datebox = document.getElementById('cal_date');
infobox = document.getElementById('cal_description');

function select_day(date) {
	ajax_getcontent('/ajax/calender_info.php?date=' + date, 'cal_info');
}

function select_month(date) {
	ajax_getcontent('/ajax/calender_raster.php?date=' + date, 'cal_raster');
}

function ajax_setcontent (http_request, id) {
  if (http_request.status == 200)
    document.getElementById(id).innerHTML = http_request.responseText;
  else
    document.getElementById(id).innerHTML = 'Bei der Abfrage ist ein Problem aufgetreten.';
}

function ajax_getcontent(url, objectid) {
  
  ajax_request(url, function(http_request) { ajax_setcontent(http_request, objectid) } );
  
}

function ajax_request (url, callback) {
  
	var http_request = ajax_start();
	if (!http_request)
		return false;

	http_request.open ("POST", url, true);
	
	http_request.onreadystatechange = function() {
		if (http_request.readyState == 4) {
			http_request.onreadystatechange = function(){};
			callback (http_request);
		}
	};
	http_request.send (url);
	return true;
}

function ajax_start() {
  
  if (window.XMLHttpRequest) { // Mozilla
      http_request = new XMLHttpRequest();
  } else if (window.ActiveXObject) { // MS IE
      http_request = new ActiveXObject("Msxml2.XMLHTTP");
  } else {
    return false;
  }
  
  return http_request;
  
}