var arrWeekDag = new Array("Zondag","Maandag","Dinsdag","Woensdag","Donderdag","Vrijdag","Zaterdag");
var arrWkDagen = new Array("Zo","Ma","Di","Wo","Do","Vr","Za");
var arrMaanden = new Array("Januari","Februari","Maart","April","Mei","Juni","Juli","Augustus","September","Oktober","November","December");

function DagenInMaand (cMaand,cJaar) {
  switch (cMaand) {
    case '2':
      if (cJaar % 4)
        return(28);
      else
        return(29);
    case '4':
      return(30);
    case '6':
      return(30);
    case '9':
      return(30);
    case '11':
      return(30);
    default:
      return(31);
  }         
}


function Kalender(cKalenderID,prefDate) {
var cDatum,cWeekDag,cDag,cMaand,cJaar,AantalDagen,i;
  if (prefDate.length == 8) {
    cDatum = new Date(prefDate.substr(0,4),prefDate.substr(4,2)-1,prefDate.substr(6,2));
  } else {
    cDatum = new Date();
  }
  cWeekDag = cDatum.getDay();
  cDag = cDatum.getDate();
  cMaand = cDatum.getMonth()+1;
  cJaar = cDatum.getFullYear();
  AantalDagen = DagenInMaand(cMaand,cJaar);

  document.write("<SELECT id=cmbWdg" + cKalenderID + " name=cmbWdg" + cKalenderID + " size=1 disabled=true>");
  for (i = 0; i < 7; i++) {
   if (i == cWeekDag) {
     document.write("<OPTION value=" + i + " selected>" + arrWkDagen[i]);
   } else {
     document.write("<OPTION value=" + i + ">" + arrWkDagen[i]);
   }
  }
  document.write("</SELECT><SELECT id=cmbDag" + cKalenderID + " name=cmbDag" + cKalenderID + " size=1 onChange=UpdateWeekDag(" + cKalenderID + ")>");
  for (i = 1; i <= AantalDagen; i++) {
   if (i == cDag) {
     document.write("<OPTION value=" + i + " selected>" + i);
   } else {
     document.write("<OPTION value=" + i + ">" + i);
   }
  }
  document.write("</SELECT><SELECT id=cmbMnd" + cKalenderID + " name=cmbMnd" + cKalenderID + " size=1 onChange=UpdateDagen(" + cKalenderID + ")>");
  for (i = 1; i <= 12; i++) {
   if (i == cMaand) {
     document.write("<OPTION value=" + i +" selected>" + arrMaanden[i-1]);
   } else {
     document.write("<OPTION value=" + i +">" + arrMaanden[i-1]);
   }
  }
  document.write("</SELECT><SELECT id=cmbJar" + cKalenderID + " name=cmbJar" + cKalenderID + " size=1 onChange=UpdateDagen(" + cKalenderID + ")>");
  for (i = 1990; i <= 2010; i++) {
   if (i == cJaar) {
     document.write("<OPTION value=" + i + " selected>" + i);
   } else {
     document.write("<OPTION value=" + i + ">" + i);
   }
  }
  document.write("</SELECT>");
}


function UpdateDagen(cKalenderID) {
var cMaand,cJaar,cDagenOud,cDagenNieuw,cVerschil,i,oOption;
  cJaar = document.getElementById('cmbJar' + cKalenderID).options[document.getElementById('cmbJar' + cKalenderID).selectedIndex].value;
  cMaand = document.getElementById('cmbMnd' + cKalenderID).options[document.getElementById('cmbMnd' + cKalenderID).selectedIndex].value;
  cDagenOud = document.getElementById('cmbDag' + cKalenderID).options.length;
  cDagenNieuw = DagenInMaand(cMaand,cJaar);
  cVerschil = cDagenNieuw - cDagenOud;

  if (cVerschil != 0) {
    if (cVerschil > 0) {
      for (i = cDagenOud; i < cDagenNieuw; i++) {
        oOption = document.createElement("OPTION");
        oOption.text=i+1;
        oOption.value=i+1;
        document.getElementById('cmbDag' + cKalenderID).options.add(oOption);
      }
    } else {
      for (i = cDagenOud; i > cDagenNieuw; i--) {
        document.getElementById('cmbDag' + cKalenderID).options.remove(i-1);
      }
    }
  }
  UpdateWeekDag(cKalenderID);
}


function UpdateWeekDag(cKalenderID) {
var cJaar,cMaand,cDag,cDatum,cWeekDag
  cJaar = document.getElementById('cmbJar' + cKalenderID).options[document.getElementById('cmbJar' + cKalenderID).selectedIndex].value;
  cMaand = document.getElementById('cmbMnd' + cKalenderID).options[document.getElementById('cmbMnd' + cKalenderID).selectedIndex].value;
  cDag = document.getElementById('cmbDag' + cKalenderID).options[document.getElementById('cmbDag' + cKalenderID).selectedIndex].value;
  var cDatum = new Date(cJaar, cMaand-1, cDag)
  cWeekDag = cDatum.getDay();
  document.getElementById('cmbWdg' + cKalenderID).selectedIndex = cWeekDag
}

function NieuwRooster(cKalenderID) {
var cJaar,cMaand,cDag,cDatum
  cJaar = new Number(document.getElementById('cmbJar' + cKalenderID).options[document.getElementById('cmbJar' + cKalenderID).selectedIndex].value);
  cMaand = new Number(document.getElementById('cmbMnd' + cKalenderID).options[document.getElementById('cmbMnd' + cKalenderID).selectedIndex].value);
  cDag = new Number(document.getElementById('cmbDag' + cKalenderID).options[document.getElementById('cmbDag' + cKalenderID).selectedIndex].value);
  cDatum = (cJaar*10000) + (cMaand*100) + cDag; 
  document.location="kerkdiensten.asp?datum=" + cDatum;
}