/**
 * @class Ext.state.Stateful
 * A mixin for being able to save the state of an object to an underlying 
 * {@link Ext.state.Provider}.
 */
Ext.define('Ext.state.Stateful', {
    
    /* Begin Definitions */
   
   mixins: {
        observable: 'Ext.util.Observable'
    },
    
    requires: ['Ext.state.Manager'],
    
    /* End Definitions */
    
    /**
     * @cfg {Boolean} stateful
     * <p>A flag which causes the object to attempt to restore the state of
     * internal properties from a saved state on startup. The object must have
     * a <code>{@link #stateId}</code> for state to be managed. 
     * Auto-generated ids are not guaranteed to be stable across page loads and 
     * cannot be relied upon to save and restore the same state for a object.<p>
     * <p>For state saving to work, the state manager's provider must have been
     * set to an implementation of {@link Ext.state.Provider} which overrides the
     * {@link Ext.state.Provider#set set} and {@link Ext.state.Provider#get get}
     * methods to save and recall name/value pairs. A built-in implementation,
     * {@link Ext.state.CookieProvider} is available.</p>
     * <p>To set the state provider for the current page:</p>
     * <pre><code>
Ext.state.Manager.setProvider(new Ext.state.CookieProvider({
    expires: new Date(new Date().getTime()+(1000*60*60*24*7)), //7 days from now
}));
     * </code></pre>
     * <p>A stateful object attempts to save state when one of the events
     * listed in the <code>{@link #stateEvents}</code> configuration fires.</p>
     * <p>To save state, a stateful object first serializes its state by
     * calling <b><code>{@link #getState}</code></b>. By default, this function does
     * nothing. The developer must provide an implementation which returns an
     * object hash which represents the restorable state of the object.</p>
     * <p>The value yielded by getState is passed to {@link Ext.state.Manager#set}
     * which uses the configured {@link Ext.state.Provider} to save the object
     * keyed by the <code>{@link stateId}</code></p>.
     * <p>During construction, a stateful object attempts to <i>restore</i>
     * its state by calling {@link Ext.state.Manager#get} passing the
     * <code>{@link #stateId}</code></p>
     * <p>The resulting object is passed to <b><code>{@link #applyState}</code></b>.
     * The default implementation of <code>{@link #applyState}</code> simply copies
     * properties into the object, but a developer may override this to support
     * more behaviour.</p>
     * <p>You can perform extra processing on state save and restore by attaching
     * handlers to the {@link #beforestaterestore}, {@link #staterestore},
     * {@link #beforestatesave} and {@link #statesave} events.</p>
     */
    stateful: true,
    
    /**
     * @cfg {String} stateId
     * The unique id for this object to use for state management purposes.
     * <p>See {@link #stateful} for an explanation of saving and restoring state.</p>
     */
    
    /**
     * @cfg {Array} stateEvents
     * <p>An array of events that, when fired, should trigger this object to
     * save its state (defaults to none). <code>stateEvents</code> may be any type
     * of event supported by this object, including browser or custom events
     * (e.g., <tt>['click', 'customerchange']</tt>).</p>
     * <p>See <code>{@link #stateful}</code> for an explanation of saving and
     * restoring object state.</p>
     */
    
    /**
     * @cfg {Number} saveBuffer A buffer to be applied if many state events are fired within
     * a short period. Defaults to 100.
     */
    saveDelay: 100,
    
    autoGenIdRe: /^((\w+-)|(ext-comp-))\d{4,}$/i,
    
    constructor: function(config) {
        var me = this;
        
        config = config || {};
        if (Ext.isDefined(config.stateful)) {
            me.stateful = config.stateful;
        }
        if (Ext.isDefined(config.saveDelay)) {
            me.saveDelay = config.saveDelay;
        }
        me.stateId = config.stateId;
        
        if (!me.stateEvents) {
            me.stateEvents = [];
        }
        if (config.stateEvents) {
            me.stateEvents.concat(config.stateEvents);
        }
        this.addEvents(
            /**
             * @event beforestaterestore
             * Fires before the state of the object is restored. Return false from an event handler to stop the restore.
             * @param {Ext.state.Stateful} this
             * @param {Object} state The hash of state values returned from the StateProvider. If this
             * event is not vetoed, then the state object is passed to <b><tt>applyState</tt></b>. By default,
             * that simply copies property values into this object. The method maybe overriden to
             * provide custom state restoration.
             */
            'beforestaterestore',
            
            /**
             * @event staterestore
             * Fires after the state of the object is restored.
             * @param {Ext.state.Stateful} this
             * @param {Object} state The hash of state values returned from the StateProvider. This is passed
             * to <b><tt>applyState</tt></b>. By default, that simply copies property values into this
             * object. The method maybe overriden to provide custom state restoration.
             */
            'staterestore',
            
            /**
             * @event beforestatesave
             * Fires before the state of the object is saved to the configured state provider. Return false to stop the save.
             * @param {Ext.state.Stateful} this
             * @param {Object} state The hash of state values. This is determined by calling
             * <b><tt>getState()</tt></b> on the object. This method must be provided by the
             * developer to return whetever representation of state is required, by default, Ext.state.Stateful
             * has a null implementation.
             */
            'beforestatesave',
            
            /**
             * @event statesave
             * Fires after the state of the object is saved to the configured state provider.
             * @param {Ext.state.Stateful} this
             * @param {Object} state The hash of state values. This is determined by calling
             * <b><tt>getState()</tt></b> on the object. This method must be provided by the
             * developer to return whetever representation of state is required, by default, Ext.state.Stateful
             * has a null implementation.
             */
            'statesave'
        );
        me.mixins.observable.constructor.call(me);
        if (me.stateful !== false) {
            me.initStateEvents();
            me.initState();
        }
    },
    
    /**
     * Initializes any state events for this object.
     * @private
     */
    initStateEvents: function() {
        this.addStateEvents(this.stateEvents);
    },
    
    /**
     * Add events that will trigger the state to be saved.
     * @param {String/Array} events The event name or an array of event names.
     */
    addStateEvents: function(events){
        if (!Ext.isArray(events)) {
            events = [events];
        }
        
        var me = this,
            i = 0,
            len = events.length;
            
        for (; i < len; ++i) {
            me.on(events[i], me.onStateChange, me);
        }
    },
    
    /**
     * This method is called when any of the {@link #stateEvents} are fired.
     * @private
     */
    onStateChange: function(){
        var me = this,
            delay = me.saveDelay;
        
        if (delay > 0) {
            if (!me.stateTask) {
                me.stateTask = Ext.create('Ext.util.DelayedTask', me.saveState, me);
            }
            me.stateTask.delay(me.saveDelay);
        } else {
            me.saveState();
        }
    },
    
    /**
     * Saves the state of the object to the persistence store.
     * @private
     */
    saveState: function() {
        var me = this,
            id,
            state;
        
        if (me.stateful !== false) {
            id = me.getStateId();
            if (id) {
                state = me.getState();
                if (me.fireEvent('beforestatesave', me, state) !== false) {
                    Ext.state.Manager.set(id, state);
                    me.fireEvent('statesave', me, state);
                }
            }
        }
    },
    
    /**
     * Gets the current state of the object. By default this function returns null,
     * it should be overridden in subclasses to implement methods for getting the state.
     * @return {Object} The current state
     */
    getState: function(){
        return null;    
    },
    
    /**
     * Applies the state to the object. This should be overridden in subclasses to do
     * more complex state operations. By default it applies the state properties onto
     * the current object.
     * @param {Object} state The state
     */
    applyState: function(state) {
        if (state) {
            Ext.apply(this, state);
        }
    },
    
    /**
     * Gets the state id for this object.
     * @return {String} The state id, null if not found.
     */
    getStateId: function() {
        var me = this,
            id = me.stateId;
        
        if (!id) {
            id = me.autoGenIdRe.test(String(me.id)) ? null : me.id;
        }
        return id;
    },
    
    /**
     * Initializes the state of the object upon construction.
     * @private
     */
    initState: function(){
        var me = this,
            id = me.getStateId(),
            state;
            
        if (me.stateful !== false) {
            if (id) {
                state = Ext.state.Manager.get(id);
                if (state) {
                    state = Ext.apply({}, state);
                    if (me.fireEvent('beforestaterestore', me, state) !== false) {
                        me.applyState(state);
                        me.fireEvent('staterestore', me, state);
                    }
                }
            }
        }
    },
    
    /**
     * Destroys this stateful object.
     */
    destroy: function(){
        var task = this.stateTask;
        if (task) {
            task.cancel();
        }
        this.clearListeners();
        
    }
    
});
