var calendar = {
    
    items: new Array(),
    
    init: function(config){
    
        var c = {
            title: 'Calendar',
            fieldId: "myDate",
            showButton: false,
            buttonId: "myDateButton",
            buttonIcon: "",
            onlyFutureEnabled: false,
            currentDateEnabled: true,
            activateOnFocus: true,
            validateOnBlur: false,
            errorClass: "red",
            layerClass: "ac-layer",
            transImage: "",
            daysNames: { EU: new Array('Mo', 'Di', 'Mi', 'Do', 'Fr', 'Sa', 'So'), US: new Array('Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa')},
            monthsNames: { EU: new Array('Januar', 'Februar', 'März', 'April', 'Mai', 'Juni', 'Juli','August', 'September', 'Oktober', 'November', 'Dezember'), US: new Array('Januar', 'Februar', 'March', 'April', 'May', 'June', 'July','August', 'September', 'Oktober', 'November', 'December')},
            form: 'EU', // 'US'
            position: 'topRight', //bottomLeft
            calendarLayer: null,
            isDateValid: false,
            positionDeltaTop: 3,
            positionDeltaLeft: 20,
            range: {
                from: null,
                upto: null
            },
            defaultDate: null
        },
    
        c = jQuery.extend(c, config);
        
        //Ob das Element schon mal initialisiert wurde
        var itemIndex = null;
        for (var i in this.items) {
            if (this.items[i].fieldId == c.fieldId) itemIndex = i;
        }
        if (itemIndex == null) this.items.push(c);
        else this.items[i] = c;
        
        //Button container
        var buttonObj = jQuery('#'+c.buttonId).get(0);
        
        if (jQuery('#'+c.fieldId).get(0)!=null) {
            //Show button
            if ( (c.showButton) && ( buttonObj!= null) ) {
                buttonObj.innerHTML = '<a href="javascript:void(0);" id="'+c.fieldId+'_button"><img src="'+c.buttonIcon+'" alt="" border="0"/></a> ';
            }
            //Events
            var calender = this;
            //Field
            jQuery('#'+c.fieldId).unbind('focus').bind('focus', function(){ calender.onFocus(c); });
            jQuery('#'+c.fieldId).unbind('blur').bind('blur', function(){ calender.onBlur(c); });
            //Button
            jQuery('#'+c.buttonId).unbind('click').bind('click', function(){ calender.onClick(c); });
        }        
    },
    
    onFocus: function(c){
        if (c.activateOnFocus) this.showLayer(c);
    },
    
    onBlur: function(c){
        if (c.validateOnBlur){ 
            this.refreshDateField(c);
        }; 
    },
    
    onClick: function(c){
        this.hideAllLayers();
        this.showLayer(c);
    },
    refreshDateField: function(c){
         
         //Datum des Feldes normalisieren
         var strDate = this.normalizeDateString(jQuery('#'+c.fieldId).get(0).value);
         
         //Validieren
         c.isDateValid = this.validateDate(c, strDate);
         //Wenn das Datum korrekt ist
         if (c.isDateValid) {
            jQuery('#'+c.fieldId).get(0).value = strDate;
            jQuery('#'+c.fieldId).removeClass(c.errorClass);
            this.hideLayer(c);
            return true;
         } else {
            jQuery('#'+c.fieldId).addClass(c.errorClass);
            return false;
         }
    },
    
    setDateFieldValue: function(c, strValue){
         jQuery('#'+c.fieldId).get(0).value = strValue;
         jQuery('#'+c.fieldId).change();
         this.refreshDateField(c);
    },
    
    validateDate: function(c, strDate){
         
         var isDateValid = false;
        
         //Datumformat validieren
         isDateValid = this.validateDateString(strDate);
         //Datumzeitraum validieren
         if (isDateValid) isDateValid = this.validateDateRange(c, strDate);
         c.isDateValid = isDateValid;
         
         return isDateValid;
    },
    
    
    showLayer: function(c){
        this.buildLayer(c);
    },
    
    hideLayer: function(c){
        if (c.calendarLayer != null) {
            jQuery('body').get(0).removeChild(c.calendarLayer);
            c.calendarLayer = null;
        }
    },
    hideAllLayers: function(){
        for(var i in this.items) {
            this.hideLayer(this.items[i]);
        }
    },
    
    buildLayer: function(c){
    
        if (jQuery('#'+c.fieldId+'_layer').get(0) == null) {
            
            
            var currentDate = new Date();
            var fromDate = currentDate;
            if (c.range.from != null) {
                var arrDate = c.range.from.split('.');
                fromDate = new Date(parseInt(arrDate[2]),(parseInt(arrDate[1])-1),parseInt(arrDate[0]));
            }

            var strCurrentDate = currentDate.getDate()+'.'+(currentDate.getMonth()+1)+'.'+currentDate.getFullYear();

            //Datum des Feldes normalisieren
            if (jQuery('#'+c.fieldId).get(0).value != '') {
                var strInputDate = this.normalizeDateString(jQuery('#'+c.fieldId).get(0).value);
            } else if (c.defaultDate != null) {
                var strInputDate = this.normalizeDateString(c.defaultDate);
            } else {
                var strInputDate = '';
            }
            
            //Validieren
            var isDateValid = this.validateDate(c, strInputDate);
            //Wenn das Datum im Eingabefeld korrekt ist
            if (isDateValid) {
            
                var arrayInputDate = strInputDate.split(strInputDate.substring(2,3)); 
                var month = arrayInputDate[1];
                var year =  arrayInputDate[2];
                var strMonth = c.monthsNames[c.form][arrayInputDate[1]-1];
                var strYear = arrayInputDate[2];
                
            } else {

                var startDate = (c.range.from == null) ? currentDate : fromDate;
                var month = parseInt(startDate.getMonth()+1);
                var year =  parseInt(startDate.getFullYear());
                var strMonth = c.monthsNames[c.form][startDate.getMonth()];
                var strYear = startDate.getFullYear();
            }
            
            var layer = document.createElement('div');
            layer.setAttribute('id', c.fieldId+'_layer');
            layer.className = c.layerClass;
            layer.style.position = 'absolute';
            
            if (c.position == 'bottomLeft') {
              layer.style.top = this.getElementTopPos(jQuery('#'+c.fieldId).get(0)) + jQuery('#'+c.fieldId).get(0).offsetHeight + c.positionDeltaTop + 'px';
              layer.style.left = this.getElementLeftPos(jQuery('#'+c.fieldId).get(0)) + 'px';
            } else {
              layer.style.top = this.getElementTopPos(jQuery('#'+c.fieldId).get(0)) + 'px';
              layer.style.left = this.getElementLeftPos(jQuery('#'+c.fieldId).get(0)) + jQuery('#'+c.fieldId).get(0).offsetWidth + c.positionDeltaLeft + 'px';
            }
            
            jQuery('body').get(0).appendChild(layer);
            layer.innerHTML = ''+
            '<div class="wrapper">'+
                '<div class="head">'+c.title+'</div><div class="btnClose"><a href="javascript: void(0)"><img src="'+c.transImage+'" alt="" border="0" /></a></div>'+
                '<div class="buttons">'+
                    '<div class="btnPrev"><a href="javascript:void(0)"><img src="'+c.transImage+'" alt="" border="0" /></a></div>'+
                    '<div class="info">'+strMonth+' '+strYear+'</div>'+
                    '<div class="btnNext"><a href="javascript:void(0)"><img src="'+c.transImage+'" alt="" border="0" /></a></div>'+
                '</div>'+
                '<div class="content">'+this.getDaysTable(c, month, year)+'</div>'+
                '<div class="footer"><a href="javascript:void(0)" rel="'+strCurrentDate+'">'+currentDate.getDate()+' '+c.monthsNames[c.form][currentDate.getMonth()]+' '+currentDate.getFullYear()+'</a></div>'
            '</div>';
            
            c.calendarLayer = layer;
            
            //Events*************************
            var calendar = this;
            jQuery('#'+c.fieldId+'_layer .btnClose a').bind('click', function(){ calendar.hideLayer(c); });
            
            //Days anchors
            jQuery('#'+c.fieldId+'_layer .content a').each( function(i){
                 jQuery(this).bind('click', function(){ 
                    var strDate = jQuery(this).attr('rel');
                    calendar.setDateFieldValue(c,strDate);
                 });
            });
            //Current day anchor
            jQuery('#'+c.fieldId+'_layer .footer a').each( function(i){
                 jQuery(this).bind('click', function(){ 
                    var strDate = jQuery(this).attr('rel');
                    calendar.setDateFieldValue(c,strDate);
                 });
            });
            //Next/Prev month
            jQuery('#'+c.fieldId+'_layer .btnNext').bind('click', function(){
                calendar.getNextMonth(c, month, year);
            });
            
            jQuery('#'+c.fieldId+'_layer .btnPrev').bind('click', function(){
                calendar.getPrevMonth(c, month, year);
            });
            
            
            
        } else jQuery('#'+c.fieldId+'_layer').show();
    },
    
    getDaysTable: function(c, month, year){
        
        //Header
        var html = '<table><tr>';
        for (var i=0; i<7; i++){
            html += '<th>'+c.daysNames[c.form][i]+'</th>';
        }
        html +='</tr>';
        
        var firstDate = new Date(year, month-1, 1, 0, 0, 0);
        var intDay = firstDate.getDay();
        
        if (c.form == 'EU') {
            intDay--;
            intDay = (intDay == -1) ? intDay = 6 : intDay;
        }
        
        //Days cells
        var intDayCount = 1;
        var strValue = null;
        var tdClass = null;
        var strDate = null;
        var isDateRangeValid = true;
        
        for (var cw=0; cw<6; cw++){
            html += '<tr>';
            for (var cd=0; cd<7; cd++){
                
                tdClass = '';
                strValue = '';
                strDate = '';
                isDateRangeValid = true;
                
                if (c.form=='US' && (cd==0 || cd==6)) tdClass += 'weekend ';
                if (c.form=='EU' && (cd==5 || cd==6)) tdClass += 'weekend ';
                
                if ( cw==0 && cd>=intDay ){ //Erste Woche des Monats
                    
                    strDate = this.normalizeDateString(intDayCount+'.'+month+'.'+year);
                    isDateRangeValid = this.validateDateRange(c, strDate);
                    
                    if (!isDateRangeValid) tdClass += 'disabled ';
                    
                    if ((this.isInputDate(c, strDate)) && (isDateRangeValid)) tdClass += 'selected ';
                    
                    strValue = intDayCount;
                    if (isDateRangeValid) html += '<td class="'+tdClass+'"><a href="javascript:void(0)" rel="'+strDate+'"><span>'+strValue+'</span></a></td>';
                    else html += '<td class="'+tdClass+'"><span>'+strValue+'</span></td>';
                    intDayCount++;
                    
                } else if ( cw==0 && cd<intDay ){
                    tdClass += 'blank ';
                    strValue = '&nbsp;';
                    html += '<td class="'+tdClass+'">'+strValue+'</td>';
                    
                } else { //Folgewochen
                    
                    if (!this.isNextMonth(intDayCount,month, year)) {
                        strDate = this.normalizeDateString(intDayCount+'.'+month+'.'+year);
                        isDateRangeValid = this.validateDateRange(c, strDate);
                        
                        if (!isDateRangeValid) tdClass += 'disabled ';
                        
                        if ((this.isInputDate(c, strDate)) && (isDateRangeValid)) tdClass += 'selected ';
                        
                        strValue = intDayCount;
                        if (isDateRangeValid) html += '<td class="'+tdClass+'"><a href="javascript:void(0)" rel="'+strDate+'"><span>'+strValue+'</span></a></td>';
                        else html += '<td class="'+tdClass+'"><span>'+strValue+'</span></td>';
                        intDayCount++;
                        
                    } else {
                        tdClass += 'blank ';
                        strValue = '&nbsp;';
                        
                        html += '<td class="'+tdClass+'">'+strValue+'</td>';
                    }
                    
                }
                
                
            }
            html += '</tr>';
        }
        
        html += '</table>';
        
        return html;
        
    },    
    
    isNextMonth: function(day, month, year){
        var objDate = new Date(year, month-1, day, 0, 0, 0);
        var calcMonth = objDate.getMonth();
        if (calcMonth!=(month-1)) return true;
        else return false;
    },
    
    isInputDate: function(c, strDate){
       
        //Datum des Feldes normalisieren
        var strInputDate = this.normalizeDateString(jQuery('#'+c.fieldId).get(0).value);
        
        //Validieren
        var isDateValid = this.validateDate(c, strInputDate);
        
        //Wenn das Datum im Eingabefeld korrekt ist
        if (isDateValid) {
            if (this.isDatesEq(strInputDate, strDate)) return true;
        } else return false;
    
    },
    
    getElementTopPos: function(obj)    {        
      var returnValue = obj.offsetTop;
      while((obj = obj.offsetParent) != null){
        if (obj.tagName!='HTML') returnValue += obj.offsetTop;
      }
      return returnValue;
    },
    
    getElementLeftPos: function(obj)    {
      var returnValue = obj.offsetLeft;
      while((obj = obj.offsetParent) != null){
        if (obj.tagName!='HTML') returnValue += obj.offsetLeft;
      }
      return returnValue;
    },
    
    getNextMonth: function(c, month, year){
    
        var nextMonth =  1;
        var nextYear = 1970;
        
        if (typeof(month) == 'string') month = (month.substr(0,1) == '0') ? month.substr(1,1) : month;
        
        month = parseInt(month);
        year = parseInt(year);
        
        nextMonth = ((month+1)>12) ? 1 : (month+1); 
        nextYear =   ((month+1)>12) ?(year+1) : year; 
        
        jQuery('#'+c.fieldId+'_layer .content').html(this.getDaysTable(c, nextMonth, nextYear));
        
        //Title mit Datum
        jQuery('#'+c.fieldId+'_layer .info').html(c.monthsNames[c.form][nextMonth-1] + ' ' + nextYear);
        
        //Buttons events
        var calendar = this;
        //Next
        jQuery('#'+c.fieldId+'_layer .btnNext').unbind('click');
        jQuery('#'+c.fieldId+'_layer .btnNext').bind('click', function(){
           calendar.getNextMonth(c, nextMonth, nextYear);
        });
        //Prev
        jQuery('#'+c.fieldId+'_layer .btnPrev').unbind('click');
        jQuery('#'+c.fieldId+'_layer .btnPrev').bind('click', function(){
           calendar.getPrevMonth(c, nextMonth, nextYear);
        });
        
        //Days anchors events
        jQuery('#'+c.fieldId+'_layer .content a').each( function(i){
             jQuery(this).bind('click', function(){ 
                var strDate = jQuery(this).attr('rel');
                calendar.setDateFieldValue(c,strDate);
             });
        });
        
    },
    
    getPrevMonth: function(c, month, year){
        var prevMonth =  1;
        var prevYear = 1970;
    
        month = parseInt(month);
        year = parseInt(year);
        var prevMonth =  ((month-1)<=0) ? 12 : (month-1) ; 
        var prevYear =   ((month-1)<=0) ? (year-1) : year; 
        jQuery('#'+c.fieldId+'_layer .content').html(this.getDaysTable(c, prevMonth, prevYear));
        //Title mit Datum
        jQuery('#'+c.fieldId+'_layer .info').html(c.monthsNames[c.form][prevMonth-1] + ' ' + prevYear);
        
        //Buttons events
        var calendar = this;
        //Next
        jQuery('#'+c.fieldId+'_layer .btnNext').unbind('click');
        jQuery('#'+c.fieldId+'_layer .btnNext').bind('click', function(){
           calendar.getNextMonth(c, prevMonth, prevYear);
        });
        //Prev
        jQuery('#'+c.fieldId+'_layer .btnPrev').unbind('click');
        jQuery('#'+c.fieldId+'_layer .btnPrev').bind('click', function(){
           calendar.getPrevMonth(c, prevMonth, prevYear);
        });
        
        //Days anchors events
        jQuery('#'+c.fieldId+'_layer .content a').each( function(i){
             jQuery(this).bind('click', function(){ 
                var strDate = jQuery(this).attr('rel');
                calendar.setDateFieldValue(c,strDate);
             });
        });
        
        
    },
    
    normalizeDateString: function(strDate){
        
        if (strDate == null) return null;
        
        //Zum Format fuehren: dd.mm.yyyy | dd-mm-yyyy | dd/mm/yyyy
        //Fehlende '0' und '20' einfuegen, wenn es notwendig ist
        //- Separator ermitteln. Moegliche Variante: . - /
        var separator = null;
        separator = ((strDate.indexOf('.') != -1) && (separator == null)) ? '.' : separator;
        separator = ((strDate.indexOf('-') != -1) && (separator == null)) ? '-' : separator;
        separator = ((strDate.indexOf('/') != -1) && (separator == null)) ? '/' : separator;
        if (separator!=null) {
        
            //- '0' einfuegen, zusammenfueren
            var arrayDate = strDate.split(separator);
            strDate = '';
            for (var i=0; i<arrayDate.length; i++){
                if (arrayDate[i].length==1) arrayDate[i] = '0'+ arrayDate[i];
                if ((i==2) && (arrayDate[i].length==2)) arrayDate[i] = '20'+ arrayDate[i]; //Jahr
                strDate = strDate + arrayDate[i] + separator;
            }
            strDate = strDate.substring(0, strDate.length-1);
        }
        
        return strDate;
    },
    
    validateDateString: function(strDate){
        
        var objRegExp = /^\d{1,2}(\-|\/|\.)\d{1,2}\1\d{4}$/
        
        if(!objRegExp.test(strDate)){
            return false; //falscher Datumformat
        } else {
            var strSeparator = strDate.substring(2,3) 
            var arrayDate = strDate.split(strSeparator); 
            
            //Zuordnung "Monat"->"Max. Anzahl von Tagen" erstellen, nicht fuer Februar relevant
            var arrayLookup = { '01': 31, '03': 31, 
                                '04': 30, '05': 31, '06': 30,
                                '07': 31, '08': 31, '09': 30,
                                '10': 31, '11': 30, '12': 31 };
                                
            var intDay = parseInt(arrayDate[0],10); 
        
            //Tagwert und Monatwert pruefen
            if (arrayLookup[arrayDate[1]] != null) {
                if ((intDay <= arrayLookup[arrayDate[1]]) && (intDay != 0))
                    return true; //richtig, in der Zuordnungstabelle gefunden wurde
            }
            
            //Pruefung fuer Februar
            var intMonth = parseInt(arrayDate[1],10);
            if (intMonth == 2) { 
               var intYear = parseInt(arrayDate[2]);
               if ((intDay > 0) && (intDay < 29)) {
                   return true;
               } else if (intDay == 29) {
                    if ((intYear % 4 == 0) && (intYear % 100 != 0) || (intYear % 400 == 0)) {
                        // year div by 4 and ((not div by 100) or div by 400) ->ok
                        return true;
                    }   
               }
            }
        }
        
        return false; //Alles anderes ist falsch
           
    },
    
    validateDateRange: function(c, strDate){
        
        var currentDateFull = new Date();
        var strCurrentDate = currentDateFull.getDate()+'.'+ parseInt(currentDateFull.getMonth()+1)+'.'+currentDateFull.getFullYear();
        strCurrentDate = this.normalizeDateString(strCurrentDate);
        
        strDate = this.normalizeDateString(strDate);
        
        c.range = (typeof(c.range) == 'undefined') ? { from: null, upto: null} : c.range;
        
        //From
        var rangeFrom = this.normalizeDateString(c.range.from);
        
        if (c.onlyFutureEnabled) {
            if ((rangeFrom != null) && (this.isDatesLt(c.range.from, strCurrentDate))) rangeFrom = strCurrentDate;
            else if (rangeFrom == null) rangeFrom = strCurrentDate;
        }
        
        //To
        var rangeUpto = this.normalizeDateString(c.range.upto);
        if ((c.onlyFutureEnabled) && (rangeUpto != null) && (this.isDatesLt(rangeUpto, strCurrentDate))) rangeUpto = null;
        
        
        //
        if (c.onlyFutureEnabled) {
            if ((c.currentDateEnabled)  && (this.isDatesLt(strDate, rangeFrom))) return false;
            if ((!c.currentDateEnabled) && (this.isDatesLtEq(strDate, rangeFrom))) return false;   
        } 
        if ((rangeFrom != null) && (this.isDatesLt(strDate, rangeFrom))) return false;
        if ((rangeUpto != null) && (this.isDatesLt(rangeUpto, strDate))) return false;
        
        return true;
    },
    
    isDatesEq: function(strDate1, strDate2){
    
        var strSeparator1 = strDate1.substring(2,3) 
        var arrayDate1 = strDate1.split(strSeparator1); 
        var strSeparator2 = strDate2.substring(2,3) 
        var arrayDate2 = strDate2.split(strSeparator2); 
        if ( arrayDate1[0] == arrayDate2[0] &&
             arrayDate1[1] == arrayDate2[1] &&
             arrayDate1[2] == arrayDate2[2] ) return true;
        else return false;      
    },
    
    isDatesLt: function(strDate1, strDate2){
   
        var strSeparator1 = strDate1.substring(2,3) 
        var arrayDate1 = strDate1.split(strSeparator1); 
        var strSeparator2 = strDate2.substring(2,3) 
        var arrayDate2 = strDate2.split(strSeparator2);
        
        var day1   = parseInt(arrayDate1[0],10);
        var month1 = parseInt(arrayDate1[1],10);
        var year1  = parseInt(arrayDate1[2],10);
        var day2   = parseInt(arrayDate2[0],10);
        var month2 = parseInt(arrayDate2[1],10);
        var year2  = parseInt(arrayDate2[2],10);
        
        //alert(strDate1 +'#'+ strDate2 + ' | ' +day1+'.'+month1+'#'+day2+'.'+month2);
        
        if (year1 < year2) return true;
        else if (year1 > year2) return false;
        else{
            if (month1 < month2) return true;
            else if (month1 > month2) return false;
            else {
                if (day1 < day2) return true;
                else if (day1 > day2) return false;
                else return false;
            }
        }
        
        return false;
    },
    
    isDatesLtEq: function(strDate1, strDate2){
        
        if (this.isDatesEq(strDate1, strDate2)) return true;
        if (this.isDatesLt(strDate1, strDate2)) return true;
        return false;
    }
    
    
};