/*!
 * Ext JS Library 3.0.0
 * Copyright(c) 2006-2009 Ext JS, LLC
 * licensing@extjs.com
 * http://www.extjs.com/license
 */
/**

 * @class Ext.dd.DropZone

 * @extends Ext.dd.DropTarget

 * <p>This class provides a container DD instance that allows dropping on multiple child target nodes.</p>

 * <p>By default, this class requires that child nodes accepting drop are registered with {@link Ext.dd.Registry}.

 * However a simpler way to allow a DropZone to manage any number of target elements is to configure the

 * DropZone with an implementation of {@link #getTargetFromEvent} which interrogates the passed

 * mouse event to see if it has taken place within an element, or class of elements. This is easily done

 * by using the event's {@link Ext.EventObject#getTarget getTarget} method to identify a node based on a

 * {@link Ext.DomQuery} selector.</p>

 * <p>Once the DropZone has detected through calling getTargetFromEvent, that the mouse is over

 * a drop target, that target is passed as the first parameter to {@link #onNodeEnter}, {@link #onNodeOver},

 * {@link #onNodeOut}, {@link #onNodeDrop}. You may configure the instance of DropZone with implementations

 * of these methods to provide application-specific behaviour for these events to update both

 * application state, and UI state.</p>

 * <p>For example to make a GridPanel a cooperating target with the example illustrated in

 * {@link Ext.dd.DragZone DragZone}, the following technique might be used:</p><pre><code>

myGridPanel.on('render', function() {

    myGridPanel.dropZone = new Ext.dd.DropZone(myGridPanel.getView().scroller, {



//      If the mouse is over a grid row, return that node. This is

//      provided as the "target" parameter in all "onNodeXXXX" node event handling functions

        getTargetFromEvent: function(e) {

            return e.getTarget(myGridPanel.getView().rowSelector);

        },



//      On entry into a target node, highlight that node.

        onNodeEnter : function(target, dd, e, data){ 

            Ext.fly(target).addClass('my-row-highlight-class');

        },



//      On exit from a target node, unhighlight that node.

        onNodeOut : function(target, dd, e, data){ 

            Ext.fly(target).removeClass('my-row-highlight-class');

        },



//      While over a target node, return the default drop allowed class which

//      places a "tick" icon into the drag proxy.

        onNodeOver : function(target, dd, e, data){ 

            return Ext.dd.DropZone.prototype.dropAllowed;

        },



//      On node drop we can interrogate the target to find the underlying

//      application object that is the real target of the dragged data.

//      In this case, it is a Record in the GridPanel's Store.

//      We can use the data set up by the DragZone's getDragData method to read

//      any data we decided to attach in the DragZone's getDragData method.

        onNodeDrop : function(target, dd, e, data){

            var rowIndex = myGridPanel.getView().findRowIndex(target);

            var r = myGridPanel.getStore().getAt(rowIndex);

            Ext.Msg.alert('Drop gesture', 'Dropped Record id ' + data.draggedRecord.id +

                ' on Record id ' + r.id);

            return true;

        }

    });

}

</code></pre>

 * See the {@link Ext.dd.DragZone DragZone} documentation for details about building a DragZone which

 * cooperates with this DropZone.

 * @constructor

 * @param {Mixed} el The container element

 * @param {Object} config

 */

Ext.dd.DropZone = function(el, config){

    Ext.dd.DropZone.superclass.constructor.call(this, el, config);

};



Ext.extend(Ext.dd.DropZone, Ext.dd.DropTarget, {

    /**

     * Returns a custom data object associated with the DOM node that is the target of the event.  By default

     * this looks up the event target in the {@link Ext.dd.Registry}, although you can override this method to

     * provide your own custom lookup.

     * @param {Event} e The event

     * @return {Object} data The custom data

     */

    getTargetFromEvent : function(e){

        return Ext.dd.Registry.getTargetFromEvent(e);

    },



    /**

     * Called when the DropZone determines that a {@link Ext.dd.DragSource} has entered a drop node

     * that has either been registered or detected by a configured implementation of {@link #getTargetFromEvent}.

     * This method has no default implementation and should be overridden to provide

     * node-specific processing if necessary.

     * @param {Object} nodeData The custom data associated with the drop node (this is the same value returned from 

     * {@link #getTargetFromEvent} for this node)

     * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone

     * @param {Event} e The event

     * @param {Object} data An object containing arbitrary data supplied by the drag source

     */

    onNodeEnter : function(n, dd, e, data){

        

    },



    /**

     * Called while the DropZone determines that a {@link Ext.dd.DragSource} is over a drop node

     * that has either been registered or detected by a configured implementation of {@link #getTargetFromEvent}.

     * The default implementation returns this.dropNotAllowed, so it should be

     * overridden to provide the proper feedback.

     * @param {Object} nodeData The custom data associated with the drop node (this is the same value returned from

     * {@link #getTargetFromEvent} for this node)

     * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone

     * @param {Event} e The event

     * @param {Object} data An object containing arbitrary data supplied by the drag source

     * @return {String} status The CSS class that communicates the drop status back to the source so that the

     * underlying {@link Ext.dd.StatusProxy} can be updated

     */

    onNodeOver : function(n, dd, e, data){

        return this.dropAllowed;

    },



    /**

     * Called when the DropZone determines that a {@link Ext.dd.DragSource} has been dragged out of

     * the drop node without dropping.  This method has no default implementation and should be overridden to provide

     * node-specific processing if necessary.

     * @param {Object} nodeData The custom data associated with the drop node (this is the same value returned from

     * {@link #getTargetFromEvent} for this node)

     * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone

     * @param {Event} e The event

     * @param {Object} data An object containing arbitrary data supplied by the drag source

     */

    onNodeOut : function(n, dd, e, data){

        

    },



    /**

     * Called when the DropZone determines that a {@link Ext.dd.DragSource} has been dropped onto

     * the drop node.  The default implementation returns false, so it should be overridden to provide the

     * appropriate processing of the drop event and return true so that the drag source's repair action does not run.

     * @param {Object} nodeData The custom data associated with the drop node (this is the same value returned from

     * {@link #getTargetFromEvent} for this node)

     * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone

     * @param {Event} e The event

     * @param {Object} data An object containing arbitrary data supplied by the drag source

     * @return {Boolean} True if the drop was valid, else false

     */

    onNodeDrop : function(n, dd, e, data){

        return false;

    },



    /**

     * Called while the DropZone determines that a {@link Ext.dd.DragSource} is being dragged over it,

     * but not over any of its registered drop nodes.  The default implementation returns this.dropNotAllowed, so

     * it should be overridden to provide the proper feedback if necessary.

     * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone

     * @param {Event} e The event

     * @param {Object} data An object containing arbitrary data supplied by the drag source

     * @return {String} status The CSS class that communicates the drop status back to the source so that the

     * underlying {@link Ext.dd.StatusProxy} can be updated

     */

    onContainerOver : function(dd, e, data){

        return this.dropNotAllowed;

    },



    /**

     * Called when the DropZone determines that a {@link Ext.dd.DragSource} has been dropped on it,

     * but not on any of its registered drop nodes.  The default implementation returns false, so it should be

     * overridden to provide the appropriate processing of the drop event if you need the drop zone itself to

     * be able to accept drops.  It should return true when valid so that the drag source's repair action does not run.

     * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone

     * @param {Event} e The event

     * @param {Object} data An object containing arbitrary data supplied by the drag source

     * @return {Boolean} True if the drop was valid, else false

     */

    onContainerDrop : function(dd, e, data){

        return false;

    },



    /**

     * The function a {@link Ext.dd.DragSource} calls once to notify this drop zone that the source is now over

     * the zone.  The default implementation returns this.dropNotAllowed and expects that only registered drop

     * nodes can process drag drop operations, so if you need the drop zone itself to be able to process drops

     * you should override this method and provide a custom implementation.

     * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone

     * @param {Event} e The event

     * @param {Object} data An object containing arbitrary data supplied by the drag source

     * @return {String} status The CSS class that communicates the drop status back to the source so that the

     * underlying {@link Ext.dd.StatusProxy} can be updated

     */

    notifyEnter : function(dd, e, data){

        return this.dropNotAllowed;

    },



    /**

     * The function a {@link Ext.dd.DragSource} calls continuously while it is being dragged over the drop zone.

     * This method will be called on every mouse movement while the drag source is over the drop zone.

     * It will call {@link #onNodeOver} while the drag source is over a registered node, and will also automatically

     * delegate to the appropriate node-specific methods as necessary when the drag source enters and exits

     * registered nodes ({@link #onNodeEnter}, {@link #onNodeOut}). If the drag source is not currently over a

     * registered node, it will call {@link #onContainerOver}.

     * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone

     * @param {Event} e The event

     * @param {Object} data An object containing arbitrary data supplied by the drag source

     * @return {String} status The CSS class that communicates the drop status back to the source so that the

     * underlying {@link Ext.dd.StatusProxy} can be updated

     */

    notifyOver : function(dd, e, data){

        var n = this.getTargetFromEvent(e);

        if(!n){ // not over valid drop target

            if(this.lastOverNode){

                this.onNodeOut(this.lastOverNode, dd, e, data);

                this.lastOverNode = null;

            }

            return this.onContainerOver(dd, e, data);

        }

        if(this.lastOverNode != n){

            if(this.lastOverNode){

                this.onNodeOut(this.lastOverNode, dd, e, data);

            }

            this.onNodeEnter(n, dd, e, data);

            this.lastOverNode = n;

        }

        return this.onNodeOver(n, dd, e, data);

    },



    /**

     * The function a {@link Ext.dd.DragSource} calls once to notify this drop zone that the source has been dragged

     * out of the zone without dropping.  If the drag source is currently over a registered node, the notification

     * will be delegated to {@link #onNodeOut} for node-specific handling, otherwise it will be ignored.

     * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop target

     * @param {Event} e The event

     * @param {Object} data An object containing arbitrary data supplied by the drag zone

     */

    notifyOut : function(dd, e, data){

        if(this.lastOverNode){

            this.onNodeOut(this.lastOverNode, dd, e, data);

            this.lastOverNode = null;

        }

    },



    /**

     * The function a {@link Ext.dd.DragSource} calls once to notify this drop zone that the dragged item has

     * been dropped on it.  The drag zone will look up the target node based on the event passed in, and if there

     * is a node registered for that event, it will delegate to {@link #onNodeDrop} for node-specific handling,

     * otherwise it will call {@link #onContainerDrop}.

     * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone

     * @param {Event} e The event

     * @param {Object} data An object containing arbitrary data supplied by the drag source

     * @return {Boolean} True if the drop was valid, else false

     */

    notifyDrop : function(dd, e, data){

        if(this.lastOverNode){

            this.onNodeOut(this.lastOverNode, dd, e, data);

            this.lastOverNode = null;

        }

        var n = this.getTargetFromEvent(e);

        return n ?

            this.onNodeDrop(n, dd, e, data) :

            this.onContainerDrop(dd, e, data);

    },



    // private

    triggerCacheRefresh : function(){

        Ext.dd.DDM.refreshCache(this.groups);

    }  

});