// ===================================================================
// Author: Matt Kruse <matt@ajaxtoolbox.com>
// WWW: http://www.AjaxToolbox.com/
//
// NOTICE: You may use this code for any purpose, commercial or
// private, without any further permission from the author. You may
// remove this notice from your final code if you wish, however it is
// appreciated by the author if at least my web site address is kept.
//
// You may *NOT* re-distribute this code in any way except through its
// use. That means, you can include it in your product, or your web  
// site, or any other form where the code is actually being used. You
// may not put the plain javascript up on your site for download or
// include it in your javascript libraries for download. 
// If you wish to share this code with others, please just point them
// to the URL instead.
// Please DO NOT link directly to my .js files from your site. Copy
// the files to your server and use them there. Thank you.
// ===================================================================

/**
 * The AjaxRequest class is a wrapper for the XMLHttpRequest objects which 
 * are available in most modern browsers. It simplifies the interfaces for
 * making Ajax requests, adds commonly-used convenience methods, and makes 
 * the process of handling state changes more intuitive.
 * An object may be instantiated and used, or the Class methods may be used 
 * which internally create an AjaxRequest object.
 */
function AjaxRequest()
{
    var req = new Object();
    // -------------------
    // Instance properties
    // -------------------

    /**
     * Timeout period (in ms) until an async request will be aborted, and
     * the onTimeout function will be called
     */
    req.timeout = null;
    /**
     *	Since some browsers cache GET requests via XMLHttpRequest, an
     * additional parameter called AjaxRequestUniqueId will be added to
     * the request URI with a unique numeric value appended so that the requested
     * URL will not be cached.
     */
    req.generateUniqueUrl = true;
    /**
     * The url that the request will be made to, which defaults to the current 
     * url of the window
     */
    req.url = window.location.href;
    /**
     * The method of the request, either GET (default), POST, or HEAD
     */
    req.method = "GET";
    /**
     * Whether or not the request will be asynchronous. In general, synchronous 
     * requests should not be used so this should rarely be changed from true
     */
    req.async = true;
    /**
     * The username used to access the URL
     */
    req.username = null;
    /**
     * The password used to access the URL
     */
    req.password = null;
    /**
     * The parameters is an object holding name/value pairs which will be 
     * added to the url for a GET request or the request content for a POST request
     */
    req.parameters = new Object();
    /**
     * The sequential index number of this request, updated internally
     */
    req.requestIndex = AjaxRequest.numAjaxRequests++;
    /**
     * Indicates whether a response has been received yet from the server
     */
    req.responseReceived = false;
    /**
     * The name of the group that this request belongs to, for activity 
     * monitoring purposes
     */
    req.groupName = null;
    /**
     * The query string to be added to the end of a GET request, in proper 
     * URIEncoded format
     */
    req.queryString = "";
    /**
     * After a response has been received, this will hold the text contents of 
     * the response - even in case of error
     */
    req.responseText = null;
    /**
     * After a response has been received, this will hold the XML content
     */
    req.responseXML = null;
    /**
     * After a response has been received, this will hold the status code of 
     * the response as returned by the server.
     */
    req.status = null;
    /**
     * After a response has been received, this will hold the text description 
     * of the response code
     */
    req.statusText = null;
    /**
     * An internal flag to indicate whether the request has been aborted
     */
    req.aborted = false;
    /**
     * The XMLHttpRequest object used internally
     */
    req.xmlHttpRequest = null;
    // --------------
    // Event handlers
    // --------------

    /**
     * If a timeout period is set, and it is reached before a response is 
     * received, a function reference assigned to onTimeout will be called
     */
    req.onTimeout = null;
    /**
     * A function reference assigned will be called when readyState=1
     */
    req.onLoading = null;
    /**
     * A function reference assigned will be called when readyState=2
     */
    req.onLoaded = null;
    /**
     * A function reference assigned will be called when readyState=3
     */
    req.onInteractive = null;
    /**
     * A function reference assigned will be called when readyState=4
     */
    req.onComplete = null;
    /**
     * A function reference assigned will be called after onComplete, if 
     * the statusCode=200
     */
    req.onSuccess = null;
    /**
     * A function reference assigned will be called after onComplete, if 
     * the statusCode != 200
     */
    req.onError = null;
    /**
     * If this request has a group name, this function reference will be called 
     * and passed the group name if this is the first request in the group to 
     * become active
     */
    req.onGroupBegin = null;
    /**
     * If this request has a group name, and this request is the last request 
     * in the group to complete, this function reference will be called
     */
    req.onGroupEnd = null;
    // Get the XMLHttpRequest object itself
    req.xmlHttpRequest = AjaxRequest.getXmlHttpRequest();

    if (req.xmlHttpRequest == null)
    {
        return null;
    }
    // -------------------------------------------------------
    // Attach the event handlers for the XMLHttpRequest object
    // -------------------------------------------------------
    req.xmlHttpRequest.onreadystatechange = function()
    {
        if (req == null || req.xmlHttpRequest == null)
        {
            return;
        }

        if (req.xmlHttpRequest.readyState == 1)
        {
            req.onLoadingInternal(req);
        }

        if (req.xmlHttpRequest.readyState == 2)
        {
            req.onLoadedInternal(req);
        }

        if (req.xmlHttpRequest.readyState == 3)
        {
            req.onInteractiveInternal(req);
        }

        if (req.xmlHttpRequest.readyState == 4)
        {
            req.onCompleteInternal(req);
        }
    };
    // ---------------------------------------------------------------------------
    // Internal event handlers that fire, and in turn fire the user event handlers
    // ---------------------------------------------------------------------------
    // Flags to keep track if each event has been handled, in case of 
    // multiple calls (some browsers may call the onreadystatechange 
    // multiple times for the same state)
    req.onLoadingInternalHandled = false;
    req.onLoadedInternalHandled = false;
    req.onInteractiveInternalHandled = false;
    req.onCompleteInternalHandled = false;
    req.onLoadingInternal = function()
    {
        if (req.onLoadingInternalHandled)
        {
            return;
        }

        AjaxRequest.numActiveAjaxRequests++;

        if (AjaxRequest.numActiveAjaxRequests == 1 && typeof (window['AjaxRequestBegin']) == "function")
        {
            AjaxRequestBegin();
        }

        if (req.groupName != null)
        {
            if (typeof (AjaxRequest.numActiveAjaxGroupRequests[req.groupName]) == "undefined")
            {
                AjaxRequest.numActiveAjaxGroupRequests[req.groupName] = 0;
            }

            AjaxRequest.numActiveAjaxGroupRequests[req.groupName]++;

            if (AjaxRequest.numActiveAjaxGroupRequests[req.groupName] == 1 && typeof (req.onGroupBegin) == "function")
            {
                req.onGroupBegin(req.groupName);
            }
        }

        if (typeof (req.onLoading) == "function")
        {
            req.onLoading(req);
        }

        req.onLoadingInternalHandled = true;
    };

    req.onLoadedInternal = function()
    {
        if (req.onLoadedInternalHandled)
        {
            return;
        }

        if (typeof (req.onLoaded) == "function")
        {
            req.onLoaded(req);
        }

        req.onLoadedInternalHandled = true;
    };

    req.onInteractiveInternal = function()
    {
        if (req.onInteractiveInternalHandled)
        {
            return;
        }

        if (typeof (req.onInteractive) == "function")
        {
            req.onInteractive(req);
        }

        req.onInteractiveInternalHandled = true;
    };

    req.onCompleteInternal = function()
    {
        if (req.onCompleteInternalHandled || req.aborted)
        {
            return;
        }

        req.onCompleteInternalHandled = true;
        AjaxRequest.numActiveAjaxRequests--;

        if (AjaxRequest.numActiveAjaxRequests == 0 && typeof (window['AjaxRequestEnd']) == "function")
        {
            AjaxRequestEnd(req.groupName);
        }

        if (req.groupName != null)
        {
            AjaxRequest.numActiveAjaxGroupRequests[req.groupName]--;

            if (AjaxRequest.numActiveAjaxGroupRequests[req.groupName] == 0 && typeof (req.onGroupEnd) == "function")
            {
                req.onGroupEnd(req.groupName);
            }
        }

        req.responseReceived = true;
        req.status = req.xmlHttpRequest.status;
        req.statusText = req.xmlHttpRequest.statusText;
        req.responseText = req.xmlHttpRequest.responseText;
        req.responseXML = req.xmlHttpRequest.responseXML;

        if (typeof (req.onComplete) == "function")
        {
            req.onComplete(req);
        }

        if (req.xmlHttpRequest.status == 200 && typeof (req.onSuccess) == "function")
        {
            req.onSuccess(req);
        }
        else if (typeof (req.onError) == "function")
        {
            req.onError(req);
        }
        // Clean up so IE doesn't leak memory
        delete req.xmlHttpRequest['onreadystatechange'];
        req.xmlHttpRequest = null;
    };

    req.onTimeoutInternal = function()
    {
        if (req != null && req.xmlHttpRequest != null && !req.onCompleteInternalHandled)
        {
            req.aborted = true;
            req.xmlHttpRequest.abort();
            AjaxRequest.numActiveAjaxRequests--;

            if (AjaxRequest.numActiveAjaxRequests == 0 && typeof (window['AjaxRequestEnd']) == "function")
            {
                AjaxRequestEnd(req.groupName);
            }

            if (req.groupName != null)
            {
                AjaxRequest.numActiveAjaxGroupRequests[req.groupName]--;

                if (AjaxRequest.numActiveAjaxGroupRequests[req.groupName] == 0 && typeof (req.onGroupEnd) == "function")
                {
                    req.onGroupEnd(req.groupName);
                }
            }

            if (typeof (req.onTimeout) == "function")
            {
                req.onTimeout(req);
            }
            // Opera won't fire onreadystatechange after abort, but other browsers do. 
            // So we can't rely on the onreadystate function getting called. Clean up here!
            delete req.xmlHttpRequest['onreadystatechange'];
            req.xmlHttpRequest = null;
        }
    };
    // ----------------
    // Instance methods
    // ----------------
    /**
     * The process method is called to actually make the request. It builds the
     * querystring for GET requests (the content for POST requests), sets the
     * appropriate headers if necessary, and calls the 
     * XMLHttpRequest.send() method
    */
    req.process = function()
    {
        if (req.xmlHttpRequest != null)
        {
            // Some logic to get the real request URL
            if (req.generateUniqueUrl && req.method == "GET")
            {
                req.parameters["AjaxRequestUniqueId"] = new Date().getTime() + "" + req.requestIndex;
            }

            var content = null; // For POST requests, to hold query string

            for (var i in req.parameters)
            {
            if (req.queryString.length > 0)
            {
                req.queryString += "&";
            }

            req.queryString += encodeURIComponent(i) + "=" + encodeURIComponent(req.parameters[i]);
            }

            if (req.method == "GET")
            {
                if (req.queryString.length > 0)
                {
                    req.url += ((req.url.indexOf("?") > -1) ? "&" : "?") + req.queryString;
                }
            }

            req.xmlHttpRequest.open(req.method, req.url, req.async, req.username, req.password);

            if (req.method == "POST")
            {
                if (typeof (req.xmlHttpRequest.setRequestHeader) != "undefined")
                {
                    req.xmlHttpRequest.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
                }

                content = req.queryString;
            }

            if (req.timeout > 0)
            {
                setTimeout(req.onTimeoutInternal, req.timeout);
            }

            req.xmlHttpRequest.send(content);
        }
    };
    /**
     * An internal function to handle an Object argument, which may contain
     * either AjaxRequest field values or parameter name/values
     */
    req.handleArguments = function(args)
    {
        for (var i in args)
        {
        // If the AjaxRequest object doesn't have a property which was passed, treat it as a url parameter
        if (typeof (req[i]) == "undefined")
        {
            req.parameters[i] = args[i];
        }
        else
        {
            req[i] = args[i];
        }
        }
    };
    /**
     * Returns the results of XMLHttpRequest.getAllResponseHeaders().
     * Only available after a response has been returned
     */
    req.getAllResponseHeaders = function()
    {
        if (req.xmlHttpRequest != null)
        {
            if (req.responseReceived)
            {
                return req.xmlHttpRequest.getAllResponseHeaders();
            }

            alert("Cannot getAllResponseHeaders because a response has not yet been received");
        }
    };
    /**
     * Returns the the value of a response header as returned by 
     * XMLHttpRequest,getResponseHeader().
     * Only available after a response has been returned
     */
    req.getResponseHeader = function(headerName)
    {
        if (req.xmlHttpRequest != null)
        {
            if (req.responseReceived)
            {
                return req.xmlHttpRequest.getResponseHeader(headerName);
            }

            alert("Cannot getResponseHeader because a response has not yet been received");
        }
    };

    return req;
}
// ---------------------------------------
// Static methods of the AjaxRequest class
// ---------------------------------------

/**
 * Returns an XMLHttpRequest object, either as a core object or an ActiveX 
 * implementation. If an object cannot be instantiated, it will return null;
 */
AjaxRequest.getXmlHttpRequest = function()
{
    if (window.XMLHttpRequest)
    {
        return new XMLHttpRequest();
    }
    else if (window.ActiveXObject)
    {
    // Based on http://jibbering.com/2002/4/httprequest.html
    /*@cc_on @*/
    /*@if (@_jscript_version >= 5)
    try {
        return new ActiveXObject("Msxml2.XMLHTTP");
    } catch (e) {
        try {
            return new ActiveXObject("Microsoft.XMLHTTP");
        } catch (E) {
            return null;
        }
    }
    @end @*/
    }
    else
    {
        return null;
    }
};
/**
 * See if any request is active in the background
 */
AjaxRequest.isActive = function()
{
    return (AjaxRequest.numActiveAjaxRequests > 0);
};
/**
 * Make a GET request. Pass an object containing parameters and arguments as 
 * the second argument.
 * These areguments may be either AjaxRequest properties to set on the request 
 * object or name/values to set in the request querystring.
 */
AjaxRequest.get = function(args)
{
    AjaxRequest.doRequest("GET", args);
};
/**
 * Make a POST request. Pass an object containing parameters and arguments as 
 * the second argument.
 * These areguments may be either AjaxRequest properties to set on the request 
 * object or name/values to set in the request querystring.
 */
AjaxRequest.post = function(args)
{
    AjaxRequest.doRequest("POST", args);
};
/**
 * The internal method used by the .get() and .post() methods
 */
AjaxRequest.doRequest = function(method, args)
{
    if (typeof (args) != "undefined" && args != null)
    {
        var myRequest = new AjaxRequest();
        myRequest.method = method;
        myRequest.handleArguments(args);
        myRequest.process();
    }
};
/**
 * Submit a form. The requested URL will be the form's ACTION, and the request 
 * method will be the form's METHOD.
 * Returns true if the submittal was handled successfully, else false so it 
 * can easily be used with an onSubmit event for a form, and fallback to 
 * submitting the form normally.
 */
AjaxRequest.submit = function(theform, args)
{
    var myRequest = new AjaxRequest();

    if (myRequest == null)
    {
        return false;
    }

    var serializedForm = AjaxRequest.serializeForm(theform);
    myRequest.method = theform.method.toUpperCase();
    myRequest.url = theform.action;
    myRequest.handleArguments(args);
    myRequest.queryString = serializedForm;
    myRequest.process();
    return true;
};
/**
 * Serialize a form into a format which can be sent as a GET string or a POST 
 * content.It correctly ignores disabled fields, maintains order of the fields 
 * as in the elements[] array. The 'file' input type is not supported, as 
 * its content is not available to javascript. This method is used internally
 * by the submit class method.
 */
AjaxRequest.serializeForm = function(theform)
{
    var els = theform.elements;
    var len = els.length;
    var queryString = "";
    this.addField = function(name, value)
    {
        if (queryString.length > 0)
        {
            queryString += "&";
        }

        queryString += encodeURIComponent(name) + "=" + encodeURIComponent(value);
    };

    for (var i = 0; i < len; i++)
    {
    var el = els[i];

    if (!el.disabled)
    {
        switch (el.type)
        {
            case 'text':
            case 'password':
            case 'hidden':
            case 'textarea':
                this.addField(el.name, el.value);

                break;

            case 'select-one':
                if (el.selectedIndex >= 0)
                {
                    this.addField(el.name, el.options[el.selectedIndex].value);
                }

                break;

            case 'select-multiple':
                for (var j = 0; j < el.options.length; j++)
                {
                if (el.options[j].selected)
                {
                    this.addField(el.name, el.options[j].value);
                }
                }

                break;

            case 'checkbox':
            case 'radio':
                if (el.checked)
                {
                    this.addField(el.name, el.value);
                }

                break;
        }
    }
    }

    return queryString;
};
// -----------------------
// Static Class variables
// -----------------------

/**
 * The number of total AjaxRequest objects currently active and running
 */
AjaxRequest.numActiveAjaxRequests = 0;
/**
 * An object holding the number of active requests for each group
 */
AjaxRequest.numActiveAjaxGroupRequests = new Object();
/**
 * The total number of AjaxRequest objects instantiated
 */
AjaxRequest.numAjaxRequests = 0;