path: root/toolkit/mozapps/downloads/content/downloads.js

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

// Globals

const PREF_BDM_CLOSEWHENDONE = "browser.download.manager.closeWhenDone";
const PREF_BDM_ALERTONEXEOPEN = "browser.download.manager.alertOnEXEOpen";
const PREF_BDM_SCANWHENDONE = "browser.download.manager.scanWhenDone";

const nsLocalFile = Components.Constructor("@mozilla.org/file/local;1",
                                           "nsILocalFile", "initWithPath");

var Cc = Components.classes;
var Ci = Components.interfaces;
var Cu = Components.utils;
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
Cu.import("resource://gre/modules/DownloadUtils.jsm");
Cu.import("resource://gre/modules/Services.jsm");
Cu.import("resource://gre/modules/AppConstants.jsm");

XPCOMUtils.defineLazyModuleGetter(this, "PluralForm",
                                  "resource://gre/modules/PluralForm.jsm");

const nsIDM = Ci.nsIDownloadManager;

var gDownloadManager = Cc["@mozilla.org/download-manager;1"].getService(nsIDM);
var gDownloadManagerUI = Cc["@mozilla.org/download-manager-ui;1"].
                         getService(Ci.nsIDownloadManagerUI);

var gDownloadListener = null;
var gDownloadsView = null;
var gSearchBox = null;
var gSearchTerms = [];
var gBuilder = 0;

// This variable is used when performing commands on download items and gives
// the command the ability to do something after all items have been operated
// on. The following convention is used to handle the value of the variable:
// whenever we aren't performing a command, the value is |undefined|; just
// before executing commands, the value will be set to |null|; and when
// commands want to create a callback, they set the value to be a callback
// function to be executed after all download items have been visited.
var gPerformAllCallback;

// Control the performance of the incremental list building by setting how many
// milliseconds to wait before building more of the list and how many items to
// add between each delay.
const gListBuildDelay = 300;
const gListBuildChunk = 3;

// Array of download richlistitem attributes to check when searching
const gSearchAttributes = [
  "target",
  "status",
  "dateTime",
];

// If the user has interacted with the window in a significant way, we should
// not auto-close the window. Tough UI decisions about what is "significant."
var gUserInteracted = false;

// These strings will be converted to the corresponding ones from the string
// bundle on startup.
var gStr = {
  paused: "paused",
  cannotPause: "cannotPause",
  doneStatus: "doneStatus",
  doneSize: "doneSize",
  doneSizeUnknown: "doneSizeUnknown",
  stateFailed: "stateFailed",
  stateCanceled: "stateCanceled",
  stateBlockedParentalControls: "stateBlocked",
  stateBlockedPolicy: "stateBlockedPolicy",
  stateDirty: "stateDirty",
  downloadsTitleFiles: "downloadsTitleFiles",
  downloadsTitlePercent: "downloadsTitlePercent",
  fileExecutableSecurityWarningTitle: "fileExecutableSecurityWarningTitle",
  fileExecutableSecurityWarningDontAsk: "fileExecutableSecurityWarningDontAsk"
};

// The statement to query for downloads that are active or match the search
var gStmt = null;

// Start/Stop Observers

function downloadCompleted(aDownload)
{
  // The download is changing state, so update the clear list button
  updateClearListButton();

  // Wrap this in try...catch since this can be called while shutting down...
  // it doesn't really matter if it fails then since well.. we're shutting down
  // and there's no UI to update!
  try {
    let dl = getDownload(aDownload.id);

    // Update attributes now that we've finished
    dl.setAttribute("startTime", Math.round(aDownload.startTime / 1000));
    dl.setAttribute("endTime", Date.now());
    dl.setAttribute("currBytes", aDownload.amountTransferred);
    dl.setAttribute("maxBytes", aDownload.size);

    // Move the download below active if it should stay in the list
    if (downloadMatchesSearch(dl)) {
      // Iterate down until we find a non-active download
      let next = dl.nextSibling;
      while (next && next.inProgress)
        next = next.nextSibling;

      // Move the item
      gDownloadsView.insertBefore(dl, next);
    } else {
      removeFromView(dl);
    }

    // getTypeFromFile fails if it can't find a type for this file.
    try {
      // Refresh the icon, so that executable icons are shown.
      var mimeService = Cc["@mozilla.org/mime;1"].
                        getService(Ci.nsIMIMEService);
      var contentType = mimeService.getTypeFromFile(aDownload.targetFile);

      var listItem = getDownload(aDownload.id)
      var oldImage = listItem.getAttribute("image");
      // Tacking on contentType bypasses cache
      listItem.setAttribute("image", oldImage + "&contentType=" + contentType);
    } catch (e) { }

    if (gDownloadManager.activeDownloadCount == 0)
      document.title = document.documentElement.getAttribute("statictitle");

    gDownloadManagerUI.getAttention();
  }
  catch (e) { }
}

function autoRemoveAndClose(aDownload)
{
  var pref = Cc["@mozilla.org/preferences-service;1"].
             getService(Ci.nsIPrefBranch);

  if (gDownloadManager.activeDownloadCount == 0) {
    // For the moment, just use the simple heuristic that if this window was
    // opened by the download process, rather than by the user, it should
    // auto-close if the pref is set that way. If the user opened it themselves,
    // it should not close until they explicitly close it.  Additionally, the
    // preference to control the feature may not be set, so defaulting to
    // keeping the window open.
    let autoClose = false;
    try {
      autoClose = pref.getBoolPref(PREF_BDM_CLOSEWHENDONE);
    } catch (e) { }
    var autoOpened =
      !window.opener || window.opener.location.href == window.location.href;
    if (autoClose && autoOpened && !gUserInteracted) {
      gCloseDownloadManager();
      return true;
    }
  }

  return false;
}

// This function can be overwritten by extensions that wish to place the
// Download Window in another part of the UI.
function gCloseDownloadManager()
{
  window.close();
}

// Download Event Handlers

function cancelDownload(aDownload)
{
  gDownloadManager.cancelDownload(aDownload.getAttribute("dlid"));

  // XXXben -
  // If we got here because we resumed the download, we weren't using a temp file
  // because we used saveURL instead. (this is because the proper download mechanism
  // employed by the helper app service isn't fully accessible yet... should be fixed...
  // talk to bz...)
  // the upshot is we have to delete the file if it exists.
  var f = getLocalFileFromNativePathOrUrl(aDownload.getAttribute("file"));

  if (f.exists())
    f.remove(false);
}

function pauseDownload(aDownload)
{
  var id = aDownload.getAttribute("dlid");
  gDownloadManager.pauseDownload(id);
}

function resumeDownload(aDownload)
{
  gDownloadManager.resumeDownload(aDownload.getAttribute("dlid"));
}

function removeDownload(aDownload)
{
  gDownloadManager.removeDownload(aDownload.getAttribute("dlid"));
}

function retryDownload(aDownload)
{
  removeFromView(aDownload);
  gDownloadManager.retryDownload(aDownload.getAttribute("dlid"));
}

function showDownload(aDownload)
{
  var f = getLocalFileFromNativePathOrUrl(aDownload.getAttribute("file"));

  try {
    // Show the directory containing the file and select the file
    f.reveal();
  } catch (e) {
    // If reveal fails for some reason (e.g., it's not implemented on unix or
    // the file doesn't exist), try using the parent if we have it.
    let parent = f.parent.QueryInterface(Ci.nsILocalFile);
    if (!parent)
      return;

    try {
      // "Double click" the parent directory to show where the file should be
      parent.launch();
    } catch (e) {
      // If launch also fails (probably because it's not implemented), let the
      // OS handler try to open the parent
      openExternal(parent);
    }
  }
}

function onDownloadDblClick(aEvent)
{
  // Only do the default action for double primary clicks
  if (aEvent.button == 0 && aEvent.target.selected)
    doDefaultForSelected();
}

function openDownload(aDownload)
{
  var f = getLocalFileFromNativePathOrUrl(aDownload.getAttribute("file"));
  if (f.isExecutable()) {
    var dontAsk = false;
    var pref = Cc["@mozilla.org/preferences-service;1"].
               getService(Ci.nsIPrefBranch);
    try {
      dontAsk = !pref.getBoolPref(PREF_BDM_ALERTONEXEOPEN);
    } catch (e) { }

    if (AppConstants.platform == "win") {
      // On Vista and above, we rely on native security prompting for
      // downloaded content unless it's disabled.
      try {
        var sysInfo = Cc["@mozilla.org/system-info;1"].
                      getService(Ci.nsIPropertyBag2);
        if (parseFloat(sysInfo.getProperty("version")) >= 6 &&
            pref.getBoolPref(PREF_BDM_SCANWHENDONE)) {
          dontAsk = true;
        }
      } catch (ex) { }
    }

    if (!dontAsk) {
      var strings = document.getElementById("downloadStrings");
      var name = aDownload.getAttribute("target");
      var message = strings.getFormattedString("fileExecutableSecurityWarning", [name, name]);

      let title = gStr.fileExecutableSecurityWarningTitle;
      let dontAsk = gStr.fileExecutableSecurityWarningDontAsk;

      var promptSvc = Cc["@mozilla.org/embedcomp/prompt-service;1"].
                      getService(Ci.nsIPromptService);
      var checkbox = { value: false };
      var open = promptSvc.confirmCheck(window, title, message, dontAsk, checkbox);

      if (!open)
        return;
      pref.setBoolPref(PREF_BDM_ALERTONEXEOPEN, !checkbox.value);
    }
  }
  try {
    try {
      let download = gDownloadManager.getDownload(aDownload.getAttribute("dlid"));
      let mimeInfo = download.MIMEInfo;
      if (mimeInfo.preferredAction == mimeInfo.useHelperApp) {
        mimeInfo.launchWithFile(f);
        return;
      }
    } catch (ex) {
    }
    f.launch();
  } catch (ex) {
    // if launch fails, try sending it through the system's external
    // file: URL handler
    openExternal(f);
  }
}

function openReferrer(aDownload)
{
  openURL(getReferrerOrSource(aDownload));
}

function copySourceLocation(aDownload)
{
  var uri = aDownload.getAttribute("uri");
  var clipboard = Cc["@mozilla.org/widget/clipboardhelper;1"].
                  getService(Ci.nsIClipboardHelper);

  // Check if we should initialize a callback
  if (gPerformAllCallback === null) {
    let uris = [];
    gPerformAllCallback = aURI => aURI ? uris.push(aURI) :
      clipboard.copyString(uris.join("\n"));
  }

  // We have a callback to use, so use it to add a uri
  if (typeof gPerformAllCallback == "function")
    gPerformAllCallback(uri);
  else {
    // It's a plain copy source, so copy it
    clipboard.copyString(uri);
  }
}

/**
 * Remove the currently shown downloads from the download list.
 */
function clearDownloadList() {
  // Clear the whole list if there's no search
  if (gSearchTerms == "") {
    gDownloadManager.cleanUp();
    return;
  }

  // Remove each download starting from the end until we hit a download
  // that is in progress
  let item;
  while ((item = gDownloadsView.lastChild) && !item.inProgress)
    removeDownload(item);

  // Clear the input as if the user did it and move focus to the list
  gSearchBox.value = "";
  gSearchBox.doCommand();
  gDownloadsView.focus();
}

// This is called by the progress listener.
var gLastComputedMean = -1;
var gLastActiveDownloads = 0;
function onUpdateProgress()
{
  let numActiveDownloads = gDownloadManager.activeDownloadCount;

  // Use the default title and reset "last" values if there's no downloads
  if (numActiveDownloads == 0) {
    document.title = document.documentElement.getAttribute("statictitle");
    gLastComputedMean = -1;
    gLastActiveDownloads = 0;

    return;
  }

  // Establish the mean transfer speed and amount downloaded.
  var mean = 0;
  var base = 0;
  var dls = gDownloadManager.activeDownloads;
  while (dls.hasMoreElements()) {
    let dl = dls.getNext();
    if (dl.percentComplete < 100 && dl.size > 0) {
      mean += dl.amountTransferred;
      base += dl.size;
    }
  }

  // Calculate the percent transferred, unless we don't have a total file size
  let title = gStr.downloadsTitlePercent;
  if (base == 0)
    title = gStr.downloadsTitleFiles;
  else
    mean = Math.floor((mean / base) * 100);

  // Update title of window
  if (mean != gLastComputedMean || gLastActiveDownloads != numActiveDownloads) {
    gLastComputedMean = mean;
    gLastActiveDownloads = numActiveDownloads;

    // Get the correct plural form and insert number of downloads and percent
    title = PluralForm.get(numActiveDownloads, title);
    title = replaceInsert(title, 1, numActiveDownloads);
    title = replaceInsert(title, 2, mean);

    document.title = title;
  }
}

// Startup, Shutdown

function Startup()
{
  gDownloadsView = document.getElementById("downloadView");
  gSearchBox = document.getElementById("searchbox");

  // convert strings to those in the string bundle
  let sb = document.getElementById("downloadStrings");
  let getStr = string => sb.getString(string);
  for (let [name, value] of Object.entries(gStr))
    gStr[name] = typeof value == "string" ? getStr(value) : value.map(getStr);

  initStatement();
  buildDownloadList(true);

  // The DownloadProgressListener (DownloadProgressListener.js) handles progress
  // notifications.
  gDownloadListener = new DownloadProgressListener();
  gDownloadManager.addListener(gDownloadListener);

  // If the UI was displayed because the user interacted, we need to make sure
  // we update gUserInteracted accordingly.
  if (window.arguments[1] == Ci.nsIDownloadManagerUI.REASON_USER_INTERACTED)
    gUserInteracted = true;

  // downloads can finish before Startup() does, so check if the window should
  // close and act accordingly
  if (!autoRemoveAndClose())
    gDownloadsView.focus();

  let obs = Cc["@mozilla.org/observer-service;1"].
            getService(Ci.nsIObserverService);
  obs.addObserver(gDownloadObserver, "download-manager-remove-download", false);
  obs.addObserver(gDownloadObserver, "browser-lastwindow-close-granted", false);

  // Clear the search box and move focus to the list on escape from the box
  gSearchBox.addEventListener("keypress", function(e) {
    if (e.keyCode == e.DOM_VK_ESCAPE) {
      // Move focus to the list instead of closing the window
      gDownloadsView.focus();
      e.preventDefault();
    }
  }, false);

  let DownloadTaskbarProgress =
    Cu.import("resource://gre/modules/DownloadTaskbarProgress.jsm", {}).DownloadTaskbarProgress;
  DownloadTaskbarProgress.onDownloadWindowLoad(window);
}

function Shutdown()
{
  gDownloadManager.removeListener(gDownloadListener);

  let obs = Cc["@mozilla.org/observer-service;1"].
            getService(Ci.nsIObserverService);
  obs.removeObserver(gDownloadObserver, "download-manager-remove-download");
  obs.removeObserver(gDownloadObserver, "browser-lastwindow-close-granted");

  clearTimeout(gBuilder);
  gStmt.reset();
  gStmt.finalize();
}

var gDownloadObserver = {
  observe: function gdo_observe(aSubject, aTopic, aData) {
    switch (aTopic) {
      case "download-manager-remove-download":
        // A null subject here indicates "remove multiple", so we just rebuild.
        if (!aSubject) {
          // Rebuild the default view
          buildDownloadList(true);
          break;
        }

        // Otherwise, remove a single download
        let id = aSubject.QueryInterface(Ci.nsISupportsPRUint32);
        let dl = getDownload(id.data);
        removeFromView(dl);
        break;
      case "browser-lastwindow-close-granted":
        if (AppConstants.platform != "macosx" &&
            gDownloadManager.activeDownloadCount == 0) {
          setTimeout(gCloseDownloadManager, 0);
        }
        break;
    }
  }
};

// View Context Menus

var gContextMenus = [
  // DOWNLOAD_DOWNLOADING
  [
    "menuitem_pause"
    , "menuitem_cancel"
    , "menuseparator"
    , "menuitem_show"
    , "menuseparator"
    , "menuitem_openReferrer"
    , "menuitem_copyLocation"
    , "menuseparator"
    , "menuitem_selectAll"
  ],
  // DOWNLOAD_FINISHED
  [
    "menuitem_open"
    , "menuitem_show"
    , "menuseparator"
    , "menuitem_openReferrer"
    , "menuitem_copyLocation"
    , "menuseparator"
    , "menuitem_selectAll"
    , "menuseparator"
    , "menuitem_removeFromList"
  ],
  // DOWNLOAD_FAILED
  [
    "menuitem_retry"
    , "menuseparator"
    , "menuitem_openReferrer"
    , "menuitem_copyLocation"
    , "menuseparator"
    , "menuitem_selectAll"
    , "menuseparator"
    , "menuitem_removeFromList"
  ],
  // DOWNLOAD_CANCELED
  [
    "menuitem_retry"
    , "menuseparator"
    , "menuitem_openReferrer"
    , "menuitem_copyLocation"
    , "menuseparator"
    , "menuitem_selectAll"
    , "menuseparator"
    , "menuitem_removeFromList"
  ],
  // DOWNLOAD_PAUSED
  [
    "menuitem_resume"
    , "menuitem_cancel"
    , "menuseparator"
    , "menuitem_show"
    , "menuseparator"
    , "menuitem_openReferrer"
    , "menuitem_copyLocation"
    , "menuseparator"
    , "menuitem_selectAll"
  ],
  // DOWNLOAD_QUEUED
  [
    "menuitem_cancel"
    , "menuseparator"
    , "menuitem_show"
    , "menuseparator"
    , "menuitem_openReferrer"
    , "menuitem_copyLocation"
    , "menuseparator"
    , "menuitem_selectAll"
  ],
  // DOWNLOAD_BLOCKED_PARENTAL
  [
    "menuitem_openReferrer"
    , "menuitem_copyLocation"
    , "menuseparator"
    , "menuitem_selectAll"
    , "menuseparator"
    , "menuitem_removeFromList"
  ],
  // DOWNLOAD_SCANNING
  [
    "menuitem_show"
    , "menuseparator"
    , "menuitem_openReferrer"
    , "menuitem_copyLocation"
    , "menuseparator"
    , "menuitem_selectAll"
  ],
  // DOWNLOAD_DIRTY
  [
    "menuitem_openReferrer"
    , "menuitem_copyLocation"
    , "menuseparator"
    , "menuitem_selectAll"
    , "menuseparator"
    , "menuitem_removeFromList"
  ],
  // DOWNLOAD_BLOCKED_POLICY
  [
    "menuitem_openReferrer"
    , "menuitem_copyLocation"
    , "menuseparator"
    , "menuitem_selectAll"
    , "menuseparator"
    , "menuitem_removeFromList"
  ]
];

function buildContextMenu(aEvent)
{
  if (aEvent.target.id != "downloadContextMenu")
    return false;

  var popup = document.getElementById("downloadContextMenu");
  while (popup.hasChildNodes())
    popup.removeChild(popup.firstChild);

  if (gDownloadsView.selectedItem) {
    let dl = gDownloadsView.selectedItem;
    let idx = parseInt(dl.getAttribute("state"));
    if (idx < 0)
      idx = 0;

    var menus = gContextMenus[idx];
    for (let i = 0; i < menus.length; ++i) {
      let menuitem = document.getElementById(menus[i]).cloneNode(true);
      let cmd = menuitem.getAttribute("cmd");
      if (cmd)
        menuitem.disabled = !gDownloadViewController.isCommandEnabled(cmd, dl);

      popup.appendChild(menuitem);
    }

    return true;
  }

  return false;
}
// Drag and Drop
var gDownloadDNDObserver =
{
  onDragStart: function (aEvent)
  {
    if (!gDownloadsView.selectedItem)
      return;
    var dl = gDownloadsView.selectedItem;
    var f = getLocalFileFromNativePathOrUrl(dl.getAttribute("file"));
    if (!f.exists())
      return;

    var dt = aEvent.dataTransfer;
    dt.mozSetDataAt("application/x-moz-file", f, 0);
    var url = Services.io.newFileURI(f).spec;
    dt.setData("text/uri-list", url);
    dt.setData("text/plain", url);
    dt.effectAllowed = "copyMove";
    dt.addElement(dl);
  },

  onDragOver: function (aEvent)
  {
    var types = aEvent.dataTransfer.types;
    if (types.includes("text/uri-list") ||
        types.includes("text/x-moz-url") ||
        types.includes("text/plain"))
      aEvent.preventDefault();
  },

  onDrop: function(aEvent)
  {
    var dt = aEvent.dataTransfer;
    // If dragged item is from our source, do not try to
    // redownload already downloaded file.
    if (dt.mozGetDataAt("application/x-moz-file", 0))
      return;

    var url = dt.getData("URL");
    var name;
    if (!url) {
      url = dt.getData("text/x-moz-url") || dt.getData("text/plain");
      [url, name] = url.split("\n");
    }
    if (url) {
      let sourceDoc = dt.mozSourceNode ? dt.mozSourceNode.ownerDocument : document;
      saveURL(url, name ? name : url, null, true, true, null, sourceDoc);
    }
  }
}

function pasteHandler() {
  let trans = Cc["@mozilla.org/widget/transferable;1"].
              createInstance(Ci.nsITransferable);
  trans.init(null);
  let flavors = ["text/x-moz-url", "text/unicode"];
  flavors.forEach(trans.addDataFlavor);

  Services.clipboard.getData(trans, Services.clipboard.kGlobalClipboard);

  // Getting the data or creating the nsIURI might fail
  try {
    let data = {};
    trans.getAnyTransferData({}, data, {});
    let [url, name] = data.value.QueryInterface(Ci.nsISupportsString).data.split("\n");

    if (!url)
      return;

    let uri = Services.io.newURI(url, null, null);

    saveURL(uri.spec, name || uri.spec, null, true, true, null, document);
  } catch (ex) {}
}

// Command Updating and Command Handlers

var gDownloadViewController = {
  isCommandEnabled: function(aCommand, aItem)
  {
    let dl = aItem;
    let download = null; // used for getting an nsIDownload object

    switch (aCommand) {
      case "cmd_cancel":
        return dl.inProgress;
      case "cmd_open": {
        let file = getLocalFileFromNativePathOrUrl(dl.getAttribute("file"));
        return dl.openable && file.exists();
      }
      case "cmd_show": {
        let file = getLocalFileFromNativePathOrUrl(dl.getAttribute("file"));
        return file.exists();
      }
      case "cmd_pause":
        download = gDownloadManager.getDownload(dl.getAttribute("dlid"));
        return dl.inProgress && !dl.paused && download.resumable;
      case "cmd_pauseResume":
        download = gDownloadManager.getDownload(dl.getAttribute("dlid"));
        return (dl.inProgress || dl.paused) && download.resumable;
      case "cmd_resume":
        download = gDownloadManager.getDownload(dl.getAttribute("dlid"));
        return dl.paused && download.resumable;
      case "cmd_openReferrer":
        return dl.hasAttribute("referrer");
      case "cmd_removeFromList":
      case "cmd_retry":
        return dl.removable;
      case "cmd_copyLocation":
        return true;
    }
    return false;
  },

  doCommand: function(aCommand, aItem)
  {
    if (this.isCommandEnabled(aCommand, aItem))
      this.commands[aCommand](aItem);
  },

  commands: {
    cmd_cancel: function(aSelectedItem) {
      cancelDownload(aSelectedItem);
    },
    cmd_open: function(aSelectedItem) {
      openDownload(aSelectedItem);
    },
    cmd_openReferrer: function(aSelectedItem) {
      openReferrer(aSelectedItem);
    },
    cmd_pause: function(aSelectedItem) {
      pauseDownload(aSelectedItem);
    },
    cmd_pauseResume: function(aSelectedItem) {
      if (aSelectedItem.paused)
        this.cmd_resume(aSelectedItem);
      else
        this.cmd_pause(aSelectedItem);
    },
    cmd_removeFromList: function(aSelectedItem) {
      removeDownload(aSelectedItem);
    },
    cmd_resume: function(aSelectedItem) {
      resumeDownload(aSelectedItem);
    },
    cmd_retry: function(aSelectedItem) {
      retryDownload(aSelectedItem);
    },
    cmd_show: function(aSelectedItem) {
      showDownload(aSelectedItem);
    },
    cmd_copyLocation: function(aSelectedItem) {
      copySourceLocation(aSelectedItem);
    },
  }
};

/**
 * Helper function to do commands.
 *
 * @param aCmd
 *        The command to be performed.
 * @param aItem
 *        The richlistitem that represents the download that will have the
 *        command performed on it. If this is null, the command is performed on
 *        all downloads. If the item passed in is not a richlistitem that
 *        represents a download, it will walk up the parent nodes until it finds
 *        a DOM node that is.
 */
function performCommand(aCmd, aItem)
{
  let elm = aItem;
  if (!elm) {
    // If we don't have a desired download item, do the command for all
    // selected items. Initialize the callback to null so commands know to add
    // a callback if they want. We will call the callback with empty arguments
    // after performing the command on each selected download item.
    gPerformAllCallback = null;

    // Convert the nodelist into an array to keep a copy of the download items
    let items = [];
    for (let i = gDownloadsView.selectedItems.length; --i >= 0; )
      items.unshift(gDownloadsView.selectedItems[i]);

    // Do the command for each download item
    for (let item of items)
      performCommand(aCmd, item);

    // Call the callback with no arguments and reset because we're done
    if (typeof gPerformAllCallback == "function")
      gPerformAllCallback();
    gPerformAllCallback = undefined;

    return;
  }
  while (elm.nodeName != "richlistitem" ||
         elm.getAttribute("type") != "download") {
    elm = elm.parentNode;
  }

  gDownloadViewController.doCommand(aCmd, elm);
}

function setSearchboxFocus()
{
  gSearchBox.focus();
  gSearchBox.select();
}

function openExternal(aFile)
{
  var uri = Cc["@mozilla.org/network/io-service;1"].
            getService(Ci.nsIIOService).newFileURI(aFile);

  var protocolSvc = Cc["@mozilla.org/uriloader/external-protocol-service;1"].
                    getService(Ci.nsIExternalProtocolService);
  protocolSvc.loadUrl(uri);

  return;
}

// Utility Functions

/**
 * Create a download richlistitem with the provided attributes. Some attributes
 * are *required* while optional ones will only be set on the item if provided.
 *
 * @param aAttrs
 *        An object that must have the following properties: dlid, file,
 *        target, uri, state, progress, startTime, endTime, currBytes,
 *        maxBytes; optional properties: referrer
 * @return An initialized download richlistitem
 */
function createDownloadItem(aAttrs)
{
  let dl = document.createElement("richlistitem");

  // Copy the attributes from the argument into the item
  for (let attr in aAttrs)
    dl.setAttribute(attr, aAttrs[attr]);

  // Initialize other attributes
  dl.setAttribute("type", "download");
  dl.setAttribute("id", "dl" + aAttrs.dlid);
  dl.setAttribute("image", "moz-icon://" + aAttrs.file + "?size=32");
  dl.setAttribute("lastSeconds", Infinity);

  // Initialize more complex attributes
  updateTime(dl);
  updateStatus(dl);

  try {
    let file = getLocalFileFromNativePathOrUrl(aAttrs.file);
    dl.setAttribute("path", file.nativePath || file.path);
    return dl;
  } catch (e) {
    // aFile might not be a file: url or a valid native path
    // see bug #392386 for details
  }
  return null;
}

/**
 * Updates the disabled state of the buttons of a downlaod.
 *
 * @param aItem
 *        The richlistitem representing the download.
 */
function updateButtons(aItem)
{
  let buttons = aItem.buttons;

  for (let i = 0; i < buttons.length; ++i) {
    let cmd = buttons[i].getAttribute("cmd");
    let enabled = gDownloadViewController.isCommandEnabled(cmd, aItem);
    buttons[i].disabled = !enabled;

    if ("cmd_pause" == cmd && !enabled) {
      // We need to add the tooltip indicating that the download cannot be
      // paused now.
      buttons[i].setAttribute("tooltiptext", gStr.cannotPause);
    }
  }
}

/**
 * Updates the status for a download item depending on its state
 *
 * @param aItem
 *        The richlistitem that has various download attributes.
 * @param aDownload
 *        The nsDownload from the backend. This is an optional parameter, but
 *        is useful for certain states such as DOWNLOADING.
 */
function updateStatus(aItem, aDownload) {
  let status = "";
  let statusTip = "";

  let state = Number(aItem.getAttribute("state"));
  switch (state) {
    case nsIDM.DOWNLOAD_PAUSED:
    {
      let currBytes = Number(aItem.getAttribute("currBytes"));
      let maxBytes = Number(aItem.getAttribute("maxBytes"));

      let transfer = DownloadUtils.getTransferTotal(currBytes, maxBytes);
      status = replaceInsert(gStr.paused, 1, transfer);

      break;
    }
    case nsIDM.DOWNLOAD_DOWNLOADING:
    {
      let currBytes = Number(aItem.getAttribute("currBytes"));
      let maxBytes = Number(aItem.getAttribute("maxBytes"));
      // If we don't have an active download, assume 0 bytes/sec
      let speed = aDownload ? aDownload.speed : 0;
      let lastSec = Number(aItem.getAttribute("lastSeconds"));

      let newLast;
      [status, newLast] =
        DownloadUtils.getDownloadStatus(currBytes, maxBytes, speed, lastSec);

      // Update lastSeconds to be the new value
      aItem.setAttribute("lastSeconds", newLast);

      break;
    }
    case nsIDM.DOWNLOAD_FINISHED:
    case nsIDM.DOWNLOAD_FAILED:
    case nsIDM.DOWNLOAD_CANCELED:
    case nsIDM.DOWNLOAD_BLOCKED_PARENTAL:
    case nsIDM.DOWNLOAD_BLOCKED_POLICY:
    case nsIDM.DOWNLOAD_DIRTY:
    {
      let stateSize = {};
      stateSize[nsIDM.DOWNLOAD_FINISHED] = function() {
        // Display the file size, but show "Unknown" for negative sizes
        let fileSize = Number(aItem.getAttribute("maxBytes"));
        let sizeText = gStr.doneSizeUnknown;
        if (fileSize >= 0) {
          let [size, unit] = DownloadUtils.convertByteUnits(fileSize);
          sizeText = replaceInsert(gStr.doneSize, 1, size);
          sizeText = replaceInsert(sizeText, 2, unit);
        }
        return sizeText;
      };
      stateSize[nsIDM.DOWNLOAD_FAILED] = () => gStr.stateFailed;
      stateSize[nsIDM.DOWNLOAD_CANCELED] = () => gStr.stateCanceled;
      stateSize[nsIDM.DOWNLOAD_BLOCKED_PARENTAL] = () => gStr.stateBlockedParentalControls;
      stateSize[nsIDM.DOWNLOAD_BLOCKED_POLICY] = () => gStr.stateBlockedPolicy;
      stateSize[nsIDM.DOWNLOAD_DIRTY] = () => gStr.stateDirty;

      // Insert 1 is the download size or download state
      status = replaceInsert(gStr.doneStatus, 1, stateSize[state]());

      let [displayHost, fullHost] =
        DownloadUtils.getURIHost(getReferrerOrSource(aItem));

      // Insert 2 is the eTLD + 1 or other variations of the host
      status = replaceInsert(status, 2, displayHost);
      // Set the tooltip to be the full host
      statusTip = fullHost;

      break;
    }
  }

  aItem.setAttribute("status", status);
  aItem.setAttribute("statusTip", statusTip != "" ? statusTip : status);
}

/**
 * Updates the time that gets shown for completed download items
 *
 * @param aItem
 *        The richlistitem representing a download in the UI
 */
function updateTime(aItem)
{
  // Don't bother updating for things that aren't finished
  if (aItem.inProgress)
    return;

  let end = new Date(parseInt(aItem.getAttribute("endTime")));
  let [dateCompact, dateComplete] = DownloadUtils.getReadableDates(end);
  aItem.setAttribute("dateTime", dateCompact);
  aItem.setAttribute("dateTimeTip", dateComplete);
}

/**
 * Helper function to replace a placeholder string with a real string
 *
 * @param aText
 *        Source text containing placeholder (e.g., #1)
 * @param aIndex
 *        Index number of placeholder to replace
 * @param aValue
 *        New string to put in place of placeholder
 * @return The string with placeholder replaced with the new string
 */
function replaceInsert(aText, aIndex, aValue)
{
  return aText.replace("#" + aIndex, aValue);
}

/**
 * Perform the default action for the currently selected download item
 */
function doDefaultForSelected()
{
  // Make sure we have something selected
  let item = gDownloadsView.selectedItem;
  if (!item)
    return;

  // Get the default action (first item in the menu)
  let state = Number(item.getAttribute("state"));
  let menuitem = document.getElementById(gContextMenus[state][0]);

  // Try to do the action if the command is enabled
  gDownloadViewController.doCommand(menuitem.getAttribute("cmd"), item);
}

function removeFromView(aDownload)
{
  // Make sure we have an item to remove
  if (!aDownload) return;

  let index = gDownloadsView.selectedIndex;
  gDownloadsView.removeChild(aDownload);
  gDownloadsView.selectedIndex = Math.min(index, gDownloadsView.itemCount - 1);

  // We might have removed the last item, so update the clear list button
  updateClearListButton();
}

function getReferrerOrSource(aDownload)
{
  // Give the referrer if we have it set
  if (aDownload.hasAttribute("referrer"))
    return aDownload.getAttribute("referrer");

  // Otherwise, provide the source
  return aDownload.getAttribute("uri");
}

/**
 * Initiate building the download list to have the active downloads followed by
 * completed ones filtered by the search term if necessary.
 *
 * @param aForceBuild
 *        Force the list to be built even if the search terms don't change
 */
function buildDownloadList(aForceBuild)
{
  // Stringify the previous search
  let prevSearch = gSearchTerms.join(" ");

  // Array of space-separated lower-case search terms
  gSearchTerms = gSearchBox.value.replace(/^\s+|\s+$/g, "").
                 toLowerCase().split(/\s+/);

  // Unless forced, don't rebuild the download list if the search didn't change
  if (!aForceBuild && gSearchTerms.join(" ") == prevSearch)
    return;

  // Clear out values before using them
  clearTimeout(gBuilder);
  gStmt.reset();

  // Clear the list before adding items by replacing with a shallow copy
  let empty = gDownloadsView.cloneNode(false);
  gDownloadsView.parentNode.replaceChild(empty, gDownloadsView);
  gDownloadsView = empty;

  try {
    gStmt.bindByIndex(0, nsIDM.DOWNLOAD_NOTSTARTED);
    gStmt.bindByIndex(1, nsIDM.DOWNLOAD_DOWNLOADING);
    gStmt.bindByIndex(2, nsIDM.DOWNLOAD_PAUSED);
    gStmt.bindByIndex(3, nsIDM.DOWNLOAD_QUEUED);
    gStmt.bindByIndex(4, nsIDM.DOWNLOAD_SCANNING);
  } catch (e) {
    // Something must have gone wrong when binding, so clear and quit
    gStmt.reset();
    return;
  }

  // Take a quick break before we actually start building the list
  gBuilder = setTimeout(function() {
    // Start building the list
    stepListBuilder(1);

    // We just tried to add a single item, so we probably need to enable
    updateClearListButton();
  }, 0);
}

/**
 * Incrementally build the download list by adding at most the requested number
 * of items if there are items to add. After doing that, it will schedule
 * another chunk of items specified by gListBuildDelay and gListBuildChunk.
 *
 * @param aNumItems
 *        Number of items to add to the list before taking a break
 */
function stepListBuilder(aNumItems) {
  try {
    // If we're done adding all items, we can quit
    if (!gStmt.executeStep()) {
      // Send a notification that we finished, but wait for clear list to update
      updateClearListButton();
      setTimeout(() => Cc["@mozilla.org/observer-service;1"].
        getService(Ci.nsIObserverService).
        notifyObservers(window, "download-manager-ui-done", null), 0);

      return;
    }

    // Try to get the attribute values from the statement
    let attrs = {
      dlid: gStmt.getInt64(0),
      file: gStmt.getString(1),
      target: gStmt.getString(2),
      uri: gStmt.getString(3),
      state: gStmt.getInt32(4),
      startTime: Math.round(gStmt.getInt64(5) / 1000),
      endTime: Math.round(gStmt.getInt64(6) / 1000),
      currBytes: gStmt.getInt64(8),
      maxBytes: gStmt.getInt64(9)
    };

    // Only add the referrer if it's not null
    let referrer = gStmt.getString(7);
    if (referrer)
      attrs.referrer = referrer;

    // If the download is active, grab the real progress, otherwise default 100
    let isActive = gStmt.getInt32(10);
    attrs.progress = isActive ? gDownloadManager.getDownload(attrs.dlid).
      percentComplete : 100;

    // Make the item and add it to the end if it's active or matches the search
    let item = createDownloadItem(attrs);
    if (item && (isActive || downloadMatchesSearch(item))) {
      // Add item to the end
      gDownloadsView.appendChild(item);

      // Because of the joys of XBL, we can't update the buttons until the
      // download object is in the document.
      updateButtons(item);
    } else {
      // We didn't add an item, so bump up the number of items to process, but
      // not a whole number so that we eventually do pause for a chunk break
      aNumItems += .9;
    }
  } catch (e) {
    // Something went wrong when stepping or getting values, so clear and quit
    gStmt.reset();
    return;
  }

  // Add another item to the list if we should; otherwise, let the UI update
  // and continue later
  if (aNumItems > 1) {
    stepListBuilder(aNumItems - 1);
  } else {
    // Use a shorter delay for earlier downloads to display them faster
    let delay = Math.min(gDownloadsView.itemCount * 10, gListBuildDelay);
    gBuilder = setTimeout(stepListBuilder, delay, gListBuildChunk);
  }
}

/**
 * Add a download to the front of the download list
 *
 * @param aDownload
 *        The nsIDownload to make into a richlistitem
 */
function prependList(aDownload)
{
  let attrs = {
    dlid: aDownload.id,
    file: aDownload.target.spec,
    target: aDownload.displayName,
    uri: aDownload.source.spec,
    state: aDownload.state,
    progress: aDownload.percentComplete,
    startTime: Math.round(aDownload.startTime / 1000),
    endTime: Date.now(),
    currBytes: aDownload.amountTransferred,
    maxBytes: aDownload.size
  };

  // Make the item and add it to the beginning
  let item = createDownloadItem(attrs);
  if (item) {
    // Add item to the beginning
    gDownloadsView.insertBefore(item, gDownloadsView.firstChild);

    // Because of the joys of XBL, we can't update the buttons until the
    // download object is in the document.
    updateButtons(item);

    // We might have added an item to an empty list, so update button
    updateClearListButton();
  }
}

/**
 * Check if the download matches the current search term based on the texts
 * shown to the user. All search terms are checked to see if each matches any
 * of the displayed texts.
 *
 * @param aItem
 *        Download richlistitem to check if it matches the current search
 * @return Boolean true if it matches the search; false otherwise
 */
function downloadMatchesSearch(aItem)
{
  // Search through the download attributes that are shown to the user and
  // make it into one big string for easy combined searching
  let combinedSearch = "";
  for (let attr of gSearchAttributes)
    combinedSearch += aItem.getAttribute(attr).toLowerCase() + " ";

  // Make sure each of the terms are found
  for (let term of gSearchTerms)
    if (combinedSearch.indexOf(term) == -1)
      return false;

  return true;
}

// we should be using real URLs all the time, but until
// bug 239948 is fully fixed, this will do...
//
// note, this will thrown an exception if the native path
// is not valid (for example a native Windows path on a Mac)
// see bug #392386 for details
function getLocalFileFromNativePathOrUrl(aPathOrUrl)
{
  if (aPathOrUrl.substring(0, 7) == "file://") {
    // if this is a URL, get the file from that
    let ioSvc = Cc["@mozilla.org/network/io-service;1"].
                getService(Ci.nsIIOService);

    // XXX it's possible that using a null char-set here is bad
    const fileUrl = ioSvc.newURI(aPathOrUrl, null, null).
                    QueryInterface(Ci.nsIFileURL);
    return fileUrl.file.clone().QueryInterface(Ci.nsILocalFile);
  }
  // if it's a pathname, create the nsILocalFile directly
  var f = new nsLocalFile(aPathOrUrl);

  return f;
}

/**
 * Update the disabled state of the clear list button based on whether or not
 * there are items in the list that can potentially be removed.
 */
function updateClearListButton()
{
  let button = document.getElementById("clearListButton");
  // The button is enabled if we have items in the list and we can clean up
  button.disabled = !(gDownloadsView.itemCount && gDownloadManager.canCleanUp);
}

function getDownload(aID)
{
  return document.getElementById("dl" + aID);
}

/**
 * Initialize the statement which is used to retrieve the list of downloads.
 */
function initStatement()
{
  if (gStmt)
    gStmt.finalize();

  gStmt = gDownloadManager.DBConnection.createStatement(
    "SELECT id, target, name, source, state, startTime, endTime, referrer, " +
           "currBytes, maxBytes, state IN (?1, ?2, ?3, ?4, ?5) isActive " +
    "FROM moz_downloads " +
    "ORDER BY isActive DESC, endTime DESC, startTime DESC");
}