YUI.add('model-sync-local', function (Y, NAME) {

/*

An extension which provides a sync implementation through locally stored

key value pairs, either through the HTML localStorage API or falling back

onto an in-memory cache, that can be mixed into a Model or ModelList subclass.

@module app

@submodule model-sync-local

@since 3.13.0

**/

/**

An extension which provides a sync implementation through locally stored

key value pairs, either through the HTML localStorage API or falling back

onto an in-memory cache, that can be mixed into a Model or ModelList subclass.

A group of Models/ModelLists is serialized in localStorage by either its

class name, or a specified 'root' that is provided.

    var User = Y.Base.create('user', Y.Model, [Y.ModelSync.Local], {

        root: 'user'

    });

    var Users = Y.Base.create('users', Y.ModelList, [Y.ModelSync.Local], {

        model: User,

    });

@class ModelSync.Local

@extensionfor Model

@extensionfor ModelList

@since 3.13.0

**/

function LocalSync() {}

/**

Properties that shouldn't be turned into ad-hoc attributes when passed to a

Model or ModelList constructor.

@property _NON_ATTRS_CFG

@type Array

@default ['root']

@static

@protected

@since 3.13.0

**/

LocalSync._NON_ATTRS_CFG = ['root'];

/**

Feature testing for `localStorage` availability.

Will return falsey for browsers with `localStorage`, but that don't

actually work, such as iOS Safari in private browsing mode.

@property _hasLocalStorage

@type Boolean

@private

**/

LocalSync._hasLocalStorage = (function () {

    var LS   = Y.config.win.localStorage,

        test = Y.guid();

    try {

        LS.setItem(test, test);

        LS.removeItem(test);

        return true;

    } catch (e) {

        return false;

    }

})(),

/**

Object of key/value pairs to fall back on when localStorage is not available.

@property _data

@type Object

@private

**/

LocalSync._data = LocalSync._data || {};

/**

Cache to quickly access a specific object with a given ID.

@property _store

@type Array

@private

**/

LocalSync._store = LocalSync._store || {};

LocalSync.prototype = {

    // -- Public Methods -------------------------------------------------------

    /**

    Root used as the key inside of localStorage and/or the in-memory store.

    @property root

    @type String

    @default ""

    @since 3.13.0

    **/

    root: '',

    /**

    Shortcut for access to localStorage.

    @property storage

    @type Storage

    @default null

    @since 3.13.0

    **/

    storage: null,

    // -- Lifecycle Methods -----------------------------------------------------

    initializer: function (config) {

        var store, data;

        config || (config = {});

        if ('root' in config) {

            this.root = config.root || '';

        }

        // This is checking to see if the sync layer is being applied to

        // a ModelList, and if so, is looking for a `root` property on its

        // Model's prototype instead.

        if (!this.root && this.model && this.model.prototype.root) {

            this.root = this.model.prototype.root;

        }

        if (LocalSync._hasLocalStorage) {

            this.storage = Y.config.win.localStorage;

            store = this.storage.getItem(this.root);

        } else {

            Y.log("Could not access localStorage.", "warn");

        }

        // Pull in existing data from localStorage, if possible.

        // Otherwise, see if there's existing data on the local cache.

        if (store) {

            LocalSync._store[this.root] = store.split('|') || [];

            Y.Array.each(LocalSync._store[this.root], function (id) {

                LocalSync._data[id] = Y.JSON.parse(this.storage.getItem(id));

            }, this);

        } else {

            LocalSync._store[this.root] || (LocalSync._store[this.root] = []);

        }

    },

    // -- Public Methods -----------------------------------------------------------

    /**

    Creates a synchronization layer with the localStorage API, if available.

    Otherwise, falls back to a in-memory data store.

    This method is called internally by load(), save(), and destroy().

    @method sync

    @param {String} action Sync action to perform. May be one of the following:

      * **create**: Store a newly-created model for the first time.

      * **read**  : Load an existing model.

      * **update**: Update an existing model.

      * **delete**: Delete an existing model.

    @param {Object} [options] Sync options

    @param {Function} [callback] Called when the sync operation finishes.

      @param {Error|null} callback.err If an error occurred, this parameter will

        contain the error. If the sync operation succeeded, _err_ will be

        falsey.

      @param {Any} [callback.response] The response from our sync. This value will

        be passed to the parse() method, which is expected to parse it and

        return an attribute hash.

    **/

    sync: function (action, options, callback) {

        options || (options = {});

        var response, errorInfo;

        try {

            switch (action) {

                case 'read':

                    if (this._isYUIModelList) {

                        response = this._index(options);

                    } else {

                        response = this._show(options);

                    }

                    break;

                case 'create':

                    response = this._create(options);

                    break;

                case 'update':

                    response = this._update(options);

                    break;

                case 'delete':

                    response = this._destroy(options);

                    break;

            }

        } catch (error) {

            errorInfo = error.message;

        }

        if (response) {

            callback(null, response);

        } else if (errorInfo) {

            callback(errorInfo);

        } else {

            callback("Data not found in LocalStorage");

        }

    },

    /**

    Generate a random GUID for our Models. This can be overriden if you have

    another method of generating different IDs.

    @method generateID

    @protected

    @param {String} pre Optional GUID prefix

    **/

    generateID: function (pre) {

        return Y.guid(pre + '_');

    },

    // -- Protected Methods ----------------------------------------------------

    /**

    Sync method correlating to the "read" operation, for a Model List

    @method _index

    @return {Object[]} Array of objects found for that root key

    @protected

    @since 3.13.0

    **/

    _index: function () {

        var store = LocalSync._store[this.root],

            data  = Y.Array.map(store, function (id) {

                return LocalSync._data[id];

            });

        return data;

    },

    /**

    Sync method correlating to the "read" operation, for a Model

    @method _show

    @return {Object} Object found for that root key and model ID

    @protected

    @since 3.13.0

    **/

    _show: function () {

        return LocalSync._data[this.get('id')] || null;

    },

    /**

    Sync method correlating to the "create" operation

    @method _show

    @return {Object} The new object created.

    @protected

    @since 3.13.0

    **/

    _create: function () {

        var hash  = this.toJSON();

        hash.id = this.generateID(this.root);

        LocalSync._data[hash.id] = hash;

        if (this.storage) {

            this.storage.setItem(hash.id, hash);

        }

        LocalSync._store[this.root].push(hash.id);

        this._save();

        return hash;

    },

    /**

    Sync method correlating to the "update" operation

    @method _update

    @return {Object} The updated object.

    @protected

    @since 3.13.0

    **/

    _update: function () {

        var hash = this.toJSON(),

            id = this.get('id');

        LocalSync._data[id] = hash;

        if (this.storage) {

            this.storage.setItem(id, hash);

        }

        if (Y.Array.indexOf(LocalSync._store[this.root], id) === -1) {

            LocalSync._store[this.root].push(id);

        }

        this._save();

        return hash;

    },

    /**

    Sync method correlating to the "delete" operation.  Deletes the data

    from the in-memory object, and saves into localStorage if available.

    @method _destroy

    @protected

    @since 3.13.0

    **/

    _destroy: function () {

        var id = this.get('id'),

            storage = this.storage;

        if (!LocalSync._data[id]) {

            return;

        }

        delete LocalSync._data[id];

        if (storage) {

            storage.removeItem(id);

        }

        LocalSync._store[this.root] = Y.Array.filter(LocalSync._store[this.root], function (item) {

            return item.id != id;

        });

        this._save();

        return this.toJSON();

    },

    /**

    Saves the current in-memory store into a localStorage key/value pair

    if localStorage is available; otherwise, does nothing.

    @method _save

    @protected

    @since 3.13.0

    **/

    _save: function () {

        if (LocalSync._hasLocalStorage && this.storage) {

            this.storage.setItem(

                this.root,

                LocalSync._store[this.root].join('|')

            );

        }

    }

};

// -- Namespace ---------------------------------------------------------------

Y.namespace('ModelSync').Local = LocalSync;

}, '@VERSION@', {"requires": ["model", "json-stringify"]});