YAHOO.ext.DatePicker = function(id, parentElement){
    this.id = id;
    this.selectedDate = new Date();
    this.visibleDate = new Date();
    this.element = null;
    this.shadow = null;
    this.callback = null;
    this.buildControl(parentElement || document.body);
    this.mouseDownHandler = YAHOO.ext.EventManager.wrap(this.handleMouseDown, this, true);
    this.keyDownHandler = YAHOO.ext.EventManager.wrap(this.handleKeyDown, this, true);
    this.wheelHandler = YAHOO.ext.EventManager.wrap(this.handleMouseWheel, this, true);
};

YAHOO.ext.DatePicker.prototype = {
    show : function(x, y, value, callback){
        this.hide();
        this.selectedDate = value;
        this.visibleDate = value;
        this.callback = callback;
        this.refresh();
        this.element.show();
        this.element.setXY(this.constrainToViewport ? this.constrainXY(x, y) : [x, y]);
        this.shadow.show();
        this.shadow.setRegion(this.element.getRegion());
        this.element.dom.tabIndex = 1;
        this.element.focus();
        YAHOO.util.Event.on(document, "mousedown", this.mouseDownHandler);
        YAHOO.util.Event.on(document, "keydown", this.keyDownHandler);
        YAHOO.util.Event.on(document, "mousewheel", this.wheelHandler);
        YAHOO.util.Event.on(document, "DOMMouseScroll", this.wheelHandler);
    },
    
    constrainXY : function(x, y){
        var w = YAHOO.util.Dom.getViewportWidth();
        var h = YAHOO.util.Dom.getViewportHeight();
        var size = this.element.getSize();
        return [
            Math.min(w-size.width, x),
            Math.min(h-size.height, y)
        ];
    },
    
    hide : function(){
        this.shadow.hide();
        this.element.hide();
        YAHOO.util.Event.removeListener(document, "mousedown", this.mouseDownHandler);
        YAHOO.util.Event.removeListener(document, "keydown", this.keyDownHandler);
        YAHOO.util.Event.removeListener(document, "mousewheel", this.wheelHandler);
        YAHOO.util.Event.removeListener(document, "DOMMouseScroll", this.wheelHandler);
    },
    
    setSelectedDate : function(date){
        this.selectedDate = date;
    },
    
    getSelectedDate : function(){
        return this.selectedDate;
    },
    
    showPrevMonth : function(){
        this.visibleDate = this.getPrevMonth(this.visibleDate);
        this.refresh();
    },
    
    showNextMonth : function(){
        this.visibleDate = this.getNextMonth(this.visibleDate);
        this.refresh();
    },
    
    showPrevYear : function(){
        var d = this.visibleDate;
        this.visibleDate = new Date(d.getFullYear()-1, d.getMonth(), d.getDate());
        this.refresh();
    },
    
    showNextYear : function(){
        var d = this.visibleDate;
        this.visibleDate = new Date(d.getFullYear()+1, d.getMonth(), d.getDate());
        this.refresh();
    },
    
    handleMouseDown : function(e){
        var target = e.getTarget();
        if(target != this.element.dom && !YAHOO.util.Dom.isAncestor(this.element.dom, target)){
            this.hide();
        }
    },
    
    handleKeyDown : function(e){
        switch(e.browserEvent.keyCode){
            case e.LEFT:
                this.showPrevMonth();
                e.stopEvent();
            break;
            case e.RIGHT:
                this.showNextMonth();
                e.stopEvent();
            break;
            case e.DOWN:
                this.showPrevYear();
                e.stopEvent();
            break;
            case e.UP:
                this.showNextYear();
                e.stopEvent();
            break;
        }
    },
    
    handleMouseWheel : function(e){
        var delta = e.getWheelDelta();
        if(delta > 0){
            this.showPrevMonth();
            e.stopEvent();
        } else if(delta < 0){
            this.showNextMonth();
            e.stopEvent();
        }
    },
    
    handleClick : function(e){
        var d = this.visibleDate;
        var t = e.getTarget();
        if(t && t.className){
            var cls = t.className.split(' ')[0];
            switch(cls){
                case 'active':
                    this.handleSelection(new Date(d.getFullYear(), d.getMonth(), parseInt(t.innerHTML)));
                break;
                case 'prevday':
                    var p = this.getPrevMonth(d);
                    this.handleSelection(new Date(p.getFullYear(), p.getMonth(), parseInt(t.innerHTML)));
                break;
                case 'nextday':
                    var n = this.getNextMonth(d);
                    this.handleSelection(new Date(n.getFullYear(), n.getMonth(), parseInt(t.innerHTML)));
                break;
                case 'ypopcal-today':
                    this.handleSelection(new Date());
                break;
                case 'next-month':
                    this.showNextMonth();
                break;
                case 'prev-month':
                    this.showPrevMonth();
                break;
            }   
        }
        e.stopEvent();
    },
    
    selectToday : function(){
        this.handleSelection(new Date());
    },
    
    handleSelection: function(date){
        this.selectedDate = date;
        this.callback(date);
        this.hide();    
    },
    
    getPrevMonth : function(d){
        var m = d.getMonth();var y = d.getFullYear();
        return (m == 0 ? new Date(--y, 11, 1) : new Date(y, --m, 1));
    },
    
    getNextMonth : function(d){
        var m = d.getMonth();var y = d.getFullYear();
        return (m == 11 ? new Date(++y, 0, 1) : new Date(y, ++m, 1));
    },
    
    getDaysInMonth : function(m, y){
        return (m == 1 || m == 3 || m == 5 || m == 7 || m == 8 || m == 10 || m == 12) ? 31 : (m == 4 || m == 6 || m == 9 || m == 11) ? 30 : this.isLeapYear(y) ? 29 : 28;
    },
    
    isLeapYear : function(y){
        return (((y % 4) == 0) && ((y % 100) != 0) || ((y % 400) == 0));
    },
    
    clearTime : function(date){
        if(date){
            date.setHours(0);
            date.setMinutes(0);
            date.setSeconds(0);
            date.setMilliseconds(0);
        }
        return date;
    },
    
    refresh : function(){
        var d = this.visibleDate;
        this.buildInnerCal(d);
        this.calHead.update(this.monthNames[d.getMonth()] + ' ' + d.getFullYear());
        if(this.element.isVisible()){
            this.shadow.setRegion(this.element.getRegion());
        }
    }
};

/**
 * This code is not pretty, but it is fast!
 * @ignore
 */ 
YAHOO.ext.DatePicker.prototype.buildControl = function(parentElement){
    var c = document.createElement('div');
    c.style.position = 'absolute';
    c.style.visibility = 'hidden';
    document.body.appendChild(c);
    var html = '<iframe id="'+this.id+'_shdw" frameborder="0" class="ypopcal-shadow" src="'+YAHOO.ext.SSL_SECURE_URL+'"></iframe>' +
    '<div hidefocus="true" class="ypopcal" id="'+this.id+'">' +
    '<table class="ypopcal-head" border=0 cellpadding=0 cellspacing=0><tbody><tr><td class="ypopcal-arrow"><div class="prev-month">&#160;</div></td><td class="ypopcal-month">&#160;</td><td class="ypopcal-arrow"><div class="next-month">&#160;</div></td></tr></tbody></table>' +
    '<center><div class="ypopcal-inner">';
    html += "<table border=0 cellspacing=0 class=\"ypopcal-table\"><thead><tr class=\"ypopcal-daynames\">";
    var names = this.dayNames;
    for(var i = 0; i < names.length; i++){
        html += '<td>' + names[i].substr(0, 1) + '</td>';
    }
    html+= "</tr></thead><tbody><tr>";
    for(var i = 0; i < 42; i++) {
        if(i % 7 == 0 && i != 0){
            html += '</tr><tr>';
        }
        html += "<td>&nbsp;</td>";
    }
    html += "</tr></tbody></table>";
    html += '</div><button class="ypopcal-today">'+this.todayText+'</button></center></div>';
    c.innerHTML = html;
    this.shadow = getEl(c.childNodes[0], true);
    this.shadow.enableDisplayMode('block');
    this.element = getEl(c.childNodes[1], true);
    this.element.enableDisplayMode('block');
    document.body.appendChild(this.shadow.dom);
    document.body.appendChild(this.element.dom);
    document.body.removeChild(c);
    this.element.on("selectstart", function(){return false;});
    var tbody = this.element.dom.getElementsByTagName('tbody')[1];
    this.cells = tbody.getElementsByTagName('td');
    this.calHead = this.element.getChildrenByClassName('ypopcal-month', 'td')[0];
    this.element.mon('mousedown', this.handleClick, this, true);
};

YAHOO.ext.DatePicker.prototype.buildInnerCal = function(dateVal){
    var days = this.getDaysInMonth(dateVal.getMonth() + 1, dateVal.getFullYear());
    var firstOfMonth = new Date(dateVal.getFullYear(), dateVal.getMonth(), 1);
    var startingPos = firstOfMonth.getDay();
    if(startingPos == 0) startingPos = 7;
    var pm = this.getPrevMonth(dateVal);
    var prevStart = this.getDaysInMonth(pm.getMonth()+1, pm.getFullYear())-startingPos;
    var cells = this.cells;
    days += startingPos;
    
    // convert everything to numbers so it's fast
    var day = 86400000;
    var date = this.clearTime(new Date(pm.getFullYear(), pm.getMonth(), prevStart));
    var today = this.clearTime(new Date()).getTime();
    var sel = this.selectedDate ? this.clearTime(this.selectedDate).getTime() : today + 1; //today +1 will never match anything
    var min = this.minDate ? this.clearTime(this.minDate).getTime() : Number.NEGATIVE_INFINITY;
    var max = this.maxDate ? this.clearTime(this.maxDate).getTime() : Number.POSITIVE_INFINITY;
    var ddMatch = this.disabledDatesRE;
    var ddText = this.disabledDatesText;
    var ddays = this.disabledDays;
    var ddaysText = this.disabledDaysText;
    var format = this.format;
    
    var setCellClass = function(cal, cell, d){
        cell.title = '';
        var t = d.getTime();
        if(t == today){
            cell.className += ' today';
            cell.title = cal.todayText;
        }
        if(t == sel){
            cell.className += ' selected';
        }
        // disabling
        if(t < min) {
            cell.className = ' ypopcal-disabled';
            cell.title = cal.minText;
            return;
        }
        if(t > max) {
            cell.className = ' ypopcal-disabled';
            cell.title = cal.maxText;
            return;
        }
        if(ddays){
            var day = d.getDay();
            for(var i = 0; i < ddays.length; i++) {
            	if(day === ddays[i]){
            	    cell.title = ddaysText;
                    cell.className = ' ypopcal-disabled';
                    return;
                }
            }
        }
        if(ddMatch && format){
            var fvalue = d.format(format);
            if(ddMatch.test(fvalue)){
                cell.title = ddText.replace('%0', fvalue);
                cell.className = ' ypopcal-disabled';
                return;
            }
        }
    };
    
    var i = 0;
    for(; i < startingPos; i++) {
        cells[i].innerHTML = (++prevStart);
        date.setDate(date.getDate()+1);
        cells[i].className = 'prevday';
        setCellClass(this, cells[i], date);
    }
    for(; i < days; i++){
        intDay = i - startingPos + 1;
        cells[i].innerHTML = (intDay);
        date.setDate(date.getDate()+1);
        cells[i].className = 'active';
        setCellClass(this, cells[i], date);
    }
    var extraDays = 0;
    for(; i < 42; i++) {
         cells[i].innerHTML = (++extraDays);
         date.setDate(date.getDate()+1);
         cells[i].className = 'nextday';
         setCellClass(this, cells[i], date);
    }
};

YAHOO.ext.DatePicker.prototype.todayText = "Today";
YAHOO.ext.DatePicker.prototype.minDate = null;
YAHOO.ext.DatePicker.prototype.maxDate = null;
YAHOO.ext.DatePicker.prototype.minText = "This date is before the minimum date";
YAHOO.ext.DatePicker.prototype.maxText = "This date is after the maximum date";
YAHOO.ext.DatePicker.prototype.format = 'm/d/y';
YAHOO.ext.DatePicker.prototype.disabledDays = null;
YAHOO.ext.DatePicker.prototype.disabledDaysText = '';
YAHOO.ext.DatePicker.prototype.disabledDatesRE = null;
YAHOO.ext.DatePicker.prototype.disabledDatesText = '';
YAHOO.ext.DatePicker.prototype.constrainToViewport = true;


YAHOO.ext.DatePicker.prototype.monthNames = Date.monthNames;

YAHOO.ext.DatePicker.prototype.dayNames = Date.dayNames;