// 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 Šego

var Calendar = new Class({        

  Implements: Options,

        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 = true;
                        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);