/*

Copyright (c) 2009, Yahoo! Inc. All rights reserved.

Code licensed under the BSD License:

http://developer.yahoo.net/yui/license.txt

version: 3.0.0b1

build: 1163

*/

YUI.add('datasource-cache', function(Y) {

/**

 * Extends DataSource with caching functionality.

 *

 * @module datasource

 * @submodule datasource-cache

 */

/**

 * Adds cacheability to the DataSource Utility.

 * @class DataSourceCache

 * @extends Cache

 */    

var DataSourceCache = function() {

    DataSourceCache.superclass.constructor.apply(this, arguments);

};

Y.mix(DataSourceCache, {

    /**

     * The namespace for the plugin. This will be the property on the host which

     * references the plugin instance.

     *

     * @property NS

     * @type String

     * @static

     * @final

     * @value "cache"

     */

    NS: "cache",

    /**

     * Class name.

     *

     * @property NAME

     * @type String

     * @static

     * @final

     * @value "dataSourceCache"

     */

    NAME: "dataSourceCache",

    /////////////////////////////////////////////////////////////////////////////

    //

    // DataSourceCache Attributes

    //

    /////////////////////////////////////////////////////////////////////////////

    ATTRS: {

    }

});

Y.extend(DataSourceCache, Y.Cache, {

    /**

    * Internal init() handler.

    *

    * @method initializer

    * @param config {Object} Config object.

    * @private

    */

    initializer: function(config) {

        this.doBefore("_defRequestFn", this._beforeDefRequestFn);

        this.doBefore("_defResponseFn", this._beforeDefResponseFn);

    },

    /**

     * First look for cached response, then send request to live data.

     *

     * @method _beforeDefRequestFn

     * @param e {Event.Facade} 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.</dd>

     * <dt>cfg (Object)</dt> <dd>Configuration object.</dd>

     * </dl>

     * @protected

     */

    _beforeDefRequestFn: function(e) {

        // Is response already in the Cache?

        var entry = (this.retrieve(e.request)) || null;

        if(entry && entry.response) {

            this.get("host").fire("response", Y.mix({response: entry.response}, e));

            return new Y.Do.Halt("DataSourceCache plugin halted _defRequestFn");

        }

    },

    /**

     * Adds data to cache before returning data.

     *

     * @method _beforeDefResponseFn

     * @param e {Event.Facade} 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 with the following properties:

     *     <dl>

     *         <dt>success (Function)</dt> <dd>Success handler.</dd>

     *         <dt>failure (Function)</dt> <dd>Failure handler.</dd>

     *     </dl>

     * </dd>

     * <dt>data (Object)</dt> <dd>Raw data.</dd>

     * <dt>response (Object)</dt> <dd>Normalized response object with the following properties:

     *     <dl>

     *         <dt>cached (Object)</dt> <dd>True when response is cached.</dd>

     *         <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>cfg (Object)</dt> <dd>Configuration object.</dd>

     * </dl>

     * @protected

     */

     _beforeDefResponseFn: function(e) {

        // Add to Cache before returning

        if(e.response && !e.response.cached) {

            e.response.cached = true;

            this.add(e.request, e.response, (e.callback && e.callback.argument));

        }

     }

});

Y.namespace('Plugin').DataSourceCache = DataSourceCache;

}, '3.0.0b1' ,{requires:['datasource-local', 'cache']});