/**
 * @class Ext.ComponentMgr
 * 
Provides a registry of all Components (instances of {@link Ext.Component} or any subclass
 * thereof) on a page so that they can be easily accessed by {@link Ext.Component component}
 * {@link Ext.Component#id id} (see {@link #get}, or the convenience method {@link Ext#getCmp Ext.getCmp}).
 * 
This object also provides a registry of available Component classes
 * indexed by a mnemonic code known as the Component's {@link Ext.Component#xtype xtype}.
 * The {@link Ext.Component#xtype xtype} provides a way to avoid instantiating child Components
 * when creating a full, nested config object for a complete Ext page.
 * 
A child Component may be specified simply as a config object
 * as long as the correct {@link Ext.Component#xtype xtype} is specified so that if and when the Component
 * needs rendering, the correct type can be looked up for lazy instantiation.
 * 
For a list of all available {@link Ext.Component#xtype xtypes}, see {@link Ext.Component}.
 * @singleton
 */
Ext.ComponentMgr = function(){
    var all = new Ext.util.MixedCollection();
    var types = {};
    var ptypes = {};

    return {
        
/**
         * Registers a component.
         * @param {Ext.Component} c The component
         */
        register : function(c){
            all.add(c);
        },

        
/**
         * Unregisters a component.
         * @param {Ext.Component} c The component
         */
        unregister : function(c){
            all.remove(c);
        },

        
/**
         * Returns a component by {@link Ext.Component#id id}.
         * For additional details see {@link Ext.util.MixedCollection#get}.
         * @param {String} id The component {@link Ext.Component#id id}
         * @return Ext.Component The Component, undefined if not found, or null if a
         * Class was found.
         */
        get : function(id){
            return all.get(id);
        },

        
/**
         * Registers a function that will be called when a specified component is added to ComponentMgr
         * @param {String} id The component {@link Ext.Component#id id}
         * @param {Function} fn The callback function
         * @param {Object} scope The scope of the callback
         */
        onAvailable : function(id, fn, scope){
            all.on("add", function(index, o){
                if(o.id == id){
                    fn.call(scope || o, o);
                    all.un("add", fn, scope);
                }
            });
        },

        
/**
         * The MixedCollection used internally for the component cache. An example usage may be subscribing to
         * events on the MixedCollection to monitor addition or removal.  Read-only.
         * @type {MixedCollection}
         */
        all : all,
        
        
/**
         * Checks if a Component type is registered.
         * @param {Ext.Component} xtype The mnemonic string by which the Component class may be looked up
         * @return {Boolean} Whether the type is registered.
         */
        isRegistered : function(xtype){
            return types[xtype] !== undefined;    
        },

        
/**
         * 
Registers a new Component constructor, keyed by a new
         * {@link Ext.Component#xtype}.
         * 
Use this method (or its alias {@link Ext#reg Ext.reg}) to register new
         * subclasses of {@link Ext.Component} so that lazy instantiation may be used when specifying
         * child Components.
         * see {@link Ext.Container#items}
         * @param {String} xtype The mnemonic string by which the Component class may be looked up.
         * @param {Constructor} cls The new Component class.
         */
        registerType : function(xtype, cls){
            types[xtype] = cls;
            cls.xtype = xtype;
        },

        
/**
         * Creates a new Component from the specified config object using the
         * config object's {@link Ext.component#xtype xtype} to determine the class to instantiate.
         * @param {Object} config A configuration object for the Component you wish to create.
         * @param {Constructor} defaultType The constructor to provide the default Component type if
         * the config object does not contain a xtype. (Optional if the config contains a xtype).
         * @return {Ext.Component} The newly instantiated Component.
         */
        create : function(config, defaultType){
            return config.render ? config : new types[config.xtype || defaultType](config);
        },

        
/**
         * 
Registers a new Plugin constructor, keyed by a new
         * {@link Ext.Component#ptype}.
         * 
Use this method (or its alias {@link Ext#preg Ext.preg}) to register new
         * plugins for {@link Ext.Component}s so that lazy instantiation may be used when specifying
         * Plugins.
         * @param {String} ptype The mnemonic string by which the Plugin class may be looked up.
         * @param {Constructor} cls The new Plugin class.
         */
        registerPlugin : function(ptype, cls){
            ptypes[ptype] = cls;
            cls.ptype = ptype;
        },

        
/**
         * Creates a new Plugin from the specified config object using the
         * config object's {@link Ext.component#ptype ptype} to determine the class to instantiate.
         * @param {Object} config A configuration object for the Plugin you wish to create.
         * @param {Constructor} defaultType The constructor to provide the default Plugin type if
         * the config object does not contain a ptype. (Optional if the config contains a ptype).
         * @return {Ext.Component} The newly instantiated Plugin.
         */
        createPlugin : function(config, defaultType){
            return new ptypes[config.ptype || defaultType](config);
        }
    };
}();

/**
 * Shorthand for {@link Ext.ComponentMgr#registerType}
 * @param {String} xtype The {@link Ext.component#xtype mnemonic string} by which the Component class
 * may be looked up.
 * @param {Constructor} cls The new Component class.
 * @member Ext
 * @method reg
 */
Ext.reg = Ext.ComponentMgr.registerType; // this will be called a lot internally, shorthand to keep the bytes down
/**
 * Shorthand for {@link Ext.ComponentMgr#registerPlugin}
 * @param {String} ptype The {@link Ext.component#ptype mnemonic string} by which the Plugin class
 * may be looked up.
 * @param {Constructor} cls The new Plugin class.
 * @member Ext
 * @method preg
 */
Ext.preg = Ext.ComponentMgr.registerPlugin;
Ext.create = Ext.ComponentMgr.create;