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
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: "use strict";
michael@0: 
michael@0: module.metadata = {
michael@0:   "stability": "unstable"
michael@0: };
michael@0: 
michael@0: const { Class } = require('../core/heritage');
michael@0: const { EventTarget } = require('../event/target');
michael@0: const { on, off, emit, setListeners } = require('../event/core');
michael@0: const {
michael@0:   attach, detach, destroy
michael@0: } = require('./utils');
michael@0: const { method } = require('../lang/functional');
michael@0: const { Ci, Cu, Cc } = require('chrome');
michael@0: const unload = require('../system/unload');
michael@0: const events = require('../system/events');
michael@0: const { getInnerId } = require("../window/utils");
michael@0: const { WorkerSandbox } = require('./sandbox');
michael@0: const { getTabForWindow } = require('../tabs/helpers');
michael@0: 
michael@0: // A weak map of workers to hold private attributes that
michael@0: // should not be exposed
michael@0: const workers = new WeakMap();
michael@0: 
michael@0: let modelFor = (worker) => workers.get(worker);
michael@0: 
michael@0: const ERR_DESTROYED =
michael@0:   "Couldn't find the worker to receive this message. " +
michael@0:   "The script may not be initialized yet, or may already have been unloaded.";
michael@0: 
michael@0: const ERR_FROZEN = "The page is currently hidden and can no longer be used " +
michael@0:                    "until it is visible again.";
michael@0: 
michael@0: /**
michael@0:  * Message-passing facility for communication between code running
michael@0:  * in the content and add-on process.
michael@0:  * @see https://addons.mozilla.org/en-US/developers/docs/sdk/latest/modules/sdk/content/worker.html
michael@0:  */
michael@0: const Worker = Class({
michael@0:   implements: [EventTarget],
michael@0:   initialize: function WorkerConstructor (options) {
michael@0:     // Save model in weak map to not expose properties
michael@0:     let model = createModel();
michael@0:     workers.set(this, model);
michael@0: 
michael@0:     options = options || {};
michael@0: 
michael@0:     if ('contentScriptFile' in options)
michael@0:       this.contentScriptFile = options.contentScriptFile;
michael@0:     if ('contentScriptOptions' in options)
michael@0:       this.contentScriptOptions = options.contentScriptOptions;
michael@0:     if ('contentScript' in options)
michael@0:       this.contentScript = options.contentScript;
michael@0:     if ('injectInDocument' in options)
michael@0:       this.injectInDocument = !!options.injectInDocument;
michael@0: 
michael@0:     setListeners(this, options);
michael@0: 
michael@0:     unload.ensure(this, "destroy");
michael@0: 
michael@0:     // Ensure that worker.port is initialized for contentWorker to be able
michael@0:     // to send events during worker initialization.
michael@0:     this.port = createPort(this);
michael@0: 
michael@0:     model.documentUnload = documentUnload.bind(this);
michael@0:     model.pageShow = pageShow.bind(this);
michael@0:     model.pageHide = pageHide.bind(this);
michael@0: 
michael@0:     if ('window' in options)
michael@0:       attach(this, options.window);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Sends a message to the worker's global scope. Method takes single
michael@0:    * argument, which represents data to be sent to the worker. The data may
michael@0:    * be any primitive type value or `JSON`. Call of this method asynchronously
michael@0:    * emits `message` event with data value in the global scope of this
michael@0:    * symbiont.
michael@0:    *
michael@0:    * `message` event listeners can be set either by calling
michael@0:    * `self.on` with a first argument string `"message"` or by
michael@0:    * implementing `onMessage` function in the global scope of this worker.
michael@0:    * @param {Number|String|JSON} data
michael@0:    */
michael@0:   postMessage: function (...data) {
michael@0:     let model = modelFor(this);
michael@0:     let args = ['message'].concat(data);
michael@0:     if (!model.inited) {
michael@0:       model.earlyEvents.push(args);
michael@0:       return;
michael@0:     }
michael@0:     processMessage.apply(null, [this].concat(args));
michael@0:   },
michael@0: 
michael@0:   get url () {
michael@0:     let model = modelFor(this);
michael@0:     // model.window will be null after detach
michael@0:     return model.window ? model.window.document.location.href : null;
michael@0:   },
michael@0: 
michael@0:   get contentURL () {
michael@0:     let model = modelFor(this);
michael@0:     return model.window ? model.window.document.URL : null;
michael@0:   },
michael@0: 
michael@0:   get tab () {
michael@0:     let model = modelFor(this);
michael@0:     // model.window will be null after detach
michael@0:     if (model.window)
michael@0:       return getTabForWindow(model.window);
michael@0:     return null;
michael@0:   },
michael@0: 
michael@0:   // Implemented to provide some of the previous features of exposing sandbox
michael@0:   // so that Worker can be extended
michael@0:   getSandbox: function () {
michael@0:     return modelFor(this).contentWorker;
michael@0:   },
michael@0: 
michael@0:   toString: function () { return '[object Worker]'; },
michael@0:   attach: method(attach),
michael@0:   detach: method(detach),
michael@0:   destroy: method(destroy)
michael@0: });
michael@0: exports.Worker = Worker;
michael@0: 
michael@0: attach.define(Worker, function (worker, window) {
michael@0:   let model = modelFor(worker);
michael@0:   model.window = window;
michael@0:   // Track document unload to destroy this worker.
michael@0:   // We can't watch for unload event on page's window object as it
michael@0:   // prevents bfcache from working:
michael@0:   // https://developer.mozilla.org/En/Working_with_BFCache
michael@0:   model.windowID = getInnerId(model.window);
michael@0:   events.on("inner-window-destroyed", model.documentUnload);
michael@0: 
michael@0:   // Listen to pagehide event in order to freeze the content script
michael@0:   // while the document is frozen in bfcache:
michael@0:   model.window.addEventListener("pageshow", model.pageShow, true);
michael@0:   model.window.addEventListener("pagehide", model.pageHide, true);
michael@0: 
michael@0:   // will set model.contentWorker pointing to the private API:
michael@0:   model.contentWorker = WorkerSandbox(worker, model.window);
michael@0: 
michael@0:   // Mainly enable worker.port.emit to send event to the content worker
michael@0:   model.inited = true;
michael@0:   model.frozen = false;
michael@0: 
michael@0:   // Fire off `attach` event
michael@0:   emit(worker, 'attach', window);
michael@0: 
michael@0:   // Process all events and messages that were fired before the
michael@0:   // worker was initialized.
michael@0:   model.earlyEvents.forEach(args => processMessage.apply(null, [worker].concat(args)));
michael@0: });
michael@0: 
michael@0: /**
michael@0:  * Remove all internal references to the attached document
michael@0:  * Tells _port to unload itself and removes all the references from itself.
michael@0:  */
michael@0: detach.define(Worker, function (worker, reason) {
michael@0:   let model = modelFor(worker);
michael@0: 
michael@0:   // maybe unloaded before content side is created
michael@0:   if (model.contentWorker) {
michael@0:     model.contentWorker.destroy(reason);
michael@0:   }
michael@0: 
michael@0:   model.contentWorker = null;
michael@0:   if (model.window) {
michael@0:     model.window.removeEventListener("pageshow", model.pageShow, true);
michael@0:     model.window.removeEventListener("pagehide", model.pageHide, true);
michael@0:   }
michael@0:   model.window = null;
michael@0:   // This method may be called multiple times,
michael@0:   // avoid dispatching `detach` event more than once
michael@0:   if (model.windowID) {
michael@0:     model.windowID = null;
michael@0:     events.off("inner-window-destroyed", model.documentUnload);
michael@0:     model.earlyEvents.length = 0;
michael@0:     emit(worker, 'detach');
michael@0:   }
michael@0:   model.inited = false;
michael@0: });
michael@0: 
michael@0: /**
michael@0:  * Tells content worker to unload itself and
michael@0:  * removes all the references from itself.
michael@0:  */
michael@0: destroy.define(Worker, function (worker, reason) {
michael@0:   detach(worker, reason);
michael@0:   modelFor(worker).inited = true;
michael@0:   // Specifying no type or listener removes all listeners
michael@0:   // from target
michael@0:   off(worker);
michael@0: });
michael@0: 
michael@0: /**
michael@0:  * Events fired by workers
michael@0:  */
michael@0: function documentUnload ({ subject, data }) {
michael@0:   let model = modelFor(this);
michael@0:   let innerWinID = subject.QueryInterface(Ci.nsISupportsPRUint64).data;
michael@0:   if (innerWinID != model.windowID) return false;
michael@0:   detach(this);
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: function pageShow () {
michael@0:   let model = modelFor(this);
michael@0:   model.contentWorker.emitSync('pageshow');
michael@0:   emit(this, 'pageshow');
michael@0:   model.frozen = false;
michael@0: }
michael@0: 
michael@0: function pageHide () {
michael@0:   let model = modelFor(this);
michael@0:   model.contentWorker.emitSync('pagehide');
michael@0:   emit(this, 'pagehide');
michael@0:   model.frozen = true;
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Fired from postMessage and emitEventToContent, or from the earlyMessage
michael@0:  * queue when fired before the content is loaded. Sends arguments to
michael@0:  * contentWorker if able
michael@0:  */
michael@0: 
michael@0: function processMessage (worker, ...args) {
michael@0:   let model = modelFor(worker) || {};
michael@0:   if (!model.contentWorker)
michael@0:     throw new Error(ERR_DESTROYED);
michael@0:   if (model.frozen)
michael@0:     throw new Error(ERR_FROZEN);
michael@0:   model.contentWorker.emit.apply(null, args);
michael@0: }
michael@0: 
michael@0: function createModel () {
michael@0:   return {
michael@0:     // List of messages fired before worker is initialized
michael@0:     earlyEvents: [],
michael@0:     // Is worker connected to the content worker sandbox ?
michael@0:     inited: false,
michael@0:     // Is worker being frozen? i.e related document is frozen in bfcache.
michael@0:     // Content script should not be reachable if frozen.
michael@0:     frozen: true,
michael@0:     /**
michael@0:      * Reference to the content side of the worker.
michael@0:      * @type {WorkerGlobalScope}
michael@0:      */
michael@0:     contentWorker: null,
michael@0:     /**
michael@0:      * Reference to the window that is accessible from
michael@0:      * the content scripts.
michael@0:      * @type {Object}
michael@0:      */
michael@0:     window: null
michael@0:   };
michael@0: }
michael@0: 
michael@0: function createPort (worker) {
michael@0:   let port = EventTarget();
michael@0:   port.emit = emitEventToContent.bind(null, worker);
michael@0:   return port;
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Emit a custom event to the content script,
michael@0:  * i.e. emit this event on `self.port`
michael@0:  */
michael@0: function emitEventToContent (worker, ...eventArgs) {
michael@0:   let model = modelFor(worker);
michael@0:   let args = ['event'].concat(eventArgs);
michael@0:   if (!model.inited) {
michael@0:     model.earlyEvents.push(args);
michael@0:     return;
michael@0:   }
michael@0:   processMessage.apply(null, [worker].concat(args));
michael@0: }