

function show_calendar(str_target, str_datetime) {

	var arr_months = ["Január", "Február", "Marec", "Apríl", "Máj", "Jún",
		"Júl", "August", "September", "Október", "November", "December"];
	var week_days = ["Ne", "Po", "Ut", "St", "Št", "Pi", "So"];
	var n_weekstart = 1; // day week starts from (normally 0 or 1)

	var dt_datetime = (str_datetime == null || str_datetime =="" ?  new Date() : str2dt(str_datetime));

	var dt_prev_month = new Date(dt_datetime);
	dt_prev_month.setMonth(dt_datetime.getMonth()-1);
	var dt_next_month = new Date(dt_datetime);
	dt_next_month.setMonth(dt_datetime.getMonth()+1);

	var dt_prev_year = new Date(dt_datetime);
	dt_prev_year.setMonth(dt_datetime.getMonth()-12);
	var dt_next_year = new Date(dt_datetime);
	dt_next_year.setMonth(dt_datetime.getMonth()+12);

	var dt_firstday = new Date(dt_datetime);
	dt_firstday.setDate(1);
	dt_firstday.setDate(1-(7+dt_firstday.getDay()-n_weekstart)%7);
	var dt_lastday = new Date(dt_next_month);
	dt_lastday.setDate(0);
	
	// html generation (feel free to tune it for your particular application)
	// print calendar header
	var str_buffer = new String (
		"<html>\n"+
		"<head>\n"+
		"	<title>Calendar</title>\n"+
		"	<style type='text/css'>"+
		"	a {color: #FFFFFF; text-decoration: none; font-weight:bold;}"+
		"	a:link {color: #FFFFFF; text-decoration: none; font-weight:bold;}"+
		"	a:visited {color: #FFFFFF; text-decoration: none; font-weight:bold;}"+
		"	a:hover {color: #FFFFFF; text-decoration: none; font-weight:bold;}"+
		"	a:active {color: #FFFFFF; text-decoration: none; font-weight:bold;}"+
		"	</style>\n"+
		"</head>\n"+
		"<body bgcolor=\"White\">\n"+
		"<table class=\"clsOTable\" cellspacing=\"0\" border=\"0\" width=\"185\" align=\"center\">\n"+
		"<tr><td bgcolor=\"#003480\">\n"+
		"<table cellspacing=\"1\" cellpadding=\"3\" border=\"0\" width=\"100%\">\n"+
		"<tr>\n	<td bgcolor=\"#003480\"><a href=\"javascript:window.opener.show_calendar('"+
		str_target+"', '"+ dt2dtstr(dt_prev_month)+"');\">"+
		"«</a></td>\n"+
		"	<td bgcolor=\"#003480\" colspan=\"5\" style=\"text-align: center;\">"+
		"<font color=\"white\" face=\"tahoma, verdana\" size=\"2\"><b>"
		+arr_months[dt_datetime.getMonth()]+" "+dt_datetime.getFullYear()+"</b></font></td>\n"+
		"	<td bgcolor=\"#003480\" align=\"right\"><a href=\"javascript:window.opener.show_calendar('"
		+str_target+"', '"+dt2dtstr(dt_next_month)+"');\">"+
		"»</a></td>\n</tr>\n"
	);

	var dt_current_day = new Date(dt_firstday);
	// print weekdays titles
	str_buffer += "<tr>\n";
	for (var n=0; n<7; n++)
		str_buffer += "	<td bgcolor=\"#3982A5\">"+
		"<font color=\"white\" face=\"tahoma, verdana\" size=\"2\">"+
		week_days[(n_weekstart+n)%7]+"</font></td>\n";
	// print calendar table
	str_buffer += "</tr>\n";
	
/*	while (dt_current_day.getMonth() == dt_datetime.getMonth() ||
		dt_current_day.getMonth() == dt_firstday.getMonth()) {
*/
          for (var imy=0; imy<6; imy++) {
		// print row heder
		str_buffer += "<tr>\n";
		for (var n_current_wday=0; n_current_wday<7; n_current_wday++) {
				if (dt_current_day.getDate() == dt_datetime.getDate() &&
					dt_current_day.getMonth() == dt_datetime.getMonth())
					// print current date
					str_buffer += "	<td bgcolor=\"#89c2f5\" align=\"right\">";
				else if (dt_current_day.getDay() == 0 || dt_current_day.getDay() == 6)
					// weekend days
					str_buffer += "	<td bgcolor=\"#EBF8FF\" align=\"right\">";
				else
					// print working days of current month
					str_buffer += "	<td bgcolor=\"white\" align=\"right\">";

				if (dt_current_day.getMonth() == dt_datetime.getMonth())
					// print days of current month
					str_buffer += "<a href=\"javascript:window.opener.document."+str_target+
					".value='"+dt2dtstr(dt_current_day)+"';window.close();\">"+
					"<font color=\"black\" face=\"tahoma, verdana\" size=\"2\">";
				else 
					// print days of other months
					str_buffer += "<a href=\"javascript:window.opener.document."+str_target+
					".value='"+dt2dtstr(dt_current_day)+"'; window.close();\">"+
					"<font color=\"gray\" face=\"tahoma, verdana\" size=\"2\">";
				str_buffer += dt_current_day.getDate()+"</font></a></td>\n";
				dt_current_day.setDate(dt_current_day.getDate()+1);
		}
		// print row footer
		str_buffer += "</tr>\n";
	}
	// print calendar footer
	
	/*
	str_buffer +=
		"<form name=\"cal\">\n<tr><td colspan=\"7\" bgcolor=\"#87CEFA\">"+
		"<font color=\"White\" face=\"tahoma, verdana\" size=\"2\">"+
		"Time: <input type=\"text\" name=\"time\" value=\""+dt2tmstr(dt_datetime)+
		"\" size=\"8\" maxlength=\"8\"></font></td></tr>\n</form>\n" +
		*/
		
     str_buffer +=""+
		"<tr>\n	<td bgcolor=\"#003480\"><a href=\"javascript:window.opener.show_calendar('"+
		str_target+"', '"+ dt2dtstr(dt_prev_year)+"');\">"+
		"«</a></td>\n"+
		"	<td bgcolor=\"#003480\" colspan=\"5\" style=\"text-align: center;\">"+
		"<font color=\"white\" face=\"tahoma, verdana\" size=\"1\">"+
		"posúvanie po rokoch"+
		"	<td bgcolor=\"#003480\" align=\"right\"><a href=\"javascript:window.opener.show_calendar('"
		+str_target+"', '"+dt2dtstr(dt_next_year)+"');\">"+
		"»</a></td>\n</tr>\n";
		
	str_buffer +=	"</table>\n" +
					"</tr>\n</td>\n</table>\n" +
					"</body>\n" +
					"</html>\n";


     width=202;
     height=240;
     win_width=(screen.width/2)-width/2;
     win_height=(screen.height/2)-height/2;
     win_info="status=no,resizable=yes,width="+width+",height="+height+",top="+win_height+",left="+win_width;


	var vWinCal = window.open("", "Calendar",win_info);
	vWinCal.opener = self;
	var calc_doc = vWinCal.document;
	calc_doc.write (str_buffer);
	calc_doc.close();
}

// datetime parsing and formatting routimes. modify them if you wish other datetime format
function str2dt (str_datetime) {
	var re_date = /^(\d+)\.(\d+)\.(\d+)/;
	if (!re_date.exec(str_datetime))
		return alert("Invalid Datetime format: "+ str_datetime);
	return (new Date (RegExp.$3, RegExp.$2-1, RegExp.$1, RegExp.$4, RegExp.$5, RegExp.$6));
}
function dt2dtstr (dt_datetime) {
	return (new String (
			dt_datetime.getDate()+"."+(dt_datetime.getMonth()+1)+"."+dt_datetime.getFullYear()+""));
}
function dt2tmstr (dt_datetime) {
	return (new String (
			dt_datetime.getHours()+":"+dt_datetime.getMinutes()+":"+dt_datetime.getSeconds()));
}





