function getXmlHttpRequest() {
   var httpRequest = null;
   try {
      httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
   }
   catch (e) {
      try {
         httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
      }
      catch (e) {
         httpRequest = null;
      }
   }
   if (!httpRequest && typeof XMLHttpRequest != "undefined") {
      httpRequest = new XMLHttpRequest();
   }
   return httpRequest;
}

function getUrlSync(url) {
   return getUrl(url, false, null);
}

function getUrlAsync(url, handleStateChange) {
   return getUrl(url, true, handleStateChange);
}

// call a url
function getUrl(url, async, handleStateChange) {
   var xmlHttpReq = getXmlHttpRequest();

   if (!xmlHttpReq)
      return;

   if (handleStateChange) {
      xmlHttpReq.onreadystatechange = function() {
            handleStateChange(xmlHttpReq);
         };
   } else {
      xmlHttpReq.onreadystatechange = function() {;}
   }

   xmlHttpReq.open("GET", url, async);
   xmlHttpReq.send(null);
}

function postUrl(url, data, async, stateChangeCallback) {
   var xmlHttpReq = getXmlHttpRequest();

   if (!xmlHttpReq)
      return;

   xmlHttpReq.open("POST", url, async);
   xmlHttpReq.onreadystatechange = function() {
         stateChangeCallback(xmlHttpReq);
      };
   xmlHttpReq.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
   xmlHttpReq.send(data);
}

function urlEncodeDict(dict) {
   var result = "";
   for (var i=0; i<dict.length; i++) {
      result += "&" + encodeURIComponent(dict[i].name) + "=" + encodeURIComponent(dict[i].value);
   }
   return result;
}

function execOnSuccess(stateChangeCallback) {
   return function(xmlHttpReq) {
      if (xmlHttpReq.readyState == 4 && xmlHttpReq.status == 200)
         stateChangeCallback(xmlHttpReq);
      };
}


function postFormByForm(form, async, successCallback) {
   var formVars = new Array();
   for (var i = 0; i < form.elements.length; i++) {
      var formElement = form.elements[i];

      // Special handling for checkboxes (we need an array of selected checkboxes..)!
      if(formElement.type=='checkbox' && !formElement.checked) {
         continue;
      }
      var v=new Object;
      v.name=formElement.name;
      v.value=formElement.value;
      formVars.push(v);
   }
   postUrl(form.action, urlEncodeDict(formVars), async, execOnSuccess(successCallback));
}


function urlRequest(url, async, successCallback) {
   postUrl(url, '', async, execOnSuccess(successCallback));
}


function postForm(formName, async, successCallback) {
   // postFormByName
   var form = document.forms[formName];
   return postFormByForm(form, async, successCallback);
}


function execJS(node) {
   /* Element auf Javascript �berpr�fen, und falls n�tig ausf�hren */
   var bSaf = (navigator.userAgent.indexOf('Safari') != -1);
   var bOpera = (navigator.userAgent.indexOf('Opera') != -1);
   var bMoz = (navigator.appName == 'Netscape');
   var st = node.getElementsByTagName('script');
   var strExec;
   
   for(var i=0;i<st.length; i++) { 
      if (bSaf) {
         strExec = st[i].innerHTML;
      } else if (bOpera) {
         strExec = st[i].text;
      } else if (bMoz) {
         strExec = st[i].textContent;
      } else {
         strExec = st[i].text;
      }
      try {
         eval(strExec);
      } catch(e) { 
         alert(e);
      }
   }
}


function replaceDivContents(xmlHttpRequest, dstDivId) {

  var dstDiv = document.getElementById(dstDivId);
   dstDiv.innerHTML = xmlHttpRequest.responseText;
   execJS(document.getElementById(dstDivId));
}

function closeDiv(dstDivId) {

  var dstDiv = document.getElementById(dstDivId);
   dstDiv.innerHTML = "";
}

function getUrlXMLResponseCallback(xmlHttpReq) {
   if(xmlHttpReq.responseXML == null) {
      alert("Error while processing your request.");
      return;
   }
   var root_node = getRootNode(xmlHttpReq);
   var return_code = getNodeValue(root_node, 'return_code');
   //alert("return code " + return_code);

   if(return_code == 0) {
      redirect_val = getNodeValue(root_node, 'redirect_on_success');
      if(redirect_val != null) {
         window.location=redirect_val;
      } else {
         success_message = getNodeValue(root_node, 'success_message');
         if (success_message != null) {
            alert(success_message);
         }
         if(this.successCallback != null) {
            this.successCallback(xmlHttpReq);
         }
      }
   } else {
      var error_msg = getNodeValue(root_node, 'error_message');
      if (error_msg == null || error_msg.length == 0) {
         error_msg = "An error occured while performing this operation.";
      }
      alert(error_msg)
   }
}

function getUrlXMLResponseCallbackFillDiv(xmlHttpReq) {
   getUrlXMLResponseCallback(xmlHttpReq);
   document.getElementById(this.div_id).innerHTML=getNodeValue(xmlHttpReq.responseXML, "html_content");
}

function getNodeValue(obj,tag) {
   node=obj.getElementsByTagName(tag);
   if(node!=null && node.length>0) {
      return node[0].firstChild.nodeValue;
   } else {
      return null;
   }
}

function getRootNode(xmlHttpReq) {
   return xmlHttpReq.responseXML.getElementsByTagName('root')[0];
}

function getUrlXMLResponse(url, successCallback) {
   this.successCallback = successCallback;
   this.urlResponseCallback = getUrlXMLResponseCallback;
   getUrl(url, true, execOnSuccess(this.urlResponseCallback))
}

function getUrlXMLResponseAndFillDiv(url, div_id, successCallback) {
   this.successCallback = successCallback;
   this.urlResponseCallback = getUrlXMLResponseCallbackFillDiv;
   this.div_id = div_id;
   getUrl(url, true, execOnSuccess(this.urlResponseCallback))
}

function postUrlXMLResponse(url, data, successCallback) {
   this.successCallback = successCallback;
   this.urlResponseCallback = getUrlXMLResponseCallback;
   postUrl(url, data, true, execOnSuccess(this.urlResponseCallback))
}
// ANGUS - This appears to be unused...
function confirmAndPostUrlXMLResponse(url, confirmMessage, data, successCallback) {
   if (confirm(confirmMessage)) {
      postUrlXMLResponse(url, data, successCallback);
   }
}

function postFormXMLResponse(formName, successCallback) {
   this.successCallback = successCallback;
   postForm(formName, true, execOnSuccess(getUrlXMLResponseCallback))
}