/*
Copyright (c) 2007, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.net/yui/license.txt
version: 2.2.0
*/
/**
 * The DataSource utility provides a common configurable interface for widgets
 * to access a variety of data, from JavaScript arrays to online servers over
 * XHR.
 *
 * @module datasource
 * @requires yahoo, event
 * @optional xhr
 * @title DataSource Utility
 * @beta
 */

/****************************************************************************/
/****************************************************************************/
/****************************************************************************/

/**
 * The DataSource class defines and manages a live set of data for widgets to
 * interact with. Examples of live databases include in-memory
 * local data such as a JavaScript array, a JavaScript function, or JSON, or
 * remote data such as data retrieved through an XHR connection.
 *
 * @class DataSource
 * @uses YAHOO.util.EventProvider
 * @constructor
 * @param oLiveData {Object} Pointer to live database
 * @param oConfigs {Object} (optional) Object literal of configuration values
 */
YAHOO.util.DataSource = function(oLiveData, oConfigs) {
    // Set any config params passed in to override defaults
    if(typeof oConfigs == "object") {
        for(var sConfig in oConfigs) {
            if (sConfig) {
                this[sConfig] = oConfigs[sConfig];
            }
        }
    }

    if(!oLiveData) {
        return;
    }
    else {
        switch(oLiveData.constructor) {
            case Function:
                this.dataType = YAHOO.util.DataSource.TYPE_JSFUNCTION;
                break;
            case Array:
                this.dataType = YAHOO.util.DataSource.TYPE_JSARRAY;
                break;
            case String:
                this.dataType = YAHOO.util.DataSource.TYPE_XHR;
                break;
            case Object:
                this.dataType = YAHOO.util.DataSource.TYPE_JSON;
                break;
            default:
                this.dataType = YAHOO.util.DataSource.TYPE_UNKNOWN;
                break;
        }
        this.liveData = oLiveData;
    }

    // Validate and initialize public configs
    var maxCacheEntries = this.maxCacheEntries;
    if(isNaN(maxCacheEntries) || (maxCacheEntries < 0)) {
        maxCacheEntries = 0;
    }

    // Initialize local cache
    if(maxCacheEntries > 0 && !this._aCache) {
        this._aCache = [];
    }

    this._sName = "instance" + YAHOO.util.DataSource._nIndex;
    YAHOO.util.DataSource._nIndex++;


    /////////////////////////////////////////////////////////////////////////////
    //
    // Custom Events
    //
    /////////////////////////////////////////////////////////////////////////////

    /**
     * Fired when a request is made to the local cache.
     *
     * @event cacheRequestEvent
     * @param oArgs.request {Object} The request object.
     * @param oArgs.callback {Function} The callback function.
     * @param oArgs.caller {Object} The parent object of the callback function.
     */
    this.createEvent("cacheRequestEvent");

    /**
     * Fired when data is retrieved from the local cache.
     *
     * @event getCachedResponseEvent
     * @param oArgs.request {Object} The request object.
     * @param oArgs.response {Object} The response object.
     * @param oArgs.callback {Function} The callback function.
     * @param oArgs.caller {Object} The parent object of the callback function.
     */
    this.createEvent("cacheResponseEvent");

    /**
     * Fired when a request is sent to the live data source.
     *
     * @event requestEvent
     * @param oArgs.request {Object} The request object.
     * @param oArgs.callback {Function} The callback function.
     * @param oArgs.caller {Object} The parent object of the callback function.
     */
    this.createEvent("requestEvent");

    /**
     * Fired when live data source sends response.
     *
     * @event parseResponseEvent
     * @param oArgs.request {Object} The request object.
     * @param oArgs.response {Object} The raw response object.
     * @param oArgs.callback {Function} The callback function.
     * @param oArgs.caller {Object} The parent object of the callback function.
     */
    this.createEvent("responseEvent");

    /**
     * Fired when response is parsed.
     *
     * @event responseParseEvent
     * @param oArgs.request {Object} The request object.
     * @param oArgs.response {Object} The parsed response object.
     * @param oArgs.callback {Function} The callback function.
     * @param oArgs.caller {Object} The parent object of the callback function.
     */
    this.createEvent("responseParseEvent");

    /**
     * Fired when response is cached.
     *
     * @event responseCacheEvent
     * @param oArgs.request {Object} The request object.
     * @param oArgs.response {Object} The parsed response object.
     * @param oArgs.callback {Function} The callback function.
     * @param oArgs.caller {Object} The parent object of the callback function.
     */
    this.createEvent("responseCacheEvent");
    /**
     * Fired when an error is encountered with the live data source.
     *
     * @event dataErrorEvent
     * @param oArgs.request {Object} The request object.
     * @param oArgs.callback {Function} The callback function.
     * @param oArgs.caller {Object} The parent object of the callback function.
     * @param oArgs.message {String} The error message.
     */
    this.createEvent("dataErrorEvent");

    /**
     * Fired when the local cache is flushed.
     *
     * @event cacheFlushEvent
     */
    this.createEvent("cacheFlushEvent");
};

YAHOO.augment(YAHOO.util.DataSource, YAHOO.util.EventProvider);

/////////////////////////////////////////////////////////////////////////////
//
// Public constants
//
/////////////////////////////////////////////////////////////////////////////

/**
 * Type is unknown.
 *
 * @property TYPE_UNKNOWN
 * @type Number
 * @final
 * @default -1
 */
YAHOO.util.DataSource.TYPE_UNKNOWN = -1;

/**
 * Type is a JavaScript Array.
 *
 * @property TYPE_JSARRAY
 * @type Number
 * @final
 * @default 0
 */
YAHOO.util.DataSource.TYPE_JSARRAY = 0;

/**
 * Type is a JavaScript Function.
 *
 * @property TYPE_JSFUNCTIOn
 * @type Number
 * @final
 * @default 1
 */
YAHOO.util.DataSource.TYPE_JSFUNCTION = 1;

/**
 * Type is hosted on a server via an XHR connection.
 *
 * @property TYPE_XHR
 * @type Number
 * @final
 * @default 2
 */
YAHOO.util.DataSource.TYPE_XHR = 2;

/**
 * Type is JSON.
 *
 * @property TYPE_JSON
 * @type Number
 * @final
 * @default 3
 */
YAHOO.util.DataSource.TYPE_JSON = 3;

/**
 * Type is XML.
 *
 * @property TYPE_XML
 * @type Number
 * @final
 * @default 4
 */
YAHOO.util.DataSource.TYPE_XML = 4;

/**
 * Type is plain text.
 *
 * @property TYPE_TEXT
 * @type Number
 * @final
 * @default 5
 */
YAHOO.util.DataSource.TYPE_TEXT = 5;
/**
 * Error message for invalid data responses.
 *
 * @property ERROR_DATAINVALID
 * @type String
 * @final
 * @default "Invalid data"
 */
YAHOO.util.DataSource.ERROR_DATAINVALID = "Invalid data";

/**
 * Error message for null data responses.
 *
 * @property ERROR_DATANULL
 * @type String
 * @final
 * @default "Null data"
 */
YAHOO.util.DataSource.ERROR_DATANULL = "Null data";

/////////////////////////////////////////////////////////////////////////////
//
// Private member variables
//
/////////////////////////////////////////////////////////////////////////////

/**
 * Internal class variable to index multiple DataSource instances.
 *
 * @property _nIndex
 * @type Number
 * @private
 */
YAHOO.util.DataSource._nIndex = 0;

/**
 * Name of DataSource instance.
 *
 * @property _sName
 * @type String
 * @private
 */
YAHOO.util.DataSource.prototype._sName = null;

/**
 * Local cache of data result objects indexed chronologically.
 *
 * @property _aCache
 * @type Object[]
 * @private
 */
YAHOO.util.DataSource.prototype._aCache = null;

/////////////////////////////////////////////////////////////////////////////
//
// Private methods
//
/////////////////////////////////////////////////////////////////////////////



/////////////////////////////////////////////////////////////////////////////
//
// Public member variables
//
/////////////////////////////////////////////////////////////////////////////

/**
 * Max size of the local cache.  Set to 0 to turn off caching.  Caching is
 * useful to reduce the number of server connections.  Recommended only for data
 * sources that return comprehensive results for queries or when stale data is
 * not an issue.
 *
 * @property maxCacheEntries
 * @type Number
 * @default 0
 */
YAHOO.util.DataSource.prototype.maxCacheEntries = 0;

 /**
 * Pointer to live database.
 *
 * @property liveData
 * @type Object
 */
YAHOO.util.DataSource.prototype.liveData = null;

 /**
 * If data is accessed over XHR via Connection Manager, the connection timeout is
 * configurable in milliseconds the XHR connection will wait for a server
 * response. A a value of zero indicates the XHR connection will wait forever.
 * Any value greater than zero will use the Connection utility's Auto-Abort
 * feature.
 *
 * @property connTimeout
 * @type Number
 * @default 0
 */
YAHOO.util.DataSource.prototype.connTimeout = null;

 /**
 * Alias to YUI Connection Manager. Allows implementers to specify their own
 * subclasses of the YUI Connection Manager utility.
 *
 * @property connMgr
 * @type Object
 * @default YAHOO.util.Connect
 */
YAHOO.util.DataSource.prototype.connMgr = YAHOO.util.Connect || null;

/**
 * Where the live data is held.
 *
 * @property dataType
 * @type Number
 * @default YAHOO.util.DataSource.TYPE_UNKNOWN
 *
 */
YAHOO.util.DataSource.prototype.dataType = YAHOO.util.DataSource.TYPE_UNKNOWN;

/**
 * Format of response.
 *
 * @property responseType
 * @type Number
 * @default YAHOO.util.DataSource.TYPE_UNKNOWN
 */
YAHOO.util.DataSource.prototype.responseType = YAHOO.util.DataSource.TYPE_UNKNOWN;

/////////////////////////////////////////////////////////////////////////////
//
// Public methods
//
/////////////////////////////////////////////////////////////////////////////

/**
 * Public accessor to the unique name of the DataSource instance.
 *
 * @method toString
 * @return {String} Unique name of the DataSource instance.
 */
YAHOO.util.DataSource.prototype.toString = function() {
    return "DataSource " + this._sName;
};

/**
 * Overridable method passes request to cache and returns cached response if any,
 * refreshing the hit in the cache as the newest item. Returns null if there is
 * no cache hit.
 *
 * @method getCachedResponse
 * @param oRequest {Object} Request object.
 * @param oCallback {Function} Handler function to receive the response
 * @param oCaller {Object} The Calling object that is making the request
 * @return {Object} Cached response object or null.
 */
YAHOO.util.DataSource.prototype.getCachedResponse = function(oRequest, oCallback, oCaller) {
    var aCache = this._aCache;
    var nCacheLength = (aCache) ? aCache.length : 0;
    var oResponse = null;

    // If cache is enabled...
    if((this.maxCacheEntries > 0) && aCache && (nCacheLength > 0)) {
        this.fireEvent("cacheRequestEvent", {request:oRequest,callback:oCallback,caller:oCaller});

        // Loop through each cached element
        for(var i = nCacheLength-1; i >= 0; i--) {
            var oCacheElem = aCache[i];

            // Defer cache hit logic to a public overridable method
            if(this.isCacheHit(oRequest,oCacheElem.request)) {
                // Grab the cached response
                oResponse = oCacheElem.response;
                // The cache returned a hit!
                // Remove element from its original location
                aCache.splice(i,1);
                // Add as newest
                this.addToCache(oRequest, oResponse);
                this.fireEvent("cacheResponseEvent", {request:oRequest,response:oResponse,callback:oCallback,caller:oCaller});
                break;
            }
        }
    }
    return oResponse;
};

/**
 * Default overridable method matches given request to given cached request.
 * Returns true if is a hit, returns false otherwise.  Implementers should
 * override this method to customize the cache-matching algorithm.
 *
 * @method isCacheHit
 * @param oRequest {Object} Request object.
 * @param oCachedRequest {Object} Cached request object.
 * @return {Boolean} True if given request matches cached request, false otherwise.
 */
YAHOO.util.DataSource.prototype.isCacheHit = function(oRequest, oCachedRequest) {
    return (oRequest === oCachedRequest);
};

/**
 * Adds a new item to the cache. If cache is full, evicts the stalest item
 * before adding the new item.
 *
 * @method addToCache
 * @param oRequest {Object} Request object.
 * @param oResponse {Object} Response object to cache.
 */
YAHOO.util.DataSource.prototype.addToCache = function(oRequest, oResponse) {
    //TODO: check for duplicate entries
    var aCache = this._aCache;
    // Don't add if anything important is missing.
    if(!aCache || !oRequest || !oResponse) {
        return;
    }

    // If the cache is full, make room by removing stalest element (index=0)
    while(aCache.length >= this.maxCacheEntries) {
        aCache.shift();
    }

    // Add to cache in the newest position, at the end of the array
    var oCacheElem = {request:oRequest,response:oResponse};
    aCache.push(oCacheElem);
    this.fireEvent("responseCacheEvent",{request:oRequest,response:oResponse});

};

/**
 * Flushes cache.
 *
 * @method flushCache
 */
YAHOO.util.DataSource.prototype.flushCache = function() {
    if(this._aCache) {
        this._aCache = [];
    }
    this.fireEvent("cacheFlushEvent");
};

/**
 * First looks for cached response, then sends request to live data.
 *
 * @method sendRequest
 * @param oRequest {Object} Request object
 * @param oCallback {Function} Handler function to receive the response
 * @param oCaller {Object} The Calling object that is making the request
 */
YAHOO.util.DataSource.prototype.sendRequest = function(oRequest, oCallback, oCaller) {
    // First look in cache
    var oCachedResponse = this.getCachedResponse(oRequest, oCallback, oCaller);
    if(oCachedResponse) {
        oCallback.call(oCaller, oRequest, oCachedResponse);
        return;
    }

    // Not in cache, so forward request to live data
    this.makeConnection(oRequest, oCallback, oCaller);
};

/**
 * Overridable method provides default functionality to make a connection to
 * live data in order to send request. The response coming back is then
 * forwarded to the handleResponse function. This method should be customized
 * for more complex implementations.
 *
 * @method makeConnection
 * @param oRequest {Object} Request object.
 * @param oCallback {Function} Handler function to receive the response
 * @param oCaller {Object} The Calling object that is making the request
 */
YAHOO.util.DataSource.prototype.makeConnection = function(oRequest, oCallback, oCaller) {
    this.fireEvent("requestEvent", {request:oRequest,callback:oCallback,caller:oCaller});
    var oRawResponse = null;
    
    // How to make the connection depends on the type of data
    switch(this.dataType) {
    
        // If the live data is a JavaScript Array
        // simply forward the entire array to the handler
        case YAHOO.util.DataSource.TYPE_JSARRAY:
        case YAHOO.util.DataSource.TYPE_JSON:
            oRawResponse = this.liveData;
            this.handleResponse(oRequest, oRawResponse, oCallback, oCaller);
            break;
            
        // If the live data is a JavaScript Function
        // pass the request in as a parameter and
        // forward the return value to the handler
        case YAHOO.util.DataSource.TYPE_JSFUNCTION:
            oRawResponse = this.liveData(oRequest);
            this.handleResponse(oRequest, oRawResponse, oCallback, oCaller);
            break;
            
        // If the live data is over Connection Manager
        // set up the callback object and
        // pass the request in as a URL query and
        // forward the response to the handler
        case YAHOO.util.DataSource.TYPE_XHR:
            /**
             * Connection Manager success handler
             *
             * @method _xhrSuccess
             * @param oResponse {Object} HTTPXMLRequest object
             * @private
             */
            var _xhrSuccess = function(oResponse) {
                // Error if no response
                if(!oResponse) {
                    this.fireEvent("dataErrorEvent", {request:oRequest,callback:oCallback,caller:oCaller,message:YAHOO.util.DataSource.ERROR_DATANULL});
                    return null;
                }
                // Error if response ID does not match last made request ID.
               else if(!this._oConn || (oResponse.tId != this._oConn.tId)) {
                    this.fireEvent("dataErrorEvent", {request:oRequest,callback:oCallback,caller:oCaller,message:YAHOO.util.DataSource.ERROR_DATAINVALID});
                    return null;
                }
                // Forward to handler
                else {
                    this.handleResponse(oRequest, oResponse, oCallback, oCaller);
                }
            };

            /**
             * Connection Manager failure handler
             *
             * @method _xhrFailure
             * @param oResponse {Object} HTTPXMLRequest object
             * @private
             */
            var _xhrFailure = function(oResponse) {
                this.fireEvent("dataErrorEvent", {request:oRequest,callback:oCallback,caller:oCaller,message:YAHOO.util.DataSource.ERROR_DATAXHR});
                return null;
            };

            /**
             * Connection Manager callback object
             *
             * @property _xhrCallback
             * @param oResponse {Object} HTTPXMLRequest object
             * @private
             */
             var _xhrCallback = {
                success:_xhrSuccess,
                failure:_xhrFailure,
                scope: this
            };

            //TODO: connTimeout config
            if(this.connTimeout && !isNaN(this.connTimeout) && this.connTimeout > 0) {
                _xhrCallback.timeout = this.connTimeout;
            }

            //TODO: oConn config
            if(this._oConn && this.connMgr) {
                this.connMgr.abort(this._oConn);
            }

            var sUri = this.liveData+"?"+oRequest;
            if(this.connMgr) {
                this._oConn = this.connMgr.asyncRequest("GET", sUri, _xhrCallback, null);
            }
            else {
            }

            break;
        default:
            //TODO: any default?
            break;
    }
};

/**
 * Handles raw data response from live data source.
 *
 * @method handleResponse
 * @param oRequest {Object} Request object
 * @param oRawResponse {Object} The raw response from the live database
 * @param oCallback {Function} Handler function to receive the response
 * @param oCaller {Object} The calling object that is making the request
 */
YAHOO.util.DataSource.prototype.handleResponse = function(oRequest, oRawResponse, oCallback, oCaller) {
    this.fireEvent("responseEvent", {request:oRequest,response:oRawResponse,callback:oCallback,caller:oCaller});
    var xhr = (this.dataType == YAHOO.util.DataSource.TYPE_XHR) ? true : false;
    var oParsedResponse = null;
    //TODO: break out into overridable methods
    switch(this.responseType) {
        case YAHOO.util.DataSource.TYPE_JSARRAY:
            if(xhr && oRawResponse.responseText) {
                oRawResponse = oRawResponse.responseText;
            }
            oParsedResponse = this.parseArrayData(oRequest, oRawResponse);
            break;
        case YAHOO.util.DataSource.TYPE_JSON:
            if(xhr && oRawResponse.responseText) {
                oRawResponse = oRawResponse.responseText;
            }
            oParsedResponse = this.parseJSONData(oRequest, oRawResponse);
            break;
        case YAHOO.util.DataSource.TYPE_XML:
            if(xhr && oRawResponse.responseXML) {
                oRawResponse = oRawResponse.responseXML;
            }
            oParsedResponse = this.parseXMLData(oRequest, oRawResponse);
            break;
        case YAHOO.util.DataSource.TYPE_TEXT:
            if(xhr && oRawResponse.responseText) {
                oRawResponse = oRawResponse.responseText;
            }
            oParsedResponse = this.parseTextData(oRequest, oRawResponse);
            break;
        default:
            //TODO: pass off to custom function
            //var contentType = oRawResponse.getResponseHeader["Content-Type"];
            break;
    }

    if(oParsedResponse) {
        this.fireEvent("responseParseEvent", {request:oRequest,response:oParsedResponse,callback:oCallback,caller:oCaller});
        // Cache the response
        this.addToCache(oRequest, oParsedResponse);
    }
    else {
        this.fireEvent("dataErrorEvent", {request:oRequest,callback:oCallback,caller:oCaller,message:YAHOO.util.DataSource.ERROR_DATANULL});
    }

    // Send the response back to the caller
    oCallback.call(oCaller, oRequest, oParsedResponse);
};

/**
 * Overridable method parses raw array data into a response object.
 *
 * @method parseArrayData
 * @param oRequest {Object} Request object.
 * @param oRawResponse {Object} The raw response from the live database
 * @return {Object} Parsed response object
 */
YAHOO.util.DataSource.prototype.parseArrayData = function(oRequest, oRawResponse) {
    var oParsedResponse = [];
    var fields = this.responseSchema.fields;
    for(var i=oRawResponse.length-1; i>-1; i--) {
        var oResult = {};
        for(var j=fields.length; j>-1; j--) {
            oResult[fields[j]] = oRawResponse[i][j] || oRawResponse[i][fields[j]];
        }
        oParsedResponse.unshift(oResult);
    }
    return oParsedResponse;
};

/**
 * Overridable method parses raw plain text data into a response object.
 *
 * @method parseTextData
 * @param oRequest {Object} Request object
 * @param oRawResponse {Object} The raw response from the live database
 * @return {Object} Parsed response object
 */
YAHOO.util.DataSource.prototype.parseTextData = function(oRequest, oRawResponse) {
    var oParsedResponse = [];
    var recDelim = this.responseSchema.recordDelim;
    var fieldDelim = this.responseSchema.fieldDelim;
    var aSchema = this.responseSchema.fields;
    if(oRawResponse.length > 0) {
        // Delete the last line delimiter at the end of the data if it exists
        var newLength = oRawResponse.length-recDelim.length;
        if(oRawResponse.substr(newLength) == recDelim) {
            oRawResponse = oRawResponse.substr(0, newLength);
        }
        // Split along record delimiter to get an array of strings
        var recordsarray = oRawResponse.split(recDelim);
        // Cycle through each record, except the first which contains header info
        for(var i = recordsarray.length-1; i >= 1; i--) {
            var dataobject = {};
            for(var j=aSchema.length-1; j >= 0; j--) {
                // Split along field delimter to get each data value
                var fielddataarray = recordsarray[i].split(fieldDelim);

                // Remove quotation marks from edges, if applicable
                var string = fielddataarray[j];
                if(string.charAt(0) == "\"") {
                    string = string.substr(1);
                }
                if(string.charAt(string.length-1) == "\"") {
                    string = string.substr(0,string.length-1);
                }
                dataobject[aSchema[j]] = string;
            }
            oParsedResponse.push(dataobject);
        }
    }
    return oParsedResponse;
};

/**
 * Overridable method parses raw XML data into a response object.
 *
 * @method parseXMLData
 * @param oRequest {Object} Request object
 * @param oRawResponse {Object} The raw response from the live database
 * @return {Object} Parsed response object
 */
YAHOO.util.DataSource.prototype.parseXMLData = function(oRequest, oRawResponse) {
    var bError = false;
    var oParsedResponse = [];
    var xmlList = oRawResponse.getElementsByTagName(this.responseSchema.resultNode);
    if(!xmlList) {
        bError = true;
    }
    // Loop through each result
    else {
        for(var k = xmlList.length-1; k >= 0 ; k--) {
            var result = xmlList.item(k);
            var oResult = {};
            // Loop through each data field in each result using the schema
            for(var m = this.responseSchema.fields.length-1; m >= 0 ; m--) {
                var field = this.responseSchema.fields[m];
                var sValue = null;
                // Values may be held in an attribute...
                var xmlAttr = result.attributes.getNamedItem(field);
                if(xmlAttr) {
                    sValue = xmlAttr.value;
                }
                // ...or in a node
                else {
                    var xmlNode = result.getElementsByTagName(field);
                    if(xmlNode && xmlNode.item(0) && xmlNode.item(0).firstChild) {
                        sValue = xmlNode.item(0).firstChild.nodeValue;
                    }
                    else {
                           sValue = "";
                    }
                }
                // Capture the schema-mapped data field values into an array
                oResult[field] = sValue;
            }
            // Capture each array of values into an array of results
            oParsedResponse.unshift(oResult);
        }
    }
    if(bError) {
        return null;
    }
    return oParsedResponse;
};

/**
 * Overridable method parses raw JSON data into a response object.
 *
 * @method parseJSONData
 * @param oRequest {Object} Request object
 * @param oRawResponse {Object} The raw response from the live database
 * @return {Object} Parsed response object
 */
YAHOO.util.DataSource.prototype.parseJSONData = function(oRequest, oRawResponse) {
    //TODO: validate oRawResponse
    var bError = false;
    var oParsedResponse = [];
    var aSchema = this.responseSchema.fields;

    var jsonObj,jsonList;
    if(oRawResponse) {
        // Parse JSON object out if it's a string
        if(oRawResponse.constructor == String) {
            // Check for latest JSON lib but divert KHTML clients
            if(oRawResponse.parseJSON && (navigator.userAgent.toLowerCase().indexOf('khtml')== -1)) {
                // Use the new JSON utility if available
                jsonObj = oRawResponse.parseJSON();
                if(!jsonObj) {
                    bError = true;
                }
            }
            // Check for older JSON lib but divert KHTML clients
            else if(window.JSON && JSON.parse && (navigator.userAgent.toLowerCase().indexOf('khtml')== -1)) {
                // Use the JSON utility if available
                jsonObj = JSON.parse(oRawResponse);
                if(!jsonObj) {
                    bError = true;
                }
            }
            // No JSON lib found so parse the string
            else {
                try {
                    // Trim leading spaces
                    while (oRawResponse.length > 0 &&
                            (oRawResponse.charAt(0) != "{") &&
                            (oRawResponse.charAt(0) != "[")) {
                        oRawResponse = oRawResponse.substring(1, oResponse.length);
                    }

                    if(oRawResponse.length > 0) {
                        // Strip extraneous stuff at the end
                        var objEnd = Math.max(oRawResponse.lastIndexOf("]"),oRawResponse.lastIndexOf("}"));
                        oRawResponse = oRawResponse.substring(0,objEnd+1);

                        // Turn the string into an object literal...
                        // ...eval is necessary here
                        jsonObj = eval("(" + oRawResponse + ")");
                        if(!jsonObj) {
                            bError = true;
                        }

                    }
                }
                catch(e) {
                    bError = true;
               }
            }
        }
        // Response must already be a JSON object
        else if(oRawResponse.constructor == Object) {
            jsonObj = oRawResponse;
        }
        // Now that we have a JSON object, parse a jsonList out of it
        if(jsonObj && jsonObj.constructor == Object) {
            try {
                // eval is necessary here since schema can be of unknown depth
                jsonList = eval("jsonObj." + this.responseSchema.resultsList);
            }
            catch(e) {
                bError = true;
            }
        }
    }
    if(bError || !jsonList) {
        // Something went wrong
        return null;
   }

    if(jsonList.constructor != Array) {
        jsonList = [jsonList];
    }

    // Loop through the array of all responses...
    for(var i = jsonList.length-1; i >= 0 ; i--) {
        var oResult = {};
        var jsonResult = jsonList[i];
        // ...and loop through each data field value of each response
        for(var j = aSchema.length-1; j >= 0 ; j--) {
            // ...and capture data into an array mapped according to the schema...
            var dataFieldValue = jsonResult[aSchema[j]];
            if(!dataFieldValue) {
                dataFieldValue = "";
            }
            oResult[aSchema[j]] = dataFieldValue;
        }
        // Capture the array of data field values in an array of results
        oParsedResponse.unshift(oResult);
    }
    return oParsedResponse;
};

YAHOO.register("datasource", YAHOO.util.DataSource, {version: "2.2.0", build: "127"});
