ui/file_manager/gallery/js/entry_list_watcher.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * Watcher for entry lists.
   7  * It watches entries and remove the item if the entry is removed from file
   8  * system.
   9  * @param {!cr.ui.ArrayDataModel} list
  10  * @constructor
  11  * @struct
  12  */
  13 function EntryListWatcher(list) {
  14   /**
  15    * Watched list.
  16    * @type {!cr.ui.ArrayDataModel}
  17    * @const
  18    * @private
  19    */
  20   this.list_ = list;
  21
  22   /**
  23    * Set of watched URL.
  24    * Key is watched entry URL. Value is always true.
  25    * @type {!Object.<string, boolean>}
  26    * @private
  27    */
  28   this.watchers_ = {};
  29
  30   this.list_.addEventListener('splice', this.onSplice_.bind(this));
  31   chrome.fileManagerPrivate.onDirectoryChanged.addListener(
  32       this.onDirectoryChanged_.bind(this));
  33
  34   this.onSplice_(null);
  35 }
  36
  37 /**
  38  * Obtains entry from ArrayDataModel's item.
  39  * @param {*} item Item in ArrayDataModel.
  40  * @protected
  41  * @return {!FileEntry}
  42  */
  43 EntryListWatcher.prototype.getEntry = function(item) {
  44   return /** @type {!FileEntry} */ (item);
  45 };
  46
  47 /**
  48  * @param {Event} event
  49  * @private
  50  */
  51 EntryListWatcher.prototype.onSplice_ = function(event) {
  52   // Mark all existing watchers as candidates to be removed.
  53   var diff = {};
  54   for (var url in this.watchers_) {
  55     diff[url] = -1;
  56   }
  57
  58   // Obtains the set of new watcher.
  59   this.watchers_ = {};
  60   for (var i = 0; i < this.list_.length; i++) {
  61     var entry = this.getEntry(this.list_.item(i));
  62     var parentURL = entry.toURL().replace(/[^\/]+\/?$/, '');
  63     this.watchers_[parentURL] = true;
  64   }
  65
  66   // Mark new watchers to be added, and existing watchers to be kept.
  67   for (var url in this.watchers_) {
  68     diff[url] = (diff[url] || 0) + 1;
  69   }
  70
  71   // Check the number in diff.
  72   // -1: watcher exists in the old set, but does not exists in the new set.
  73   // 0: watcher exists in both sets.
  74   // 1: watcher does not exists in the old set, but exists in the new set.
  75   var reportError = function() {
  76     if (chrome.runtime.lastError)
  77       console.error(chrome.runtime.lastError);
  78   };
  79   for (var url in diff) {
  80     switch (diff[url]) {
  81       case 1:
  82         chrome.fileManagerPrivate.addFileWatch(url, reportError);
  83         break;
  84       case -1:
  85         chrome.fileManagerPrivate.removeFileWatch(url, reportError);
  86         break;
  87       case 0:
  88         break;
  89       default:
  90         assertNotReached();
  91         break;
  92     }
  93   }
  94 };
  95
  96 /**
  97  * @param {!FileWatchEvent} event
  98  * @private
  99  */
 100 EntryListWatcher.prototype.onDirectoryChanged_ = function(event) {
 101   // Add '/' to the tail for checking if the each entry's URL is child URL of
 102   // the URL or not by using entryURL.indexOf(thisUrl) === 0.
 103   var url = event.entry.toURL().replace(/\/?$/, '/');
 104   var promiseList = [];
 105   var removedEntryURL = {};
 106   for (var i = 0; i < this.list_.length; i++) {
 107     var entry = this.getEntry(this.list_.item(i));
 108     // Remove trailing '/' to prevent calling getMetadata in the case where the
 109     // event.entry and the entry are same.
 110     var entryURL = entry.toURL().replace(/\/$/, '');
 111     if (entry.toURL().indexOf(url) !== 0)
 112       continue;
 113     // Look for non-existing files by using getMetadata.
 114     // getMetadata returns NOT_FOUND error for non-existing files.
 115     promiseList.push(new Promise(entry.getMetadata.bind(entry)).catch(
 116         function(url) {
 117           removedEntryURL[url] = true;
 118         }.bind(null, entry.toURL())));
 119   }
 120   Promise.all(promiseList).then(function() {
 121     var i = 0;
 122     while (i < this.list_.length) {
 123       var url = this.getEntry(this.list_.item(i)).toURL();
 124       if (removedEntryURL[url]) {
 125         this.list_.splice(i, 1);
 126       } else {
 127         i++;
 128       }
 129     }
 130   }.bind(this));
 131 };