// Title: Timestamp picker
// Version: 0.1

function show_calendar(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 = 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);

   // 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"+
      "  <link href=\"style/drmac.css\" rel=\"stylesheet\" type=\"text/css\">" +
      "</head>\n"+
      "<body bgcolor=\"White\">\n"+
      "<table class=\"clsOTable\" cellspacing=\"0\" border=\"0\" width=\"100%\">\n"+
      "<tr><td bgcolor=\"#660066\">\n"+
      "<table cellspacing=\"1\" cellpadding=\"3\" border=\"0\" width=\"100%\">\n"+
      "<tr>\n  <td bgcolor=\"#660066\"><a href=\"javascript:window.opener.show_calendar("+
      "'"+ dt2dtstr(dt_prev_month)+"'+document.cal.time.value);\">"+
      "<img src=\"images/prev.gif\" width=\"16\" height=\"16\" border=\"0\""+
      " alt=\"previous month\"></a></td>\n"+
      "  <td bgcolor=\"#660066\" colspan=\"5\" align=\"center\">"+
      "<font color=\"white\" face=\"tahoma, verdana\" size=\"3\">"
      +arr_months[dt_datetime.getMonth()]+" "+dt_datetime.getFullYear()+"</font></td>\n"+
      "  <td bgcolor=\"#660066\" align=\"right\"><a href=\"javascript:window.opener.show_calendar('"
      +dt2dtstr(dt_next_month)+"'+document.cal.time.value);\">"+
      "<img src=\"images/next.gif\" width=\"16\" height=\"16\" border=\"0\""+
      " alt=\"next month\"></a></td>\n</tr>\n"
   );
  //alert("dt_prev_month "+dt_prev_month+"\ndt_next_month "+dt_next_month);

   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=\"#D3B8E0\">"+
      "<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()) {
      // 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=\"#FFFF9D\" align=\"right\">";
            else if (dt_current_day.getDay() == 0 || dt_current_day.getDay() == 6)
               // weekend days
               str_buffer += "   <td bgcolor=\"#EFEBF1\" 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 += "<font color=\"black\" face=\"tahoma, verdana\" size=\"2\">";
            else
               // print days of other months
               str_buffer += "<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=\"#D3B8E0\">"+
      "<font color=\"White\" face=\"tahoma, verdana\" size=\"2\">"+
      "<input type=\"hidden\" name=\"time\" value=\""+dt2tmstr(dt_datetime)+
      "\" size=\"8\" maxlength=\"8\"></font></td></tr>\n</form>\n" +
      "</table>\n" +
      "</tr>\n</td>\n</table>\n" +
      //"<br><center><A HREF=\"javascript:window.close()\">Close Window</A></center><br>" +
      "<br><center><input class=\"mcButton\" type=\"button\" value=\"Close\" onClick=\"window.close()\" onMouseOver=\"this.className='mcButton_mouseOver'\" onMouseOut=\"this.className='mcButton'\"></center>" +
      "</body>\n" +
      "</html>\n";

   var vWinCal = window.open("", "Calendar",
      "width=200,height=250,status=no,resizable=yes,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) {
   // Changed to validate date only not [Date time]
   //var re_date = /^(\d+)\-(\d+)\-(\d+)\s+(\d+)\:(\d+)\:(\d+)$/;
   str_datetime = str_datetime.trim();
   var re_date = /^(\d+)\-(\d+)\-(\d+)$/;

   if (!re_date.exec(str_datetime))
      return alert("Invalid Datetime format: "+ str_datetime);

   return (new Date (RegExp.$3, RegExp.$1-1, RegExp.$2, 0, 0, 0));
}
function dt2dtstr (dt_datetime) {
   //return (new String (dt_datetime.getDate()+"-"+(dt_datetime.getMonth()+1)+"-"+dt_datetime.getFullYear()+" "));
   return (new String (dt_datetime.getMonth()+1)+"-"+(dt_datetime.getDate()+"-"+dt_datetime.getFullYear()+" "));
}
function dt2tmstr (dt_datetime) {
   //return (new String (dt_datetime.getHours()+":"+dt_datetime.getMinutes()+":"+dt_datetime.getSeconds()));
   return "";;
}


String.prototype.trim = function() {

 // skip leading and trailing whitespace
 // and return everything in between
  var x=this;
  x=x.replace(/^\s*(.*)/, "$1");
  x=x.replace(/(.*?)\s*$/, "$1");
  return x;
}