text: // Copyright 2011 The Closure Library Authors. All Rights Reserved.
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //      http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS-IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  /**
   * @fileoverview Wrappers for the HTML5 IndexedDB. The wrappers export nearly
   * the same interface as the standard API, but return goog.async.Deferred
   * objects instead of request objects and use Closure events. The wrapper works
   * and has been tested on Chrome version 22+. It may work on older Chrome
   * versions, but they aren't explicitly supported.
   *
   * Example usage:
   *
   *  <code>
   *  goog.db.openDatabase('mydb', 1, function(ev, db, tx) {
   *    db.createObjectStore('mystore');
   *  }).addCallback(function(db) {
   *    var putTx = db.createTransaction(
   *        [],
   *        goog.db.Transaction.TransactionMode.READ_WRITE);
   *    var store = putTx.objectStore('mystore');
   *    store.put('value', 'key');
   *    goog.listen(putTx, goog.db.Transaction.EventTypes.COMPLETE, function() {
   *      var getTx = db.createTransaction([]);
   *      var request = getTx.objectStore('mystore').get('key');
   *      request.addCallback(function(result) {
   *        ...
   *      });
   *  });
   *  </code>
   *
   */
  
  
  goog.provide('goog.db');
  
  goog.require('goog.async.Deferred');
  goog.require('goog.db.Error');
  goog.require('goog.db.IndexedDb');
  goog.require('goog.db.Transaction');
  
  
  /**
   * The IndexedDB factory object.
   *
   * @type {IDBFactory}
   * @private
   */
  goog.db.indexedDb_ = goog.global.indexedDB || goog.global.mozIndexedDB ||
      goog.global.webkitIndexedDB || goog.global.moz_indexedDB;
  
  
  /**
   * A callback that's called if a blocked event is received. When a database is
   * supposed to be deleted or upgraded (i.e. versionchange), and there are open
   * connections to this database, a block event will be fired to prevent the
   * operations from going through until all such open connections are closed.
   * This callback can be used to notify users that they should close other tabs
   * that have open connections, or to close the connections manually. Databases
   * can also listen for the {@link goog.db.IndexedDb.EventType.VERSION_CHANGE}
   * event to automatically close themselves when they're blocking such
   * operations.
   *
   * This is passed a VersionChangeEvent that has the version of the database
   * before it was deleted, and "null" as the new version.
   *
   * @typedef {function(!goog.db.IndexedDb.VersionChangeEvent)}
   */
  goog.db.BlockedCallback;
  
  
  /**
   * A callback that's called when opening a database whose internal version is
   * lower than the version passed to {@link goog.db.openDatabase}.
   *
   * This callback is passed three arguments: a VersionChangeEvent with both the
   * old version and the new version of the database; the database that's being
   * opened, for which you can create and delete object stores; and the version
   * change transaction, with which you can abort the version change.
   *
   * Note that the transaction is not active, which means that it can't be used to
   * make changes to the database. However, since there is a transaction running,
   * you can't create another one via {@link goog.db.IndexedDb.createTransaction}.
   * This means that it's not possible to manipulate the database other than
   * creating or removing object stores in this callback.
   *
   * @typedef {function(!goog.db.IndexedDb.VersionChangeEvent,
   *                    !goog.db.IndexedDb,
   *                    !goog.db.Transaction)}
   */
  goog.db.UpgradeNeededCallback;
  
  
  /**
   * Opens a database connection and wraps it.
   *
   * @param {string} name The name of the database to open.
   * @param {number=} opt_version The expected version of the database. If this is
   *     larger than the actual version, opt_onUpgradeNeeded will be called
   *     (possibly after opt_onBlocked; see {@link goog.db.BlockedCallback}). If
   *     this is passed, opt_onUpgradeNeeded must be passed as well.
   * @param {goog.db.UpgradeNeededCallback=} opt_onUpgradeNeeded Called if
   *     opt_version is greater than the old version of the database. If
   *     opt_version is passed, this must be passed as well.
   * @param {goog.db.BlockedCallback=} opt_onBlocked Called if there are active
   *     connections to the database.
   * @return {!goog.async.Deferred} The deferred database object.
   */
  goog.db.openDatabase = function(name, opt_version, opt_onUpgradeNeeded,
                                  opt_onBlocked) {
    goog.asserts.assert(
        goog.isDef(opt_version) == goog.isDef(opt_onUpgradeNeeded),
        'opt_version must be passed to goog.db.openDatabase if and only if ' +
            'opt_onUpgradeNeeded is also passed');
  
    var d = new goog.async.Deferred();
    var openRequest = opt_version ?
        goog.db.indexedDb_.open(name, opt_version) :
        goog.db.indexedDb_.open(name);
    openRequest.onsuccess = function(ev) {
      var db = new goog.db.IndexedDb(ev.target.result);
      d.callback(db);
    };
    openRequest.onerror = function(ev) {
      var msg = 'opening database ' + name;
      d.errback(goog.db.Error.fromRequest(ev.target, msg));
    };
    openRequest.onupgradeneeded = function(ev) {
      if (!opt_onUpgradeNeeded) return;
      var db = new goog.db.IndexedDb(ev.target.result);
      opt_onUpgradeNeeded(
          new goog.db.IndexedDb.VersionChangeEvent(ev.oldVersion, ev.newVersion),
          db,
          new goog.db.Transaction(ev.target.transaction, db));
    };
    openRequest.onblocked = function(ev) {
      if (opt_onBlocked) {
        opt_onBlocked(new goog.db.IndexedDb.VersionChangeEvent(
            ev.oldVersion, ev.newVersion));
      }
    };
    return d;
  };
  
  
  /**
   * Deletes a database once all open connections have been closed.
   *
   * @param {string} name The name of the database to delete.
   * @param {goog.db.BlockedCallback=} opt_onBlocked Called if there are active
   *     connections to the database.
   * @return {!goog.async.Deferred} A deferred object that will fire once the
   *     database is deleted.
   */
  goog.db.deleteDatabase = function(name, opt_onBlocked) {
    var d = new goog.async.Deferred();
    var deleteRequest = goog.db.indexedDb_.deleteDatabase(name);
    deleteRequest.onsuccess = function(ev) {
      d.callback();
    };
    deleteRequest.onerror = function(ev) {
      var msg = 'deleting database ' + name;
      d.errback(goog.db.Error.fromRequest(ev.target, msg));
    };
    deleteRequest.onblocked = function(ev) {
      if (opt_onBlocked) {
        opt_onBlocked(new goog.db.IndexedDb.VersionChangeEvent(
            ev.oldVersion, ev.newVersion));
      }
    };
    return d;
  };
  