/**
 * Base class for any Ext.Component that may contain other Components. Containers handle the basic behavior of
 * containing items, namely adding, inserting and removing items.
 *
 * The most commonly used Container classes are Ext.panel.Panel, Ext.window.Window and
 * Ext.tab.Panel. If you do not need the capabilities offered by the aforementioned classes you can create a
 * lightweight Container to be encapsulated by an HTML element to your specifications by using the
 * {@link Ext.Component#autoEl autoEl} config option.
 *
 * The code below illustrates how to explicitly create a Container:
 *
 *     @example
 *     // Explicitly create a Container
 *     Ext.create('Ext.container.Container', {
 *         layout: {
 *             type: 'hbox'
 *         },
 *         width: 400,
 *         renderTo: Ext.getBody(),
 *         border: 1,
 *         style: {borderColor:'#000000', borderStyle:'solid', borderWidth:'1px'},
 *         defaults: {
 *             labelWidth: 80,
 *             // implicitly create Container by specifying xtype
 *             xtype: 'datefield',
 *             flex: 1,
 *             style: {
 *                 padding: '10px'
 *             }
 *         },
 *         items: [{
 *             xtype: 'datefield',
 *             name: 'startDate',
 *             fieldLabel: 'Start date'
 *         },{
 *             xtype: 'datefield',
 *             name: 'endDate',
 *             fieldLabel: 'End date'
 *         }]
 *     });
 *
 * ## Layout
 *
 * Container classes delegate the rendering of child Components to a layout manager class which must be configured into
 * the Container using the `{@link #layout}` configuration property.
 *
 * When either specifying child `{@link #cfg-items}` of a Container, or dynamically {@link #method-add adding} Components to a
 * Container, remember to consider how you wish the Container to arrange those child elements, and whether those child
 * elements need to be sized using one of Ext's built-in `{@link #layout}` schemes. By default, Containers use the
 * {@link Ext.layout.container.Auto Auto} scheme which only renders child components, appending them one after the other
 * inside the Container, and **does not apply any sizing** at all.
 *
 * A common mistake is when a developer neglects to specify a `{@link #layout}` (e.g. widgets like GridPanels or
 * TreePanels are added to Containers for which no `{@link #layout}` has been specified). If a Container is left to
 * use the default {@link Ext.layout.container.Auto Auto} scheme, none of its child components will be resized, or changed in
 * any way when the Container is resized.
 *
 * Certain layout managers allow dynamic addition of child components. Those that do include
 * Ext.layout.container.Card, Ext.layout.container.Anchor, Ext.layout.container.VBox,
 * Ext.layout.container.HBox, and Ext.layout.container.Table. For example:
 *
 *     //  Create the GridPanel.
 *     var myNewGrid = Ext.create('Ext.grid.Panel', {
 *         store: myStore,
 *         headers: myHeaders,
 *         title: 'Results', // the title becomes the title of the tab
 *     });
 *
 *     myTabPanel.add(myNewGrid); // {@link Ext.tab.Panel} implicitly uses {@link Ext.layout.container.Card Card}
 *     myTabPanel.{@link Ext.tab.Panel#setActiveTab setActiveTab}(myNewGrid);
 *
 * The example above adds a newly created GridPanel to a TabPanel. Note that a TabPanel uses {@link
 * Ext.layout.container.Card} as its layout manager which means all its child items are sized to {@link
 * Ext.layout.container.Fit fit} exactly into its client area.
 *
 * **_Overnesting is a common problem_**. An example of overnesting occurs when a GridPanel is added to a TabPanel by
 * wrapping the GridPanel _inside_ a wrapping Panel (that has no `{@link #layout}` specified) and then add that
 * wrapping Panel to the TabPanel. The point to realize is that a GridPanel **is** a Component which can be added
 * directly to a Container. If the wrapping Panel has no `{@link #layout}` configuration, then the overnested
 * GridPanel will not be sized as expected.
 *
 * ## Adding via remote configuration
 *
 * A server side script can be used to add Components which are generated dynamically on the server. An example of
 * adding a GridPanel to a TabPanel where the GridPanel is generated by the server based on certain parameters:
 *
 *     // execute an Ajax request to invoke server side script:
 *     Ext.Ajax.request({
 *         url: 'gen-invoice-grid.php',
 *         // send additional parameters to instruct server script
 *         params: {
 *             startDate: Ext.getCmp('start-date').getValue(),
 *             endDate: Ext.getCmp('end-date').getValue()
 *         },
 *         // process the response object to add it to the TabPanel:
 *         success: function(xhr) {
 *             var newComponent = eval(xhr.responseText); // see discussion below
 *             myTabPanel.add(newComponent); // add the component to the TabPanel
 *             myTabPanel.setActiveTab(newComponent);
 *         },
 *         failure: function() {
 *             Ext.Msg.alert("Grid create failed", "Server communication failure");
 *         }
 *     });
 *
 * The server script needs to return a JSON representation of a configuration object, which, when decoded will return a
 * config object with an {@link Ext.Component#xtype xtype}. The server might return the following JSON:
 *
 *     {
 *         "xtype": 'grid',
 *         "title": 'Invoice Report',
 *         "store": {
 *             "model": 'Invoice',
 *             "proxy": {
 *                 "type": 'ajax',
 *                 "url": 'get-invoice-data.php',
 *                 "reader": {
 *                     "type": 'json'
 *                     "record": 'transaction',
 *                     "idProperty": 'id',
 *                     "totalRecords": 'total'
 *                 })
 *             },
 *             "autoLoad": {
 *                 "params": {
 *                     "startDate": '01/01/2008',
 *                     "endDate": '01/31/2008'
 *                 }
 *             }
 *         },
 *         "headers": [
 *             {"header": "Customer", "width": 250, "dataIndex": 'customer', "sortable": true},
 *             {"header": "Invoice Number", "width": 120, "dataIndex": 'invNo', "sortable": true},
 *             {"header": "Invoice Date", "width": 100, "dataIndex": 'date', "renderer": Ext.util.Format.dateRenderer('M d, y'), "sortable": true},
 *             {"header": "Value", "width": 120, "dataIndex": 'value', "renderer": 'usMoney', "sortable": true}
 *         ]
 *     }
 *
 * When the above code fragment is passed through the `eval` function in the success handler of the Ajax request, the
 * result will be a config object which, when added to a Container, will cause instantiation of a GridPanel. **Be sure
 * that the Container is configured with a layout which sizes and positions the child items to your requirements.**
 *
 * **Note:** since the code above is _generated_ by a server script, the `autoLoad` params for the Store, the user's
 * preferred date format, the metadata to allow generation of the Model layout, and the ColumnModel can all be generated
 * into the code since these are all known on the server.
 */
Ext.define('Ext.container.Container', {
    extend: 'Ext.container.AbstractContainer',
    alias: 'widget.container',
    alternateClassName: 'Ext.Container',
    
    /*
     * For more information on the following methods, see the note for the
     * hierarchyEventSource observer defined in the class' callback
     */
    fireHierarchyEvent: function (ename) {
        this.hierarchyEventSource.fireEvent(ename, this);
    },

    // note that the collapse and expand events are fired explicitly from Panel.js
    afterHide: function() {
        this.callParent(arguments);
        this.fireHierarchyEvent('hide');
    },
    
    afterShow: function(){
        this.callParent(arguments);
        this.fireHierarchyEvent('show');
    },

    /**
     * Return the immediate child Component in which the passed element is located.
     * @param {Ext.Element/HTMLElement/String} el The element to test (or ID of element).
     * @param {Boolean} deep If `true`, returns the deepest descendant Component which contains the passed element.
     * @return {Ext.Component} The child item which contains the passed element.
     */
    getChildByElement: function(el, deep) {
        var item,
            itemEl,
            i = 0,
            it = this.getRefItems(),
            ln = it.length;

        el = Ext.getDom(el);
        for (; i < ln; i++) {
            item = it[i];
            itemEl = item.getEl();
            if (itemEl && ((itemEl.dom === el) || itemEl.contains(el))) {
                return (deep && item.getChildByElement) ? item.getChildByElement(el, deep) : item;
            }
        }
        return null;
    }
}, function () {
    /*
     * The observer below is used to be able to detect showing/hiding at various levels
     * in the hierarchy. While it's not particularly expensive to bubble an event up,
     * cascading an event down can be quite costly.
     * 
     * The main usage for this is to do with floating components. For example, the load mask
     * is a floating component. The component it is masking may be inside several containers.
     * As such, we need to know when component is hidden, either directly, or via a parent
     * container being hidden. We can subscribe to these events and filter out the appropriate
     * container.
     */
    this.hierarchyEventSource = this.prototype.hierarchyEventSource = new Ext.util.Observable({ events: {
        hide: true,
        show: true,
        collapse: true,
        expand: true
    }});
});
