/*
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 (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);
    }
  }
 },

 onReadyState:function(){
  var req=this.req;
  var ready=req.readyState;
  if (ready==net.READY_STATE_COMPLETE){
    /* mnascimento - ADJ3: Movida a definição da variável para dentro do teste de READY */
    var httpStatus=req.status;
    if (httpStatus==200 || httpStatus==0){
      this.onload.call(this);
    }else{
      this.onerror.call(this);
    }
  }
 },

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



/*--- queue system for efficient transfer of many small commands in a single request ---*/
net.cmdQueues=new Array();


net.CommandQueue=function(id,url,onUpdate,freq){
  this.id=id;
  net.cmdQueues[id]=this;
  this.url=url;
  this.queued=new Array();
  this.sent=new Array();
  this.onUpdate=onUpdate;
  if (freq){
    this.repeat(freq);
  }
  this.lastUpdateTime=0;
}

net.CommandQueue.STATUS_QUEUED=-1;
net.CommandQueue.STATE_UNINITIALIZED=net.READY_STATE_UNINITIALIZED;
net.CommandQueue.STATE_LOADING=net.READY_STATE_LOADING;
net.CommandQueue.STATE_LOADED=net.READY_STATE_LOADED;
net.CommandQueue.STATE_INTERACTIVE=net.READY_STATE_INTERACTIVE;
net.CommandQueue.STATE_COMPLETE=net.READY_STATE_COMPLETE;
net.CommandQueue.STATE_PROCESSED=5;

net.CommandQueue.PRIORITY_NORMAL=0;
net.CommandQueue.PRIORITY_IMMEDIATE=1;


net.CommandQueue.prototype={
 addCommand:function(command){
  if (this.isCommand(command)){
    this.queue.append(command,true);
    if (command.priority==net.CommandQueue.PRIORITY_IMMEDIATE){
      this.fireRequest();
    }
  }
 },

 fireRequest:function(){
  if (!this.onUpdate && this.queued.length==0){
    return;
  }
  var data="lastUpdate="+this.lastUpdateTime+"&data=";
  for(var i=0;i<this.queued.length;i++){
    var cmd=this.queued[i];
    if (this.isCommand(cmd)){
      data+=cmd.toRequestString();
      this.sent[cmd.id]=cmd;
    }
  }
  this.queued=new Array();
  this.loader=new net.ContentLoader(
    this.url,
    net.CommandQueue.onload,
    net.CommandQueue.onerror,
    "POST",data
  );
 },

 isCommand:function(obj){
  return (
    obj.implementsProp("id")
    && obj.implementsProp("priority")
    && obj.implementsFunc("toRequestString")
    && obj.implementsFunc("parseResponse")
  );
 },

 repeat:function(freq){
  this.unrepeat();
  if (freq>0){
    this.freq=freq;
    var cmd="net.cmdQueues["+this.id+"].fireRequest()";
    this.repeater=setInterval(cmd,freq*1000);
  }
 },

 unrepeat:function(){
  if (this.repeater){
    clearInterval(this.repeater);
  }
  this.repeater=null;
 }
}

net.CommandQueue.onload=function(){
  var xmlDoc=this.req.responseXML;
  var elDocRoot=xmlDoc.getElementsByTagName("responses")[0];
  var lastUpdate=elDocRoot.attributes.getNamedItem("updateTime");
  if (parseInt(lastUpdate)>this.lastUpdateTime){
    this.lastUpdateTime=lastUpdate;
  }
  if (elDocRoot){
    for(i=0;i<elDocRoot.childNodes.length;i++){
      elChild=elDocRoot.childNodes[i];
      if (elChild.nodeName=="command"){
        var attrs=elChild.attributes;
        var id=attrs.getNamedItem("id").value;
        var command=net.commandQueue.sent[id];
        if (command){
          command.parseResponse(elChild);
        }
      }else if (elChild.nodeName=="update"){
        if (this.implementsFunc("onUpdate")){
          this.onUpdate.call(this,elChild);
        }
      }
    }
  }
}

net.CommandQueue.onerror=function(){
  alert("problem sending the data to the server");
}