// JavaScript Document
function show_calendar(str_target, str_datetime) {
  var arr_months = ["January", "February", "March", "April", "May", "June",
    "July", "August", "September", "October", "November", "December"];
  var week_days = ["Su", "Mo", "Tu", "We", "Th", "Fr", "Sa"];
  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_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);
  
  // print calendar header
  var str_buffer = new String (
    "<html>\n"+
    "<head>\n"+
    "<title>Calendar</title>\n"+
	"<link rel=\"stylesheet\" href=\"../views/minimal/default.css\" type=\"text/css\">\n"+
    "</head>\n"+
    "<body>\n"+
    "<table cellspacing=\"0\" border=\"0\" width=\"100%\">\n"+
    "<tr><td>\n"+
    "<table cellspacing=\"1\" cellpadding=\"3\" border=\"0\" width=\"100%\">\n"+
    "<tr class=\"calendarheader\">\n  <td>&nbsp;<a href=\"javascript:window.opener.show_calendar('"+
    str_target+"', '"+ dt2dtstr(dt_prev_month)+"'+document.cal.time.value);\">"+
    "<</a></td>\n"+
    "  <td colspan=\"5\">"+
    "<font color=\"white\" face=\"tahoma, verdana\" size=\"2\">"
    +arr_months[dt_datetime.getMonth()]+" "+dt_datetime.getFullYear()+"</font></td>\n"+
    "<td align=\"right\"><a href=\"javascript:window.opener.show_calendar('"
    +str_target+"', '"+dt2dtstr(dt_next_month)+"'+document.cal.time.value);\">"+
    "></a>&nbsp;</td>\n</tr>\n"
  );

  var dt_current_day = new Date(dt_firstday);
  // print weekdays titles
  str_buffer += "<tr class=\"calendarheaderweeks\">\n";
  for (var n=0; n<7; n++)
    str_buffer += "  <td>"+
    "<font 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()) {
    // print row header
    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=\"#5697ca\" align=\"right\">";
        else if (dt_current_day.getDay() == 0 || dt_current_day.getDay() == 6)
          // weekend days
          str_buffer += "  <td class=\"calendarenddays\" align=\"right\">";
        else
          // print working days of current month
          str_buffer += "  <td class=\"calendarworkdays\" align=\"right\">";

        if (dt_current_day.getMonth() == dt_datetime.getMonth())
          // print days of current month
          str_buffer += "<a href=\"javascript:window.opener."+str_target+
          ".value='"+dt2dtstr(dt_current_day)+"'+document.cal.time.value; window.close();\">"+
          "<font color=\"black\" face=\"tahoma, verdana\" size=\"2\">";
        else 
          // print days of other months
          str_buffer += "<a href=\"javascript:window.opener."+str_target+
          ".value='"+dt2dtstr(dt_current_day)+"'+document.cal.time.value; 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"+
    "<input type=\"hidden\" name=\"time\" value=\""+
    "\" size=\"8\" maxlength=\"8\"></td></tr>\n</form>\n" +
    "</table>\n" +
    "</tr>\n</td>\n</table>\n" +
    "</body>\n" +
    "</html>\n";

  var vWinCal = window.open("", "Calendar", "width=200,height=170,status=no,resizable=no,top=300,left=300");
  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 new Date();
  return (new Date (RegExp.$3, RegExp.$2-1, RegExp.$1));
}
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()));
}
