/**
 * @author Ed Spencer
 *
 * AbstractStore is a superclass of {@link Ext.data.Store} and {@link Ext.data.TreeStore}. It's never used directly,
 * but offers a set of methods used by both of those subclasses.
 *
 * We've left it here in the docs for reference purposes, but unless you need to make a whole new type of Store, what
 * you're probably looking for is {@link Ext.data.Store}. If you're still interested, here's a brief description of what
 * AbstractStore is and is not.
 *
 * AbstractStore provides the basic configuration for anything that can be considered a Store. It expects to be
 * given a {@link Ext.data.Model Model} that represents the type of data in the Store. It also expects to be given a
 * {@link Ext.data.proxy.Proxy Proxy} that handles the loading of data into the Store.
 *
 * AbstractStore provides a few helpful methods such as {@link #method-load} and {@link #sync}, which load and save data
 * respectively, passing the requests through the configured {@link #proxy}. Both built-in Store subclasses add extra
 * behavior to each of these functions. Note also that each AbstractStore subclass has its own way of storing data -
 * in {@link Ext.data.Store} the data is saved as a flat {@link Ext.util.MixedCollection MixedCollection}, whereas in
 * {@link Ext.data.TreeStore TreeStore} we use a {@link Ext.data.Tree} to maintain the data's hierarchy.
 *
 * The store provides filtering and sorting support. This sorting/filtering can happen on the client side
 * or can be completed on the server. This is controlled by the {@link Ext.data.Store#remoteSort remoteSort} and
 * {@link Ext.data.Store#remoteFilter remoteFilter} config options. For more information see the {@link #sort} and
 * {@link Ext.data.Store#filter filter} methods.
 */
Ext.define('Ext.data.AbstractStore', {
	requires: [
        'Ext.util.MixedCollection',
        'Ext.data.proxy.Proxy',
        'Ext.data.Operation',
        'Ext.util.Filter'
    ],

    mixins: {
        observable: 'Ext.util.Observable',
        sortable: 'Ext.util.Sortable'
    },

    statics: {
        create: function(store) {
            if (!store.isStore) {
                if (!store.type) {
                    store.type = 'store';
                }
                store = Ext.createByAlias('store.' + store.type, store);
            }
            return store;
        }
    },

    remoteSort  : false,
    remoteFilter: false,

    /**
     * @cfg {String/Ext.data.proxy.Proxy/Object} proxy
     * The Proxy to use for this Store. This can be either a string, a config object or a Proxy instance -
     * see {@link #setProxy} for details.
     */

    /**
     * @cfg {Boolean/Object} autoLoad
     * If data is not specified, and if autoLoad is true or an Object, this store's load method is automatically called
     * after creation. If the value of autoLoad is an Object, this Object will be passed to the store's load method.
     * Defaults to false.
     */
    autoLoad: undefined,

    /**
     * @cfg {Boolean} autoSync
     * True to automatically sync the Store with its Proxy after every edit to one of its Records. Defaults to false.
     */
    autoSync: false,

    /**
     * @property {String} batchUpdateMode
     * Sets the updating behavior based on batch synchronization. 'operation' (the default) will update the Store's
     * internal representation of the data after each operation of the batch has completed, 'complete' will wait until
     * the entire batch has been completed before updating the Store's data. 'complete' is a good choice for local
     * storage proxies, 'operation' is better for remote proxies, where there is a comparatively high latency.
     */
    batchUpdateMode: 'operation',

    /**
     * @property {Boolean} filterOnLoad
     * If true, any filters attached to this Store will be run after loading data, before the datachanged event is fired.
     * Defaults to true, ignored if {@link Ext.data.Store#remoteFilter remoteFilter} is true
     */
    filterOnLoad: true,

    /**
     * @property {Boolean} sortOnLoad
     * If true, any sorters attached to this Store will be run after loading data, before the datachanged event is fired.
     * Defaults to true, igored if {@link Ext.data.Store#remoteSort remoteSort} is true
     */
    sortOnLoad: true,

    /**
     * @property {Boolean} implicitModel
     * True if a model was created implicitly for this Store. This happens if a fields array is passed to the Store's
     * constructor instead of a model constructor or name.
     * @private
     */
    implicitModel: false,

    /**
     * @property {String} defaultProxyType
     * The string type of the Proxy to create if none is specified. This defaults to creating a
     * {@link Ext.data.proxy.Memory memory proxy}.
     */
    defaultProxyType: 'memory',

    /**
     * @property {Boolean} isDestroyed
     * True if the Store has already been destroyed. If this is true, the reference to Store should be deleted
     * as it will not function correctly any more.
     */
    isDestroyed: false,

    /**
     * @property {Boolean} isStore
     * `true` in this class to identify an object as an instantiated Store, or subclass thereof.
     */
    isStore: true,

    /**
     * @cfg {String} storeId
     * Unique identifier for this store. If present, this Store will be registered with the {@link Ext.data.StoreManager},
     * making it easy to reuse elsewhere.
     *
     * Note that when store is instatiated by Controller, the storeId will be overridden by the name of the store.
     */

    /**
     * @cfg {Object[]} fields
     * This may be used in place of specifying a {@link #model} configuration. The fields should be a
     * set of {@link Ext.data.Field} configuration objects. The store will automatically create a {@link Ext.data.Model}
     * with these fields. In general this configuration option should be avoided, it exists for the purposes of
     * backwards compatibility. For anything more complicated, such as specifying a particular id property or
     * associations, a {@link Ext.data.Model} should be defined and specified for the {@link #model}
     * config.
     */

    /**
     * @cfg {String} model
     * Name of the {@link Ext.data.Model Model} associated with this store.
     * The string is used as an argument for {@link Ext.ModelManager#getModel}.
     */

    /**
     * @cfg {Object[]} filters
     * Array of {@link Ext.util.Filter Filters} for this store.
     */

    sortRoot: 'data',

    //documented above
    constructor: function(config) {
        var me = this,
            filters;

        /**
         * @event add
         * Fired when a Model instance has been added to this Store
         * @param {Ext.data.Store} store The store
         * @param {Ext.data.Model[]} records The Model instances that were added
         * @param {Number} index The index at which the instances were inserted
         */

        /**
         * @event remove
         * Fired when a Model instance has been removed from this Store
         * @param {Ext.data.Store} store The Store object
         * @param {Ext.data.Model} record The record that was removed
         * @param {Number} index The index of the record that was removed
         */

        /**
         * @event update
         * Fires when a Model instance has been updated
         * @param {Ext.data.Store} this
         * @param {Ext.data.Model} record The Model instance that was updated
         * @param {String} operation The update operation being performed. Value may be one of:
         *
         *     Ext.data.Model.EDIT
         *     Ext.data.Model.REJECT
         *     Ext.data.Model.COMMIT
         * @param {String[]} modifiedFieldNames Array of field names changed during edit.
         */

        /**
         * @event datachanged
         * Fires whenever the records in the Store have changed in some way - this could include adding or removing
         * records, or updating the data in existing records
         * @param {Ext.data.Store} this The data store
         */
        
        /**
         * @event refresh
         * Fires when the data cache has changed in a bulk manner (e.g., it has been sorted, filtered, etc.) and a
         * widget that is using this Store as a Record cache should refresh its view.
         * @param {Ext.data.Store} this The data store
         */

        /**
         * @event beforeload
         * Fires before a request is made for a new data object. If the beforeload handler returns false the load
         * action will be canceled.
         * @param {Ext.data.Store} store This Store
         * @param {Ext.data.Operation} operation The Ext.data.Operation object that will be passed to the Proxy to
         * load the Store
         */

        /**
         * @event load
         * Fires whenever the store reads data from a remote data source.
         * @param {Ext.data.Store} this
         * @param {Ext.data.Model[]} records An array of records
         * @param {Boolean} successful True if the operation was successful.
         */

        /**
         * @event write
         * Fires whenever a successful write has been made via the configured {@link #proxy Proxy}
         * @param {Ext.data.Store} store This Store
         * @param {Ext.data.Operation} operation The {@link Ext.data.Operation Operation} object that was used in
         * the write
         */

        /**
         * @event beforesync
         * Fired before a call to {@link #sync} is executed. Return false from any listener to cancel the sync
         * @param {Object} options Hash of all records to be synchronized, broken down into create, update and destroy
         */
        /**
         * @event clear
         * Fired after the {@link #removeAll} method is called.
         * @param {Ext.data.Store} this
         */
        /**
         * @event metachange
         * Fires when this store's underlying reader (available via the proxy) provides new metadata.
         * Metadata usually consists of new field definitions, but can include any configuration data
         * required by an application, and can be processed as needed in the event handler.
         * This event is currently only fired for JsonReaders.
         * @param {Ext.data.Store} this
         * @param {Object} meta The JSON metadata
         */

        Ext.apply(me, config);
        // don't use *config* anymore from here on... use *me* instead...

        /**
         * Temporary cache in which removed model instances are kept until successfully synchronised with a Proxy,
         * at which point this is cleared.
         * @protected
         * @property {Ext.data.Model[]} removed
         */
        me.removed = [];

        me.mixins.observable.constructor.apply(me, arguments);
        me.model = Ext.ModelManager.getModel(me.model);

        /**
         * @property {Object} modelDefaults
         * @private
         * A set of default values to be applied to every model instance added via {@link #insert} or created via {@link #create}.
         * This is used internally by associations to set foreign keys and other fields. See the Association classes source code
         * for examples. This should not need to be used by application developers.
         */
        Ext.applyIf(me, {
            modelDefaults: {}
        });

        //Supports the 3.x style of simply passing an array of fields to the store, implicitly creating a model
        if (!me.model && me.fields) {
            me.model = Ext.define('Ext.data.Store.ImplicitModel-' + (me.storeId || Ext.id()), {
                extend: 'Ext.data.Model',
                fields: me.fields,
                proxy: me.proxy || me.defaultProxyType
            });

            delete me.fields;

            me.implicitModel = true;
        }

        // <debug>
        if (!me.model && me.useModelWarning !== false) {
            if (Ext.isDefined(Ext.global.console)) {
                Ext.global.console.warn('Store defined with no model. You may have mistyped the model name.');
            }
        }
        // </debug>

        //ensures that the Proxy is instantiated correctly
        me.setProxy(me.proxy || me.model.getProxy());

        me.proxy.on('metachange', me.onMetaChange, me);

        if (me.id && !me.storeId) {
            me.storeId = me.id;
            delete me.id;
        }

        if (me.storeId) {
            Ext.data.StoreManager.register(me);
        }

        me.mixins.sortable.initSortable.call(me);

        /**
         * @property {Ext.util.MixedCollection} filters
         * The collection of {@link Ext.util.Filter Filters} currently applied to this Store
         */
        filters = me.decodeFilters(me.filters);
        me.filters = new Ext.util.MixedCollection();
        me.filters.addAll(filters);
    },

    /**
     * Sets the Store's Proxy by string, config object or Proxy instance
     * @param {String/Object/Ext.data.proxy.Proxy} proxy The new Proxy, which can be either a type string, a configuration object
     * or an Ext.data.proxy.Proxy instance
     * @return {Ext.data.proxy.Proxy} The attached Proxy object
     */
    setProxy: function(proxy) {
        var me = this;

        if (proxy instanceof Ext.data.proxy.Proxy) {
            proxy.setModel(me.model);
        } else {
            if (Ext.isString(proxy)) {
                proxy = {
                    type: proxy
                };
            }
            Ext.applyIf(proxy, {
                model: me.model
            });

            proxy = Ext.createByAlias('proxy.' + proxy.type, proxy);
        }

        me.proxy = proxy;

        return me.proxy;
    },

    /**
     * Returns the proxy currently attached to this proxy instance
     * @return {Ext.data.proxy.Proxy} The Proxy instance
     */
    getProxy: function() {
        return this.proxy;
    },

    // private
    onMetaChange: function(proxy, meta) {
        this.fireEvent('metachange', this, meta);
    },

    //saves any phantom records
    create: function(data, options) {
        var me = this,
            instance = Ext.ModelManager.create(Ext.applyIf(data, me.modelDefaults), me.model.modelName),
            operation;

        options = options || {};

        Ext.applyIf(options, {
            action : 'create',
            records: [instance]
        });

        operation = new Ext.data.Operation(options);

        me.proxy.create(operation, me.onProxyWrite, me);

        return instance;
    },

    read: function() {
        return this.load.apply(this, arguments);
    },

    update: function(options) {
        var me = this,
            operation;
        options = options || {};

        Ext.applyIf(options, {
            action : 'update',
            records: me.getUpdatedRecords()
        });

        operation = new Ext.data.Operation(options);

        return me.proxy.update(operation, me.onProxyWrite, me);
    },

    /**
     * @private
     * Callback for any write Operation over the Proxy. Updates the Store's MixedCollection to reflect
     * the updates provided by the Proxy
     */
    onProxyWrite: function(operation) {
        var me = this,
            success = operation.wasSuccessful(),
            records = operation.getRecords();

        switch (operation.action) {
            case 'create':
                me.onCreateRecords(records, operation, success);
                break;
            case 'update':
                me.onUpdateRecords(records, operation, success);
                break;
            case 'destroy':
                me.onDestroyRecords(records, operation, success);
                break;
        }

        if (success) {
            me.fireEvent('write', me, operation);
            me.fireEvent('datachanged', me);
            me.fireEvent('refresh', me);
        }
        //this is a callback that would have been passed to the 'create', 'update' or 'destroy' function and is optional
        Ext.callback(operation.callback, operation.scope || me, [records, operation, success]);
    },
    
    // may be implemented by store subclasses
    onCreateRecords: Ext.emptyFn,
    
    // may be implemented by store subclasses
    onUpdateRecords: Ext.emptyFn,
    
    /**
     * Removes any records when a write is returned from the server.
     * @private
     * @param {Ext.data.Model[]} records The array of removed records
     * @param {Ext.data.Operation} operation The operation that just completed
     * @param {Boolean} success True if the operation was successful
     */
    onDestroyRecords: function(records, operation, success) {
        if (success) {
            this.removed = [];
        }
    },

    //tells the attached proxy to destroy the given records
    destroy: function(options) {
        var me = this,
            operation;

        options = options || {};

        Ext.applyIf(options, {
            action : 'destroy',
            records: me.getRemovedRecords()
        });

        operation = new Ext.data.Operation(options);

        return me.proxy.destroy(operation, me.onProxyWrite, me);
    },

    /**
     * @private
     * Attached as the 'operationcomplete' event listener to a proxy's Batch object. By default just calls through
     * to onProxyWrite.
     */
    onBatchOperationComplete: function(batch, operation) {
        return this.onProxyWrite(operation);
    },

    /**
     * @private
     * Attached as the 'complete' event listener to a proxy's Batch object. Iterates over the batch operations
     * and updates the Store's internal data MixedCollection.
     */
    onBatchComplete: function(batch, operation) {
        var me = this,
            operations = batch.operations,
            length = operations.length,
            i;

        me.suspendEvents();

        for (i = 0; i < length; i++) {
            me.onProxyWrite(operations[i]);
        }

        me.resumeEvents();

        me.fireEvent('datachanged', me);
        me.fireEvent('refresh', me);
    },

    onBatchException: function(batch, operation) {
        // //decide what to do... could continue with the next operation
        // batch.start();
        //
        // //or retry the last operation
        // batch.retry();
    },

    /**
     * @private
     * Filter function for new records.
     */
    filterNew: function(item) {
        // only want phantom records that are valid
        return item.phantom === true && item.isValid();
    },

    /**
     * Returns all Model instances that are either currently a phantom (e.g. have no id), or have an ID but have not
     * yet been saved on this Store (this happens when adding a non-phantom record from another Store into this one)
     * @return {Ext.data.Model[]} The Model instances
     */
    getNewRecords: function() {
        return [];
    },

    /**
     * Returns all Model instances that have been updated in the Store but not yet synchronized with the Proxy
     * @return {Ext.data.Model[]} The updated Model instances
     */
    getUpdatedRecords: function() {
        return [];
    },

    /**
     * Gets all {@link Ext.data.Model records} added or updated since the last commit. Note that the order of records
     * returned is not deterministic and does not indicate the order in which records were modified. Note also that
     * removed records are not included (use {@link #getRemovedRecords} for that).
     * @return {Ext.data.Model[]} The added and updated Model instances
     */
    getModifiedRecords : function(){
        return [].concat(this.getNewRecords(), this.getUpdatedRecords());
    },
    
    /**
     * @private
     * Filter function for updated records.
     */
    filterUpdated: function(item) {
        // only want dirty records, not phantoms that are valid
        return item.dirty === true && item.phantom !== true && item.isValid();
    },

    /**
     * Returns any records that have been removed from the store but not yet destroyed on the proxy.
     * @return {Ext.data.Model[]} The removed Model instances
     */
    getRemovedRecords: function() {
        return this.removed;
    },

    filter: function(filters, value) {

    },

    /**
     * @private
     * Normalizes an array of filter objects, ensuring that they are all Ext.util.Filter instances
     * @param {Object[]} filters The filters array
     * @return {Ext.util.Filter[]} Array of Ext.util.Filter objects
     */
    decodeFilters: function(filters) {
        if (!Ext.isArray(filters)) {
            if (filters === undefined) {
                filters = [];
            } else {
                filters = [filters];
            }
        }

        var length = filters.length,
            Filter = Ext.util.Filter,
            config, i;

        for (i = 0; i < length; i++) {
            config = filters[i];

            if (!(config instanceof Filter)) {
                Ext.apply(config, {
                    root: 'data'
                });

                //support for 3.x style filters where a function can be defined as 'fn'
                if (config.fn) {
                    config.filterFn = config.fn;
                }

                //support a function to be passed as a filter definition
                if (typeof config == 'function') {
                    config = {
                        filterFn: config
                    };
                }

                filters[i] = new Filter(config);
            }
        }

        return filters;
    },

    clearFilter: function(supressEvent) {

    },

    isFiltered: function() {

    },

    filterBy: function(fn, scope) {

    },

    /**
     * Synchronizes the store with its {@link #proxy}. This asks the proxy to batch together any new, updated
     * and deleted records in the store, updating the store's internal representation of the records
     * as each operation completes.
     * 
     * @param {Object} [options] Object containing one or more properties supported by the sync method (these get 
     * passed along to the underlying proxy's {@link Ext.data.Proxy#batch batch} method):
     * 
     * @param {Ext.data.Batch/Object} [options.batch] A {@link Ext.data.Batch} object (or batch config to apply 
     * to the created batch). If unspecified a default batch will be auto-created as needed.
     * 
     * @param {Function} [options.callback] The function to be called upon completion of the sync.
     * The callback is called regardless of success or failure and is passed the following parameters:
     * @param {Ext.data.Batch} options.callback.batch The {@link Ext.data.Batch batch} that was processed,
     * containing all operations in their current state after processing
     * @param {Object} options.callback.options The options argument that was originally passed into sync
     * 
     * @param {Function} [options.success] The function to be called upon successful completion of the sync. The 
     * success function is called only if no exceptions were reported in any operations. If one or more exceptions
     * occurred then the failure function will be called instead. The success function is called 
     * with the following parameters:
     * @param {Ext.data.Batch} options.success.batch The {@link Ext.data.Batch batch} that was processed,
     * containing all operations in their current state after processing
     * @param {Object} options.success.options The options argument that was originally passed into sync
     * 
     * @param {Function} [options.failure] The function to be called upon unsuccessful completion of the sync. The 
     * failure function is called when one or more operations returns an exception during processing (even if some
     * operations were also successful). In this case you can check the batch's {@link Ext.data.Batch#exceptions 
     * exceptions} array to see exactly which operations had exceptions. The failure function is called with the 
     * following parameters:
     * @param {Ext.data.Batch} options.failure.batch The {@link Ext.data.Batch} that was processed, containing all
     * operations in their current state after processing
     * @param {Object} options.failure.options The options argument that was originally passed into sync
     * 
     * @param {Object} [options.scope] The scope in which to execute any callbacks (i.e. the `this` object inside
     * the callback, success and/or failure functions). Defaults to the store's proxy.
     * 
     * @return {Ext.data.Store} this
     */
    sync: function(options) {
        var me = this,
            operations = {},
            toCreate = me.getNewRecords(),
            toUpdate = me.getUpdatedRecords(),
            toDestroy = me.getRemovedRecords(),
            needsSync = false;

        if (toCreate.length > 0) {
            operations.create = toCreate;
            needsSync = true;
        }

        if (toUpdate.length > 0) {
            operations.update = toUpdate;
            needsSync = true;
        }

        if (toDestroy.length > 0) {
            operations.destroy = toDestroy;
            needsSync = true;
        }

        if (needsSync && me.fireEvent('beforesync', operations) !== false) {
            options = options || {};

            me.proxy.batch(Ext.apply(options, {
                operations: operations,
                listeners: me.getBatchListeners()
            }));
        }
        
        return me;
    },
    
    /**
     * @private
     * Returns an object which is passed in as the listeners argument to proxy.batch inside this.sync.
     * This is broken out into a separate function to allow for customisation of the listeners
     * @return {Object} The listeners object
     */
    getBatchListeners: function() {
        var me = this,
            listeners = {
                scope: me,
                exception: me.onBatchException
            };

        if (me.batchUpdateMode == 'operation') {
            listeners.operationcomplete = me.onBatchOperationComplete;
        } else {
            listeners.complete = me.onBatchComplete;
        }

        return listeners;
    },

    /**
     * Saves all pending changes via the configured {@link #proxy}. Use {@link #sync} instead.
     * @deprecated 4.0.0 Will be removed in the next major version
     */
    save: function() {
        return this.sync.apply(this, arguments);
    },

    /**
     * Loads the Store using its configured {@link #proxy}.
     * @param {Object} options (optional) config object. This is passed into the {@link Ext.data.Operation Operation}
     * object that is created and then sent to the proxy's {@link Ext.data.proxy.Proxy#read} function
     * 
     * @return {Ext.data.Store} this
     */
    load: function(options) {
        var me = this,
            operation;

        options = options || {};
        
        options.action = options.action || 'read';
        options.filters = options.filters || me.filters.items;
        options.sorters = options.sorters || me.getSorters();
        
        operation = new Ext.data.Operation(options);

        if (me.fireEvent('beforeload', me, operation) !== false) {
            me.loading = true;
            me.proxy.read(operation, me.onProxyLoad, me);
        }

        return me;
    },

    /**
     * @private
     * A model instance should call this method on the Store it has been {@link Ext.data.Model#join joined} to.
     * @param {Ext.data.Model} record The model instance that was edited
     * @param {String[]} modifiedFieldNames Array of field names changed during edit.
     */
    afterEdit : function(record, modifiedFieldNames) {
        var me = this,
            i, shouldSync;

        if (me.autoSync && !me.autoSyncSuspended) {
            for(i = modifiedFieldNames.length; i--;) {
                // only sync if persistent fields were modified
                if(record.fields.get(modifiedFieldNames[i]).persist) {
                    shouldSync = true;
                    break;
                }
            }
            if(shouldSync) {
                me.sync();
            }
        }

        me.fireEvent('update', me, record, Ext.data.Model.EDIT, modifiedFieldNames);
    },

    /**
     * @private
     * A model instance should call this method on the Store it has been {@link Ext.data.Model#join joined} to..
     * @param {Ext.data.Model} record The model instance that was edited
     */
    afterReject : function(record) {
        // Must pass the 5th param (modifiedFieldNames) as null, otherwise the
        // event firing machinery appends the listeners "options" object to the arg list
        // which may get used as the modified fields array by a handler.
        // This array is used for selective grid cell updating by Grid View.
        // Null will be treated as though all cells need updating.
        this.fireEvent('update', this, record, Ext.data.Model.REJECT, null);
    },

    /**
     * @private
     * A model instance should call this method on the Store it has been {@link Ext.data.Model#join joined} to.
     * @param {Ext.data.Model} record The model instance that was edited
     */
    afterCommit : function(record) {
        // Must pass the 5th param (modifiedFieldNames) as null, otherwise the
        // event firing machinery appends the listeners "options" object to the arg list
        // which may get used as the modified fields array by a handler.
        // This array is used for selective grid cell updating by Grid View.
        // Null will be treated as though all cells need updating.
        this.fireEvent('update', this, record, Ext.data.Model.COMMIT, null);
    },

    // private
    destroyStore: function() {
        var me = this;

        if (!me.isDestroyed) {
            if (me.storeId) {
                Ext.data.StoreManager.unregister(me);
            }
            me.clearData();
            me.data = me.tree = me.sorters = me.filters = me.groupers = null;
            if (me.reader) {
                me.reader.destroyReader();
            }
            me.proxy = me.reader = me.writer = null;
            me.clearListeners();
            me.isDestroyed = true;

            if (me.implicitModel) {
                Ext.destroy(me.model);
            } else {
                me.model = null;
            }
        }
    },

    // private
    doSort: function(sorterFn) {
        var me = this;
        if (me.remoteSort) {
            //the load function will pick up the new sorters and request the sorted data from the proxy
            me.load();
        } else {
            me.data.sortBy(sorterFn);
            me.fireEvent('datachanged', me);
            me.fireEvent('refresh', me);
        }
    },

    // to be implemented by subclasses
    clearData: Ext.emptyFn,
    
    // to be implemented by subclasses
    getCount: Ext.emptyFn,

    // to be implemented by subclasses
    getById: Ext.emptyFn,

    /**
     * Removes all records from the store. This method does a "fast remove",
     * individual remove events are not called. The {@link #clear} event is
     * fired upon completion.
     * @method
     */
    removeAll: Ext.emptyFn,
    // individual store subclasses should implement a "fast" remove
    // and fire a clear event afterwards

    /**
     * Returns true if the Store is currently performing a load operation
     * @return {Boolean} True if the Store is currently loading
     */
    isLoading: function() {
        return !!this.loading;
    },

    /**
     * Suspends automatically syncing the Store with its Proxy.  Only applicable if {@link #autoSync} is `true`
     */
    suspendAutoSync: function() {
        this.autoSyncSuspended = true;
    },

    /**
     * Resumes automatically syncing the Store with its Proxy.  Only applicable if {@link #autoSync} is `true`
     */
    resumeAutoSync: function() {
        this.autoSyncSuspended = false;
    }

});