/******************************************************************************
 Client/Server Gateway JSAPI

 Author: Dan G. Switzer, II
 Date:   December 08, 2000
 Build:  203

 Description:
 This library provides the foundation for easily creating a communication
 gateway between the client and a server.

 With this library you'll be able to push and recieve information from
 the server, inline to the page.

 Version History
 ---------------
 Build 203 (July 24, 2003)
 - Added the GatewayAPI.build property
 - Added the iframeSrc attribute. It seems that on HTTPS
   IE was throwing a message complaining about secure and
   unsecure items running on the page together. If you're
   running SSL/HTTPS on the site, just set this property
   to a blank html document. I'm including one with the
   build you can use.
 - Added the LGPL to the build. Some asked me about
   licensing for the code.

 Build 202a (March 14, 2003)
 - Released the code w/an unused function I used for debugging
   as well as I forgot to update the build number in the comments.
   No real changes.

 Build 202 (March 14, 2003)
 - Opera 5 does not properly cache the variables--it seems to
   make pointers to the iframe, so once a page is reloaded
   the references no longer exist. To work around this problem
   caching is turned off automatically for Opera 5.
 - Fixed bugs causing Opera 5 & 6 not to work. In order for
   Opera to reload a document into an iframe, the iframe tag
   needed a src attribute
 - Removed the script tag that was trying to load the wddx library.
   This wasn't used anyway and was the result of some legacy code.
   This was causes problems in NS4.7x.

 Build 201 (March 12, 2003)
 - Added caching routine. Caching is enabled by default. You can
   either turn caching off completely setting the obj.enableCache
   to false, or you can overwrite the cache settings per call
   to the server using the obj.sendPacket(value, useCache) argument.

 Build 200 (March 10, 2003)
 - Rewrote majority of API

 Build 104 (December 20, 2000)
 - Made the status bar updatable by changing the hard code delay to a var
   (this.statusdelay)
 - Changed delay of status bar updates from 10 to 100

 Build 103
 - Added catch for testing whether or not the WDDX library was actually loaded
   if it's not, we warn the user and disable the gateway.
 - Changed the name of the disable variable to disabled
 - Added onTimeout prototype for defining a function to run if the event times
   out

 Build 102
 - First release
******************************************************************************/

function Queue () {
	this.queue = new Array();
	this.lower = 0; this.upper = 0;
	this.empty = function () { return this.lower == this.upper; }
	this.size = function () { return this.upper - this.lower; }
	this.clear = function () { this.lower = this.upper = 0; }
	this.push = function (val) { this.queue[this.upper++] = val; }
	this.pop = function () {
	  if (this.empty()) return undefined;
	  var val = this.queue[this.lower++];
		if (this.empty()) this.clear(); 
		return val;
	}
}

function _GatewayAPI(){
  this.build = "203";
  this.items = [];
  this.opera = (new RegExp("opera( |/)[56]", "i")).test(navigator.userAgent);
  this.opera5 = (new RegExp("opera( |/)5", "i")).test(navigator.userAgent);
  this.supported = (document.layers || document.all || document.getElementById);
}
GatewayAPI = new _GatewayAPI();

_GatewayAPI.prototype.register = function (o){
  var i = this.items.length;
  this.items[i] = o;
  return "GatewayAPI.items['" + i + "']";
}

// define Gateway object
function Gateway(u, _d){
  // create an array to store any errors that are found
  this.errors = [];
  this.cache = {};
  if(!u) this.throwError("No server gateway was specified.", true);
  if(!GatewayAPI.supported) this.throwError("Your browser does not meet the minimum requirements. \nPortions of the page have been disabled and therefore \nthe page may not work as expected.", true);

  this.disabled = false;
  this.url = u;
  this.useWddx = (!!window.WddxSerializer);
  this.enableCache = (GatewayAPI.opera5) ? false : true;
  this.iframeSrc = null;

  this.mode = (!!_d && _d == true) ? "debug" : "release";
  this.html = "";
  this.sent = null;
  this.received = null;
  this.counter = 0;
  this.status = "idle";
  this.multithreaded = true;
	this.queued = false;
	this.packetQueue = new Queue();
  this.delay = 1;        // in milliseconds
  this.timeout = 5;      // in seconds
  this.statusReset = 3;  // in seconds
  this.statusdelay = 100;
  this.statusID = null;
  this.delayID = null;
  this.timeoutID = null;
  this.statusResetID = null;
  this.method = "get";
	
	
  // hold current object in place holder
  this.idGateway = "idGatewayAPI_" + GatewayAPI.items.length;
  this.idForm = "idGatewayAPI_Form_" + GatewayAPI.items.length;

  this.id = GatewayAPI.register(this);
}

Gateway.prototype.isWddxEnabled = function(){
  return (!!window.WddxSerializer && this.useWddx);
}

Gateway.prototype.getUrl = function(){
  var uuid = ((this.url.indexOf("?") == -1) ? "?" : "&") + "uuid=" + (new Date().getTime() + "" + Math.floor(1000 * Math.random()));
  return this.url + uuid;
}

// define Gateway create(); prototype
Gateway.prototype.onReceive = function(){}

// define Gateway create(); prototype
Gateway.prototype.onTimeout = function(){
  this.throwError("The current request has timed out. Please \ntry your request again.");
}

// define Gateway create(); prototype
Gateway.prototype.create = function() {
  if (this.created) {
    if (this.mode == "debug")
      this.throwError("You have already createed the gateway "+this.idGateway);
    return;
  }
  this.width = (this.mode == "release") ? "1" : "400";
  this.height = (this.mode == "release") ? "1" : "200";
  this.visibility = (this.mode == "release") ? ((document.layers) ? "hide" : "hidden") : ((document.layers) ? "show" : "visible");
  this.bgcolor = (this.mode == "release") ? "#ffffff" : "#cccccc";

  if( this.disabled ) return false;

  this.createCSS();
  this.createFrame();
  this.createForm();
  if (this.mode == "debug") 
    document.write('<form><textarea rows=10, cols=80>'+this.html+'</textarea></form>');
  document.write(this.html);
}

// define throwError(); prototype
Gateway.prototype.throwError = function(error, _disable){
  var disable = (typeof _disable == "boolean") ? _disable : false;
  this.errors[this.errors.length++] = error;
  if( this.status == "sending" ) this.receivePacket(null, false);
  if( disable ) this.disabled = true;
  alert(error);
}

// define createCSS(); prototype
Gateway.prototype.createCSS = function(){
  this.html += "<style type=\"text\/css\">\n";
  this.html += "#" + this.idGateway + " {position:absolute; width: " + this.width + "px; height: " + this.height + "px; clip:rect(0px " + this.width + "px " + this.height + "px 0px); visibility: " + this.visibility + "; background: " + this.bgcolor + "; }\n";
  this.html += "</style>\n";
}

// define createForm(); prototype
Gateway.prototype.createForm = function(){
  this.html += "<form name=\"" + this.idForm + "\" action=\"" + this.url + "\" target=\"" + this.idGateway + "\" method=\"post\" style=\"width:0px; height:0px; margin:0px 0px 0px 0px;\">\n";
  this.html += "<input type=\"Hidden\" name=\"packet\" value=\"\"></form>\n";
}

// define createFrame(); prototype
Gateway.prototype.createFrame = function(){
  var sSrc = (typeof this.iframeSrc == "string") ? "src=\"" + this.iframeSrc + "\" " : (GatewayAPI.opera) ? "src=\"opera:about\" " : "";
  if( document.layers ) this.html += "<ilayer name=\"" + this.idGateway + "\" id=\"" + this.idGateway + "\" width=\"" + this.width + "\" height=\"" + this.height + "\" bgcolor=\"" + this.bgcolor + "\" visibility=\"" + this.visibility + "\"></ilayer>\n";
  else this.html += "<iframe " + sSrc + "width=\"" + this.width + "\" height=\"" + this.height + "\" name=\"" + this.idGateway + "\" id=\"" + this.idGateway + "\" frameBorder=\"1\" frameSpacing=\"0\" marginWidth=\"0\" marginHeight=\"0\"></iframe>\n";
}

// define serverTimeout(); prototype
Gateway.prototype.serverTimeout = function(id){
  if( this.status == "sending" && this.counter == id ){
    this.status = "timedout";
    // stop updating status bar
    clearInterval(this.statusID);
    window.status = "";
    this.timeoutID = null;
    this.onTimeout();

		// send any queued packets
		this.sendNext();
  }
}

// define resetStatus(); prototype
Gateway.prototype.resetStatus = function(){
  this.status = "idle";
  this.statusResetID = null;

}

// define receivePacket(); prototype
Gateway.prototype.receivePacket = function(packet, _bRunEvent){
  if( this.disabled || this.status == "timedout" ) return false;
  var b = (typeof _bRunEvent != "boolean") ? true : _b;

  // stop updating status bar
  clearInterval(this.statusID);
  window.status = "";

  // initialize the wddx packet to server
  this.received = packet;

  if( this.cacheResults == true ){
    this.cache[this.packetString] = packet;
    this.cacheResults = null;
  }

  // run the onReceive function
  if( b ) this.onReceive();

  // stop updating status bar
  clearInterval(this.statusID);
  this.statusID = null;
  this.status = "received";

	// send any queued packets
	if (!this.sendNext()) {
		// make sure to reset the status
		this.statusResetID = setTimeout(this.id + ".resetStatus();", this.statusReset * 1000);
	}
}

// define sendNext(); prototype
Gateway.prototype.sendNext = function(){
	// send any queued packets
	if (this.queued && !this.packetQueue.empty()) {
	  var o = this.packetQueue.pop();
	  return this.sendPacket(o.packet, o.useCache);
	}

	return false;
}

// define sendPacket(); prototype
Gateway.prototype.sendPacket = function(packet, _bUseCache){
  if( this.disabled ) return false;
  var bUseCache = (typeof _bUseCache == "boolean") ? _bUseCache : true;

  //if( !this.multithreaded && this.status == "sending" ) return false;
  if (this.status == "sending" || this.delayID != null) {
    if (this.multithreaded) {
      // do nothing, continue sending this packet
    } else if ( this.queued ) {

      // queue the packet to be sent later
      this.packetQueue.push({packet:packet, useCache:_bUseCache});
      return "queud";
    } else {
      return false;
    }
  }
	
  if( this.delayID != null ) clearTimeout(this.delayID);
  if( this.statusResetID != null ) clearTimeout(this.statusResetID);

  this.sent = packet;

//  this.serializeAndSend(packet);
  return this.delayID = setTimeout(this.id + ".serializeAndSend(" + String(bUseCache) + ")", this.delay);
}

// define sendPacket(); prototype
Gateway.prototype.serializeAndSend = function(_bUseCache){
  if( this.disabled ) return false;

  // update window status
  this.counter++;
  this.delayID = null; // clear the delay timeout
  this.received = null; // clear the received packet
  this.status = "sending";
  window.status = "Sending.";
  if( this.statusID != null ) clearInterval(this.statusID);
  this.statusID = setInterval("window.status = window.status + '.'", this.statusdelay);
  this.timeoutID = setTimeout(this.id + ".serverTimeout(" + this.counter + ")", this.timeout * 1000);

  // send data to server
  switch( this.method ){
    case "post":
/*
      this.methodPost(this.sent, _bUseCache);
    break;
*/
    case "get":
      this.methodGet(this.sent, _bUseCache);
    break;
  }

}

Gateway.prototype.formatPacket = function(packet){
  if( this.isWddxEnabled() ){
    // create serializer object
    var oWddx = new WddxSerializer();
    return "&wddx=" + escape(oWddx.serialize(packet));
  } else {
    if( typeof packet == "string" ) return "&data=" + packet;
    else if( typeof packet == "object" ){
      var p = [];
      for( var k in packet ) p[p.length] = k + "=" + escape(packet[k]);
      return "&" + p.join("&");
    }
  }
}

Gateway.prototype.methodPost = function(packet, _bUseCache){
  return alert("The post method is currently unsupported. Netscape v4.0 does not support posting to a layer.");
  if( this.disabled ) return false;
  oForm = document[this.idForm];

  // submit the packet to the server
  oForm.submit();
}

Gateway.prototype.methodGet = function(packet, _bUseCache){
  // get the packet to send to the server
  var sPacket = this.formatPacket(packet);
  // generate the url and packet to send
  var sUrl = this.getUrl() + sPacket;

  // check to see if you should use a cached version of the request
  // and if so, pass the cached results to the recievePacket method
  if( this.enableCache && (_bUseCache == true) && !!this.cache[sPacket] ) 
    return this.receivePacket(this.cache[sPacket]);

  this.cacheResults = (this.enableCache && (_bUseCache == true));
  this.packetString = sPacket;

  // if IE then change the location of the IFRAME
  if( !!document.getElementById && !!document.getElementById(this.idGateway).contentDocument ){
    // this loads the URL stored in the sUrl variable into the hidden frame
    document.getElementById(this.idGateway).contentDocument.location.replace(sUrl);

  } else if( GatewayAPI.opera ){
    document.getElementById(this.idGateway).location.replace(sUrl);

  } else if( document.all ){
    // this loads the URL stored in the sUrl variable into the
    // hidden frame
    document[this.idGateway].location.replace(sUrl);

  // otherwise, change Netscape v4's ILAYER source file
  } else if( document.layers ){
    // this loads the URL stored in the sUrl variable into the
    // hidden frame
    document[this.idGateway].src = sUrl;
  }
}