// ===================================================================
// 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;
            //alert(req.responseText);
            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;
            }
        }
    }
    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;