/*
 * Copyright 2005 Joe Walker
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * Declare an object to which we can add real functions.
 */
if (dwr == null) var dwr = {};
if (dwr.engine == null) dwr.engine = {};
if (DWREngine == null) var DWREngine = dwr.engine;

/**
 * Set an alternative error handler from the default alert box.
 * @see getahead.org/dwr/browser/engine/errors
 */
dwr.engine.setErrorHandler = function(handler)
{
    dwr.engine._errorHandler = handler;
};

/**
 * Set an alternative warning handler from the default alert box.
 * @see getahead.org/dwr/browser/engine/errors
 */
dwr.engine.setWarningHandler = function(handler)
{
    dwr.engine._warningHandler = handler;
};

/**
 * Setter for the text/html handler - what happens if a DWR request gets an HTML
 * reply rather than the expected Javascript. Often due to login timeout
 */
dwr.engine.setTextHtmlHandler = function(handler)
{
    dwr.engine._textHtmlHandler = handler;
}

/**
 * Set a default timeout value for all calls. 0 (the default) turns timeouts off.
 * @see getahead.org/dwr/browser/engine/errors
 */
dwr.engine.setTimeout = function(timeout)
{
    dwr.engine._timeout = timeout;
};

/**
 * The Pre-Hook is called before any DWR remoting is done.
 * @see getahead.org/dwr/browser/engine/hooks
 */
dwr.engine.setPreHook = function(handler)
{
    dwr.engine._preHook = handler;
};

/**
 * The Post-Hook is called after any DWR remoting is done.
 * @see getahead.org/dwr/browser/engine/hooks
 */
dwr.engine.setPostHook = function(handler)
{
    dwr.engine._postHook = handler;
};

/**
 * Custom headers for all DWR calls
 * @see getahead.org/dwr/????
 */
dwr.engine.setHeaders = function(headers)
{
    dwr.engine._headers = headers;
};

/**
 * Custom parameters for all DWR calls
 * @see getahead.org/dwr/????
 */
dwr.engine.setParameters = function(parameters)
{
    dwr.engine._parameters = parameters;
};

/** XHR remoting type constant. See dwr.engine.set[Rpc|Poll]Type() */
dwr.engine.XMLHttpRequest = 1;

/** XHR remoting type constant. See dwr.engine.set[Rpc|Poll]Type() */
dwr.engine.IFrame = 2;

/** XHR remoting type constant. See dwr.engine.setRpcType() */
dwr.engine.ScriptTag = 3;

/**
 * Set the preferred remoting type.
 * @param newType One of dwr.engine.XMLHttpRequest or dwr.engine.IFrame or dwr.engine.ScriptTag
 * @see getahead.org/dwr/browser/engine/options
 */
dwr.engine.setRpcType = function(newType)
{
    if (newType != dwr.engine.XMLHttpRequest && newType != dwr.engine.IFrame && newType != dwr.engine.ScriptTag)
    {
        dwr.engine._handleError(null, { name:"dwr.engine.invalidRpcType", message:"RpcType must be one of dwr.engine.XMLHttpRequest or dwr.engine.IFrame or dwr.engine.ScriptTag" });
        return;
    }
    dwr.engine._rpcType = newType;
};

/**
 * Which HTTP method do we use to send results? Must be one of "GET" or "POST".
 * @see getahead.org/dwr/browser/engine/options
 */
dwr.engine.setHttpMethod = function(httpMethod)
{
    if (httpMethod != "GET" && httpMethod != "POST")
    {
        dwr.engine._handleError(null, { name:"dwr.engine.invalidHttpMethod", message:"Remoting method must be one of GET or POST" });
        return;
    }
    dwr.engine._httpMethod = httpMethod;
};

/**
 * Ensure that remote calls happen in the order in which they were sent? (Default: false)
 * @see getahead.org/dwr/browser/engine/ordering
 */
dwr.engine.setOrdered = function(ordered)
{
    dwr.engine._ordered = ordered;
};

/**
 * Do we ask the XHR object to be asynchronous? (Default: true)
 * @see getahead.org/dwr/browser/engine/options
 */
dwr.engine.setAsync = function(async)
{
    dwr.engine._async = async;
};

/**
 * Does DWR poll the server for updates? (Default: false)
 * @see getahead.org/dwr/browser/engine/options
 */
dwr.engine.setActiveReverseAjax = function(activeReverseAjax)
{
    if (activeReverseAjax)
    {
        // Bail if we are already started
        if (dwr.engine._activeReverseAjax) return;
        dwr.engine._activeReverseAjax = true;
        dwr.engine._poll();
    }
    else
    {
        // Can we cancel an existing request?
        if (dwr.engine._activeReverseAjax && dwr.engine._pollReq) dwr.engine._pollReq.abort();
        dwr.engine._activeReverseAjax = false;
    }
    // TODO: in iframe mode, if we start, stop, start then the second start may
    // well kick off a second iframe while the first is still about to return
    // we should cope with this but we don't
};

/**
 * Set the preferred polling type.
 * @param newPollType One of dwr.engine.XMLHttpRequest or dwr.engine.IFrame
 * @see getahead.org/dwr/browser/engine/options
 */
dwr.engine.setPollType = function(newPollType)
{
    if (newPollType != dwr.engine.XMLHttpRequest && newPollType != dwr.engine.IFrame)
    {
        dwr.engine._handleError(null, { name:"dwr.engine.invalidPollType", message:"PollType must be one of dwr.engine.XMLHttpRequest or dwr.engine.IFrame"  });
        return;
    }
    dwr.engine._pollType = newPollType;
};

/**
 * The default message handler.
 * @see getahead.org/dwr/browser/engine/errors
 */
dwr.engine.defaultErrorHandler = function(message, ex)
{
    dwr.engine._debug("Error: " + ex.name + ", " + ex.message, true);

    if (message == null || message == "") alert("A server error has occured. More information may be available in the console.");
    // Ignore NS_ERROR_NOT_AVAILABLE if Mozilla is being narky
    else if (message.indexOf("0x80040111") != -1) dwr.engine._debug(message);
    else alert(message);
};

/**
 * The default warning handler.
 * @see getahead.org/dwr/browser/engine/errors
 */
dwr.engine.defaultWarningHandler = function(message, ex)
{
    dwr.engine._debug(message);
};

/**
 * For reduced latency you can group several remote calls together using a batch.
 * @see getahead.org/dwr/browser/engine/batch
 */
dwr.engine.beginBatch = function()
{
    if (dwr.engine._batch)
    {
        dwr.engine._handleError(null, { name:"dwr.engine.batchBegun", message:"Batch already begun" });
        return;
    }
    dwr.engine._batch = dwr.engine._createBatch();
};

/**
 * Finished grouping a set of remote calls together. Go and execute them all.
 * @see getahead.org/dwr/browser/engine/batch
 */
dwr.engine.endBatch = function(options)
{
    var batch = dwr.engine._batch;
    if (batch == null)
    {
        dwr.engine._handleError(null, { name:"dwr.engine.batchNotBegun", message:"No batch in progress" });
        return;
    }
    dwr.engine._batch = null;
    if (batch.map.callCount == 0) return;

    // The hooks need to be merged carefully to preserve ordering
    if (options) dwr.engine._mergeBatch(batch, options);

    // In ordered mode, we don't send unless the list of sent items is empty
    if (dwr.engine._ordered && dwr.engine._batchesLength != 0)
    {
        dwr.engine._batchQueue[dwr.engine._batchQueue.length] = batch;
    }
    else
    {
        dwr.engine._sendData(batch);
    }
};

/** @deprecated */
dwr.engine.setPollMethod = function(type)
{
    dwr.engine.setPollType(type);
};
dwr.engine.setMethod = function(type)
{
    dwr.engine.setRpcType(type);
};
dwr.engine.setVerb = function(verb)
{
    dwr.engine.setHttpMethod(verb);
};

//==============================================================================
// Only private stuff below here
//==============================================================================

/** The original page id sent from the server */
dwr.engine._origScriptSessionId = "17CD363FB25A1E5B9CE0729CAB3C1C1A";

/** The session cookie name */
dwr.engine._sessionCookieName = "JSESSIONID"; // JSESSIONID

/** Is GET enabled for the benefit of Safari? */
dwr.engine._allowGetForSafariButMakeForgeryEasier = "false";

/** The script prefix to strip in the case of scriptTagProtection. */
dwr.engine._scriptTagProtection = "throw 'allowScriptTagRemoting is false.';";

/** The default path to the DWR servlet */
dwr.engine._defaultPath = DWRConnector.path;

/** The read page id that we calculate */
dwr.engine._scriptSessionId = null;

/** The function that we use to fetch/calculate a session id */
dwr.engine._getScriptSessionId = function()
{
    if (dwr.engine._scriptSessionId == null)
    {
        dwr.engine._scriptSessionId = dwr.engine._origScriptSessionId + Math.floor(Math.random() * 1000);
    }
    return dwr.engine._scriptSessionId;
};

/** A function to call if something fails. */
dwr.engine._errorHandler = dwr.engine.defaultErrorHandler;

/** For debugging when something unexplained happens. */
dwr.engine._warningHandler = dwr.engine.defaultWarningHandler;

/** A function to be called before requests are marshalled. Can be null. */
dwr.engine._preHook = null;

/** A function to be called after replies are received. Can be null. */
dwr.engine._postHook = null;

/** An map of the batches that we have sent and are awaiting a reply on. */
dwr.engine._batches = {};

/** A count of the number of outstanding batches. Should be == to _batches.length unless prototype has messed things up */
dwr.engine._batchesLength = 0;

/** In ordered mode, the array of batches waiting to be sent */
dwr.engine._batchQueue = [];

/** What is the default rpc type */
dwr.engine._rpcType = dwr.engine.XMLHttpRequest;

/** What is the default remoting method (ie GET or POST) */
dwr.engine._httpMethod = "POST";

/** Do we attempt to ensure that calls happen in the order in which they were sent? */
dwr.engine._ordered = false;

/** Do we make the calls async? */
dwr.engine._async = true;

/** The current batch (if we are in batch mode) */
dwr.engine._batch = null;

/** The global timeout */
dwr.engine._timeout = 0;

/** ActiveX objects to use when we want to convert an xml string into a DOM object. */
dwr.engine._DOMDocument = ["Msxml2.DOMDocument.6.0", "Msxml2.DOMDocument.5.0", "Msxml2.DOMDocument.4.0", "Msxml2.DOMDocument.3.0", "MSXML2.DOMDocument", "MSXML.DOMDocument", "Microsoft.XMLDOM"];

/** The ActiveX objects to use when we want to do an XMLHttpRequest call. */
dwr.engine._XMLHTTP = ["Msxml2.XMLHTTP.6.0", "Msxml2.XMLHTTP.5.0", "Msxml2.XMLHTTP.4.0", "MSXML2.XMLHTTP.3.0", "MSXML2.XMLHTTP", "Microsoft.XMLHTTP"];

/** Are we doing comet or polling? */
dwr.engine._activeReverseAjax = false;

/** What is the default polling type */
dwr.engine._pollType = dwr.engine.XMLHttpRequest;
//dwr.engine._pollType = dwr.engine.IFrame;

/** The iframe that we are using to poll */
dwr.engine._outstandingIFrames = [];

/** The xhr object that we are using to poll */
dwr.engine._pollReq = null;

/** How many milliseconds between internal comet polls */
dwr.engine._pollCometInterval = 200;

/** How many times have we re-tried to poll? */
dwr.engine._pollRetries = 0;
dwr.engine._maxPollRetries = 0;

/** Do we do a document.reload if we get a text/html reply? */
dwr.engine._textHtmlHandler = null;

/** If you wish to send custom headers with every request */
dwr.engine._headers = null;

/** If you wish to send extra custom request parameters with each request */
dwr.engine._parameters = null;

/** Undocumented interceptors - do not use */
dwr.engine._postSeperator = "\n";
dwr.engine._defaultInterceptor = function(data)
{
    return data;
}
dwr.engine._urlRewriteHandler = dwr.engine._defaultInterceptor;
dwr.engine._contentRewriteHandler = dwr.engine._defaultInterceptor;
dwr.engine._replyRewriteHandler = dwr.engine._defaultInterceptor;

/** Batch ids allow us to know which batch the server is answering */
dwr.engine._nextBatchId = 0;

/** A list of the properties that need merging from calls to a batch */
dwr.engine._propnames = [ "rpcType", "httpMethod", "async", "timeout", "errorHandler", "warningHandler", "textHtmlHandler" ];

/** Do we stream, or can be hacked to do so? */
dwr.engine._partialResponseNo = 0;
dwr.engine._partialResponseYes = 1;
dwr.engine._partialResponseFlush = 2;

/**
 * @private Send a request. Called by the Javascript interface stub
 * @param path part of URL after the host and before the exec bit without leading or trailing /s
 * @param scriptName The class to execute
 * @param methodName The method on said class to execute
 * @param func The callback function to which any returned data should be passed
 *       if this is null, any returned data will be ignored
 * @param vararg_params The parameters to pass to the above class
 */
dwr.engine._execute = function(path, scriptName, methodName, vararg_params)
{
    var singleShot = false;
    if (dwr.engine._batch == null)
    {
        dwr.engine.beginBatch();
        singleShot = true;
    }
    var batch = dwr.engine._batch;
    // To make them easy to manipulate we copy the arguments into an args array
    var args = [];
    for (var i = 0; i < arguments.length - 3; i++)
    {
        args[i] = arguments[i + 3];
    }
    // All the paths MUST be to the same servlet
    if (batch.path == null)
    {
        batch.path = path;
    }
    else
    {
        if (batch.path != path)
        {
            dwr.engine._handleError(batch, { name:"dwr.engine.multipleServlets", message:"Can't batch requests to multiple DWR Servlets." });
            return;
        }
    }
    // From the other params, work out which is the function (or object with
    // call meta-data) and which is the call parameters
    var callData;
    var lastArg = args[args.length - 1];
    if (typeof lastArg == "function" || lastArg == null) callData = { callback:args.pop() };
    else callData = args.pop();

    // Merge from the callData into the batch
    dwr.engine._mergeBatch(batch, callData);
    batch.handlers[batch.map.callCount] = {
        exceptionHandler:callData.exceptionHandler,
        callback:callData.callback
    };

    // Copy to the map the things that need serializing
    var prefix = "c" + batch.map.callCount + "-";
    batch.map[prefix + "scriptName"] = scriptName;
    batch.map[prefix + "methodName"] = methodName;
    batch.map[prefix + "id"] = batch.map.callCount;
    for (i = 0; i < args.length; i++)
    {
        dwr.engine._serializeAll(batch, [], args[i], prefix + "param" + i);
    }

    // Now we have finished remembering the call, we incr the call count
    batch.map.callCount++;
    if (singleShot) dwr.engine.endBatch();
};

/** @private Poll the server to see if there is any data waiting */
dwr.engine._poll = function(overridePath)
{
    if (!dwr.engine._activeReverseAjax) return;

    var batch = dwr.engine._createBatch();
    batch.map.id = 0; // TODO: Do we need this??
    batch.map.callCount = 1;
    batch.isPoll = true;
    if (navigator.userAgent.indexOf("Gecko/") != -1)
    {
        batch.rpcType = dwr.engine._pollType;
        batch.map.partialResponse = dwr.engine._partialResponseYes;
    }
    else if (document.all)
    {
        batch.rpcType = dwr.engine.IFrame;
        batch.map.partialResponse = dwr.engine._partialResponseFlush;
    }
    else
    {
        batch.rpcType = dwr.engine._pollType;
        batch.map.partialResponse = dwr.engine._partialResponseNo;
    }
    batch.httpMethod = "POST";
    batch.async = true;
    batch.timeout = 0;
    batch.path = (overridePath) ? overridePath : dwr.engine._defaultPath;
    batch.preHooks = [];
    batch.postHooks = [];
    batch.errorHandler = dwr.engine._pollErrorHandler;
    batch.warningHandler = dwr.engine._pollErrorHandler;
    batch.handlers[0] = {
        callback:function(pause)
        {
            dwr.engine._pollRetries = 0;
            setTimeout("dwr.engine._poll()", pause);
        }
    };

    // Send the data
    dwr.engine._sendData(batch);
    if (batch.rpcType == dwr.engine.XMLHttpRequest)
    {
        // if (batch.map.partialResponse != dwr.engine._partialResponseNo) {
        dwr.engine._checkCometPoll();
    }
};

/** Try to recover from polling errors */
dwr.engine._pollErrorHandler = function(msg, ex)
{
    // if anything goes wrong then just silently try again (up to 3x) after 10s
    dwr.engine._pollRetries++;
    dwr.engine._debug("Reverse Ajax poll failed (pollRetries=" + dwr.engine._pollRetries + "): " + ex.name + " : " + ex.message);
    if (dwr.engine._pollRetries < dwr.engine._maxPollRetries)
    {
        setTimeout("dwr.engine._poll()", 10000);
    }
    else
    {
        dwr.engine._debug("Giving up.");
    }
};

/** @private Generate a new standard batch */
dwr.engine._createBatch = function()
{
    var batch = {
        map:{
            callCount:0,
            page:window.location.pathname + window.location.search,
            httpSessionId:dwr.engine._getJSessionId(),
            scriptSessionId:dwr.engine._getScriptSessionId()
        },
        charsProcessed:0, paramCount:0,
        headers:[], parameters:[],
        isPoll:false, headers:{}, handlers:{}, preHooks:[], postHooks:[],
        rpcType:dwr.engine._rpcType,
        httpMethod:dwr.engine._httpMethod,
        async:dwr.engine._async,
        timeout:dwr.engine._timeout,
        errorHandler:dwr.engine._errorHandler,
        warningHandler:dwr.engine._warningHandler,
        textHtmlHandler:dwr.engine._textHtmlHandler
    };
    if (dwr.engine._preHook) batch.preHooks.push(dwr.engine._preHook);
    if (dwr.engine._postHook) batch.postHooks.push(dwr.engine._postHook);
    var propname, data;
    if (dwr.engine._headers)
    {
        for (propname in dwr.engine._headers)
        {
            data = dwr.engine._headers[propname];
            if (typeof data != "function") batch.headers[propname] = data;
        }
    }
    if (dwr.engine._parameters)
    {
        for (propname in dwr.engine._parameters)
        {
            data = dwr.engine._parameters[propname];
            if (typeof data != "function") batch.parameters[propname] = data;
        }
    }
    return batch;
}

/** @private Take further options and merge them into */
dwr.engine._mergeBatch = function(batch, overrides)
{
    var propname, data;
    for (var i = 0; i < dwr.engine._propnames.length; i++)
    {
        propname = dwr.engine._propnames[i];
        if (overrides[propname] != null) batch[propname] = overrides[propname];
    }
    if (overrides.preHook != null) batch.preHooks.unshift(overrides.preHook);
    if (overrides.postHook != null) batch.postHooks.push(overrides.postHook);
    if (overrides.headers)
    {
        for (propname in overrides.headers)
        {
            data = overrides.headers[propname];
            if (typeof data != "function") batch.headers[propname] = data;
        }
    }
    if (overrides.parameters)
    {
        for (propname in overrides.parameters)
        {
            data = overrides.parameters[propname];
            if (typeof data != "function") batch.map["p-" + propname] = "" + data;
        }
    }
};

/** @private What is our session id? */
dwr.engine._getJSessionId = function()
{
    var cookies = document.cookie.split(';');
    for (var i = 0; i < cookies.length; i++)
    {
        var cookie = cookies[i];
        while (cookie.charAt(0) == ' ') cookie = cookie.substring(1, cookie.length);
        if (cookie.indexOf(dwr.engine._sessionCookieName + "=") == 0)
        {
            return cookie.substring(11, cookie.length);
        }
    }
    return "";
}

/** @private Check for reverse Ajax activity */
dwr.engine._checkCometPoll = function()
{
    for (var i = 0; i < dwr.engine._outstandingIFrames.length; i++)
    {
        var text = "";
        var iframe = dwr.engine._outstandingIFrames[i];
        try
        {
            text = dwr.engine._getTextFromCometIFrame(iframe);
        }
        catch (ex)
        {
            dwr.engine._handleWarning(iframe.batch, ex);
        }
        if (text != "") dwr.engine._processCometResponse(text, iframe.batch);
    }
    if (dwr.engine._pollReq)
    {
        var req = dwr.engine._pollReq;
        var text = req.responseText;
        dwr.engine._processCometResponse(text, req.batch);
    }

    // If the poll resources are still there, come back again
    if (dwr.engine._outstandingIFrames.length > 0 || dwr.engine._pollReq)
    {
        setTimeout("dwr.engine._checkCometPoll()", dwr.engine._pollCometInterval);
    }
};

/** @private Extract the whole (executed an all) text from the current iframe */
dwr.engine._getTextFromCometIFrame = function(frameEle)
{
    var body = frameEle.contentWindow.document.body;
    if (body == null) return "";
    var text = body.innerHTML;
    // We need to prevent IE from stripping line feeds
    if (text.indexOf("<PRE>") == 0 || text.indexOf("<pre>") == 0)
    {
        text = text.substring(5, text.length - 7);
    }
    return text;
};

/** @private Some more text might have come in, test and execute the new stuff */
dwr.engine._processCometResponse = function(response, batch)
{
    if (batch.charsProcessed == response.length) return;
    if (response.length == 0)
    {
        batch.charsProcessed = 0;
        return;
    }

    var firstStartTag = response.indexOf("//#DWR-START#", batch.charsProcessed);
    if (firstStartTag == -1)
    {
        // dwr.engine._debug("No start tag (search from " + batch.charsProcessed + "). skipping '" + response.substring(batch.charsProcessed) + "'");
        batch.charsProcessed = response.length;
        return;
    }
    // if (firstStartTag > 0) {
    //   dwr.engine._debug("Start tag not at start (search from " + batch.charsProcessed + "). skipping '" + response.substring(batch.charsProcessed, firstStartTag) + "'");
    // }

    var lastEndTag = response.lastIndexOf("//#DWR-END#");
    if (lastEndTag == -1)
    {
        // dwr.engine._debug("No end tag. unchanged charsProcessed=" + batch.charsProcessed);
        return;
    }

    // Skip the end tag too for next time, remembering CR and LF
    if (response.charCodeAt(lastEndTag + 11) == 13 && response.charCodeAt(lastEndTag + 12) == 10)
    {
        batch.charsProcessed = lastEndTag + 13;
    }
    else
    {
        batch.charsProcessed = lastEndTag + 11;
    }

    var exec = response.substring(firstStartTag + 13, lastEndTag);

    dwr.engine._receivedBatch = batch;
    dwr.engine._eval(exec);
    dwr.engine._receivedBatch = null;
};

/** @private Actually send the block of data in the batch object. */
dwr.engine._sendData = function(batch)
{
    batch.map.batchId = dwr.engine._nextBatchId++;
    dwr.engine._batches[batch.map.batchId] = batch;
    dwr.engine._batchesLength++;
    batch.completed = false;

    for (var i = 0; i < batch.preHooks.length; i++)
    {
        batch.preHooks[i]();
    }
    batch.preHooks = null;
    // Set a timeout
    if (batch.timeout && batch.timeout != 0)
    {
        batch.interval = setInterval(function()
        {
            dwr.engine._abortRequest(batch);
        }, batch.timeout);
    }
    // Get setup for XMLHttpRequest if possible
    if (batch.rpcType == dwr.engine.XMLHttpRequest)
    {
        if (window.XMLHttpRequest)
        {
            batch.req = new XMLHttpRequest();
        }
        // IE5 for the mac claims to support window.ActiveXObject, but throws an error when it's used
        else if (window.ActiveXObject && !(navigator.userAgent.indexOf("Mac") >= 0 && navigator.userAgent.indexOf("MSIE") >= 0))
        {
            batch.req = dwr.engine._newActiveXObject(dwr.engine._XMLHTTP);
        }
    }

    var prop, request;
    if (batch.req)
    {
        // Proceed using XMLHttpRequest
        if (batch.async)
        {
            batch.req.onreadystatechange = function()
            {
                dwr.engine._stateChange(batch);
            };
        }
        // If we're polling, record this for monitoring
        if (batch.isPoll)
        {
            dwr.engine._pollReq = batch.req;
            // In IE XHR is an ActiveX control so you can't augment it like this
            // however batch.isPoll uses IFrame on IE so were safe here
            batch.req.batch = batch;
        }
        // Workaround for Safari 1.x POST bug
        var indexSafari = navigator.userAgent.indexOf("Safari/");
        if (indexSafari >= 0)
        {
            var version = navigator.userAgent.substring(indexSafari + 7);
            if (parseInt(version, 10) < 400)
            {
                if (dwr.engine._allowGetForSafariButMakeForgeryEasier == "true") batch.httpMethod = "GET";
                else dwr.engine._handleWarning(batch, { name:"dwr.engine.oldSafari", message:"Safari GET support disabled. See getahead.org/dwr/server/servlet and allowGetForSafariButMakeForgeryEasier." });
            }
        }
        batch.mode = batch.isPoll ? dwr.engine._ModePlainPoll : dwr.engine._ModePlainCall;
        request = dwr.engine._constructRequest(batch);
        try
        {
            batch.req.open(batch.httpMethod, request.url, batch.async);
            try
            {
                for (prop in batch.headers)
                {
                    var value = batch.headers[prop];
                    if (typeof value == "string") batch.req.setRequestHeader(prop, value);
                }
                if (!batch.headers["Content-Type"]) batch.req.setRequestHeader("Content-Type", "text/plain");
            }
            catch (ex)
            {
                dwr.engine._handleWarning(batch, ex);
            }
            batch.req.send(request.body);
            if (!batch.async) dwr.engine._stateChange(batch);
        }
        catch (ex)
        {
            dwr.engine._handleError(batch, ex);
        }
    }
    else if (batch.rpcType != dwr.engine.ScriptTag)
    {
        // Proceed using iframe
        var idname = batch.isPoll ? "dwr-if-poll-" + batch.map.batchId : "dwr-if-" + batch.map["c0-id"];
        batch.div = document.createElement("div");
        batch.div.innerHTML = "<iframe src='javascript:void(0)' frameborder='0' style='width:0px;height:0px;border:0;' id='" + idname + "' name='" + idname + "'></iframe>";
        document.body.appendChild(batch.div);
        batch.iframe = document.getElementById(idname);
        batch.iframe.batch = batch;
        batch.mode = batch.isPoll ? dwr.engine._ModeHtmlPoll : dwr.engine._ModeHtmlCall;
        if (batch.isPoll) dwr.engine._outstandingIFrames.push(batch.iframe);
        request = dwr.engine._constructRequest(batch);
        if (batch.httpMethod == "GET")
        {
            batch.iframe.setAttribute("src", request.url);
            // document.body.appendChild(batch.iframe);
        }
        else
        {
            batch.form = document.createElement("form");
            batch.form.setAttribute("id", "dwr-form");
            batch.form.setAttribute("action", request.url);
            batch.form.setAttribute("target", idname);
            batch.form.target = idname;
            batch.form.setAttribute("method", batch.httpMethod);
            for (prop in batch.map)
            {
                var value = batch.map[prop];
                if (typeof value != "function")
                {
                    var formInput = document.createElement("input");
                    formInput.setAttribute("type", "hidden");
                    formInput.setAttribute("name", prop);
                    formInput.setAttribute("value", value);
                    batch.form.appendChild(formInput);
                }
            }
            document.body.appendChild(batch.form);
            batch.form.submit();
        }
    }
    else
    {
        batch.httpMethod = "GET"; // There's no such thing as ScriptTag using POST
        batch.mode = batch.isPoll ? dwr.engine._ModePlainPoll : dwr.engine._ModePlainCall;
        request = dwr.engine._constructRequest(batch);
        batch.script = document.createElement("script");
        batch.script.id = "dwr-st-" + batch.map["c0-id"];
        batch.script.src = request.url;
        document.body.appendChild(batch.script);
    }
};

dwr.engine._ModePlainCall = "/call/plaincall/";
dwr.engine._ModeHtmlCall = "/call/htmlcall/";
dwr.engine._ModePlainPoll = "/call/plainpoll/";
dwr.engine._ModeHtmlPoll = "/call/htmlpoll/";

/** @private Work out what the URL should look like */
dwr.engine._constructRequest = function(batch)
{
    // A quick string to help people that use web log analysers
    var request = { url:batch.path + batch.mode, body:null };
    if (batch.isPoll == true)
    {
        request.url += "ReverseAjax.dwr";
    }
    else if (batch.map.callCount == 1)
    {
        request.url += batch.map["c0-scriptName"] + "." + batch.map["c0-methodName"] + ".dwr";
    }
    else
    {
        request.url += "Multiple." + batch.map.callCount + ".dwr";
    }
    // Play nice with url re-writing
    var sessionMatch = location.href.match(/jsessionid=([^?]+)/);
    if (sessionMatch != null)
    {
        request.url += ";jsessionid=" + sessionMatch[1];
    }

    var prop;
    if (batch.httpMethod == "GET")
    {
        // Some browsers (Opera/Safari2) seem to fail to convert the callCount value
        // to a string in the loop below so we do it manually here.
        batch.map.callCount = "" + batch.map.callCount;
        request.url += "?";
        for (prop in batch.map)
        {
            if (typeof batch.map[prop] != "function")
            {
                request.url += encodeURIComponent(prop) + "=" + encodeURIComponent(batch.map[prop]) + "&";
            }
        }
        request.url = request.url.substring(0, request.url.length - 1);
    }
    else
    {
        // PERFORMANCE: for iframe mode this is thrown away.
        request.body = "";
        for (prop in batch.map)
        {
            if (typeof batch.map[prop] != "function")
            {
                request.body += prop + "=" + batch.map[prop] + dwr.engine._postSeperator;
            }
        }
        request.body = dwr.engine._contentRewriteHandler(request.body);
    }
    request.url = dwr.engine._urlRewriteHandler(request.url);
    return request;
};

/** @private Called by XMLHttpRequest to indicate that something has happened */
dwr.engine._stateChange = function(batch)
{
    var toEval;

    if (batch.completed)
    {
        dwr.engine._debug("Error: _stateChange() with batch.completed");
        return;
    }

    var req = batch.req;
    try
    {
        if (req.readyState != 4) return;
    }
    catch (ex)
    {
        dwr.engine._handleWarning(batch, ex);
        // It's broken - clear up and forget this call
        dwr.engine._clearUp(batch);
        return;
    }

    try
    {
        var reply = req.responseText;
        reply = dwr.engine._replyRewriteHandler(reply);
        var status = req.status; // causes Mozilla to except on page moves

        if (reply == null || reply == "")
        {
            dwr.engine._handleWarning(batch, { name:"dwr.engine.missingData", message:"No data received from server" });
        }
        else if (status != 200)
        {
            dwr.engine._handleError(batch, { name:"dwr.engine.http." + status, message:req.statusText });
        }
        else
        {
            var contentType = req.getResponseHeader("Content-Type");
            if (!contentType.match(/^text\/plain/) && !contentType.match(/^text\/javascript/))
            {
                if (contentType.match(/^text\/html/) && typeof batch.textHtmlHandler == "function")
                {
                    batch.textHtmlHandler();
                }
                else
                {
                    dwr.engine._handleWarning(batch, { name:"dwr.engine.invalidMimeType", message:"Invalid content type: '" + contentType + "'" });
                }
            }
            else
            {
                // Comet replies might have already partially executed
                if (batch.isPoll && batch.map.partialResponse == dwr.engine._partialResponseYes)
                {
                    dwr.engine._processCometResponse(reply, batch);
                }
                else
                {
                    if (reply.search("//#DWR") == -1)
                    {
                        dwr.engine._handleWarning(batch, { name:"dwr.engine.invalidReply", message:"Invalid reply from server" });
                    }
                    else
                    {
                        toEval = reply;
                    }
                }
            }
        }
    }
    catch (ex)
    {
        dwr.engine._handleWarning(batch, ex);
    }

    dwr.engine._callPostHooks(batch);

    // Outside of the try/catch so errors propogate normally:
    dwr.engine._receivedBatch = batch;
    if (toEval != null) toEval = toEval.replace(dwr.engine._scriptTagProtection, "");
    dwr.engine._eval(toEval);
    dwr.engine._receivedBatch = null;

    dwr.engine._clearUp(batch);
};

/** @private Called by the server: Execute a callback */
dwr.engine._remoteHandleCallback = function(batchId, callId, reply)
{
    var batch = dwr.engine._batches[batchId];
    if (batch == null)
    {
        dwr.engine._debug("Warning: batch == null in remoteHandleCallback for batchId=" + batchId, true);
        return;
    }
    // Error handlers inside here indicate an error that is nothing to do
    // with DWR so we handle them differently.
    try
    {
        var handlers = batch.handlers[callId];
        if (!handlers)
        {
            dwr.engine._debug("Warning: Missing handlers. callId=" + callId, true);
        }
        else if (typeof handlers.callback == "function") handlers.callback(reply);
    }
    catch (ex)
    {
        dwr.engine._handleError(batch, ex);
    }
};

/** @private Called by the server: Handle an exception for a call */
dwr.engine._remoteHandleException = function(batchId, callId, ex)
{
    var batch = dwr.engine._batches[batchId];
    if (batch == null)
    {
        dwr.engine._debug("Warning: null batch in remoteHandleException", true);
        return;
    }
    var handlers = batch.handlers[callId];
    if (handlers == null)
    {
        dwr.engine._debug("Warning: null handlers in remoteHandleException", true);
        return;
    }
    if (ex.message == undefined) ex.message = "";
    if (typeof handlers.exceptionHandler == "function") handlers.exceptionHandler(ex.message, ex);
    else if (typeof batch.errorHandler == "function") batch.errorHandler(ex.message, ex);
};

/** @private Called by the server: The whole batch is broken */
dwr.engine._remoteHandleBatchException = function(ex, batchId)
{
    var searchBatch = (dwr.engine._receivedBatch == null && batchId != null);
    if (searchBatch)
    {
        dwr.engine._receivedBatch = dwr.engine._batches[batchId];
    }
    if (ex.message == undefined) ex.message = "";
    dwr.engine._handleError(dwr.engine._receivedBatch, ex);
    if (searchBatch)
    {
        dwr.engine._receivedBatch = null;
        dwr.engine._clearUp(dwr.engine._batches[batchId]);
    }
};

/** @private Called by the server: Reverse ajax should not be used */
dwr.engine._remotePollCometDisabled = function(ex, batchId)
{
    dwr.engine.setActiveReverseAjax(false);
    var searchBatch = (dwr.engine._receivedBatch == null && batchId != null);
    if (searchBatch)
    {
        dwr.engine._receivedBatch = dwr.engine._batches[batchId];
    }
    if (ex.message == undefined) ex.message = "";
    dwr.engine._handleError(dwr.engine._receivedBatch, ex);
    if (searchBatch)
    {
        dwr.engine._receivedBatch = null;
        dwr.engine._clearUp(dwr.engine._batches[batchId]);
    }
};

/** @private Called by the server: An IFrame reply is about to start */
dwr.engine._remoteBeginIFrameResponse = function(iframe, batchId)
{
    if (iframe != null) dwr.engine._receivedBatch = iframe.batch;
    dwr.engine._callPostHooks(dwr.engine._receivedBatch);
};

/** @private Called by the server: An IFrame reply is just completing */
dwr.engine._remoteEndIFrameResponse = function(batchId)
{
    dwr.engine._clearUp(dwr.engine._receivedBatch);
    dwr.engine._receivedBatch = null;
};

/** @private This is a hack to make the context be this window */
dwr.engine._eval = function(script)
{
    if (script == null) return null;
    if (script == "")
    {
        dwr.engine._debug("Warning: blank script", true);
        return null;
    }
    // dwr.engine._debug("Exec: [" + script + "]", true);
    return eval(script);
};

/** @private Called as a result of a request timeout */
dwr.engine._abortRequest = function(batch)
{
    if (batch && !batch.completed)
    {
        clearInterval(batch.interval);
        dwr.engine._clearUp(batch);
        if (batch.req) batch.req.abort();
        dwr.engine._handleError(batch, { name:"dwr.engine.timeout", message:"Timeout" });
    }
};

/** @private call all the post hooks for a batch */
dwr.engine._callPostHooks = function(batch)
{
    if (batch.postHooks)
    {
        for (var i = 0; i < batch.postHooks.length; i++)
        {
            batch.postHooks[i]();
        }
        batch.postHooks = null;
    }
}

/** @private A call has finished by whatever means and we need to shut it all down. */
dwr.engine._clearUp = function(batch)
{
    if (!batch)
    {
        dwr.engine._debug("Warning: null batch in dwr.engine._clearUp()", true);
        return;
    }
    if (batch.completed == "true")
    {
        dwr.engine._debug("Warning: Double complete", true);
        return;
    }

    // IFrame tidyup
    if (batch.div) batch.div.parentNode.removeChild(batch.div);
    if (batch.iframe)
    {
        // If this is a poll frame then stop comet polling
        for (var i = 0; i < dwr.engine._outstandingIFrames.length; i++)
        {
            if (dwr.engine._outstandingIFrames[i] == batch.iframe)
            {
                dwr.engine._outstandingIFrames.splice(i, 1);
            }
        }
        batch.iframe.parentNode.removeChild(batch.iframe);
    }
    if (batch.form) batch.form.parentNode.removeChild(batch.form);

    // XHR tidyup: avoid IE handles increase
    if (batch.req)
    {
        // If this is a poll frame then stop comet polling
        if (batch.req == dwr.engine._pollReq) dwr.engine._pollReq = null;
        delete batch.req;
    }

    if (batch.map && batch.map.batchId)
    {
        delete dwr.engine._batches[batch.map.batchId];
        dwr.engine._batchesLength--;
    }

    batch.completed = true;

    // If there is anything on the queue waiting to go out, then send it.
    // We don't need to check for ordered mode, here because when ordered mode
    // gets turned off, we still process *waiting* batches in an ordered way.
    if (dwr.engine._batchQueue.length != 0)
    {
        var sendbatch = dwr.engine._batchQueue.shift();
        dwr.engine._sendData(sendbatch);
    }
};

/** @private Generic error handling routing to save having null checks everywhere */
dwr.engine._handleError = function(batch, ex)
{
    if (typeof ex == "string") ex = { name:"unknown", message:ex };
    if (ex.message == null) ex.message = "";
    if (ex.name == null) ex.name = "unknown";
    if (batch && typeof batch.errorHandler == "function") batch.errorHandler(ex.message, ex);
    else if (dwr.engine._errorHandler) dwr.engine._errorHandler(ex.message, ex);
    dwr.engine._clearUp(batch);
};

/** @private Generic error handling routing to save having null checks everywhere */
dwr.engine._handleWarning = function(batch, ex)
{
    if (typeof ex == "string") ex = { name:"unknown", message:ex };
    if (ex.message == null) ex.message = "";
    if (ex.name == null) ex.name = "unknown";
    if (batch && typeof batch.warningHandler == "function") batch.warningHandler(ex.message, ex);
    else if (dwr.engine._warningHandler) dwr.engine._warningHandler(ex.message, ex);
    dwr.engine._clearUp(batch);
};

/**
 * @private Marshall a data item
 * @param batch A map of variables to how they have been marshalled
 * @param referto An array of already marshalled variables to prevent recurrsion
 * @param data The data to be marshalled
 * @param name The name of the data being marshalled
 */
dwr.engine._serializeAll = function(batch, referto, data, name)
{
    if (data == null)
    {
        batch.map[name] = "null:null";
        return;
    }

    switch (typeof data)
            {
    case "boolean":
        batch.map[name] = "boolean:" + data;
        break;
    case "number":
        batch.map[name] = "number:" + data;
        break;
    case "string":
        batch.map[name] = "string:" + encodeURIComponent(data);
        break;
    case "object":
        if (data instanceof String) batch.map[name] = "String:" + encodeURIComponent(data);
        else if (data instanceof Boolean) batch.map[name] = "Boolean:" + data;
        else if (data instanceof Number) batch.map[name] = "Number:" + data;
        else if (data instanceof Date) batch.map[name] = "Date:" + data.getTime();
        else if (data && data.join) batch.map[name] = dwr.engine._serializeArray(batch, referto, data, name);
        else batch.map[name] = dwr.engine._serializeObject(batch, referto, data, name);
        break;
    case "function":
    // We just ignore functions.
        break;
    default:
        dwr.engine._handleWarning(null, { name:"dwr.engine.unexpectedType", message:"Unexpected type: " + typeof data + ", attempting default converter." });
        batch.map[name] = "default:" + data;
        break;
    }
};

/** @private Have we already converted this object? */
dwr.engine._lookup = function(referto, data, name)
{
    var lookup;
    // Can't use a map: getahead.org/ajax/javascript-gotchas
    for (var i = 0; i < referto.length; i++)
    {
        if (referto[i].data == data)
        {
            lookup = referto[i];
            break;
        }
    }
    if (lookup) return "reference:" + lookup.name;
    referto.push({ data:data, name:name });
    return null;
};

/** @private Marshall an object */
dwr.engine._serializeObject = function(batch, referto, data, name)
{
    var ref = dwr.engine._lookup(referto, data, name);
    if (ref) return ref;

    // This check for an HTML is not complete, but is there a better way?
    // Maybe we should add: data.hasChildNodes typeof "function" == true
    if (data.nodeName && data.nodeType)
    {
        return dwr.engine._serializeXml(batch, referto, data, name);
    }

    // treat objects as an associative arrays
    var reply = "Object_" + dwr.engine._getObjectClassName(data) + ":{";
    var element;
    for (element in data)
    {
        if (typeof data[element] != "function")
        {
            batch.paramCount++;
            var childName = "c" + dwr.engine._batch.map.callCount + "-e" + batch.paramCount;
            dwr.engine._serializeAll(batch, referto, data[element], childName);

            reply += encodeURIComponent(element) + ":reference:" + childName + ", ";
        }
    }

    if (reply.substring(reply.length - 2) == ", ")
    {
        reply = reply.substring(0, reply.length - 2);
    }
    reply += "}";

    return reply;
};

/** @private Returns the classname of supplied argument obj */
dwr.engine._errorClasses = { "Error":Error, "EvalError":EvalError, "RangeError":RangeError, "ReferenceError":ReferenceError, "SyntaxError":SyntaxError, "TypeError":TypeError, "URIError":URIError };
dwr.engine._getObjectClassName = function(obj)
{
    // Try to find the classname by stringifying the object's constructor
    // and extract <class> from "function <class>".
    if (obj && obj.constructor && obj.constructor.toString)
    {
        var str = obj.constructor.toString();
        var regexpmatch = str.match(/function\s+(\w+)/);
        if (regexpmatch && regexpmatch.length == 2)
        {
            return regexpmatch[1];
        }
    }

    // Now manually test against the core Error classes, as these in some
    // browsers successfully match to the wrong class in the
    // Object.toString() test we will do later
    if (obj && obj.constructor)
    {
        for (var errorname in dwr.engine._errorClasses)
        {
            if (obj.constructor == dwr.engine._errorClasses[errorname]) return errorname;
        }
    }

    // Try to find the classname by calling Object.toString() on the object
    // and extracting <class> from "[object <class>]"
    if (obj)
    {
        var str = Object.prototype.toString.call(obj);
        var regexpmatch = str.match(/\[object\s+(\w+)/);
        if (regexpmatch && regexpmatch.length == 2)
        {
            return regexpmatch[1];
        }
    }

    // Supplied argument was probably not an object, but what is better?
    return "Object";
};

/** @private Marshall an object */
dwr.engine._serializeXml = function(batch, referto, data, name)
{
    var ref = dwr.engine._lookup(referto, data, name);
    if (ref) return ref;

    var output;
    if (window.XMLSerializer) output = new XMLSerializer().serializeToString(data);
    else if (data.toXml) output = data.toXml;
    else output = data.innerHTML;

    return "XML:" + encodeURIComponent(output);
};

/** @private Marshall an array */
dwr.engine._serializeArray = function(batch, referto, data, name)
{
    var ref = dwr.engine._lookup(referto, data, name);
    if (ref) return ref;

    var reply = "Array:[";
    for (var i = 0; i < data.length; i++)
    {
        if (i != 0) reply += ",";
        batch.paramCount++;
        var childName = "c" + dwr.engine._batch.map.callCount + "-e" + batch.paramCount;
        dwr.engine._serializeAll(batch, referto, data[i], childName);
        reply += "reference:";
        reply += childName;
    }
    reply += "]";

    return reply;
};

/** @private Convert an XML string into a DOM object. */
dwr.engine._unserializeDocument = function(xml)
{
    var dom;
    if (window.DOMParser)
    {
        var parser = new DOMParser();
        dom = parser.parseFromString(xml, "text/xml");
        if (!dom.documentElement || dom.documentElement.tagName == "parsererror")
        {
            var message = dom.documentElement.firstChild.data;
            message += "\n" + dom.documentElement.firstChild.nextSibling.firstChild.data;
            throw message;
        }
        return dom;
    }
    else if (window.ActiveXObject)
    {
        dom = dwr.engine._newActiveXObject(dwr.engine._DOMDocument);
        dom.loadXML(xml); // What happens on parse fail with IE?
        return dom;
    }
    else
    {
        var div = document.createElement("div");
        div.innerHTML = xml;
        return div;
    }
};

/** @param axarray An array of strings to attempt to create ActiveX objects from */
dwr.engine._newActiveXObject = function(axarray)
{
    var returnValue;
    for (var i = 0; i < axarray.length; i++)
    {
        try
        {
            returnValue = new ActiveXObject(axarray[i]);
            break;
        }
        catch (ex)
        { /* ignore */
        }
    }
    return returnValue;
};

/** @private Used internally when some message needs to get to the programmer */
dwr.engine._debug = function(message, stacktrace)
{
    var written = false;
    try
    {
        if (window.console)
        {
            if (stacktrace && window.console.trace) window.console.trace();
            window.console.log(message);
            written = true;
        }
        else if (window.opera && window.opera.postError)
        {
            window.opera.postError(message);
            written = true;
        }
    }
    catch (ex)
    { /* ignore */
    }

    if (!written)
    {
        var debug = document.getElementById("dwr-debug");
        if (debug)
        {
            var contents = message + "<br/>" + debug.innerHTML;
            if (contents.length > 2048) contents = contents.substring(0, 2048);
            debug.innerHTML = contents;
        }
    }
};