/*

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-get', function(Y) {

/**

 * Provides a DataSource implementation which can be used to retrieve data via the Get Utility.

 *

 * @module datasource

 * @submodule datasource-get

 */

/**

 * Get Utility subclass for the DataSource Utility.

 * @class DataSource.Get

 * @extends DataSource.Local

 * @constructor

 */    

var DSGet = function() {

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

};

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

    //

    // DataSource.Get static properties

    //

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

Y.mix(DSGet, {

    /**

     * Class name.

     *

     * @property NAME

     * @type String

     * @static     

     * @final

     * @value "dataSourceGet"

     */

    NAME: "dataSourceGet",

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

    //

    // DataSource.Get Attributes

    //

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

    ATTRS: {

        /**

         * Pointer to Get Utility.

         *

         * @attribute get

         * @type Y.Get

         * @default Y.Get

         */

        get: {

            value: Y.Get,

            cloneDefaultValue: false

        },

/**

 * Defines request/response management in the following manner:

 * <dl>

 *     <!--<dt>queueRequests</dt>

 *     <dd>If a request is already in progress, wait until response is returned before sending the next request.</dd>

 *     <dt>cancelStaleRequests</dt>

 *     <dd>If a request is already in progress, cancel it before sending the next request.</dd>-->

 *     <dt>ignoreStaleResponses</dt>

 *     <dd>Send all requests, but handle only the response for the most recently sent request.</dd>

 *     <dt>allowAll</dt>

 *     <dd>Send all requests and handle all responses.</dd>

 * </dl>

 *

 * @attribute asyncMode

 * @type String

 * @default "allowAll"

 */

asyncMode: {

    value: "allowAll"

},

/**

 * Callback string parameter name sent to the remote script. By default,

 * requests are sent to

 * <URI>?<scriptCallbackParam>=callbackFunction

 *

 * @attribute scriptCallbackParam

 * @type String

 * @default "callback"

 */

scriptCallbackParam : {

    value: "callback"

},

/**

 * Accepts the DataSource instance and a callback ID, and returns a callback

 * param/value string that gets appended to the script URI. Implementers

 * can customize this string to match their server's query syntax.

 *

 * @attribute generateRequestCallback

 * @type Function

 */

generateRequestCallback : {

    value: function(self, id) {

        return "&" + self.get("scriptCallbackParam") + "=YUI.Env.DataSource.callbacks["+id+"]" ;

    }

}

    },

    /**

     * Global array of callback functions, one for each request sent.

     *

     * @property callbacks

     * @type Function[]

     * @static

     */

    callbacks : [],

    /**

     * Unique ID to track requests.

     *

     * @property _tId

     * @type Number

     * @private

     * @static

     */

    _tId : 0

});

Y.extend(DSGet, Y.DataSource.Local, {

    /**

     * Passes query string to Get Utility. Fires <code>response</code> event when

     * response is received asynchronously.

     *

     * @method _defRequestFn

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

     * </dl>

     * @protected

     */

    _defRequestFn: function(e) {

        var uri = this.get("source"),

            get = this.get("get"),

            id = DSGet._tId++,

            self = this;

    // Dynamically add handler function with a closure to the callback stack

    YUI.Env.DataSource.callbacks[id] = Y.rbind(function(response) {

        if((self.get("asyncMode") !== "ignoreStaleResponses")||

                (id === DSGet.callbacks.length-1)) { // Must ignore stale responses

            self.fire("data", Y.mix({data:response}, e));

        }

        else {

            Y.log("DataSource ignored stale response for id " + e.tId + "(" + e.request + ")", "info", "datasource-get");

        }

        delete DSGet.callbacks[id];

    }, this, id);

    // We are now creating a request

    uri += e.request + this.get("generateRequestCallback")(this, id);

    //uri = this.doBefore(sUri);

    Y.log("DataSource is querying URL " + uri, "info", "datasource-get");

    get.script(uri, {

        autopurge: true,

        // Works in Firefox only....

        onFailure: Y.bind(function(e) {

            e.error = new Error("Script node data failure");

            this.fire("error", e);

        }, this, e)

    });

        return e.tId;

    }

});

Y.DataSource.Get = DSGet;

YUI.namespace("Env.DataSource.callbacks");

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