/* $Id: ajax.js,v 1.1 2007/09/28 20:08:34 cvsuser Exp $

 * ---------------------------------------------------------------------

 * An XMLHttpRequest wrapper for running Gyrobase macros.

 * ---------------------------------------------------------------------

 */



// ---------------------------------------------------------------------

// document.getElementById() shortcut from the Prototype library



function $() {

  var elements = new Array();



  for (var i = 0; i < arguments.length; i++) {

    var element = arguments[i];

    if (typeof element == 'string')

      element = document.getElementById(element);



    if (arguments.length == 1) 

      return element;



    elements.push(element);

  }



  return elements;

}



// ---------------------------------------------------------------------

// Make sure arrays support push().



if (!Array.prototype.push) {

    Array.prototype.push = function (obj) {

        this[this.length] = obj;

    }

}



// ---------------------------------------------------------------------

// Method to test if XMLHttpRequest object is supported

function gyrobaseAjaxIsSupported () {

    if (window.XMLHttpRequest) return true;



    if (window.ActiveXObject && navigator.platform != 'MacPPC') {

        if (new ActiveXObject("Msxml2.XMLHTTP")) return true;

        if (new ActiveXObject("Microsoft.XMLHTTP")) return true;

    }



    return false;

}



// ---------------------------------------------------------------------

// GyrobaseAjaxLibrary Constructor

function GyrobaseAjaxLibrary (template, username, password, url) {

    if (!template) throw "Missing template parameter for GyrobaseAjaxLibrary().";



    this.template = template;

    this.username = username;

    this.password = password;

    this.url = url ? url : "/gyrobase/tools/ajax/run-macro.html";



    this.requests = new Array();

}



// ---------------------------------------------------------------------

// runMacro()

GyrobaseAjaxLibrary.prototype.runMacro = function (macro, params, callback) {

    if (!macro) throw "No macro specifed!";

    if (params && typeof(params) != "object") throw "The macro's parameters must be specified as an object (hash).";

    if (callback && typeof(callback) != "function") throw "The 'callback' parameter must be a function reference.";



    // Create a new XMLHttpRequest object.

    var req = false;

    if (window.XMLHttpRequest) {

        try { req = new XMLHttpRequest(); }

        catch (e) { req = false; }

    }

    else if (window.ActiveXObject) {

        try { req = new ActiveXObject("Msxml2.XMLHTTP"); }

        catch (e) {

            try { req = new ActiveXObject("Microsoft.XMLHTTP"); }

            catch (e) { throw "Failed to create XMLHTTPRequest object!"; }

        }

    }



    // It would be nice if these next two lines could be atomic. Oh well,

    // just cross your fingers.

    this.requests.push(req);

    var reqNum = this.requests.length - 1;



    // Set up the POST query string.

    var q = "__t="+escape(this.template)+"&";

    q += "__m="+encodeURIComponent(macro)+"&";

    if (this.username) q += "__u="+encodeURIComponent(this.username)+"&";

    if (this.password) q += "__p="+encodeURIComponent(this.password)+"&";

    for (var i in params) {

        q += encodeURIComponent(i)+"="+encodeURIComponent(params[i])+"&";

    }



    // Set up the callback. Yay for javascript closures!

    var me = this;

    var callbackClosure = function () {

        if (req.readyState == 4) {

            if (req.status == 200) {

                eval("var _response = " + req.responseText + ";");

                if (_response.gyrobaseAjaxResponseHeader.error)

                    throw _response.gyrobaseAjaxResponseHeader.error;

                if (callback) callback(_response.gyrobaseAjaxResult);

            }

            else {

                throw "Error executing macro: " + req.statusText;

            }



            // Remove request reference so it can be garbage collected.

            me.requests[reqNum] = null;



            // Break circular references for IE's crappy garbage collector.

            delete req.onreadystatechange;

            req = null;

        }

    };



    // Do the request!

    req.onreadystatechange = callbackClosure;

    req.open("POST", this.url, true);

    req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

    req.send(q);

}



// ---------------------------------------------------------------------