/* Script by:  Rob Patrick (rpatrick@mit.edu) 
   Adaptado y optimizado especialmente para gttnorte.com 
   Begin */
function setToday() {
	var now   = new Date();
	var day   = now.getDate();
	var month = now.getMonth();
	var year  = now.getFullYear();
	//if (year < 100) { year += 1900; }
	//else { year += 2000; }
	this.focusDay = day;
	document.calControl.month.selectedIndex = month;
	document.calControl.year.value = year;
	displayCalendar(month, year);
}
function isFourDigitYear(year) {
	if (year.length != 4) {
	alert ("El aņo debe tener 4 cifras");
	document.calControl.year.select();
	document.calControl.year.focus();
	} 
else { 
	 return true; 
	 }
}
function selectDate() {
	var year  = document.calControl.year.value;
	if (isFourDigitYear(year)) {
	var day   = 0;
	var month = document.calControl.month.selectedIndex;
	displayCalendar(month, year);
    }
}

function setPreviousYear() {
	var year  = document.calControl.year.value;
	if (isFourDigitYear(year)) {
		var day   = 0;
		var month = document.calControl.month.selectedIndex;
		year--;
		document.calControl.year.value = year;
		displayCalendar(month, year);
   }
}
function setPreviousMonth() {
	var year  = document.calControl.year.value;
	if (isFourDigitYear(year)) {
	var day   = 0;
	var month = document.calControl.month.selectedIndex;
	if (month == 0) {
		month = 11;
		if (year > 1000) {
			year--;
			document.calControl.year.value = year;
		}
	} 
	else { 
		month--; 
	}
	document.calControl.month.selectedIndex = month;
	displayCalendar(month, year);
   	}
}
function setNextMonth() {
	var year  = document.calControl.year.value;
	if (isFourDigitYear(year)) {
		var day   = 0;
		var month = document.calControl.month.selectedIndex;
		if (month == 11) {
			month = 0;
			year++;
			document.calControl.year.value = year;
		} 
		else { 
			month++; 
		}
		document.calControl.month.selectedIndex = month;
		displayCalendar(month, year);
	   }
}
function setNextYear() {
	var year = document.calControl.year.value;
	if (isFourDigitYear(year)) {
		var day = 0;
		var month = document.calControl.month.selectedIndex;
		year++;
		document.calControl.year.value = year;
		displayCalendar(month, year);
    }
}
function displayCalendar(month, year) {       
	month = parseInt(month);
	year = parseInt(year);
	var i = 0;
	var days = getDaysInMonth(month+1,year);
	var firstOfMonth = new Date (year, month, 1);
	var startingPos = firstOfMonth.getDay();
	days += startingPos;
	document.calButtons.calPage.value  =   " Su Mo Tu We Th Fr Sa";
	document.calButtons.calPage.value += "\n --------------------";
	for (i = 0; i < startingPos; i++) {
		if ( i%7 == 0 ) document.calButtons.calPage.value += "\n ";
		document.calButtons.calPage.value += "   ";
	}
	for (i = startingPos; i < days; i++) {
		if ( i%7 == 0 ) document.calButtons.calPage.value += "\n ";
		if (i-startingPos+1 < 10)
		document.calButtons.calPage.value += "0";
		document.calButtons.calPage.value += i-startingPos+1;
		document.calButtons.calPage.value += " ";
	}
	for (i=days; i<42; i++)  {
	if ( i%7 == 0 ) document.calButtons.calPage.value += "\n ";
	document.calButtons.calPage.value += "   ";
	}
//document.calControl.Go.focus();
}

function getDaysInMonth(month,year)  {
	var days;
	if (month==1 || month==3 || month==5 || month==7 || month==8 || month==10 || month==12)  days=31;
	else if (month==4 || month==6 || month==9 || month==11) days=30;
	else if (month==2)  {
		if (isLeapYear(year)) { 
			days=29; 
		}
	else { 
	days=28; 
	}
}
return (days);
}
function isLeapYear (Year) {
	if (((Year % 4)==0) && ((Year % 100)!=0) || ((Year % 400)==0)) {
	return (true);
	} 
	else { 
	return (false); 
	}
}
// End