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 = ["CustomizationTabPreloader"];
michael@0: 
michael@0: const Cu = Components.utils;
michael@0: const Cc = Components.classes;
michael@0: const Ci = Components.interfaces;
michael@0: 
michael@0: Cu.import("resource://gre/modules/Services.jsm");
michael@0: Cu.import("resource://gre/modules/Promise.jsm");
michael@0: 
michael@0: const HTML_NS = "http://www.w3.org/1999/xhtml";
michael@0: const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
michael@0: const XUL_PAGE = "data:application/vnd.mozilla.xul+xml;charset=utf-8,<window%20id='win'/>";
michael@0: const CUSTOMIZATION_URL = "about:customizing";
michael@0: 
michael@0: // The interval between swapping in a preload docShell and kicking off the
michael@0: // next preload in the background.
michael@0: const PRELOADER_INTERVAL_MS = 600;
michael@0: 
michael@0: function createTimer(obj, delay) {
michael@0:   let timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
michael@0:   timer.init(obj, delay, Ci.nsITimer.TYPE_ONE_SHOT);
michael@0:   return timer;
michael@0: }
michael@0: 
michael@0: function clearTimer(timer) {
michael@0:   if (timer) {
michael@0:     timer.cancel();
michael@0:   }
michael@0:   return null;
michael@0: }
michael@0: 
michael@0: this.CustomizationTabPreloader = {
michael@0:   uninit: function () {
michael@0:     CustomizationTabPreloaderInternal.uninit();
michael@0:   },
michael@0: 
michael@0:   newTab: function (aTab) {
michael@0:     return CustomizationTabPreloaderInternal.newTab(aTab);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * ensurePreloading starts the preloading of the about:customizing
michael@0:    * content page. This function is idempotent (until a call to uninit),
michael@0:    * so multiple calls to it are fine.
michael@0:    */
michael@0:   ensurePreloading: function() {
michael@0:     CustomizationTabPreloaderInternal.ensurePreloading();
michael@0:   },
michael@0: };
michael@0: 
michael@0: Object.freeze(CustomizationTabPreloader);
michael@0: 
michael@0: this.CustomizationTabPreloaderInternal = {
michael@0:   _browser: null,
michael@0: 
michael@0:   uninit: function () {
michael@0:     HostFrame.destroy();
michael@0: 
michael@0:     if (this._browser) {
michael@0:       this._browser.destroy();
michael@0:       this._browser = null;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   newTab: function (aTab) {
michael@0:     let win = aTab.ownerDocument.defaultView;
michael@0:     if (win.gBrowser && this._browser) {
michael@0:       return this._browser.swapWithNewTab(aTab);
michael@0:     }
michael@0: 
michael@0:     return false;
michael@0:   },
michael@0: 
michael@0:   ensurePreloading: function () {
michael@0:     if (!this._browser) {
michael@0:       this._browser = new HiddenBrowser();
michael@0:     }
michael@0:   }
michael@0: };
michael@0: 
michael@0: function HiddenBrowser() {
michael@0:   this._createBrowser();
michael@0: }
michael@0: 
michael@0: HiddenBrowser.prototype = {
michael@0:   _timer: null,
michael@0: 
michael@0:   get isPreloaded() {
michael@0:     return this._browser &&
michael@0:            this._browser.contentDocument &&
michael@0:            this._browser.contentDocument.readyState === "complete" &&
michael@0:            this._browser.currentURI.spec === CUSTOMIZATION_URL;
michael@0:   },
michael@0: 
michael@0:   swapWithNewTab: function (aTab) {
michael@0:     if (!this.isPreloaded || this._timer) {
michael@0:       return false;
michael@0:     }
michael@0: 
michael@0:     let win = aTab.ownerDocument.defaultView;
michael@0:     let tabbrowser = win.gBrowser;
michael@0: 
michael@0:     if (!tabbrowser) {
michael@0:       return false;
michael@0:     }
michael@0: 
michael@0:     // Swap docShells.
michael@0:     tabbrowser.swapNewTabWithBrowser(aTab, this._browser);
michael@0: 
michael@0:     // Load all default frame scripts attached to the target window.
michael@0:     let mm = aTab.linkedBrowser.messageManager;
michael@0:     let scripts = win.messageManager.getDelayedFrameScripts();
michael@0:     Array.forEach(scripts, ([script, runGlobal]) => mm.loadFrameScript(script, true, runGlobal));
michael@0: 
michael@0:     // Remove the browser, it will be recreated by a timer.
michael@0:     this._removeBrowser();
michael@0: 
michael@0:     // Start a timer that will kick off preloading the next page.
michael@0:     this._timer = createTimer(this, PRELOADER_INTERVAL_MS);
michael@0: 
michael@0:     // Signal that we swapped docShells.
michael@0:     return true;
michael@0:   },
michael@0: 
michael@0:   observe: function () {
michael@0:     this._timer = null;
michael@0: 
michael@0:     // Start pre-loading the customization page.
michael@0:     this._createBrowser();
michael@0:   },
michael@0: 
michael@0:   destroy: function () {
michael@0:     this._removeBrowser();
michael@0:     this._timer = clearTimer(this._timer);
michael@0:   },
michael@0: 
michael@0:   _createBrowser: function () {
michael@0:     HostFrame.get().then(aFrame => {
michael@0:       let doc = aFrame.document;
michael@0:       this._browser = doc.createElementNS(XUL_NS, "browser");
michael@0:       this._browser.setAttribute("type", "content");
michael@0:       this._browser.setAttribute("src", CUSTOMIZATION_URL);
michael@0:       this._browser.style.width = "400px";
michael@0:       this._browser.style.height = "400px";
michael@0:       doc.getElementById("win").appendChild(this._browser);
michael@0:     });
michael@0:   },
michael@0: 
michael@0:   _removeBrowser: function () {
michael@0:     if (this._browser) {
michael@0:       this._browser.remove();
michael@0:       this._browser = null;
michael@0:     }
michael@0:   }
michael@0: };
michael@0: 
michael@0: let HostFrame = {
michael@0:   _frame: null,
michael@0:   _deferred: null,
michael@0: 
michael@0:   get hiddenDOMDocument() {
michael@0:     return Services.appShell.hiddenDOMWindow.document;
michael@0:   },
michael@0: 
michael@0:   get isReady() {
michael@0:     return this.hiddenDOMDocument.readyState === "complete";
michael@0:   },
michael@0: 
michael@0:   get: function () {
michael@0:     if (!this._deferred) {
michael@0:       this._deferred = Promise.defer();
michael@0:       this._create();
michael@0:     }
michael@0: 
michael@0:     return this._deferred.promise;
michael@0:   },
michael@0: 
michael@0:   destroy: function () {
michael@0:     if (this._frame) {
michael@0:       if (!Cu.isDeadWrapper(this._frame)) {
michael@0:         this._frame.removeEventListener("load", this, true);
michael@0:         this._frame.remove();
michael@0:       }
michael@0: 
michael@0:       this._frame = null;
michael@0:       this._deferred = null;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   handleEvent: function () {
michael@0:     let contentWindow = this._frame.contentWindow;
michael@0:     if (contentWindow.location.href === XUL_PAGE) {
michael@0:       this._frame.removeEventListener("load", this, true);
michael@0:       this._deferred.resolve(contentWindow);
michael@0:     } else {
michael@0:       contentWindow.location = XUL_PAGE;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   _create: function () {
michael@0:     if (this.isReady) {
michael@0:       let doc = this.hiddenDOMDocument;
michael@0:       this._frame = doc.createElementNS(HTML_NS, "iframe");
michael@0:       this._frame.addEventListener("load", this, true);
michael@0:       doc.documentElement.appendChild(this._frame);
michael@0:     } else {
michael@0:       let flags = Ci.nsIThread.DISPATCH_NORMAL;
michael@0:       Services.tm.currentThread.dispatch(() => this._create(), flags);
michael@0:     }
michael@0:   }
michael@0: };