michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: "use strict";
michael@0: 
michael@0: this.EXPORTED_SYMBOLS = ["SessionMigration"];
michael@0: 
michael@0: const Cu = Components.utils;
michael@0: Cu.import("resource://gre/modules/XPCOMUtils.jsm", this);
michael@0: Cu.import("resource://gre/modules/Task.jsm", this);
michael@0: Cu.import("resource://gre/modules/osfile.jsm", this);
michael@0: 
michael@0: // An encoder to UTF-8.
michael@0: XPCOMUtils.defineLazyGetter(this, "gEncoder", function () {
michael@0:   return new TextEncoder();
michael@0: });
michael@0: 
michael@0: // A decoder.
michael@0: XPCOMUtils.defineLazyGetter(this, "gDecoder", function () {
michael@0:   return new TextDecoder();
michael@0: });
michael@0: 
michael@0: let SessionMigrationInternal = {
michael@0:   /**
michael@0:    * Convert the original session restore state into a minimal state. It will
michael@0:    * only contain:
michael@0:    * - open windows
michael@0:    *   - with tabs
michael@0:    *     - with history entries with only title, url
michael@0:    *     - with pinned state
michael@0:    *     - with tab group info (hidden + group id)
michael@0:    *     - with selected tab info
michael@0:    *   - with selected window info
michael@0:    *   - with tabgroups info
michael@0:    *
michael@0:    * The complete state is then wrapped into the "about:welcomeback" page as
michael@0:    * form field info to be restored when restoring the state.
michael@0:    */
michael@0:   convertState: function(aStateObj) {
michael@0:     let state = {
michael@0:       selectedWindow: aStateObj.selectedWindow,
michael@0:       _closedWindows: []
michael@0:     };
michael@0:     state.windows = aStateObj.windows.map(function(oldWin) {
michael@0:       var win = {extData: {}};
michael@0:       win.tabs = oldWin.tabs.map(function(oldTab) {
michael@0:         var tab = {};
michael@0:         // Keep only titles and urls for history entries
michael@0:         tab.entries = oldTab.entries.map(function(entry) {
michael@0:           return {url: entry.url, title: entry.title};
michael@0:         });
michael@0:         tab.index = oldTab.index;
michael@0:         tab.hidden = oldTab.hidden;
michael@0:         tab.pinned = oldTab.pinned;
michael@0:         // The tabgroup info is in the extData, so we need to get it out.
michael@0:         if (oldTab.extData && "tabview-tab" in oldTab.extData) {
michael@0:           tab.extData = {"tabview-tab": oldTab.extData["tabview-tab"]};
michael@0:         }
michael@0:         return tab;
michael@0:       });
michael@0:       // There are various tabgroup-related attributes that we need to get out
michael@0:       // of the session restore data for the window, too.
michael@0:       if (oldWin.extData) {
michael@0:         for (let k of Object.keys(oldWin.extData)) {
michael@0:           if (k.startsWith("tabview-")) {
michael@0:             win.extData[k] = oldWin.extData[k];
michael@0:           }
michael@0:         }
michael@0:       }
michael@0:       win.selected = oldWin.selected;
michael@0:       win._closedTabs = [];
michael@0:       return win;
michael@0:     });
michael@0:     let wrappedState = {
michael@0:       url: "about:welcomeback",
michael@0:       formdata: {
michael@0:         id: {"sessionData": state},
michael@0:         xpath: {}
michael@0:       }
michael@0:     };
michael@0:     return {windows: [{tabs: [{entries: [wrappedState]}]}]};
michael@0:   },
michael@0:   /**
michael@0:    * Asynchronously read session restore state (JSON) from a path
michael@0:    */
michael@0:   readState: function(aPath) {
michael@0:     return Task.spawn(function() {
michael@0:       let bytes = yield OS.File.read(aPath);
michael@0:       let text = gDecoder.decode(bytes);
michael@0:       let state = JSON.parse(text);
michael@0:       throw new Task.Result(state);
michael@0:     });
michael@0:   },
michael@0:   /**
michael@0:    * Asynchronously write session restore state as JSON to a path
michael@0:    */
michael@0:   writeState: function(aPath, aState) {
michael@0:     let bytes = gEncoder.encode(JSON.stringify(aState));
michael@0:     return OS.File.writeAtomic(aPath, bytes, {tmpPath: aPath + ".tmp"});
michael@0:   }
michael@0: }
michael@0: 
michael@0: let SessionMigration = {
michael@0:   /**
michael@0:    * Migrate a limited set of session data from one path to another.
michael@0:    */
michael@0:   migrate: function(aFromPath, aToPath) {
michael@0:     return Task.spawn(function() {
michael@0:       let inState = yield SessionMigrationInternal.readState(aFromPath);
michael@0:       let outState = SessionMigrationInternal.convertState(inState);
michael@0:       // Unfortunately, we can't use SessionStore's own SessionFile to
michael@0:       // write out the data because it has a dependency on the profile dir
michael@0:       // being known. When the migration runs, there is no guarantee that
michael@0:       // that's true.
michael@0:       yield SessionMigrationInternal.writeState(aToPath, outState);
michael@0:     });
michael@0:   }
michael@0: };