/*
 * This is a derivative of the similarly named class in the YUI Library.
 * The original license:
 * Copyright (c) 2006, Yahoo! Inc. All rights reserved.
 * Code licensed under the BSD License:
 * http://developer.yahoo.net/yui/license.txt
 */


/**
 * DragDropManager is a singleton that tracks the element interaction for
 * all DragDrop items in the window.  Generally, you will not call
 * this class directly, but it does have helper methods that could
 * be useful in your DragDrop implementations.
 */
Ext.define('Ext.dd.DragDropManager', {
    singleton: true,

    requires: ['Ext.util.Region'],

    uses: ['Ext.tip.QuickTipManager'],

    // shorter ClassName, to save bytes and use internally
    alternateClassName: ['Ext.dd.DragDropMgr', 'Ext.dd.DDM'],

    /**
     * @property {String[]} ids
     * Two dimensional Array of registered DragDrop objects.  The first
     * dimension is the DragDrop item group, the second the DragDrop
     * object.
     * @private
     */
    ids: {},

    /**
     * @property {String[]} handleIds
     * Array of element ids defined as drag handles.  Used to determine
     * if the element that generated the mousedown event is actually the
     * handle and not the html element itself.
     * @private
     */
    handleIds: {},

    /**
     * @property {Ext.dd.DragDrop} dragCurrent
     * the DragDrop object that is currently being dragged
     * @private
     */
    dragCurrent: null,

    /**
     * @property {Ext.dd.DragDrop[]} dragOvers
     * the DragDrop object(s) that are being hovered over
     * @private
     */
    dragOvers: {},

    /**
     * @property {Number} deltaX
     * the X distance between the cursor and the object being dragged
     * @private
     */
    deltaX: 0,

    /**
     * @property {Number} deltaY
     * the Y distance between the cursor and the object being dragged
     * @private
     */
    deltaY: 0,

    /**
     * @property {Boolean} preventDefault
     * Flag to determine if we should prevent the default behavior of the
     * events we define. By default this is true, but this can be set to
     * false if you need the default behavior (not recommended)
     */
    preventDefault: true,

    /**
     * @property {Boolean} stopPropagation
     * Flag to determine if we should stop the propagation of the events
     * we generate. This is true by default but you may want to set it to
     * false if the html element contains other features that require the
     * mouse click.
     */
    stopPropagation: true,

    /**
     * Internal flag that is set to true when drag and drop has been
     * intialized
     * @property initialized
     * @private
     */
    initialized: false,

    /**
     * All drag and drop can be disabled.
     * @property locked
     * @private
     */
    locked: false,

    /**
     * Called the first time an element is registered.
     * @private
     */
    init: function() {
        this.initialized = true;
    },

    /**
     * @property {Number} POINT
     * In point mode, drag and drop interaction is defined by the
     * location of the cursor during the drag/drop
     */
    POINT: 0,

    /**
     * @property {Number} INTERSECT
     * In intersect mode, drag and drop interaction is defined by the
     * overlap of two or more drag and drop objects.
     */
    INTERSECT: 1,

    /**
     * @property {Number} mode
     * The current drag and drop mode.  Default: POINT
     */
    mode: 0,

    /**
     * @property {Boolean} [notifyOccluded=false]
     * This config is only provided to provide old, usually unwanted drag/drop behaviour.
     *
     * From ExtJS 4.1.0 onwards, when drop targets are contained in floating, absolutely positioned elements
     * such as in {@link Ext.window.Window Windows}, which may overlap each other, `over` and `drop` events
     * are only delivered to the topmost drop target at the mouse position.
     *
     * If all targets below that in zIndex order should also receive notifications, set
     * `notifyOccluded` to `true`.
     */
    notifyOccluded: false,

    /**
     * @property {String} dragCls
     * @readonly
     * Class to add to the {@link Ext.dd.DragDrop#getDragEl dragged element} of a DragDrop instance.
     */
    dragCls: Ext.baseCSSPrefix + 'dd-drag-current',

    /**
     * Runs method on all drag and drop objects
     * @private
     */
    _execOnAll: function(sMethod, args) {
        var ids = this.ids,
            i, j, oDD, item;
            
        for (i in ids) {
            if (ids.hasOwnProperty(i)) {
                item = ids[i];
                for (j in item) {
                    if (item.hasOwnProperty(j)) {
                        oDD = item[j];
                        if (! this.isTypeOfDD(oDD)) {
                            continue;
                        }
                        oDD[sMethod].apply(oDD, args);
                    }
                }
            }
        }
    },

    /**
     * Drag and drop initialization.  Sets up the global event handlers
     * @private
     */
    addListeners: function() {
        var me = this;

        me.init();

        Ext.getDoc().on({
            //TODO delay: 1, // delay to let other mouseup events occur before us
            mouseup: me.handleMouseUp,

            // Mousemove events do not need to be captured because they do not contend
            // with scroll events - they're only processed when a drag has begun.
            // Capturing was causing https://sencha.jira.com/browse/EXTJS-13952
            mousemove: {
                fn: me.handleMouseMove,
                capture: false
            },
            dragstart: me.preventDrag,
            drag: me.preventDrag,
            dragend: me.preventDrag,
            capture: true,
            scope: me
        });
        Ext.getWin().on({
            unload: me._onUnload,
            resize: me._onResize,
            scope: me
        });
    },

    // if a drag/drop operation is currently underway, this method stops the dragstart,
    // drag, and dragend events from propagating down to any other listeners, e.g. scrollers
    preventDrag: function(e) {
        if (this.isMouseDown) {
            e.stopPropagation();
        }
    },

    /**
     * Reset constraints on all drag and drop objs
     * @private
     */
    _onResize: function(e) {
        this._execOnAll("resetConstraints", []);
    },

    /**
     * Lock all drag and drop functionality
     */
    lock: function() { this.locked = true; },

    /**
     * Unlock all drag and drop functionality
     */
    unlock: function() { this.locked = false; },

    /**
     * Is drag and drop locked?
     * @return {Boolean} True if drag and drop is locked, false otherwise.
     */
    isLocked: function() { return this.locked; },

    /**
     * @property {Object} locationCache
     * Location cache that is set for all drag drop objects when a drag is
     * initiated, cleared when the drag is finished.
     * @private
     */
    locationCache: {},

    /**
     * @property {Boolean} useCache
     * Set useCache to false if you want to force object the lookup of each
     * drag and drop linked element constantly during a drag.
     */
    useCache: true,

    /**
     * @property {Number} clickPixelThresh
     * The number of pixels that the mouse needs to move after the
     * mousedown before the drag is initiated.  Default=8;
     * defaults to the same value used in the LongPress gesture so that drag cannot be
     * initiated if there is a possible pending longpress
     */
    clickPixelThresh: 8,

    /**
     * @property {Boolean} dragThreshMet
     * Flag that indicates that either the drag pixel threshold or the
     * mousdown time threshold has been met
     * @private
     */
    dragThreshMet: false,

    /**
     * @property {Object} clickTimeout
     * Timeout used for the click time threshold
     * @private
     */
    clickTimeout: null,

    /**
     * @property {Number} startX
     * The X position of the mousedown event stored for later use when a
     * drag threshold is met.
     * @private
     */
    startX: 0,

    /**
     * @property {Number} startY
     * The Y position of the mousedown event stored for later use when a
     * drag threshold is met.
     * @private
     */
    startY: 0,

    /**
     * Each DragDrop instance must be registered with the DragDropManager.
     * This is executed in DragDrop.init()
     * @param {Ext.dd.DragDrop} oDD the DragDrop object to register
     * @param {String} sGroup the name of the group this element belongs to
     */
    regDragDrop: function(oDD, sGroup) {
        if (!this.initialized) { this.init(); }

        if (!this.ids[sGroup]) {
            this.ids[sGroup] = {};
        }
        this.ids[sGroup][oDD.id] = oDD;
    },

    /**
     * Removes the supplied dd instance from the supplied group. Executed
     * by DragDrop.removeFromGroup, so don't call this function directly.
     * @private
     */
    removeDDFromGroup: function(oDD, sGroup) {
        if (!this.ids[sGroup]) {
            this.ids[sGroup] = {};
        }

        var obj = this.ids[sGroup];
        if (obj && obj[oDD.id]) {
            delete obj[oDD.id];
        }
    },

    /**
     * Unregisters a drag and drop item.  This is executed in
     * DragDrop.unreg, use that method instead of calling this directly.
     * @private
     */
    _remove: function(oDD, clearGroup) {
        var me = this,
            ids = me.ids,
            groups = oDD.groups,
            g;

        // If we're clearing everything, we'll just end up wiping
        // this.ids & this.handleIds
        if (me.clearingAll) {
            return;
        }

        if (me.dragCurrent === oDD) {
            me.dragCurrent = null;
        }

        for (g in groups) {
            if (groups.hasOwnProperty(g)) {
                if (clearGroup) {
                    delete ids[g];
                } else if (ids[g]) {
                    delete ids[g][oDD.id];
                }
            }
        }
        delete me.handleIds[oDD.id];
    },

    /**
     * Each DragDrop handle element must be registered.  This is done
     * automatically when executing DragDrop.setHandleElId()
     * @param {String} sDDId the DragDrop id this element is a handle for
     * @param {String} sHandleId the id of the element that is the drag
     * handle
     */
    regHandle: function(sDDId, sHandleId) {
        if (!this.handleIds[sDDId]) {
            this.handleIds[sDDId] = {};
        }
        this.handleIds[sDDId][sHandleId] = sHandleId;
    },

    /**
     * Utility function to determine if a given element has been
     * registered as a drag drop item.
     * @param {String} id the element id to check
     * @return {Boolean} true if this element is a DragDrop item,
     * false otherwise
     */
    isDragDrop: function(id) {
        return ( this.getDDById(id) ) ? true : false;
    },

    /**
     * Returns the drag and drop instances that are in all groups the
     * passed in instance belongs to.
     * @param {Ext.dd.DragDrop} p_oDD the obj to get related data for
     * @param {Boolean} bTargetsOnly if true, only return targetable objs
     * @return {Ext.dd.DragDrop[]} the related instances
     */
    getRelated: function(p_oDD, bTargetsOnly) {
        var oDDs = [],
            i, j, dd;
        for (i in p_oDD.groups) {
            for (j in this.ids[i]) {
                dd = this.ids[i][j];
                if (! this.isTypeOfDD(dd)) {
                    continue;
                }
                if (!bTargetsOnly || dd.isTarget) {
                    oDDs[oDDs.length] = dd;
                }
            }
        }

        return oDDs;
    },

    /**
     * Returns true if the specified dd target is a legal target for
     * the specifice drag obj
     * @param {Ext.dd.DragDrop} oDD the drag obj
     * @param {Ext.dd.DragDrop} oTargetDD the target
     * @return {Boolean} true if the target is a legal target for the
     * dd obj
     */
    isLegalTarget: function (oDD, oTargetDD) {
        var targets = this.getRelated(oDD, true),
            i, len;
        for (i=0, len=targets.length;i<len;++i) {
            if (targets[i].id == oTargetDD.id) {
                return true;
            }
        }

        return false;
    },

    /**
     * My goal is to be able to transparently determine if an object is
     * typeof DragDrop, and the exact subclass of DragDrop.  typeof
     * returns "object", oDD.constructor.toString() always returns
     * "DragDrop" and not the name of the subclass.  So for now it just
     * evaluates a well-known variable in DragDrop.
     * @param {Object} the object to evaluate
     * @return {Boolean} true if typeof oDD = DragDrop
     */
    isTypeOfDD: function (oDD) {
        return (oDD && oDD.__ygDragDrop);
    },

    /**
     * Utility function to determine if a given element has been
     * registered as a drag drop handle for the given Drag Drop object.
     * @param {String} id the element id to check
     * @return {Boolean} true if this element is a DragDrop handle, false
     * otherwise
     */
    isHandle: function(sDDId, sHandleId) {
        return ( this.handleIds[sDDId] &&
                        this.handleIds[sDDId][sHandleId] );
    },

    /**
     * Returns the DragDrop instance for a given id
     * @param {String} id the id of the DragDrop object
     * @return {Ext.dd.DragDrop} the drag drop object, null if it is not found
     */
    getDDById: function(id, force) {
        var i, dd;
        for (i in this.ids) {
            dd = this.ids[i][id];
            if (dd instanceof Ext.dd.DDTarget || force) {
                return dd;
            }
        }
        return null;
    },

    /**
     * Fired after a registered DragDrop object gets the mousedown event.
     * Sets up the events required to track the object being dragged
     * @param {Event} e the event
     * @param {Ext.dd.DragDrop} oDD the DragDrop object being dragged
     * @private
     */
    handleMouseDown: function(e, oDD) {
        var me = this,
            xy, el;

        me.isMouseDown = true;

        if (Ext.quickTipsActive){
            Ext.tip.QuickTipManager.ddDisable();
        }
        me.currentPoint = e.getPoint();
        if (me.dragCurrent){
            // the original browser mouseup wasn't handled (e.g. outside FF browser window)
            // so clean up first to avoid breaking the next drag
            me.handleMouseUp(e);
        }

        me.mousedownEvent = e;
        me.currentTarget = e.getTarget();
        me.dragCurrent = oDD;

        el = oDD.getEl();

        //<feature legacyBrowser>
        // We use this to handle an issue where a mouseup will not be detected
        // if the mouseup event happens outside of the browser window. When the
        // mouse comes back, any drag will still be active
        // http://msdn.microsoft.com/en-us/library/ms537630(VS.85).aspx
        Ext.fly(el).setCapture();
        //</feature>

        // track start position
        xy = e.getXY();
        me.startX = xy[0];
        me.startY = xy[1];

        // Track the distance moved.
        me.offsetX = me.offsetY = 0;

        me.deltaX = me.startX - el.offsetLeft;
        me.deltaY = me.startY - el.offsetTop;

        me.dragThreshMet = false;
    },

    /**
     * Fired when either the drag pixel threshold or the mousedown hold
     * time threshold has been met.
     * @param {Number} x the X position of the original mousedown
     * @param {Number} y the Y position of the original mousedown
     */
    startDrag: function(x, y) {
        var me = this,
            current = me.dragCurrent,
            dragEl;

        clearTimeout(me.clickTimeout);
        if (current) {
            current.b4StartDrag(x, y);
            current.startDrag(x, y);
            dragEl = current.getDragEl();

            // Add current drag class to dragged element
            if (dragEl) {
                Ext.fly(dragEl).addCls(me.dragCls);
            }
        }
        me.dragThreshMet = true;
    },

    /**
     * Internal function to handle the mouseup event.  Will be invoked
     * from the context of the document.
     * @param {Event} e the event
     * @private
     */
    handleMouseUp: function(e) {
        var me = this;

        me.isMouseDown = false;

        if (Ext.quickTipsActive){
            Ext.tip.QuickTipManager.ddEnable();
        }
        if (!me.dragCurrent) {
            return;
        }

        // See setCapture call in handleMouseDown
        if (Ext.isIE && document.releaseCapture) {
            document.releaseCapture();
        }

        clearTimeout(me.clickTimeout);

        if (me.dragThreshMet) {
            me.fireEvents(e, true);
        }

        me.stopDrag(e);

        me.stopEvent(e);
    },

    /**
     * Utility to stop event propagation and event default, if these
     * features are turned on.
     * @param {Event} e the event as returned by this.getEvent()
     */
    stopEvent: function(e) {
        if (this.stopPropagation) {
            e.stopPropagation();
        }

        if (this.preventDefault) {
            e.preventDefault();
        }
    },

    /**
     * Internal function to clean up event handlers after the drag
     * operation is complete
     * @param {Event} e the event
     * @private
     */
    stopDrag: function(e) {
        var me = this,
            current = me.dragCurrent,
            dragEl;

        // Fire the drag end event for the item that was dragged
        if (current) {
            if (me.dragThreshMet) {

                // Remove current drag class from dragged element
                dragEl = current.getDragEl();
                if (dragEl) {
                    Ext.fly(dragEl).removeCls(me.dragCls);
                }

                current.b4EndDrag(e);
                current.endDrag(e);
            }

            me.dragCurrent.onMouseUp(e);
        }

        me.dragCurrent = null;
        me.dragOvers = {};
    },

    /**
     * Internal function to handle the mousemove event.  Will be invoked
     * from the context of the html element.
     *
     * TODO: figure out what we can do about mouse events lost when the
     * user drags objects beyond the window boundary.  Currently we can
     * detect this in internet explorer by verifying that the mouse is
     * down during the mousemove event.  Firefox doesn't give us the
     * button state on the mousemove event.
     *
     * @param {Event} e the event
     * @private
     */
    handleMouseMove: function(e) {
        var me = this,
            current = me.dragCurrent,
            point = me.currentPoint = e.getPoint(),
            currentX = point.x,
            currentY = point.y,
            diffX,
            diffY;

        me.offsetX = currentX - me.startX;
        me.offsetY = currentY - me.startY;

        if (!current) {
            return true;
        }

        if (!me.dragThreshMet) {
            diffX = Math.abs(me.offsetX);
            diffY = Math.abs(me.offsetY);
            if (diffX > me.clickPixelThresh || diffY > me.clickPixelThresh) {
                me.startDrag(me.startX, me.startY);
            }
        }

        if (me.dragThreshMet) {
            current.b4Drag(e);
            current.onDrag(e);
            if (!current.moveOnly) {
                me.fireEvents(e, false);
            }
        }

        me.stopEvent(e);

        return true;
    },

    /**
     * Iterates over all of the DragDrop elements to find ones we are
     * hovering over or dropping on
     * @param {Event} e the event
     * @param {Boolean} isDrop is this a drop op or a mouseover op?
     * @private
     */
    fireEvents: function(e, isDrop) {
        var me = this,
            isTouch = Ext.supports.Touch,
            dragCurrent = me.dragCurrent,
            mousePoint = me.currentPoint,
            currentX = mousePoint.x,
            currentY = mousePoint.y,
            dragEl,
            oldDragElTop,
            overTarget,
            overTargetEl,
            allTargets = [],
            oldOvers  = [],  // cache the previous dragOver array
            outEvts   = [],
            overEvts  = [],
            dropEvts  = [],
            enterEvts = [],
            needsSort,
            i,
            len,
            sGroup,
            zoom = isTouch ? document.documentElement.clientWidth / window.innerWidth : 1,
            overDragEl;

        // If the user did the mouse up outside of the window, we could
        // get here even though we have ended the drag.
        if (!dragCurrent || dragCurrent.isLocked()) {
            return;
        }

        // Touch's delegated event system means that the mousemove (which will be a touchmove really) target will be the element that the listener was requested for, NOT the actual lowest
        // level target . So we have to use elementFromPoint to find the target which we are currently over.
        //
        // If we need to use the current mousemove target to find the over el,
        // but pointer-events is not supported, AND the delta position does not place the mouse outside of the dragEl,
        // temporarily move the dragEl away, and fake the mousemove target by using document.elementFromPoint
        // while it's out of the way.
        // The pointer events implementation is bugged in IE9/10 and opera, so fallback even if they report that they support it.
        // IE8m do not support it so they will auto fall back
        overDragEl = !(dragCurrent.deltaX < 0 || dragCurrent.deltaY < 0);
        if (isTouch || (!me.notifyOccluded && (!Ext.supports.CSSPointerEvents || Ext.isIE10m || Ext.isOpera) && overDragEl)) {
            dragEl = dragCurrent.getDragEl();
            // Temporarily hide the dragEl instead of moving it off the page. Moving the el off the page can cause
            // problems when in an iframe with IE8 standards. See EXTJSIV-11728.
            if (overDragEl) {
                dragEl.style.visibility = 'hidden';
            }
            e.target = document.elementFromPoint(currentX / zoom, currentY/ zoom);
            if (overDragEl) {
                dragEl.style.visibility = 'visible';
            }
        }

        // Check to see if the object(s) we were hovering over is no longer
        // being hovered over so we can fire the onDragOut event
        for (i in me.dragOvers) {

            overTarget = me.dragOvers[i];
            delete me.dragOvers[i];

            // Check to make sure that the component hasn't been destroyed in the middle of a drag operation.
            if (!me.isTypeOfDD(overTarget) || overTarget.isDestroyed) {
                continue;
            }

            // If notifyOccluded set, we use mouse position
            if (me.notifyOccluded) {
                if (!this.isOverTarget(mousePoint, overTarget, me.mode)) {
                    outEvts.push(overTarget);
                }
            }
            // Otherwise we use event source of the mousemove event
            else {
                if (!e.within(overTarget.getEl())) {
                    outEvts.push(overTarget);
                }
            }

            oldOvers[i] = true;
        }

        // Collect all targets which are members of the same ddGoups that the dragCurrent is a member of, and which may recieve mouseover and drop notifications.
        // This is preparatory to seeing which one(s) we are currently over
        // Begin by iterating through the ddGroups of which the dragCurrent is a member
        for (sGroup in dragCurrent.groups) {

            if ("string" != typeof sGroup) {
                continue;
            }

            // Loop over the registered members of each group, testing each as a potential target
            for (i in me.ids[sGroup]) {
                overTarget = me.ids[sGroup][i];

                // The target is valid if it is a DD type
                // And it's got a DOM element
                // And it's configured to be a drop target
                // And it's not locked
                // And the DOM element is fully visible with no hidden ancestors
                // And it's either not the dragCurrent, or, if it is, tha dragCurrent is configured to not ignore itself.
                if (me.isTypeOfDD(overTarget) &&
                    (overTargetEl = overTarget.getEl()) &&
                    (overTarget.isTarget) &&
                    (!overTarget.isLocked()) &&
                    (Ext.fly(overTargetEl).isVisible(true)) &&
                    ((overTarget != dragCurrent) || (dragCurrent.ignoreSelf === false))) {

                    // If notifyOccluded set, we use mouse position
                    if (me.notifyOccluded) {

                        // Only sort by zIndex if there were some which had a floating zIndex value
                        if ((overTarget.zIndex = me.getZIndex(overTargetEl)) !== -1) {
                            needsSort = true;
                        }
                        allTargets.push(overTarget);
                    }
                    // Otherwise we use event source of the mousemove event
                    else {
                        if (e.within(overTarget.getEl())) {
                            allTargets.push(overTarget);
                            break;
                        }
                    }
                }
            }
        }

        // If there were floating targets, sort the highest zIndex to the top
        if (needsSort) {
            Ext.Array.sort(allTargets, me.byZIndex);
        }

        // Loop through possible targets, notifying the one(s) we are over.
        // Usually we only deliver events to the topmost.
        for (i = 0, len = allTargets.length; i < len; i++) {
            overTarget = allTargets[i];

            // If we are over the overTarget, queue it up to recieve an event of whatever type we are handling
            if (me.isOverTarget(mousePoint, overTarget, me.mode)) {
                // look for drop interactions
                if (isDrop) {
                    dropEvts.push( overTarget );
                // look for drag enter and drag over interactions
                } else {

                    // initial drag over: dragEnter fires
                    if (!oldOvers[overTarget.id]) {
                        enterEvts.push( overTarget );
                    // subsequent drag overs: dragOver fires
                    } else {
                        overEvts.push( overTarget );
                    }
                    me.dragOvers[overTarget.id] = overTarget;
                }

                // Unless this DragDropManager has been explicitly configured to deliver events to multiple targets, then we are done.
                if (!me.notifyOccluded) {
                    break;
                }
            }
        }

        if (me.mode) {
            if (outEvts.length) {
                dragCurrent.b4DragOut(e, outEvts);
                dragCurrent.onDragOut(e, outEvts);
            }

            if (enterEvts.length) {
                dragCurrent.onDragEnter(e, enterEvts);
            }

            if (overEvts.length) {
                dragCurrent.b4DragOver(e, overEvts);
                dragCurrent.onDragOver(e, overEvts);
            }

            if (dropEvts.length) {
                dragCurrent.b4DragDrop(e, dropEvts);
                dragCurrent.onDragDrop(e, dropEvts);
            }

        } else {
            // fire dragout events
            for (i=0, len=outEvts.length; i<len; ++i) {
                dragCurrent.b4DragOut(e, outEvts[i].id);
                dragCurrent.onDragOut(e, outEvts[i].id);
            }

            // fire enter events
            for (i=0,len=enterEvts.length; i<len; ++i) {
                // dc.b4DragEnter(e, oDD.id);
                dragCurrent.onDragEnter(e, enterEvts[i].id);
            }

            // fire over events
            for (i=0,len=overEvts.length; i<len; ++i) {
                dragCurrent.b4DragOver(e, overEvts[i].id);
                dragCurrent.onDragOver(e, overEvts[i].id);
            }

            // fire drop events
            for (i=0, len=dropEvts.length; i<len; ++i) {
                dragCurrent.b4DragDrop(e, dropEvts[i].id);
                dragCurrent.onDragDrop(e, dropEvts[i].id);
            }

        }

        // notify about a drop that did not find a target
        if (isDrop && !dropEvts.length) {
            dragCurrent.onInvalidDrop(e);
        }

    },

    /**
     * @private
     * Collects the z-index of the passed element, looking up the parentNode axis to find an absolutely positioned ancestor
     * which is able to yield a z-index. If found to be not absolutely positionedm returns -1.
     *
     * This is used when sorting potential drop targets into z-index order so that only the topmost receives `over` and `drop` events.
     *
     * @return {Number} The z-index of the element, or of its topmost absolutely positioned ancestor. Returns -1 if the element is not
     * absolutely positioned.
     */
    getZIndex: function(element) {
        var body = document.body,
            z,
            zIndex = -1;

        element = Ext.getDom(element);
        while (element !== body) {
            if (!isNaN(z = Number(Ext.fly(element).getStyle('zIndex')))) {
                zIndex = z;
            }
            element = element.parentNode;
        }
        return zIndex;
    },

    /**
     * @private
     * Utility method to pass to {@link Ext.Array#sort} when sorting potential drop targets by z-index.
     */
    byZIndex: function(d1, d2) {
        return d1.zIndex < d2.zIndex;
    },

    /**
     * Helper function for getting the best match from the list of drag
     * and drop objects returned by the drag and drop events when we are
     * in INTERSECT mode.  It returns either the first object that the
     * cursor is over, or the object that has the greatest overlap with
     * the dragged element.
     * @param  {Ext.dd.DragDrop[]} dds The array of drag and drop objects
     * targeted
     * @return {Ext.dd.DragDrop}       The best single match
     */
    getBestMatch: function(dds) {
        var winner = null,
            len = dds.length,
            i, dd;
        // Return null if the input is not what we expect
        //if (!dds || !dds.length || dds.length == 0) {
           // winner = null;
        // If there is only one item, it wins
        //} else if (dds.length == 1) {


        if (len == 1) {
            winner = dds[0];
        } else {
            // Loop through the targeted items
            for (i=0; i<len; ++i) {
                dd = dds[i];
                // If the cursor is over the object, it wins.  If the
                // cursor is over multiple matches, the first one we come
                // to wins.
                if (dd.cursorIsOver) {
                    winner = dd;
                    break;
                // Otherwise the object with the most overlap wins
                } else {
                    if (!winner ||
                        winner.overlap.getArea() < dd.overlap.getArea()) {
                        winner = dd;
                    }
                }
            }
        }

        return winner;
    },

    /**
     * Refreshes the cache of the top-left and bottom-right points of the
     * drag and drop objects in the specified group(s).  This is in the
     * format that is stored in the drag and drop instance, so typical
     * usage is:
     *
     *     Ext.dd.DragDropManager.refreshCache(ddinstance.groups);
     *
     * Alternatively:
     *
     *     Ext.dd.DragDropManager.refreshCache({group1:true, group2:true});
     *
     * TODO: this really should be an indexed array.  Alternatively this
     * method could accept both.
     *
     * @param {Object} groups an associative array of groups to refresh
     */
    refreshCache: function(groups) {
        var sGroup, i, oDD, loc;
        for (sGroup in groups) {
            if ("string" != typeof sGroup) {
                continue;
            }
            for (i in this.ids[sGroup]) {
                oDD = this.ids[sGroup][i];

                if (this.isTypeOfDD(oDD)) {
                // if (this.isTypeOfDD(oDD) && oDD.isTarget) {
                    loc = this.getLocation(oDD);
                    if (loc) {
                        this.locationCache[oDD.id] = loc;
                    } else {
                        delete this.locationCache[oDD.id];
                        // this will unregister the drag and drop object if
                        // the element is not in a usable state
                        // oDD.unreg();
                    }
                }
            }
        }
    },

    /**
     * This checks to make sure an element exists and is in the DOM.  The
     * main purpose is to handle cases where innerHTML is used to remove
     * drag and drop objects from the DOM.  IE provides an 'unspecified
     * error' when trying to access the offsetParent of such an element
     * @param {HTMLElement} el the element to check
     * @return {Boolean} true if the element looks usable
     */
    verifyEl: function(el) {
        if (el) {
            var parent;
            if(Ext.isIE){
                try{
                    parent = el.offsetParent;
                }catch(e){}
            }else{
                parent = el.offsetParent;
            }
            if (parent) {
                return true;
            }
        }

        return false;
    },

    /**
     * Returns a Region object containing the drag and drop element's position
     * and size, including the padding configured for it
     * @param {Ext.dd.DragDrop} oDD the drag and drop object to get the location for.
     * @return {Ext.util.Region} a Region object representing the total area
     * the element occupies, including any padding
     * the instance is configured for.
     */
    getLocation: function(oDD) {
        if (! this.isTypeOfDD(oDD)) {
            return null;
        }

        //delegate getLocation method to the
        //drag and drop target.
        if (oDD.getRegion) {
            return oDD.getRegion();
        }

        var el = oDD.getEl(), pos, x1, x2, y1, y2, t, r, b, l;

        try {
            pos= Ext.fly(el).getXY();
        } catch (e) { }

        if (!pos) {
            return null;
        }

        x1 = pos[0];
        x2 = x1 + el.offsetWidth;
        y1 = pos[1];
        y2 = y1 + el.offsetHeight;

        t = y1 - oDD.padding[0];
        r = x2 + oDD.padding[1];
        b = y2 + oDD.padding[2];
        l = x1 - oDD.padding[3];

        return new Ext.util.Region(t, r, b, l);
    },

    /**
     * Checks the cursor location to see if it over the target
     * @param {Ext.util.Point} pt The point to evaluate
     * @param {Ext.dd.DragDrop} oTarget the DragDrop object we are inspecting
     * @return {Boolean} true if the mouse is over the target
     * @private
     */
    isOverTarget: function(pt, oTarget, intersect) {
        // use cache if available
        var loc = this.locationCache[oTarget.id],
            dc,
            pos,
            el,
            curRegion,
            overlap;

        if (!loc || !this.useCache) {
            loc = this.getLocation(oTarget);
            this.locationCache[oTarget.id] = loc;
        }

        if (!loc) {
            return false;
        }

        oTarget.cursorIsOver = loc.contains( pt );

        // DragDrop is using this as a sanity check for the initial mousedown
        // in this case we are done.  In POINT mode, if the drag obj has no
        // contraints, we are also done. Otherwise we need to evaluate the
        // location of the target as related to the actual location of the
        // dragged element.
        dc = this.dragCurrent;
        if (!dc || !dc.getTargetCoord ||
                (!intersect && !dc.constrainX && !dc.constrainY)) {
            return oTarget.cursorIsOver;
        }

        oTarget.overlap = null;

        // Get the current location of the drag element, this is the
        // location of the mouse event less the delta that represents
        // where the original mousedown happened on the element.  We
        // need to consider constraints and ticks as well.
        pos = dc.getTargetCoord(pt.x, pt.y);

        el = dc.getDragEl();
        curRegion = new Ext.util.Region(pos.y,
            pos.x + el.offsetWidth,
            pos.y + el.offsetHeight,
            pos.x
        );

        overlap = curRegion.intersect(loc);

        if (overlap) {
            oTarget.overlap = overlap;
            return (intersect) ? true : oTarget.cursorIsOver;
        } else {
            return false;
        }
    },

    /**
     * unload event handler
     * @private
     */
    _onUnload: function(e, me) {
        Ext.dd.DragDropManager.unregAll();
    },

    /**
     * Cleans up the drag and drop events and objects.
     * @private
     */
    unregAll: function() {
        var me = this,
            cache = me.elementCache,
            i;
            
        if (me.dragCurrent) {
            me.stopDrag();
            me.dragCurrent = null;
        }

        me.clearingAll = true;
        me._execOnAll("unreg", []);
        delete me.clearingAll;

        for (i in cache) {
            delete cache[i];
        }

        me.elementCache = {};
        me.ids = {};
        me.handleIds = {};
    },

    /**
     * @property {Object} elementCache
     * A cache of DOM elements
     * @private
     */
    elementCache: {},

    /**
     * Get the wrapper for the DOM element specified
     * @param {String} id the id of the element to get
     * @return {Ext.dd.DragDropManager.ElementWrapper} the wrapped element
     * @private
     * @deprecated This wrapper isn't that useful
     */
    getElWrapper: function(id) {
        var oWrapper = this.elementCache[id];
        if (!oWrapper || !oWrapper.el) {
            oWrapper = this.elementCache[id] =
                new this.ElementWrapper(Ext.getDom(id));
        }
        return oWrapper;
    },

    /**
     * Returns the actual DOM element
     * @param {String} id the id of the elment to get
     * @return {Object} The element
     * @deprecated use Ext.lib.Ext.getDom instead
     */
    getElement: function(id) {
        return Ext.getDom(id);
    },

    /**
     * Returns the style property for the DOM element (i.e.,
     * document.getElById(id).style)
     * @param {String} id the id of the elment to get
     * @return {Object} The style property of the element
     */
    getCss: function(id) {
        var el = Ext.getDom(id);
        return (el) ? el.style : null;
    },

    /**
     * @class Ext.dd.DragDropManager.ElementWrapper
     * Deprecated inner class for cached elements.
     * @private
     * @deprecated This wrapper isn't that useful
     */
    ElementWrapper: function(el) {
        /** The element */
        this.el = el || null;
        /** The element id */
        this.id = this.el && el.id;
        /** A reference to the style property */
        this.css = this.el && el.style;
    },

    // Continue class docs
    /** @class Ext.dd.DragDropElement */

    /**
     * Returns the X position of an html element
     * @param {HTMLElement} el the element for which to get the position
     * @return {Number} the X coordinate
     */
    getPosX: function(el) {
        return Ext.fly(el).getX();
    },

    /**
     * Returns the Y position of an html element
     * @param {HTMLElement} el the element for which to get the position
     * @return {Number} the Y coordinate
     */
    getPosY: function(el) {
        return Ext.fly(el).getY();
    },

    /**
     * Swap two nodes.  In IE, we use the native method, for others we
     * emulate the IE behavior
     * @param {HTMLElement} n1 the first node to swap
     * @param {HTMLElement} n2 the other node to swap
     */
    swapNode: function(n1, n2) {
        if (n1.swapNode) {
            n1.swapNode(n2);
        } else {
            var p = n2.parentNode,
                s = n2.nextSibling;

            if (s == n1) {
                p.insertBefore(n1, n2);
            } else if (n2 == n1.nextSibling) {
                p.insertBefore(n2, n1);
            } else {
                n1.parentNode.replaceChild(n2, n1);
                p.insertBefore(n1, s);
            }
        }
    },

    /**
     * Returns the current scroll position
     * @private
     */
    getScroll: function () {
        var doc   = window.document,
            docEl = doc.documentElement,
            body  = doc.body,
            top   = 0,
            left  = 0;

        if (docEl && (docEl.scrollTop || docEl.scrollLeft)) {
            top  = docEl.scrollTop;
            left = docEl.scrollLeft;
        } else if (body) {
            top  = body.scrollTop;
            left = body.scrollLeft;
        }

        return {
            top: top,
            left: left
        };
    },

    /**
     * Returns the specified element style property
     * @param {HTMLElement} el          the element
     * @param {String}      styleProp   the style property
     * @return {String} The value of the style property
     */
    getStyle: function(el, styleProp) {
        return Ext.fly(el).getStyle(styleProp);
    },

    /**
     * Gets the scrollTop
     * @return {Number} the document's scrollTop
     */
    getScrollTop: function () {
        return this.getScroll().top;
    },

    /**
     * Gets the scrollLeft
     * @return {Number} the document's scrollTop
     */
    getScrollLeft: function () {
        return this.getScroll().left;
    },

    /**
     * Sets the x/y position of an element to the location of the
     * target element.
     * @param {HTMLElement} moveEl      The element to move
     * @param {HTMLElement} targetEl    The position reference element
     */
    moveToEl: function (moveEl, targetEl) {
        var aCoord = Ext.fly(targetEl).getXY();
        Ext.fly(moveEl).setXY(aCoord);
    },

    /**
     * Numeric array sort function
     * @param {Number} a
     * @param {Number} b
     * @returns {Number} positive, negative or 0
     */
    numericSort: function(a, b) {
        return (a - b);
    },

    /**
     * Recursively searches the immediate parent and all child nodes for
     * the handle element in order to determine wheter or not it was
     * clicked.
     * @param {HTMLElement} node the html element to inspect
     */
    handleWasClicked: function(node, id) {
        if (this.isHandle(id, node.id)) {
            return true;
        } else {
            // check to see if this is a text node child of the one we want
            var p = node.parentNode;

            while (p) {
                if (this.isHandle(id, p.id)) {
                    return true;
                } else {
                    p = p.parentNode;
                }
            }
        }

        return false;
    }
}, function(DragDropManager) {
    Ext.onReady(function() {
        DragDropManager.addListeners();
    });
});
