/**
 * @class Ext.util.Stateful
 * @extends Ext.util.Observable
 * Represents any object whose data can be saved by a {@link Ext.data.Proxy Proxy}. Ext.Model
 * and Ext.View both inherit from this class as both can save state (Models save field state, 
 * Views save configuration)
 */
Ext.util.Stateful = Ext.extend(Ext.util.Observable, {
    
    
/**
     * Internal flag used to track whether or not the model instance is currently being edited. Read-only
     * @property editing
     * @type Boolean
     */
    editing : false,
    
    
/**
     * Readonly flag - true if this Record has been modified.
     * @type Boolean
     */
    dirty : false,
    
    
/**
     * @cfg {String} persistanceProperty The property on this Persistable object that its data is saved to.
     * Defaults to 'data' (e.g. all persistable data resides in this.data.)
     */
    persistanceProperty: 'data',
    
    constructor: function(config) {
        Ext.applyIf(this, {
            data: {}
        });        
        
        
/**
         * Key: value pairs of all fields whose values have changed
         * @property modified
         * @type Object
         */
        this.modified = {};
        
        this[this.persistanceProperty] = {};
        
        Ext.util.Stateful.superclass.constructor.call(this, config);
    },
    
    
/**
     * Returns the value of the given field
     * @param {String} fieldName The field to fetch the value for
     * @return {Mixed} The value
     */
    get: function(field) {
        return this[this.persistanceProperty][field];
    },
    
    
/**
     * Sets the given field to the given value, marks the instance as dirty
     * @param {String|Object} fieldName The field to set, or an object containing key/value pairs
     * @param {Mixed} value The value to set
     */
    set: function(fieldName, value) {
        var fields = this.fields,
            field, key;
        
        if (arguments.length == 1 && Ext.isObject(fieldName)) {
            for (key in fieldName) {
                if (!fieldName.hasOwnProperty(key)) {
                    continue;
                }
                this.set(key, fieldName[key]);
            }
        } else {
            if (fields) {
                field = fields.get(fieldName);
                
                if (field && field.convert) {
                    value = field.convert(value, this);
                }
            }
            
            this[this.persistanceProperty][fieldName] = value;

            this.dirty = true;

            if (!this.editing) {
                this.afterEdit();
            }
        }
    },
    
    
/**
     * Gets a hash of only the fields that have been modified since this Model was created or commited.
     * @return Object
     */
    getChanges : function(){
        var modified = this.modified,
            changes  = {},
            field;
            
        for (field in modified) {
            if (modified.hasOwnProperty(field)){
                changes[field] = this[this.persistanceProperty][field];
            }
        }
        
        return changes;
    },
    
    
/**
     * Returns true if the passed field name has been {@link #modified}
     * since the load or last commit.
     * @param {String} fieldName {@link Ext.data.Field#name}
     * @return {Boolean}
     */
    isModified : function(fieldName) {
        return !!(this.modified && this.modified.hasOwnProperty(fieldName));
    },
    
    
/**
     * 
Marks this Record as {@link #dirty}.  This method
     * is used interally when adding {@link #phantom} records to a
     * {@link Ext.data.Store#writer writer enabled store}.
     * 
Marking a record {@link #dirty} causes the phantom to
     * be returned by {@link Ext.data.Store#getModifiedRecords} where it will
     * have a create action composed for it during {@link Ext.data.Store#save store save}
     * operations.
     */
    setDirty : function() {
        this.dirty = true;
        
        if (!this.modified) {
            this.modified = {};
        }
        
        this.fields.each(function(field) {
            this.modified[field.name] = this[this.persistanceProperty][field.name];
        }, this);
    },
    
    //
    markDirty : function() {
        throw "Stateful: markDirty has been deprecated. Please use setDirty.";
    },
    //
    
    
/**
     * Usually called by the {@link Ext.data.Store} to which this model instance has been {@link #join joined}.
     * Rejects all changes made to the model instance since either creation, or the last commit operation.
     * Modified fields are reverted to their original values.
     * 
Developers should subscribe to the {@link Ext.data.Store#update} event
     * to have their code notified of reject operations.
     * @param {Boolean} silent (optional) True to skip notification of the owning
     * store of the change (defaults to false)
     */
    reject : function(silent) {
        var modified = this.modified,
            field;
            
        for (field in modified) {
            if (!modified.hasOwnProperty(field)) {
                continue;
            }
            if (typeof modified[field] != "function") {
                this[this.persistanceProperty][field] = modified[field];
            }
        }
        
        this.dirty = false;
        this.editing = false;
        delete this.modified;
        
        if (silent !== true) {
            this.afterReject();
        }
    },
    
    
/**
     * Usually called by the {@link Ext.data.Store} which owns the model instance.
     * Commits all changes made to the instance since either creation or the last commit operation.
     * 
Developers should subscribe to the {@link Ext.data.Store#update} event
     * to have their code notified of commit operations.
     * @param {Boolean} silent (optional) True to skip notification of the owning
     * store of the change (defaults to false)
     */
    commit : function(silent) {
        this.dirty = false;
        this.editing = false;
        
        delete this.modified;
        
        if (silent !== true) {
            this.afterCommit();
        }
    },
    
    
/**
     * Creates a copy (clone) of this Model instance.
     * @param {String} id (optional) A new id, defaults to the id
     * of the instance being copied. See {@link #id}. 
     * To generate a phantom instance with a new id use:

var rec = record.copy(); // clone the record
Ext.data.Model.id(rec); // automatically generate a unique sequential id
     * 
     * @return {Record}
     */
    copy : function(newId) {
        return new this.constructor(Ext.apply({}, this[this.persistanceProperty]), newId || this.internalId);
    }
});