﻿function show_calendar(str_target, str_datetime) {
	var arr_months = ["Janúar", "Febrúar", "Mars", "Apríl", "Maí", "Júní",
		"Júlí", "Ágúst", "September", "Október", "Nóvember", "Desember"];
	var week_days = ["Sun", "Mán", "Þri", "Mið", "Fim", "Fös", "Lau"];
	var n_weekstart = 0; // 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_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);

	var str_buffer = new String (
		"<html>\n"+
		"<head>\n"+
		"	<title>Calendar</title>\n"+
		"	<link rel=\"StyleSheet\" href=\"/css/modules/date_picker.css\" type=\"text/css\" media=\"screen\"  />\n"+
		"	<script>\n"+
		"	function fixHeight(){\n"+
		"		string = document.getElementById(\"cal\").offsetHeight; \n"+
		"		self.resizeTo(205,string) \n"+
		"	}\n"+
		"	</script>\n"+
		"</head>\n"+
		"<body>\n"+
		"<div id=\"cal\">\n"+
		"<a href=\"javascript:window.opener.show_calendar('"+str_target+"', '"+ dt2dtstr(dt_prev_month)+"');\" class=\"prev\"></a></td>\n"+
		"<div class=\"month\">"+arr_months[dt_datetime.getMonth()]+" "+dt_datetime.getFullYear()+"</div>\n"+
		"<a href=\"javascript:window.opener.show_calendar('"+str_target+"', '"+dt2dtstr(dt_next_month)+"');\" class=\"next\"></a>\n"
	);

	var dt_current_day = new Date(dt_firstday);
	// print weekdays titles
	str_buffer += "<div class=\"week\">\n";
	for (var n=0; n<7; n++)
		if(n==0)
			str_buffer += "<div class=\"weekdayFirst\">"+ week_days[(n_weekstart+n)%7] + "</div>\n";
		else if(n==6)
			str_buffer += "<div class=\"weekdayEnd\">" + week_days[(n_weekstart+n)%7] + "</div>\n";
		else
			str_buffer += "<div class=\"weekday\">"+ week_days[(n_weekstart+n)%7] + "</div>\n";
	// print calendar table
	str_buffer += "</div>\n";
	while (dt_current_day.getMonth() == dt_datetime.getMonth() ||
		dt_current_day.getMonth() == dt_firstday.getMonth()) {
		// print row heder
		str_buffer += "<div class=\"fixweek\">\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 += "<a class=\"today ";
				else if (dt_current_day.getDay() == 0)
					// weekend days
					str_buffer += "<a class=\"weekbegin ";
				else if (dt_current_day.getDay() == 6)
					// weekend days
					str_buffer += "<a class=\"weekend ";
				else
					// print working days of current month
					str_buffer += "<a class=\"";

				if (dt_current_day.getMonth() == dt_datetime.getMonth())
					// print days of current month
					str_buffer += "\" href=\"javascript:window.opener."+str_target+".value='"+dt2dtstr(dt_current_day)+"'; window.close();\">"
				else 
					// print days of other months
					str_buffer += "offcal\" href=\"javascript:window.opener."+str_target+".value='"+dt2dtstr(dt_current_day)+"'; window.close();\">"
				str_buffer += dt_current_day.getDate()+"</a>\n";
				dt_current_day.setDate(dt_current_day.getDate()+1);
		}
		// print row footer
		str_buffer += "</div>\n";
	}
	// print calendar footer
	str_buffer +=
		"<div class=\"clear\"></div></div>\n" +
		"</body>\n" +
		"</html>\n";

	var vWinCal = window.open("", "Calendar", "width=205,height=147,status=no,resizable=no,top=200,left=200");
	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()));
}
