/**
 * @author mrdoob / http://mrdoob.com/
 */

var Storage = function () {

    var indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB;

    if (indexedDB === undefined) {

        console.warn('存储：IndexedDB不可用。');
        return { init: function () { }, get: function () { }, set: function () { }, clear: function () { } };

    }

    var name = 'threejs-editor';
    var version = 1;

    var database;

    return {

        init: function (callback) {

            var request = indexedDB.open(name, version);
            request.onupgradeneeded = function (event) {

                var db = event.target.result;

                if (db.objectStoreNames.contains('states') === false) {

                    db.createObjectStore('states');

                }

            };
            request.onsuccess = function (event) {

                database = event.target.result;

                callback();

            };
            request.onerror = function (event) {

                console.error('IndexedDB', event);

            };


        },

        get: function (callback) {

            var transaction = database.transaction(['states'], 'readwrite');
            var objectStore = transaction.objectStore('states');
            var request = objectStore.get(0);
            request.onsuccess = function (event) {

                callback(event.target.result);

            };

        },

        set: function (data, callback) {

            var start = performance.now();

            var transaction = database.transaction(['states'], 'readwrite');
            var objectStore = transaction.objectStore('states');
            var request = objectStore.put(data, 0);
            request.onsuccess = function (event) {

                console.log('[' + /\d\d\:\d\d\:\d\d/.exec(new Date())[0] + ']', '保存到IndexedDB中。 ' + (performance.now() - start).toFixed(2) + 'ms');

            };

        },

        clear: function () {

            if (database === undefined) return;

            var transaction = database.transaction(['states'], 'readwrite');
            var objectStore = transaction.objectStore('states');
            var request = objectStore.clear();
            request.onsuccess = function (event) {

                console.log('[' + /\d\d\:\d\d\:\d\d/.exec(new Date())[0] + ']', '清空IndexedDB。');

            };

        }

    };

};