }
                    this.calendars.each(function(kal){
                        if (kal.button == el || kal.els.contains(el)) {
                            stop = true;
                        }
                    });
                    
                    if (stop) {
                        e.stop();
                        return false;
                    }
                    else {
                        el = el.parentNode;
                    }
                }
                
                this.toggle(cal);
            }
.create({
                'arguments': cal,
                'bind': this,
                'event': true
            });
            
            document.addEvent('mousedown', this.fn);
            
            this.calendars.each(function(kal){
                if (kal == cal) {
                    kal.visible = true;
                    kal.button.addClass(this.classes.active); // css c-icon-active
                }
                else {
                    kal.visible = false;
                    kal.button.removeClass(this.classes.active); // css c-icon-active
                }
            }, this);
            
            var size = window.getScrollSize();
            
            var coord = cal.button.getCoordinates();
            
            var x = coord.right + this.options.tweak.x;
            var y = coord.top + this.options.tweak.y;
            
            // make sure the calendar doesn't open off screen
            if (!this.calendar.coord) {
                this.calendar.coord = this.calendar.getCoordinates();
            }
            
            if (x + this.calendar.coord.width > size.x) {
                x -= (x + this.calendar.coord.width - size.x);
            }
            if (y + this.calendar.coord.height > size.y) {
                y -= (y + this.calendar.coord.height - size.y);
            }
            
            this.calendar.setStyles({
                left: x + 'px',
                top: y + 'px'
            });
            
            if (window.ie6) {
                this.iframe.setStyles({
                    height: this.calendar.coord.height + 'px',
                    left: x + 'px',
                    top: y + 'px',
                    width: this.calendar.coord.width + 'px'
                });
            }
            
            this.display(cal);
            
            this.fx.start('opacity', 0, 1);
        }
    },
    
    
    // unformat: takes a value from an input and parses the d, m and y elements
    // @param val (string)
    // @param f (string) any combination of punctuation / separators and d, j, D, l, S, m, n, F, M, y, Y
    // @returns array
    
    unformat: function(val, f){
        f = f.escapeRegExp();
        
        var re = {
            d: '([0-9]{2})',
            j: '([0-9]{1,2})',
            D: '(' + this.options.days.map(function(day){
                return day.substr(0, 3);
            }).join('|') + ')',
            l: '(' + this.options.days.join('|') + ')',
            S: '(st|nd|rd|th)',
            F: '(' + this.options.months.join('|') + ')',
            m: '([0-9]{2})',
            M: '(' + this.options.months.map(function(month){
                return month.substr(0, 3);
            }).join('|') + ')',
            n: '([0-9]{1,2})',
            Y: '([0-9]{4})',
            y: '([0-9]{2})'
        }
        
        var arr = []; // array of indexes
        var g = '';
        
        // convert our format string to regexp
        for (var i = 0; i < f.length; i++) {
            var c = f.charAt(i);
            
            if (re[c]) {
                arr.push(c);
                
                g += re[c];
            }
            else {
                g += c;
            }
        }
        
        // match against date
        var matches = val.match('^' + g + '$');
        
        var dates = new Array(3);
        
        if (matches) {
            matches = matches.slice(1); // remove first match which is the date
            arr.each(function(c, i){
                i = matches[i];
                
                switch (c) {
                    // year cases
                    case 'y':
                        i = '19' + i; // 2 digit year assumes 19th century (same as JS)
                    case 'Y':
                        dates[0] = i.toInt();
                        break;
                        
                    // month cases
                    case 'F':
                        i = i.substr(0, 3);
                    case 'M':
                        i = this.options.months.map(function(month){
                            return month.substr(0, 3);
                        }).indexOf(i) + 1;
                    case 'm':
                    case 'n':
                        dates[1] = i.toInt() - 1;
                        break;
                        
                    // day cases
                    case 'd':
                    case 'j':
                        dates[2] = i.toInt();
                        break;
                }
            }, this);
        }
        
        return dates;
    },
    
    
    // value: returns day value of calendar if set
    // @param cal (obj)
    // @returns day (int) or null
    
    value: function(cal){
        var day = null;
        
        if (cal.val) {
            if (cal.year == cal.val.getFullYear() && cal.month == cal.val.getMonth()) {
                day = cal.val.getDate();
            }
        }
        
        return day;
    },
    
    
    // values: returns the years, months (for curr year) and days (for curr month and year) for the calendar
    // @param cal (obj)
    // @returns obj	
    
    values: function(cal){
        var years, months, days;
        
        cal.els.each(function(el){
            if (el.get('tag') == 'select') {
                if (el.format.test('(y|Y)')) { // search for a year select
                    years = [];
                    
                    el.getChildren().each(function(option){ // get options
                        var values = this.unformat(option.value, el.format);
                        
                        if (!years.contains(values[0])) {
                            years.push(values[0]);
                        } // add to years array
                    }, this);
                    
                    years.sort(this.sort);
                }
                
                if (el.format.test('(F|m|M|n)')) { // search for a month select
                    months = []; // 0 - 11 should be
                    el.getChildren().each(function(option){ // get options
                        var values = this.unformat(option.value, el.format);
                        
                        if ($type(values[0]) != 'number' || values[0] == cal.year) { // if it's a year / month combo for curr year, or simply a month select
                            if (!months.contains(values[1])) {
                                months.push(values[1]);
                            } // add to months array
                        }
                    }, this);
                    
                    months.sort(this.sort);
                }
                
                if (el.format.test('(d|j)') && !el.format.test('^(d|j)$')) { // search for a day select, but NOT a days only select
                    days = []; // 1 - 31
                    el.getChildren().each(function(option){ // get options
                        var values = this.unformat(option.value, el.format);
                        
                        // in the special case of days we dont want the value if its a days only select
                        // otherwise that will screw up the options rebuilding
                        // we will take the values if they are exact dates though
                        if (values[0] == cal.year && values[1] == cal.month) {
                            if (!days.contains(values[2])) {
                                days.push(values[2]);
                            } // add to days array
                        }
                    }, this);
                }
            }
        }, this);
        
        // we start with what would be the first and last days were there no restrictions
        var first = 1;
        var last = new Date(cal.year, cal.month + 1, 0).getDate(); // last day of the month
        // if we're in an out of bounds year
        if (cal.year == cal.start.getFullYear()) {
            // in the special case of improved navigation but no months array, we'll need to construct one
            if (months == null && this.options.navigation == 2) {
                months = [];
                
                for (var i = 0; i < 12; i++) {
                    if (i >= cal.start.getMonth()) {
                        months.push(i);
                    }
                }
            }
            
            // if we're in an out of bounds month
            if (cal.month == cal.start.getMonth()) {
                first = cal.start.getDate(); // first day equals day of bound
            }
        }
        if (cal.year == cal.end.getFullYear()) {
            // in the special case of improved navigation but no months array, we'll need to construct one
            if (months == null && this.options.navigation == 2) {
                months = [];
                
                for (var i = 0; i < 12; i++) {
                    if (i <= cal.end.getMonth()) {
                        months.push(i);
                    }
                }
            }
            
            if (cal.month == cal.end.getMonth()) {
                last = cal.end.getDate(); // last day equals day of bound
            }
        }
        
        // let's get our invalid days
        var blocked = this.blocked(cal);
        
        // finally we can prepare all the valid days in a neat little array
        if ($type(days) == 'array') { // somewhere there was a days select
            days = days.filter(function(day){
                if (day >= first && day <= last && !blocked.contains(day)) {
                    return day;
                }
            });
        }
        else { // no days select we'll need to construct a valid days array
            days = [];
            
            for (var i = first; i <= last; i++) {
                if (!blocked.contains(i)) {
                    days.push(i);
                }
            }
        }
        
        days.sort(this.sort); // sorting our days will give us first and last of month
        return {
            'days': days,
            'months': months,
            'years': years
        };
    },
    
    
    // write: sets calendars value to form elements
    // @param cal (obj)
    
    write: function(cal){
        this.rebuild(cal); // in the case of options, we'll need to make sure we have the correct number of days available
        cal.els.each(function(el){ // then we can set the value to the field
            el.value = this.format(cal.val, el.format);
        }, this);
    }
});

Calendar.implement(new Events, new Options);