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: 
michael@0: "use strict";
michael@0: 
michael@0: const Cc = Components.classes;
michael@0: const Ci = Components.interfaces;
michael@0: const Cu = Components.utils;
michael@0: 
michael@0: this.EXPORTED_SYMBOLS = ["DownloadsIPC"];
michael@0: 
michael@0: Cu.import("resource://gre/modules/XPCOMUtils.jsm");
michael@0: Cu.import("resource://gre/modules/Services.jsm");
michael@0: Cu.import("resource://gre/modules/Promise.jsm");
michael@0: 
michael@0: XPCOMUtils.defineLazyServiceGetter(this, "cpmm",
michael@0:                                    "@mozilla.org/childprocessmessagemanager;1",
michael@0:                                    "nsIMessageSender");
michael@0: 
michael@0: /**
michael@0:   * This module lives in the child process and receives the ipc messages
michael@0:   * from the parent. It saves the download's state and redispatch changes
michael@0:   * to DOM objects using an observer notification.
michael@0:   *
michael@0:   * This module needs to be loaded once and only once per process.
michael@0:   */
michael@0: 
michael@0: function debug(aStr) {
michael@0: #ifdef MOZ_DEBUG
michael@0:   dump("-*- DownloadsIPC.jsm : " + aStr + "\n");
michael@0: #endif
michael@0: }
michael@0: 
michael@0: const ipcMessages = ["Downloads:Added",
michael@0:                      "Downloads:Removed",
michael@0:                      "Downloads:Changed",
michael@0:                      "Downloads:GetList:Return",
michael@0:                      "Downloads:ClearAllDone:Return",
michael@0:                      "Downloads:Remove:Return",
michael@0:                      "Downloads:Pause:Return",
michael@0:                      "Downloads:Resume:Return"];
michael@0: 
michael@0: this.DownloadsIPC = {
michael@0:   downloads: {},
michael@0: 
michael@0:   init: function() {
michael@0:     debug("init");
michael@0:     Services.obs.addObserver(this, "xpcom-shutdown", false);
michael@0:     ipcMessages.forEach((aMessage) => {
michael@0:       cpmm.addMessageListener(aMessage, this);
michael@0:     });
michael@0: 
michael@0:     // We need to get the list of current downloads.
michael@0:     this.ready = false;
michael@0:     this.getListPromises = [];
michael@0:     this.clearAllPromises = [];
michael@0:     this.downloadPromises = {};
michael@0:     cpmm.sendAsyncMessage("Downloads:GetList", {});
michael@0:     this._promiseId = 0;
michael@0:   },
michael@0: 
michael@0:   notifyChanges: function(aId) {
michael@0:     // TODO: use the subject instead of stringifying.
michael@0:     if (this.downloads[aId]) {
michael@0:       debug("notifyChanges notifying changes for " + aId);
michael@0:       Services.obs.notifyObservers(null, "downloads-state-change-" + aId,
michael@0:                                    JSON.stringify(this.downloads[aId]));
michael@0:     } else {
michael@0:       debug("notifyChanges failed for " + aId)
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   _updateDownloadsArray: function(aDownloads) {
michael@0:     this.downloads = [];
michael@0:     // We actually have an array of downloads.
michael@0:     aDownloads.forEach((aDownload) => {
michael@0:       this.downloads[aDownload.id] = aDownload;
michael@0:     });
michael@0:   },
michael@0: 
michael@0:   receiveMessage: function(aMessage) {
michael@0:     let download = aMessage.data;
michael@0:     debug("message: " + aMessage.name);
michael@0:     switch(aMessage.name) {
michael@0:       case "Downloads:GetList:Return":
michael@0:         this._updateDownloadsArray(download);
michael@0: 
michael@0:         if (!this.ready) {
michael@0:           this.getListPromises.forEach(aPromise =>
michael@0:                                        aPromise.resolve(this.downloads));
michael@0:           this.getListPromises.length = 0;
michael@0:         }
michael@0:         this.ready = true;
michael@0:         break;
michael@0:       case "Downloads:ClearAllDone:Return":
michael@0:         this._updateDownloadsArray(download);
michael@0:         this.clearAllPromises.forEach(aPromise =>
michael@0:                                       aPromise.resolve(this.downloads));
michael@0:         this.clearAllPromises.length = 0;
michael@0:         break;
michael@0:       case "Downloads:Added":
michael@0:         this.downloads[download.id] = download;
michael@0:         this.notifyChanges(download.id);
michael@0:         break;
michael@0:       case "Downloads:Removed":
michael@0:         if (this.downloads[download.id]) {
michael@0:           this.downloads[download.id] = download;
michael@0:           this.notifyChanges(download.id);
michael@0:           delete this.downloads[download.id];
michael@0:         }
michael@0:         break;
michael@0:       case "Downloads:Changed":
michael@0:         // Only update properties that actually changed.
michael@0:         let cached = this.downloads[download.id];
michael@0:         if (!cached) {
michael@0:           debug("No download found for " + download.id);
michael@0:           return;
michael@0:         }
michael@0:         let props = ["totalBytes", "currentBytes", "url", "path", "state",
michael@0:                      "contentType", "startTime"];
michael@0:         let changed = false;
michael@0: 
michael@0:         props.forEach((aProp) => {
michael@0:           if (download[aProp] && (download[aProp] != cached[aProp])) {
michael@0:             cached[aProp] = download[aProp];
michael@0:             changed = true;
michael@0:           }
michael@0:         });
michael@0: 
michael@0:         // Updating the error property. We always get a 'state' change as
michael@0:         // well.
michael@0:         cached.error = download.error;
michael@0: 
michael@0:         if (changed) {
michael@0:           this.notifyChanges(download.id);
michael@0:         }
michael@0:         break;
michael@0:       case "Downloads:Remove:Return":
michael@0:       case "Downloads:Pause:Return":
michael@0:       case "Downloads:Resume:Return":
michael@0:         if (this.downloadPromises[download.promiseId]) {
michael@0:           if (!download.error) {
michael@0:             this.downloadPromises[download.promiseId].resolve(download);
michael@0:           } else {
michael@0:             this.downloadPromises[download.promiseId].reject(download);
michael@0:           }
michael@0:           delete this.downloadPromises[download.promiseId];
michael@0:         }
michael@0:         break;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:     * Returns a promise that is resolved with the list of current downloads.
michael@0:     */
michael@0:   getDownloads: function() {
michael@0:     debug("getDownloads()");
michael@0:     let deferred = Promise.defer();
michael@0:     if (this.ready) {
michael@0:       debug("Returning existing list.");
michael@0:       deferred.resolve(this.downloads);
michael@0:     } else {
michael@0:       this.getListPromises.push(deferred);
michael@0:     }
michael@0:     return deferred.promise;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:     * Returns a promise that is resolved with the list of current downloads.
michael@0:     */
michael@0:   clearAllDone: function() {
michael@0:     debug("clearAllDone");
michael@0:     let deferred = Promise.defer();
michael@0:     this.clearAllPromises.push(deferred);
michael@0:     cpmm.sendAsyncMessage("Downloads:ClearAllDone", {});
michael@0:     return deferred.promise;
michael@0:   },
michael@0: 
michael@0:   promiseId: function() {
michael@0:     return this._promiseId++;
michael@0:   },
michael@0: 
michael@0:   remove: function(aId) {
michael@0:     debug("remove " + aId);
michael@0:     let deferred = Promise.defer();
michael@0:     let pId = this.promiseId();
michael@0:     this.downloadPromises[pId] = deferred;
michael@0:     cpmm.sendAsyncMessage("Downloads:Remove",
michael@0:                           { id: aId, promiseId: pId });
michael@0:     return deferred.promise;
michael@0:   },
michael@0: 
michael@0:   pause: function(aId) {
michael@0:     debug("pause " + aId);
michael@0:     let deferred = Promise.defer();
michael@0:     let pId = this.promiseId();
michael@0:     this.downloadPromises[pId] = deferred;
michael@0:     cpmm.sendAsyncMessage("Downloads:Pause",
michael@0:                           { id: aId, promiseId: pId });
michael@0:     return deferred.promise;
michael@0:   },
michael@0: 
michael@0:   resume: function(aId) {
michael@0:     debug("resume " + aId);
michael@0:     let deferred = Promise.defer();
michael@0:     let pId = this.promiseId();
michael@0:     this.downloadPromises[pId] = deferred;
michael@0:     cpmm.sendAsyncMessage("Downloads:Resume",
michael@0:                           { id: aId, promiseId: pId });
michael@0:     return deferred.promise;
michael@0:   },
michael@0: 
michael@0:   observe: function(aSubject, aTopic, aData) {
michael@0:     if (aTopic == "xpcom-shutdown") {
michael@0:       ipcMessages.forEach((aMessage) => {
michael@0:         cpmm.removeMessageListener(aMessage, this);
michael@0:       });
michael@0:     }
michael@0:   }
michael@0: };
michael@0: 
michael@0: DownloadsIPC.init();