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

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

net.READY_STATE_UNINITIALIZED=0;
net.READY_STATE_LOADING=1;
net.READY_STATE_LOADED=2;
net.READY_STATE_INTERACTIVE=3;
net.READY_STATE_COMPLETE=4;


/*--- 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 (!this.req) try {
    this.req = new XMLHttpRequest();
  } catch (e){;};
  if (!this.req) try {
    this.req = new ActiveXObject('Msxml2.XMLHTTP');
  } catch (e){;};
  if (!this.req) try {
    this.req = new ActiveXObject('Microsoft.XMLHTTP');
  } catch (e){;};
  
  if (this.req){
    try{
      var loader=this;
      this.req.onreadystatechange=function(){
        net.ContentLoader.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.onReadyState=function(){
  var req=this.req;
  var ready=req.readyState;
  
  if (ready==net.READY_STATE_COMPLETE){
  	var httpStatus=req.status;
    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());
}



/* есть ли класс у объекта */
function has_class(obj, clsname) {
	return new RegExp("(^|\\s)"+clsname+"(\\s|$)").test(obj.className)
}
/* переключить класс объекта */
function switch_class(obj, clsname, ncls){
	if (has_class(obj, clsname)) {
		var ro =  new RegExp("(^|\\s)"+clsname+"(\\s|$)"); 
		obj.className = obj.className.replace(ro, '$1'+ncls+'$2') 
	}
	else {
		obj.className += " "+ncls;
	}
}
/* триггер класса */
function trigger_class(obj,clss) {
	if (has_class(obj,clss)) {
		switch_class(obj,clss,'');
	}
	else{
		obj.className += " "+clss;
	}
}