/**
 * A simple class that provides the basic implementation needed to make any element a drop target that can have
 * draggable items dropped onto it.  The drop has no effect until an implementation of notifyDrop is provided.
 */
Ext.define('Ext.dd.DropTarget', {
    extend: 'Ext.dd.DDTarget',
    requires: ['Ext.dd.ScrollManager'],

    /**
     * Creates new DropTarget.
     * @param {String/HTMLElement/Ext.Element} el The container element or ID of it.
     * @param {Object} config
     */
    constructor : function(el, config){
        this.el = Ext.get(el);

        Ext.apply(this, config);

        if(this.containerScroll){
            Ext.dd.ScrollManager.register(this.el);
        }

        this.callParent([this.el.dom, this.ddGroup || this.group,
              {isTarget: true}]);
    },

    /**
     * @cfg {String} ddGroup
     * A named drag drop group to which this object belongs.  If a group is specified, then this object will only
     * interact with other drag drop objects in the same group.
     */
    /**
     * @cfg {String} [overClass=""]
     * The CSS class applied to the drop target element while the drag source is over it.
     */
    /**
     * @cfg {String} dropAllowed
     * The CSS class returned to the drag source when drop is allowed.
     */
    dropAllowed : Ext.baseCSSPrefix + 'dd-drop-ok',
    /**
     * @cfg {String} dropNotAllowed
     * The CSS class returned to the drag source when drop is not allowed.
     */
    dropNotAllowed : Ext.baseCSSPrefix + 'dd-drop-nodrop',

    // private
    isTarget : true,

    // private
    isNotifyTarget : true,

    /**
     * The function a {@link Ext.dd.DragSource} calls once to notify this drop target that the source is now over the
     * target.  This default implementation adds the CSS class specified by overClass (if any) to the drop element
     * and returns the dropAllowed config value.  This method should be overridden if drop validation is required.
     * @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 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){
        if(this.overClass){
            this.el.addCls(this.overClass);
        }
        return this.dropAllowed;
    },

    /**
     * The function a {@link Ext.dd.DragSource} calls continuously while it is being dragged over the target.
     * This method will be called on every mouse movement while the drag source is over the drop target.
     * This default implementation simply returns the dropAllowed config value.
     * @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 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){
        return this.dropAllowed;
    },

    /**
     * The function a {@link Ext.dd.DragSource} calls once to notify this drop target that the source has been dragged
     * out of the target without dropping.  This default implementation simply removes the CSS class specified by
     * overClass (if any) from the drop element.
     * @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 source
     */
    notifyOut : function(dd, e, data){
        if(this.overClass){
            this.el.removeCls(this.overClass);
        }
    },

    /**
     * The function a {@link Ext.dd.DragSource} calls once to notify this drop target that the dragged item has
     * been dropped on it.  This method has no default implementation and returns false, so you must provide an
     * implementation that does something to process the drop event and returns true 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 target
     * @param {Event} e The event
     * @param {Object} data An object containing arbitrary data supplied by the drag source
     * @return {Boolean} False if the drop was invalid.
     */
    notifyDrop : function(dd, e, data){
        return false;
    },

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