/*
AJAX url-loading object and a request queue built on top of it

(C) author of AJAX in Action book from Manning
    bugfixes by Csaba Kiss, 2006.Jan.

$Id: net_contentloader.js,v 1.2 2006/02/16 11:13:32 csaba Exp $

 usage:
 - first include.
 - then in call it like:

 		function processData() {
 			// process data received from ajax fn here as you wish
 			// this is the context of the fn. do not worry about it how :-)
 			alert(this.req.responseText);
 			// alert(this.req.responseXML);
 		}

 		var x = new net.ContentLoader('url_supporting_data_with_params', processData,
 		                               errorFn(or null), 'GET'/'POST', params if POST, content type if POST);

	- multiple calls can be started with instantiating more objects
*/


/* namespacing object */
var net=new Object();

/*--- content loader object for cross-browser requests ---*/
net.ContentLoader=function(url,onload,onerror,method,params,contentType){
  this.req=null;
  this.onload=onload;
  this.onerror=(onerror) ? onerror : this.defaultError;
  this.loadXMLDoc(url,method,params,contentType);
}

net.ContentLoader.prototype.loadXMLDoc=function(url,method,params,contentType){
  if (!method){
    method="GET";
  }
  if (!contentType && method=="POST"){
    contentType='application/x-www-form-urlencoded';
  }
  if (window.XMLHttpRequest){
    this.req=new XMLHttpRequest();
  } else if (window.ActiveXObject){
    this.req=new ActiveXObject("Microsoft.XMLHTTP");
  }
  if (this.req){
    try {
      var loader = this;
      this.req.onreadystatechange = function() {
      	loader.onReadyState.call(loader);
      }
      this.req.open(method,url,true);
      if (contentType){
        this.req.setRequestHeader('Content-Type', contentType);
      }
      this.req.send(params);
    } catch (err){
      this.onerror.call(this);
    }
  }
}


net.ContentLoader.prototype.onReadyState=function(){
  var req=this.req;
  var ready=req.readyState;
  //var httpStatus=req.status;
  if (ready==4 && this.onload!=null){
    this.onload.call(this);
    //if (httpStatus==200 || httpStatus==0){
    //  this.onload.call(this);
    //}else{
    //  this.onerror.call(this);
    //}
  }
}


net.ContentLoader.prototype.defaultError=function(){
  alert("error fetching data!"
    +"\n\nreadyState:"+this.req.readyState
    +"\nstatus: "+this.req.status
    +"\nheaders: "+this.req.getAllResponseHeaders());
}