// how reliable is this test?
isIE = (document.all ? true : false);
isDOM = (document.getElementById ? true : false);

// Initialize arrays.
var months = new Array("Янв", "Фев", "Мар", "Апр", "Май", "Июн", "Июл",
"Авг", "Сен", "Окт", "Ноя", "Дек");
var daysInMonth = new Array(31, 28, 31, 30, 31, 30, 31, 31,
30, 31, 30, 31);
var displayMonth = new Date().getMonth();
var displayYear = new Date().getFullYear();
var displayDivName;
var displayElement;

function getDays(month, year) {
	// Test for leap year when February is selected.
	if (1 == month)
	return ((0 == year % 4) && (0 != (year % 100))) ||
	(0 == year % 400) ? 29 : 28;
	else
	return daysInMonth[month];
}

function getToday() {
	// Generate today's date.
	this.now = new Date();
	this.year = this.now.getFullYear();
	this.month = this.now.getMonth();
	this.day = this.now.getDate();
}

// Start with a calendar for today.
today = new getToday();

function newCalendar(eltName,attachedElement) {
	if (attachedElement) {
		if (displayDivName && displayDivName != eltName) hideElement(displayDivName);
		displayElement = attachedElement;
	}
	displayDivName = eltName;
	today = new getToday();
	var parseYear = parseInt(displayYear + '');
	var newCal = new Date(parseYear,displayMonth,1);
	var day = -1;
	var startDayOfWeek = newCal.getDay();
	if ((today.year == newCal.getFullYear()) &&
	(today.month == newCal.getMonth()))
	{
		day = today.day;
	}
	var intDaysInMonth =
	getDays(newCal.getMonth(), newCal.getFullYear());
	var daysGrid = makeDaysGrid(startDayOfWeek,day,intDaysInMonth,newCal,eltName)
	if (isIE) {
		var elt = document.all[eltName];
		elt.innerHTML = daysGrid;
	} else if (isDOM) {
		var elt = document.getElementById(eltName);
		elt.innerHTML = daysGrid;
	} else {
		var elt = document.layers[eltName].document;
		elt.open();
		elt.write(daysGrid);
		elt.close();
	}
}

function incMonth(delta,eltName) {
	displayMonth += delta;
	if (displayMonth >= 12) {
		displayMonth = 0;
		incYear(1,eltName);
	} else if (displayMonth <= -1) {
		displayMonth = 11;
		incYear(-1,eltName);
	} else {
		newCalendar(eltName);
	}
}

function incYear(delta,eltName) {
	displayYear = parseInt(displayYear + '') + delta;
	newCalendar(eltName);
}

function makeDaysGrid(startDay,day,intDaysInMonth,newCal,eltName) {
	var daysGrid;
	var month = newCal.getMonth();
	var year = newCal.getFullYear();
	var isThisYear = (year == new Date().getFullYear());
	var isThisMonth = (day > -1)
	daysGrid = '<table border="1" cellspacing="0" cellpadding="2" width="185px"><tr><td bgcolor="#ffffff" nowrap>';
	daysGrid += '<font face="courier new, courier" size="2">';
	daysGrid += '&nbsp;&nbsp;';
	daysGrid += '<a href="javascript:incMonth(-1,\'' + eltName + '\')">&laquo; </a>';

	daysGrid += '<b>';
	if (isThisMonth) { daysGrid += '<font color="red">' + months[month] + '</font>'; }
	else { daysGrid += months[month]; }
	daysGrid += '</b>';

	daysGrid += '<a href="javascript:incMonth(1,\'' + eltName + '\')"> &raquo;</a>';
	daysGrid += '&nbsp;&nbsp;&nbsp;';
	daysGrid += '<a href="javascript:incYear(-1,\'' + eltName + '\')">&laquo; </a>';

	daysGrid += '<b>';
	if (isThisYear) { daysGrid += '<font color="red">' + year + '</font>'; }
	else { daysGrid += ''+year; }
	daysGrid += '</b>';

	daysGrid += '<a href="javascript:incYear(1,\'' + eltName + '\')"> &raquo;</a><br>';
	daysGrid += '&nbsp;Пн Вт Ср Чт Пт Сб Вс&nbsp;<br />&nbsp;';
	var dayOfMonthOfFirstSunday = (7 - startDay + 2);
	for (var intWeek = 0; intWeek < 6; intWeek++) {
		var dayOfMonth;
		for (var intDay = 0; intDay < 7; intDay++) {
			dayOfMonth = (intWeek * 7) + intDay + dayOfMonthOfFirstSunday - 7;
			if (dayOfMonth <= 0) {
				daysGrid += "&nbsp;&nbsp; ";
			} else if (dayOfMonth <= intDaysInMonth) {
				var color = "blue";
				if (day > 0 && day == dayOfMonth) color="red";
				daysGrid += '<a href="javascript:setDay(';
				daysGrid += dayOfMonth + ',\'' + eltName + '\')" '
				daysGrid += 'style="color:' + color + '">';
				var dayString = dayOfMonth + "</a> ";
				if (dayString.length == 6) dayString = '0' + dayString;
				daysGrid += dayString;
			}
		}
		if (dayOfMonth < intDaysInMonth) daysGrid += "<br>&nbsp;";
	}
	
	daysGrid += '</td></tr><tr><td bgcolor="#ffffff" align="right" nowrap>';
	
	daysGrid += '<a href="javascript:hideElement(\'' + eltName + '\')">закрыть</a></td></tr></table>';
	
	return daysGrid;
}

function setDay(day,eltName) {
	displayElement.value = day + "-" + (displayMonth + 1) + "-" + displayYear;
	hideElement(eltName);
}