/**
 * @author Ed Spencer
 * @aside guide proxies
 *
 * The LocalStorageProxy uses the new HTML5 localStorage API to save {@link Ext.data.Model Model} data locally on the
 * client browser. HTML5 localStorage is a key-value store (e.g. cannot save complex objects like JSON), so
 * LocalStorageProxy automatically serializes and deserializes data when saving and retrieving it.
 *
 * localStorage is extremely useful for saving user-specific information without needing to build server-side
 * infrastructure to support it. Let's imagine we're writing a Twitter search application and want to save the user's
 * searches locally so they can easily perform a saved search again later. We'd start by creating a Search model:
 *
 *     Ext.define('Search', {
 *         extend: 'Ext.data.Model',
 *         config: {
 *             fields: ['id', 'query'],
 *             proxy: {
 *                 type: 'localstorage',
 *                 id  : 'twitter-Searches'
 *             }
 *         }
 *     });
 *
 * Our Search model contains just two fields - id and query - plus a Proxy definition. The only configuration we need to
 * pass to the LocalStorage proxy is an {@link #id}. This is important as it separates the Model data in this Proxy from
 * all others. The localStorage API puts all data into a single shared namespace, so by setting an id we enable
 * LocalStorageProxy to manage the saved Search data.
 *
 * Saving our data into localStorage is easy and would usually be done with a {@link Ext.data.Store Store}:
 *
 *     //our Store automatically picks up the LocalStorageProxy defined on the Search model
 *     var store = Ext.create('Ext.data.Store', {
 *         model: "Search"
 *     });
 *
 *     //loads any existing Search data from localStorage
 *     store.load();
 *
 *     //now add some Searches
 *     store.add({query: 'Sencha Touch'});
 *     store.add({query: 'Ext JS'});
 *
 *     //finally, save our Search data to localStorage
 *     store.sync();
 *
 * The LocalStorageProxy automatically gives our new Searches an id when we call store.sync(). It encodes the Model data
 * and places it into localStorage. We can also save directly to localStorage, bypassing the Store altogether:
 *
 *     var search = Ext.create('Search', {query: 'Sencha Animator'});
 *
 *     //uses the configured LocalStorageProxy to save the new Search to localStorage
 *     search.save();
 *
 * # Limitations
 *
 * If this proxy is used in a browser where local storage is not supported, the constructor will throw an error. A local
 * storage proxy requires a unique ID which is used as a key in which all record data are stored in the local storage
 * object.
 *
 * It's important to supply this unique ID as it cannot be reliably determined otherwise. If no id is provided but the
 * attached store has a storeId, the storeId will be used. If neither option is presented the proxy will throw an error.
 */
Ext.define('Ext.data.proxy.LocalStorage', {
    extend: 'Ext.data.proxy.WebStorage',
    alias: 'proxy.localstorage',
    alternateClassName: 'Ext.data.LocalStorageProxy',

    //inherit docs
    getStorageObject: function() {
        return window.localStorage;
    }
});
