function setAjaxVar(nm, val) {
  loadExternalHtml('reservering_ajax_process.php?control='+nm+'&value='+val, 'calendar');
}       

function clickblock(block) {
  document.getElementById('block-'+block).innerHTML = '<img src="images/agenda_button_blank.gif" width=18 height=14 border=0>';
  loadExternalHtml('reservering_ajax_process.php?block='+block, 'order');
}

function clicktab(tabname) {
  cur = document.getElementById('currenttab');

  document.getElementById('tab_'+cur.value).className = 'normal';
  document.getElementById('content_'+cur.value).style.display = 'none';
  
  cur.value = tabname;
  document.getElementById('tab_'+cur.value).className = 'active';
  document.getElementById('content_'+cur.value).style.display = 'block';
  
  setAjaxVar('activetab', tabname);
}

function cal(month) {
  loadExternalHtml('reservering_ajax_cal.php?month='+month, 'calendar');
}  
function delrow(item) {
  loadExternalHtml('reservering_ajax_process.php?delrow='+item, 'order');
}


/* generic functions*/
function loadExternalHtml(url, targetid) {
  if(targetid) {
    var loadingtext = '<div align=center><br><i>Loading...</i><br></div>';
    
    var tg = document.getElementById(targetid);
    tg.innerHTML = loadingtext;
  }    
  var http_request = false;

  if (window.XMLHttpRequest) { // Mozilla, Safari, ...
    http_request = new XMLHttpRequest();
    if (http_request.overrideMimeType) {
      http_request.overrideMimeType('text/html');
    }
  } else if (window.ActiveXObject) { // IE
    try {
      http_request = new ActiveXObject('Msxml2.XMLHTTP');
    } catch (e) {
      try {
        http_request = new ActiveXObject('Microsoft.XMLHTTP');
      } catch (e) {}
    }
  }

  if (!http_request) {
    alert('Error: Cannot create an XMLHTTP instance');
    return false;
  }                      
    
  http_request.onreadystatechange = function() { loadExternalHtmlResult(http_request, targetid); };
  http_request.open('GET', url, true);
  http_request.setRequestHeader("Connection", "close");
  http_request.send(url);
}
function loadExternalHtmlResult(http_request, targetid) {  
  if(!targetid) return;                                   
  var tg = document.getElementById(targetid);
  if(http_request.readyState == 4) {
    if (http_request.status == 200) {
      tg.innerHTML = http_request.responseText;
    } else {
      tg.innerHTML = '<i>Error '+http_request.status+'</i>';
    }
  }
}


function showLayer(layerid) {
  document.getElementById(layerid).style.display = 'block';
}
function hideLayer(layerid) {
  document.getElementById(layerid).style.display = 'none';
}