    /**
     * @class Ext.grid.header.Container
     * @extends Ext.container.Container
     * @private
     *
     * Container which holds headers and is docked at the top or bottom of a TablePanel.
     * The HeaderContainer drives resizing/moving/hiding of columns within the TableView.
     * As headers are hidden, moved or resized the headercontainer is responsible for
     * triggering changes within the view.
     *
     * @xtype headercontainer
     */
    Ext.define('Ext.grid.header.Container', {
        extend: 'Ext.container.Container',
        uses: [
            'Ext.grid.ColumnLayout',
            'Ext.grid.column.Column',
            'Ext.menu.Menu',
            'Ext.menu.CheckItem',
            'Ext.menu.Separator',
            'Ext.grid.plugin.HeaderResizer',
            'Ext.grid.plugin.HeaderReorderer'
        ],
        border: true,

        alias: 'widget.headercontainer',

        baseCls: Ext.baseCSSPrefix + 'grid-header-ct',
        dock: 'top',

        /**
         * @cfg {Number} weight
         * HeaderContainer overrides the default weight of 0 for all docked items to 100.
         * This is so that it has more priority over things like toolbars.
         */
        weight: 100,
        defaultType: 'gridcolumn',
        /**
         * @cfg {Number} defaultWidth
         * Width of the header if no width or flex is specified. Defaults to 100.
         */
        defaultWidth: 100,

        sortAscText: 'Sort Ascending',
        sortDescText: 'Sort Descending',
        sortClearText: 'Clear Sort',
        columnsText: 'Columns',

        lastHeaderCls: Ext.baseCSSPrefix + 'column-header-last',
        firstHeaderCls: Ext.baseCSSPrefix + 'column-header-first',
        headerOpenCls: Ext.baseCSSPrefix + 'column-header-open',

        // private; will probably be removed by 4.0
        triStateSort: false,

        ddLock: false,

        dragging: false,

        /**
         * <code>true</code> if this HeaderContainer is in fact a group header which contains sub headers.
         * @type Boolean
         * @property isGroupHeader
         */

        /**
         * @cfg {Boolean} sortable
         * Provides the default sortable state for all Headers within this HeaderContainer.
         * Also turns on or off the menus in the HeaderContainer. Note that the menu is
         * shared across every header and therefore turning it off will remove the menu
         * items for every header.
         */
        sortable: true,

        initComponent: function() {
            var me = this;

            me.headerCounter = 0;
            me.plugins = me.plugins || [];

            // TODO: Pass in configurations to turn on/off dynamic
            //       resizing and disable resizing all together

            // Only set up a Resizer and Reorderer for the topmost HeaderContainer.
            // Nested Group Headers are themselves HeaderContainers
            if (!me.isHeader) {
                me.resizer   = Ext.create('Ext.grid.plugin.HeaderResizer');
                me.reorderer = Ext.create('Ext.grid.plugin.HeaderReorderer');
                if (!me.enableColumnResize) {
                    me.resizer.disable();
                }
                if (!me.enableColumnMove) {
                    me.reorderer.disable();
                }
                me.plugins.push(me.reorderer, me.resizer);
            }

            // Base headers do not need a box layout
            if (me.isHeader && !me.items) {
                me.layout = 'auto';
            }
            // HeaderContainer and Group header needs a gridcolumn layout.
            else {
                me.layout = {
                    type: 'gridcolumn',
                    availableSpaceOffset: me.availableSpaceOffset,
                    align: 'stretchmax',
                    resetStretch: true
                };
            }
            me.defaults = me.defaults || {};
            Ext.applyIf(me.defaults, {
                width: me.defaultWidth,
                triStateSort: me.triStateSort,
                sortable: me.sortable
            });
            me.callParent();
            me.addEvents(
                /**
                 * @event columnresize
                 * @param {Ext.grid.header.Container} ct The grid's header Container which encapsulates all column headers.
                 * @param {Ext.grid.column.Column} column The Column header Component which provides the column definition
                 * @param {Number} width
                 */
                'columnresize',

                /**
                 * @event headerclick
                 * @param {Ext.grid.header.Container} ct The grid's header Container which encapsulates all column headers.
                 * @param {Ext.grid.column.Column} column The Column header Component which provides the column definition
                 * @param {Ext.EventObject} e
                 * @param {HTMLElement} t
                 */
                'headerclick',

                /**
                 * @event headertriggerclick
                 * @param {Ext.grid.header.Container} ct The grid's header Container which encapsulates all column headers.
                 * @param {Ext.grid.column.Column} column The Column header Component which provides the column definition
                 * @param {Ext.EventObject} e
                 * @param {HTMLElement} t
                 */
                'headertriggerclick',

                /**
                 * @event columnmove
                 * @param {Ext.grid.header.Container} ct The grid's header Container which encapsulates all column headers.
                 * @param {Ext.grid.column.Column} column The Column header Component which provides the column definition
                 * @param {Number} fromIdx
                 * @param {Number} toIdx
                 */
                'columnmove',
                /**
                 * @event columnhide
                 * @param {Ext.grid.header.Container} ct The grid's header Container which encapsulates all column headers.
                 * @param {Ext.grid.column.Column} column The Column header Component which provides the column definition
                 */
                'columnhide',
                /**
                 * @event columnshow
                 * @param {Ext.grid.header.Container} ct The grid's header Container which encapsulates all column headers.
                 * @param {Ext.grid.column.Column} column The Column header Component which provides the column definition
                 */
                'columnshow',
                /**
                 * @event sortchange
                 * @param {Ext.grid.header.Container} ct The grid's header Container which encapsulates all column headers.
                 * @param {Ext.grid.column.Column} column The Column header Component which provides the column definition
                 * @param {String} direction
                 */
                'sortchange',
                /**
                 * @event menucreate
                 * Fired immediately after the column header menu is created.
                 * @param {Ext.grid.header.Container} ct This instance
                 * @param {Ext.menu.Menu} menu The Menu that was created
                 */
                'menucreate'
            );
        },

        onDestroy: function() {
            Ext.destroy(this.resizer, this.reorderer);
            this.callParent();
        },

        // Invalidate column cache on add
        // We cannot refresh the View on every add because this method is called
        // when the HeaderDropZone moves Headers around, that will also refresh the view
        onAdd: function(c) {
            var me = this;
            if (!c.headerId) {
                c.headerId = 'h' + (++me.headerCounter);
            }
            me.callParent(arguments);
            me.purgeCache();
        },

        // Invalidate column cache on remove
        // We cannot refresh the View on every remove because this method is called
        // when the HeaderDropZone moves Headers around, that will also refresh the view
        onRemove: function(c) {
            var me = this;
            me.callParent(arguments);
            me.purgeCache();
        },

        afterRender: function() {
            this.callParent();
            var store   = this.up('[store]').store,
                sorters = store.sorters,
                first   = sorters.first(),
                hd;

            if (first) {
                hd = this.down('gridcolumn[dataIndex=' + first.property  +']');
                if (hd) {
                    hd.setSortState(first.direction, false, true);
                }
            }
        },

        afterLayout: function() {
            if (!this.isHeader) {
                var me = this,
                    topHeaders = me.query('>gridcolumn:not([hidden])'),
                    viewEl;

                me.callParent(arguments);

                if (topHeaders.length) {
                    topHeaders[0].el.radioCls(me.firstHeaderCls);
                    topHeaders[topHeaders.length - 1].el.radioCls(me.lastHeaderCls);
                }
            }
        },

        onHeaderShow: function(header) {
            // Pass up to the GridSection
            var me = this,
                gridSection = me.ownerCt,
                menu = me.getMenu(),
                topItems, topItemsVisible,
                colCheckItem,
                itemToEnable,
                len, i;

            if (menu) {

                colCheckItem = menu.down('menucheckitem[headerId=' + header.id + ']');
                if (colCheckItem) {
                    colCheckItem.setChecked(true, true);
                }

                // There's more than one header visible, and we've disabled some checked items... re-enable them
                topItems = menu.query('#columnItem>menucheckitem[checked]');
                topItemsVisible = topItems.length;
                if ((me.getVisibleGridColumns().length > 1) && me.disabledMenuItems && me.disabledMenuItems.length) {
                    if (topItemsVisible == 1) {
                        Ext.Array.remove(me.disabledMenuItems, topItems[0]);
                    }
                    for (i = 0, len = me.disabledMenuItems.length; i < len; i++) {
                        itemToEnable = me.disabledMenuItems[i];
                        if (!itemToEnable.isDestroyed) {
                            itemToEnable[itemToEnable.menu ? 'enableCheckChange' : 'enable']();
                        }
                    }
                    if (topItemsVisible == 1) {
                        me.disabledMenuItems = topItems;
                    } else {
                        me.disabledMenuItems = [];
                    }
                }
            }

            // Only update the grid UI when we are notified about base level Header shows;
            // Group header shows just cause a layout of the HeaderContainer
            if (!header.isGroupHeader) {
                if (me.view) {
                    me.view.onHeaderShow(me, header, true);
                }
                if (gridSection) {
                    gridSection.onHeaderShow(me, header);
                }
            }
            me.fireEvent('columnshow', me, header);

            // The header's own hide suppresses cascading layouts, so lay the headers out now
            me.doLayout();
        },

        onHeaderHide: function(header, suppressLayout) {
            // Pass up to the GridSection
            var me = this,
                gridSection = me.ownerCt,
                menu = me.getMenu(),
                colCheckItem;

            if (menu) {

                // If the header was hidden programmatically, sync the Menu state
                colCheckItem = menu.down('menucheckitem[headerId=' + header.id + ']');
                if (colCheckItem) {
                    colCheckItem.setChecked(false, true);
                }
                me.setDisabledItems();
            }

            // Only update the UI when we are notified about base level Header hides;
            if (!header.isGroupHeader) {
                if (me.view) {
                    me.view.onHeaderHide(me, header, true);
                }
                if (gridSection) {
                    gridSection.onHeaderHide(me, header);
                }

                // The header's own hide suppresses cascading layouts, so lay the headers out now
                if (!suppressLayout) {
                    me.doLayout();
                }
            }
            me.fireEvent('columnhide', me, header);
        },

        setDisabledItems: function(){
            var me = this,
                menu = me.getMenu(),
                i = 0,
                len,
                itemsToDisable,
                itemToDisable;

            // Find what to disable. If only one top level item remaining checked, we have to disable stuff.
            itemsToDisable = menu.query('#columnItem>menucheckitem[checked]');
            if ((itemsToDisable.length === 1)) {
                if (!me.disabledMenuItems) {
                    me.disabledMenuItems = [];
                }

                // If down to only one column visible, also disable any descendant checkitems
                if ((me.getVisibleGridColumns().length === 1) && itemsToDisable[0].menu) {
                    itemsToDisable = itemsToDisable.concat(itemsToDisable[0].menu.query('menucheckitem[checked]'));
                }

                len = itemsToDisable.length;
                // Disable any further unchecking at any level.
                for (i = 0; i < len; i++) {
                    itemToDisable = itemsToDisable[i];
                    if (!Ext.Array.contains(me.disabledMenuItems, itemToDisable)) {
                        itemToDisable[itemToDisable.menu ? 'disableCheckChange' : 'disable']();
                        me.disabledMenuItems.push(itemToDisable);
                    }
                }
            }
        },

        /**
         * Temporarily lock the headerCt. This makes it so that clicking on headers
         * don't trigger actions like sorting or opening of the header menu. This is
         * done because extraneous events may be fired on the headers after interacting
         * with a drag drop operation.
         * @private
         */
        tempLock: function() {
            this.ddLock = true;
            Ext.Function.defer(function() {
                this.ddLock = false;
            }, 200, this);
        },

        onHeaderResize: function(header, w, suppressFocus) {
            this.tempLock();
            if (this.view && this.view.rendered) {
                this.view.onHeaderResize(header, w, suppressFocus);
            }
            this.fireEvent('columnresize', this, header, w);
        },

        onHeaderClick: function(header, e, t) {
            this.fireEvent("headerclick", this, header, e, t);
        },

        onHeaderTriggerClick: function(header, e, t) {
            // generate and cache menu, provide ability to cancel/etc
            if (this.fireEvent("headertriggerclick", this, header, e, t) !== false) {
                this.showMenuBy(t, header);
            }
        },

        showMenuBy: function(t, header) {
            var menu = this.getMenu(),
                ascItem  = menu.down('#ascItem'),
                descItem = menu.down('#descItem'),
                sortableMth;

            menu.activeHeader = menu.ownerCt = header;
            menu.setFloatParent(header);
            // TODO: remove coupling to Header's titleContainer el
            header.titleContainer.addCls(this.headerOpenCls);

            // enable or disable asc & desc menu items based on header being sortable
            sortableMth = header.sortable ? 'enable' : 'disable';
            if (ascItem) {
                ascItem[sortableMth]();
            }
            if (descItem) {
                descItem[sortableMth]();
            }
            menu.showBy(t);
        },

        // remove the trigger open class when the menu is hidden
        onMenuDeactivate: function() {
            var menu = this.getMenu();
            // TODO: remove coupling to Header's titleContainer el
            menu.activeHeader.titleContainer.removeCls(this.headerOpenCls);
        },

        moveHeader: function(fromIdx, toIdx) {

            // An automatically expiring lock
            this.tempLock();
            this.onHeaderMoved(this.move(fromIdx, toIdx), fromIdx, toIdx);
        },

        purgeCache: function() {
            var me = this;
            // Delete column cache - column order has changed.
            delete me.gridDataColumns;

            // Menu changes when columns are moved. It will be recreated.
            if (me.menu) {
                me.menu.destroy();
                delete me.menu;
            }
        },

        onHeaderMoved: function(header, fromIdx, toIdx) {
            var me = this,
                gridSection = me.ownerCt;

            if (gridSection) {
                gridSection.onHeaderMove(me, header, fromIdx, toIdx);
            }
            me.fireEvent("columnmove", me, header, fromIdx, toIdx);
        },

        /**
         * Gets the menu (and will create it if it doesn't already exist)
         * @private
         */
        getMenu: function() {
            var me = this;

            if (!me.menu) {
                me.menu = Ext.create('Ext.menu.Menu', {
                    items: me.getMenuItems(),
                    listeners: {
                        deactivate: me.onMenuDeactivate,
                        scope: me
                    }
                });
                me.setDisabledItems();
                me.fireEvent('menucreate', me, me.menu);
            }
            return me.menu;
        },

        /**
         * Returns an array of menu items to be placed into the shared menu
         * across all headers in this header container.
         * @returns {Array} menuItems
         */
        getMenuItems: function() {
            var me = this,
                menuItems = [{
                    itemId: 'columnItem',
                    text: me.columnsText,
                    cls: Ext.baseCSSPrefix + 'cols-icon',
                    menu: me.getColumnMenu(me)
                }];

            if (me.sortable) {
                menuItems.unshift({
                    itemId: 'ascItem',
                    text: me.sortAscText,
                    cls: 'xg-hmenu-sort-asc',
                    handler: me.onSortAscClick,
                    scope: me
                },{
                    itemId: 'descItem',
                    text: me.sortDescText,
                    cls: 'xg-hmenu-sort-desc',
                    handler: me.onSortDescClick,
                    scope: me
                },'-');
            }
            return menuItems;
        },

        // sort asc when clicking on item in menu
        onSortAscClick: function() {
            var menu = this.getMenu(),
                activeHeader = menu.activeHeader;

            activeHeader.setSortState('ASC');
        },

        // sort desc when clicking on item in menu
        onSortDescClick: function() {
            var menu = this.getMenu(),
                activeHeader = menu.activeHeader;

            activeHeader.setSortState('DESC');
        },

        /**
         * Returns an array of menu CheckItems corresponding to all immediate children of the passed Container which have been configured as hideable.
         */
        getColumnMenu: function(headerContainer) {
            var menuItems = [],
                i = 0,
                item,
                items = headerContainer.query('>gridcolumn[hideable]'),
                itemsLn = items.length,
                menuItem;

            for (; i < itemsLn; i++) {
                item = items[i];
                menuItem = Ext.create('Ext.menu.CheckItem', {
                    text: item.text,
                    checked: !item.hidden,
                    hideOnClick: false,
                    headerId: item.id,
                    menu: item.isGroupHeader ? this.getColumnMenu(item) : undefined,
                    checkHandler: this.onColumnCheckChange,
                    scope: this
                });
                if (itemsLn === 1) {
                    menuItem.disabled = true;
                }
                menuItems.push(menuItem);

                // If the header is ever destroyed - for instance by dragging out the last remaining sub header,
                // then the associated menu item must also be destroyed.
                item.on({
                    destroy: Ext.Function.bind(menuItem.destroy, menuItem)
                });
            }
            return menuItems;
        },

        onColumnCheckChange: function(checkItem, checked) {
            var header = Ext.getCmp(checkItem.headerId);
            header[checked ? 'show' : 'hide']();
        },

        /**
         * Get the columns used for generating a template via TableChunker.
         * Returns an array of all columns and their
         *  - dataIndex
         *  - align
         *  - width
         *  - id
         *  - columnId - used to create an identifying CSS class
         *  - cls The tdCls configuration from the Column object
         *  @private
         */
        getColumnsForTpl: function(flushCache) {
            var cols    = [],
                headers   = this.getGridColumns(flushCache),
                headersLn = headers.length,
                i = 0,
                header;

            for (; i < headersLn; i++) {
                header = headers[i];
                cols.push({
                    dataIndex: header.dataIndex,
                    align: header.align,
                    width: header.hidden ? 0 : header.getDesiredWidth(),
                    id: header.id,
                    cls: header.tdCls,
                    columnId: header.getItemId()
                });
            }
            return cols;
        },

        /**
         * Returns the number of <b>grid columns</b> descended from this HeaderContainer.
         * Group Columns are HeaderContainers. All grid columns are returned, including hidden ones.
         */
        getColumnCount: function() {
            return this.getGridColumns().length;
        },

        /**
         * Gets the full width of all columns that are visible.
         */
        getFullWidth: function(flushCache) {
            var fullWidth = 0,
                headers     = this.getVisibleGridColumns(flushCache),
                headersLn   = headers.length,
                i         = 0;

            for (; i < headersLn; i++) {
                if (!isNaN(headers[i].width)) {
                    // use headers getDesiredWidth if its there
                    if (headers[i].getDesiredWidth) {
                        fullWidth += headers[i].getDesiredWidth();
                    // if injected a diff cmp use getWidth
                    } else {
                        fullWidth += headers[i].getWidth();
                    }
                }
            }
            return fullWidth;
        },

        // invoked internally by a header when not using triStateSorting
        clearOtherSortStates: function(activeHeader) {
            var headers   = this.getGridColumns(),
                headersLn = headers.length,
                i         = 0,
                oldSortState;

            for (; i < headersLn; i++) {
                if (headers[i] !== activeHeader) {
                    oldSortState = headers[i].sortState;
                    // unset the sortstate and dont recurse
                    headers[i].setSortState(null, true);
                    //if (!silent && oldSortState !== null) {
                    //    this.fireEvent('sortchange', this, headers[i], null);
                    //}
                }
            }
        },

        /**
         * Returns an array of the <b>visible<b> columns in the grid. This goes down to the lowest column header
         * level, and does not return <i>grouped</i> headers which contain sub headers.
         * @param {Boolean} refreshCache If omitted, the cached set of columns will be returned. Pass true to refresh the cache.
         * @returns {Array}
         */
        getVisibleGridColumns: function(refreshCache) {
            return Ext.ComponentQuery.query(':not([hidden])', this.getGridColumns(refreshCache));
        },

        /**
         * Returns an array of all columns which map to Store fields. This goes down to the lowest column header
         * level, and does not return <i>grouped</i> headers which contain sub headers.
         * @param {Boolean} refreshCache If omitted, the cached set of columns will be returned. Pass true to refresh the cache.
         * @returns {Array}
         */
        getGridColumns: function(refreshCache) {
            var me = this,
                result = refreshCache ? null : me.gridDataColumns;

            // Not already got the column cache, so collect the base columns
            if (!result) {
                me.gridDataColumns = result = [];
                me.cascade(function(c) {
                    if ((c !== me) && !c.isGroupHeader) {
                        result.push(c);
                    }
                });
            }

            return result;
        },

        /**
         * Get the index of a leaf level header regardless of what the nesting
         * structure is.
         */
        getHeaderIndex: function(header) {
            var columns = this.getGridColumns();
            return Ext.Array.indexOf(columns, header);
        },

        /**
         * Get a leaf level header by index regardless of what the nesting
         * structure is.
         */
        getHeaderAtIndex: function(index) {
            var columns = this.getGridColumns();
            return columns[index];
        },

        /**
         * Maps the record data to base it on the header id's.
         * This correlates to the markup/template generated by
         * TableChunker.
         */
        prepareData: function(data, rowIdx, record, view) {
            var obj       = {},
                headers   = this.getGridColumns(),
                headersLn = headers.length,
                colIdx    = 0,
                header, value,
                metaData,
                g = this.up('tablepanel'),
                store = g.store;

            for (; colIdx < headersLn; colIdx++) {
                metaData = {
                    tdCls: '',
                    style: ''
                };
                header = headers[colIdx];
                value = data[header.dataIndex];

                // When specifying a renderer as a string, it always resolves
                // to Ext.util.Format
                if (Ext.isString(header.renderer)) {
                    header.renderer = Ext.util.Format[header.renderer];
                }

                if (Ext.isFunction(header.renderer)) {
                    value = header.renderer.call(
                        header.scope || this.ownerCt,
                        value,
                        // metadata per cell passing an obj by reference so that
                        // it can be manipulated inside the renderer
                        metaData,
                        record,
                        rowIdx,
                        colIdx,
                        store,
                        view
                    );
                }

                // <debug>
                if (metaData.css) {
                    // This warning attribute is used by the compat layer
                    obj.cssWarning = true;
                    metaData.tdCls = metaData.css;
                    delete metaData.css;
                }
                // </debug>
                obj[header.id+'-modified'] = record.isModified(header.dataIndex) ? Ext.baseCSSPrefix + 'grid-dirty-cell' : Ext.baseCSSPrefix + 'grid-clean-cell';
                obj[header.id+'-tdCls'] = metaData.tdCls;
                obj[header.id+'-tdAttr'] = metaData.tdAttr;
                obj[header.id+'-style'] = metaData.style;
                if (value === undefined || value === null || value === '') {
                    value = '&#160;';
                }
                obj[header.id] = value;
            }
            return obj;
        },

        expandToFit: function(header) {
            if (this.view) {
                this.view.expandToFit(header);
            }
        }
    });