$.store

/* Copyright (c) 2010 Marcus Westin
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

!function($) {
    $.store = (function(){
        var api = {},
            win = window,
            doc = win.document,
            localStorageName = 'localStorage',
            globalStorageName = 'globalStorage',
            storage

        api.disabled = false
        api.set = function(key, value) {}
        api.get = function(key) {}
        api.remove = function(key) {}
        api.clear = function() {}
        api.transact = function(key, transactionFn) {
            var val = api.get(key)
            if (typeof val == 'undefined') { val = {} }
            transactionFn(val)
            api.set(key, val)
        }

        api.serialize = function(value) {
            return JSON.stringify(value);
        }
        api.deserialize = function(value) {
            return (typeof value != 'string') ? undefined : JSON.parse(value);
        }

        // Functions to encapsulate questionable FireFox 3.6.13 behavior
        // when about.config::dom.storage.enabled === false
        // See https://github.com/marcuswestin/store.js/issues#issue/13
        function isLocalStorageNameSupported() {
            try { return (localStorageName in win && win[localStorageName]) }
            catch(err) { return false }
        }

        function isGlobalStorageNameSupported() {
            try { return (globalStorageName in win && win[globalStorageName] && win[globalStorageName][win.location.hostname]) }
            catch(err) { return false }
        }

        if (isLocalStorageNameSupported()) {
            storage = win[localStorageName]
            api.set = function(key, val) { storage.setItem(key, api.serialize(val)) }
            api.get = function(key) { return api.deserialize(storage.getItem(key)) }
            api.remove = function(key) { storage.removeItem(key) }
            api.clear = function() { storage.clear() }

        } else if (isGlobalStorageNameSupported()) {
            storage = win[globalStorageName][win.location.hostname]
            api.set = function(key, val) { storage[key] = api.serialize(val) }
            api.get = function(key) { return api.deserialize(storage[key] && storage[key].value) }
            api.remove = function(key) { delete storage[key] }
            api.clear = function() { for (var key in storage ) { delete storage[key] } }

        } else if (doc.documentElement.addBehavior) {
            var storage = doc.createElement('div');
            function withIEStorage(storeFunction) {
                return function() {
                    var args = Array.prototype.slice.call(arguments, 0);
                    args.unshift(storage);
                    // See http://msdn.microsoft.com/en-us/library/ms531081(v=VS.85).aspx
                    // and http://msdn.microsoft.com/en-us/library/ms531424(v=VS.85).aspx
                    doc.body.appendChild(storage);
                    storage.addBehavior('#default#userData');
                    storage.load(localStorageName);
                    var result = storeFunction.apply(api, args);
                    doc.body.removeChild(storage);
                    return result;
                }
            }
            api.set = withIEStorage(function(storage, key, val) {
                storage.setAttribute(key, api.serialize(val));
                storage.save(localStorageName);
            })
            api.get = withIEStorage(function(storage, key) {
                return api.deserialize(storage.getAttribute(key));
            })
            api.remove = withIEStorage(function(storage, key) {
                storage.removeAttribute(key);
                storage.save(localStorageName);
            })
            api.clear = withIEStorage(function(storage) {
                var attributes = storage.XMLDocument.documentElement.attributes;
                storage.load(localStorageName);
                for (var i=0, attr; attr = attributes[i]; i++) {
                    storage.removeAttribute(attr.name);
                }
                storage.save(localStorageName);
            })
        } else {
            api.disabled = true;
        }

        return api
    })();
}(jQuery || Zepto);