/**
 * 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.dom.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 {Boolean} containerScroll
     * True to register this container with the ScrollManager for auto scrolling during
     * drag operations.
     */
    containerScroll: false,

    /**
     * @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
     * @template
     */
    notifyEnter: function(source, 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
     * @template
     */
    notifyOver: function(source, 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
     * @template
     */
    notifyOut: function(source, 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 removes any `overClass` 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.
     *
     * You should `callParent` from an override of this method to ensure proper cleanup is
     * performed.
     *
     * @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.
     * @template
     */
    notifyDrop: function(source, e, data) {
        if (this.overClass) {
            this.el.removeCls(this.overClass);
        }

        return false;
    },

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

        this.callParent();
    }
});