/**
 * The DataSource utility provides a common configurable interface for widgets to
 * access a variety of data, from JavaScript arrays to online database servers.
 *
 * @module datasource
 * @main datasource
 */
 
/**
 * Provides the base DataSource implementation, which can be extended to
 * create DataSources for specific data protocols, such as the IO Utility, the
 * Get Utility, or custom functions.
 *
 * @module datasource
 * @submodule datasource-local
 */
 
/**
 * Base class for the DataSource Utility.
 * @class DataSource.Local
 * @extends Base
 * @constructor
 */
var LANG = Y.Lang,
 
DSLocal = function() {
    DSLocal.superclass.constructor.apply(this, arguments);
};
 
    /////////////////////////////////////////////////////////////////////////////
    //
    // DataSource static properties
    //
    /////////////////////////////////////////////////////////////////////////////
Y.mix(DSLocal, {
    /**
     * Class name.
     *
     * @property NAME
     * @type String
     * @static
     * @final
     * @value "dataSourceLocal"
     */
    NAME: "dataSourceLocal",
 
    /////////////////////////////////////////////////////////////////////////////
    //
    // DataSource Attributes
    //
    /////////////////////////////////////////////////////////////////////////////
 
    ATTRS: {
        /**
        * @attribute source
        * @description Pointer to live data.
        * @type MIXED
        * @default null
        */
        source: {
            value: null
        }
    },
 
    /**
     * Global transaction counter.
     *
     * @property _tId
     * @type Number
     * @static
     * @private
     * @default 0
     */
    _tId: 0,
 
    /**
     * Global in-progress transaction objects.
     *
     * @property transactions
     * @type Object
     * @static
     */
    transactions: {},
 
    /**
     * Returns data to callback.
     *
     * @method issueCallback
     * @param e {EventFacade} Event Facade.
     * @param caller {DataSource} Calling DataSource instance.
     * @static
     */
    issueCallback: function (e, caller) {
        var callbacks = e.on || e.callback,
            callback = callbacks && callbacks.success,
            payload = e.details[0];
 
        payload.error = (e.error || e.response.error);
 
        if (payload.error) {
            caller.fire("error", payload);
            callback = callbacks && callbacks.failure;
        }
 
        if (callback) {
            //TODO: this should be executed from a specific context
            callback(payload);
        }
    }
});
 
Y.extend(DSLocal, Y.Base, {
    /**
    * Internal init() handler.
    *
    * @method initializer
    * @param config {Object} Config object.
    * @private
    */
    initializer: function(config) {
        this._initEvents();
    },
 
    /**
    * This method creates all the events for this module.
    * @method _initEvents
    * @private
    */
    _initEvents: function() {
        /**
         * Fired when a data request is received.
         *
         * @event request
         * @param e {EventFacade} Event Facade with the following properties:
         * <dl>
         * <dt>tId (Number)</dt> <dd>Unique transaction ID.</dd>
         * <dt>request (Object)</dt> <dd>The request.</dd>
         * <dt>callback (Object)</dt> <dd>The callback object
         *   (deprecated, refer to <strong>on</strong></dd>
         * <dt>on (Object)</dt> <dd>The map of configured callback
         *   functions.</dd>
         * <dt>cfg (Object)</dt> <dd>Configuration object.</dd>
         * </dl>
         * @preventable _defRequestFn
         */
        this.publish("request", {defaultFn: Y.bind("_defRequestFn", this), queuable:true});
 
        /**
         * Fired when raw data is received.
         *
         * @event data
         * @param e {EventFacade} Event Facade with the following properties:
         * <dl>
         * <dt>tId (Number)</dt> <dd>Unique transaction ID.</dd>
         * <dt>request (Object)</dt> <dd>The request.</dd>
         * <dt>callback (Object)</dt> <dd>Deprecated alias for the
         *   <strong>on</strong> property</dd>
         * <dt>on (Object)</dt> <dd>The map of configured transaction
         *   callbacks.  An object with the following properties:
         *     <dl>
         *         <dt>success (Function)</dt> <dd>Success handler.</dd>
         *         <dt>failure (Function)</dt> <dd>Failure handler.</dd>
         *     </dl>
         * </dd>
         * <dt>cfg (Object)</dt> <dd>Configuration object.</dd>
         * <dt>data (Object)</dt> <dd>Raw data.</dd>
         * </dl>
         * @preventable _defDataFn
         */
        this.publish("data", {defaultFn: Y.bind("_defDataFn", this), queuable:true});
 
        /**
         * Fired when response is returned.
         *
         * @event response
         * @param e {EventFacade} Event Facade with the following properties:
         * <dl>
         * <dt>tId (Number)</dt> <dd>Unique transaction ID.</dd>
         * <dt>request (Object)</dt> <dd>The request.</dd>
         * <dt>callback (Object)</dt> <dd>Deprecated alias for the
         *   <strong>on</strong> property</dd>
         * <dt>on (Object)</dt> <dd>The map of configured transaction
         *   callbacks.  An object with the following properties:
         *     <dl>
         *         <dt>success (Function)</dt> <dd>Success handler.</dd>
         *         <dt>failure (Function)</dt> <dd>Failure handler.</dd>
         *     </dl>
         * </dd>
         * <dt>cfg (Object)</dt> <dd>Configuration object.</dd>
         * <dt>data (Object)</dt> <dd>Raw data.</dd>
         * <dt>response (Object)</dt>
         *     <dd>Normalized response object with the following properties:
         *         <dl>
         *             <dt>results (Object)</dt> <dd>Parsed results.</dd>
         *             <dt>meta (Object)</dt> <dd>Parsed meta data.</dd>
         *             <dt>error (Boolean)</dt> <dd>Error flag.</dd>
         *         </dl>
         *     </dd>
         * <dt>error</dt>
         *     <dd>Any error that occurred along the transaction lifecycle.</dd>
         * </dl>
         * @preventable _defResponseFn
         */
         this.publish("response", {defaultFn: Y.bind("_defResponseFn", this), queuable:true});
 
        /**
         * Fired when an error is encountered.
         *
         * @event error
         * @param e {EventFacade} Event Facade with the following properties:
         * <dl>
         * <dt>tId (Number)</dt> <dd>Unique transaction ID.</dd>
         * <dt>request (Object)</dt> <dd>The request.</dd>
         * <dt>callback (Object)</dt> <dd>Deprecated alias for the
         *   <strong>on</strong> property</dd>
         * <dt>on (Object)</dt> <dd>The map of configured transaction
         *   callbacks.  An object with the following properties:
         *     <dl>
         *         <dt>success (Function)</dt> <dd>Success handler.</dd>
         *         <dt>failure (Function)</dt> <dd>Failure handler.</dd>
         *     </dl>
         * </dd>
         * <dt>cfg (Object)</dt> <dd>Configuration object.</dd>
         * <dt>data (Object)</dt> <dd>Raw data.</dd>
         * <dt>response (Object)</dt>
         *     <dd>Normalized response object with the following properties:
         *         <dl>
         *             <dt>results (Object)</dt> <dd>Parsed results.</dd>
         *             <dt>meta (Object)</dt> <dd>Parsed meta data.</dd>
         *             <dt>error (Object)</dt> <dd>Error object.</dd>
         *         </dl>
         *     </dd>
         * <dt>error</dt>
         *     <dd>Any error that occurred along the transaction lifecycle.</dd>
         * </dl>
         */
 
    },
 
    /**
     * Manages request/response transaction. Must fire <code>response</code>
     * event when response is received. This method should be implemented by
     * subclasses to achieve more complex behavior such as accessing remote data.
     *
     * @method _defRequestFn
     * @param e {EventFacade} Event Facadewith the following properties:
     * <dl>
     * <dt>tId (Number)</dt> <dd>Unique transaction ID.</dd>
     * <dt>request (Object)</dt> <dd>The request.</dd>
     * <dt>callback (Object)</dt> <dd>Deprecated alias for the
     *   <strong>on</strong> property</dd>
     * <dt>on (Object)</dt> <dd>The map of configured transaction
     *   callbacks.  An object with the following properties:
     *     <dl>
     *         <dt>success (Function)</dt> <dd>Success handler.</dd>
     *         <dt>failure (Function)</dt> <dd>Failure handler.</dd>
     *     </dl>
     * </dd>
     * <dt>cfg (Object)</dt> <dd>Configuration object.</dd>
     * </dl>
     * @protected
     */
    _defRequestFn: function(e) {
        var data = this.get("source"),
            payload = e.details[0];
 
        // Problematic data
        if(LANG.isUndefined(data)) {
            payload.error = new Error("Local source undefined");
            Y.log("Local source undefined", "error", "datasource-local");
        }
 
        payload.data = data;
        this.fire("data", payload);
        Y.log("Transaction " + e.tId + " complete. Request: " +
                Y.dump(e.request) + " . Response: " + Y.dump(e.response), "info", "datasource-local");
    },
 
    /**
     * Normalizes raw data into a response that includes results and meta properties.
     *
     * @method _defDataFn
     * @param e {EventFacade} Event Facade with the following properties:
     * <dl>
     * <dt>tId (Number)</dt> <dd>Unique transaction ID.</dd>
     * <dt>request (Object)</dt> <dd>The request.</dd>
     * <dt>callback (Object)</dt> <dd>Deprecated alias for the
     *   <strong>on</strong> property</dd>
     * <dt>on (Object)</dt> <dd>The map of configured transaction
     *   callbacks.  An object with the following properties:
     *     <dl>
     *         <dt>success (Function)</dt> <dd>Success handler.</dd>
     *         <dt>failure (Function)</dt> <dd>Failure handler.</dd>
     *     </dl>
     * </dd>
     * <dt>cfg (Object)</dt> <dd>Configuration object.</dd>
     * <dt>data (Object)</dt> <dd>Raw data.</dd>
     * </dl>
     * @protected
     */
    _defDataFn: function(e) {
        var data = e.data,
            meta = e.meta,
            response = {
                results: (LANG.isArray(data)) ? data : [data],
                meta: (meta) ? meta : {}
            },
            payload = e.details[0];
 
        payload.response = response;
        this.fire("response", payload);
    },
 
    /**
     * Sends data as a normalized response to callback.
     *
     * @method _defResponseFn
     * @param e {EventFacade} Event Facade with the following properties:
     * <dl>
     * <dt>tId (Number)</dt> <dd>Unique transaction ID.</dd>
     * <dt>request (Object)</dt> <dd>The request.</dd>
     * <dt>callback (Object)</dt> <dd>Deprecated alias for the
     *   <strong>on</strong> property</dd>
     * <dt>on (Object)</dt> <dd>The map of configured transaction
     *   callbacks.  An object with the following properties:
     *     <dl>
     *         <dt>success (Function)</dt> <dd>Success handler.</dd>
     *         <dt>failure (Function)</dt> <dd>Failure handler.</dd>
     *     </dl>
     * </dd>
     * <dt>cfg (Object)</dt> <dd>Configuration object.</dd>
     * <dt>data (Object)</dt> <dd>Raw data.</dd>
     * <dt>response (Object)</dt> <dd>Normalized response object with the following properties:
     *     <dl>
     *         <dt>results (Object)</dt> <dd>Parsed results.</dd>
     *         <dt>meta (Object)</dt> <dd>Parsed meta data.</dd>
     *         <dt>error (Boolean)</dt> <dd>Error flag.</dd>
     *     </dl>
     * </dd>
     * </dl>
     * @protected
     */
    _defResponseFn: function(e) {
        // Send the response back to the callback
        DSLocal.issueCallback(e, this);
    },
 
    /**
     * Generates a unique transaction ID and fires <code>request</code> event.
     * <strong>Note</strong>: the property <code>callback</code> is a
     * deprecated alias for the <code>on</code> transaction configuration
     * property described below.
     *
     * @method sendRequest
     * @param [request] {Object} An object literal with the following properties:
     *     <dl>
     *     <dt><code>request</code></dt>
     *     <dd>The request to send to the live data source, if any.</dd>
     *     <dt><code>on</code></dt>
     *     <dd>An object literal with the following properties:
     *         <dl>
     *         <dt><code>success</code></dt>
     *         <dd>The function to call when the data is ready.</dd>
     *         <dt><code>failure</code></dt>
     *         <dd>The function to call upon a response failure condition.</dd>
     *         <dt><code>argument</code></dt>
     *         <dd>Arbitrary data payload that will be passed back to the success and failure handlers.</dd>
     *         </dl>
     *     </dd>
     *     <dt><code>cfg</code></dt>
     *     <dd>Configuration object, if any.</dd>
     *     </dl>
     * @return {Number} Transaction ID.
     */
    sendRequest: function(request) {
        var tId = DSLocal._tId++,
            callbacks;
 
        request = request || {};
 
        callbacks = request.on || request.callback;
 
        this.fire("request", {
            tId: tId,
            request: request.request,
            on: callbacks,
            callback: callbacks,
            cfg: request.cfg || {}
        });
 
        Y.log("Transaction " + tId + " sent request: " + Y.dump(request.request), "info", "datasource-local");
 
        return tId;
    }
});
 
Y.namespace("DataSource").Local = DSLocal;