/**
 * This class provides a container DD instance that allows dragging of multiple child source nodes.
 *
 * This class does not move the drag target nodes, but a proxy element which may contain any DOM structure you wish. The
 * DOM element to show in the proxy is provided by either a provided implementation of {@link #getDragData}, or by
 * registered draggables registered with {@link Ext.dd.Registry}
 *
 * If you wish to provide draggability for an arbitrary number of DOM nodes, each of which represent some application
 * object (For example nodes in a {@link Ext.view.View DataView}) then use of this class is the most efficient way to
 * "activate" those nodes.
 *
 * By default, this class requires that draggable child nodes are registered with {@link Ext.dd.Registry}. However a
 * simpler way to allow a DragZone to manage any number of draggable elements is to configure the DragZone with an
 * implementation of the {@link #getDragData} method 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.event.Event#getTarget getTarget} method to identify a node based on a CSS selector. For example,
 * to make the nodes of a DataView draggable, use the following technique. Knowledge of the use of the DataView is
 * required:
 *
 *     myDataView.on('render', function(v) {
 *         myDataView.dragZone = new Ext.dd.DragZone(v.getEl(), {
 *
 *     //      On receipt of a mousedown event, see if it is within a DataView node.
 *     //      Return a drag data object if so.
 *             getDragData: function(e) {
 *
 *     //          Use the DataView's own itemSelector (a mandatory property) to
 *     //          test if the mousedown is within one of the DataView's nodes.
 *                 var sourceEl = e.getTarget(v.itemSelector, 10);
 *
 *     //          If the mousedown is within a DataView node, clone the node to produce
 *     //          a ddel element for use by the drag proxy. Also add application data
 *     //          to the returned data object.
 *                 if (sourceEl) {
 *                     d = sourceEl.cloneNode(true);
 *                     d.id = Ext.id();
 *                     return {
 *                         ddel: d,
 *                         sourceEl: sourceEl,
 *                         repairXY: Ext.fly(sourceEl).getXY(),
 *                         sourceStore: v.store,
 *                         draggedRecord: v.{@link Ext.view.View#getRecord getRecord}(sourceEl)
 *                     }
 *                 }
 *             },
 *
 *     //      Provide coordinates for the proxy to slide back to on failed drag.
 *     //      This is the original XY coordinates of the draggable element captured
 *     //      in the getDragData method.
 *             getRepairXY: function() {
 *                 return this.dragData.repairXY;
 *             }
 *         });
 *     });
 *
 * See the {@link Ext.dd.DropZone DropZone} documentation for details about building a DropZone which cooperates with
 * this DragZone.
 */
Ext.define('Ext.dd.DragZone', {
    extend: 'Ext.dd.DragSource',

    /**
     * Creates new DragZone.
     * @param {String/HTMLElement/Ext.dom.Element} el The container element or ID of it.
     * @param {Object} config
     */
    constructor : function(el, config){
        var me = this,
            scroll = me.containerScroll;
        
        me.callParent([el, config]);
        if (scroll) {
            el = me.scrollEl || el;
            el = Ext.get(el);
            if (Ext.isObject(scroll)) {
                el.ddScrollConfig = scroll;
            }
            Ext.dd.ScrollManager.register(el);
        }
    },

    /**
     * @cfg {Object/Boolean} containerScroll
     * True to register this container with the Scrollmanager for auto scrolling during drag operations.
     * A {@link Ext.dd.ScrollManager} configuration may also be passed.
     */
    
    /**
     * @cfg {String/HTMLElement/Ext.dom.Element} scrollEl
     * An element to register with the ScrollManager if {@link #containerScroll}
     * is set. Defaults to the drag element.
     */

    /**
     * Called when a mousedown occurs in this container. Looks in {@link Ext.dd.Registry} for a valid target to drag
     * based on the mouse down. Override this method to provide your own lookup logic (e.g. finding a child by class
     * name). Make sure your returned object has a "ddel" attribute (with an HTML Element) for other functions to work.
     * @param {Event} e The mouse down event
     * @return {Object} The dragData
     */
    getDragData : function(e){
        return Ext.dd.Registry.getHandleFromEvent(e);
    },

    /**
     * Called once drag threshold has been reached to initialize the proxy element. By default, it clones the
     * this.dragData.ddel
     * @param {Number} x The x position of the click on the dragged object
     * @param {Number} y The y position of the click on the dragged object
     * @return {Boolean} true to continue the drag, false to cancel
     * @template
     */
    onInitDrag : function(x, y){
        this.proxy.update(this.dragData.ddel.cloneNode(true));
        this.onStartDrag(x, y);
        return true;
    },

    /**
     * Called before a repair of an invalid drop to get the XY to animate to. By default returns the XY of
     * this.dragData.ddel
     * @param {Event} e The mouse up event
     * @return {Number[]} The xy location (e.g. `[100, 200]`)
     * @template
     */
    getRepairXY : function(e){
        return Ext.fly(this.dragData.ddel).getXY();
    },

    destroy : function(){
        this.callParent();
        if (this.containerScroll) {
            Ext.dd.ScrollManager.unregister(this.scrollEl || this.el);
        }
    }
});
