# 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/.


// The warden checks request to see if they are for phishy pages. It
// does so by querying our locally stored blacklists.
// 
// When the warden notices a problem, it queries all browser views
// (each of which corresopnds to an open browser window) to see
// whether one of them can handle it. A browser view can handle a
// problem if its browser window has an HTMLDocument loaded with the
// given URL and that Document hasn't already been flagged as a
// problem. For every problematic URL we notice loading, at most one
// Document is flagged as problematic. Otherwise you can get into
// trouble if multiple concurrent phishy pages load with the same URL.
//
// Since we check URLs very early in the request cycle (in a progress
// listener), the URL might not yet be associated with a Document when
// we determine that it is phishy. So the the warden retries finding
// a browser view to handle the problem until one can, or until it
// determines it should give up (see complicated logic below).
//
// The warden has displayers that the browser view uses to render
// different kinds of warnings (e.g., one that's shown before a page
// loads as opposed to one that's shown after the page has already
// loaded).
//
// Note: There is a single warden for the whole application.
//
// TODO better way to expose displayers/views to browser view

const kPhishWardenEnabledPref = "browser.safebrowsing.enabled";

/**
 * Abtracts the checking of user/browser actions for signs of
 * phishing. 
 *
 * @param progressListener nsIDocNavStartProgressListener
 * @param tabbrowser XUL tabbrowser element
 * @constructor
 */
function PROT_PhishingWarden() {
  PROT_ListWarden.call(this);

  this.debugZone = "phishwarden";

  // Use this to query preferences
  this.prefs_ = new G_Preferences();

  // We need to know whether we're enabled and whether we're in advanced
  // mode, so reflect the appropriate preferences into our state.

  // Global preference to enable the phishing warden
  this.phishWardenEnabled_ = this.prefs_.getPref(kPhishWardenEnabledPref, null);

  // Get notifications when the phishing warden enabled pref changes
  var phishWardenPrefObserver = 
    BindToObject(this.onPhishWardenEnabledPrefChanged, this);
  this.prefs_.addObserver(kPhishWardenEnabledPref, phishWardenPrefObserver);

  G_Debug(this, "phishWarden initialized");
}

PROT_PhishingWarden.inherits(PROT_ListWarden);

PROT_PhishingWarden.prototype.QueryInterface = function(iid) {
  if (iid.equals(Ci.nsISupports) || 
      iid.equals(Ci.nsISupportsWeakReference))
    return this;
  throw Components.results.NS_ERROR_NO_INTERFACE;
}

/**
 * Cleanup on shutdown.
 */
PROT_PhishingWarden.prototype.shutdown = function() {
  this.prefs_.removeAllObservers();
  this.listManager_ = null;
}

/**
 * When a preference (either advanced features or the phishwarden
 * enabled) changes, we might have to start or stop asking for updates. 
 * 
 * This is a little tricky; we start or stop management only when we
 * have complete information we can use to determine whether we
 * should.  It could be the case that one pref or the other isn't set
 * yet (e.g., they haven't opted in/out of advanced features). So do
 * nothing unless we have both pref values -- we get notifications for
 * both, so eventually we will start correctly.
 */ 
PROT_PhishingWarden.prototype.maybeToggleUpdateChecking = function() {
  var phishWardenEnabled = this.prefs_.getPref(kPhishWardenEnabledPref, null);

  G_Debug(this, "Maybe toggling update checking. " +
          "Warden enabled? " + phishWardenEnabled);

  // Do nothing unless both prefs are set.  They can be null (unset), true, or
  // false.
  if (phishWardenEnabled === null)
    return;

  // We update and save to disk all tables
  if (phishWardenEnabled === true) {
    this.enableBlacklistTableUpdates();
    this.enableWhitelistTableUpdates();
  } else {
    // Anti-phishing is off, disable table updates
    this.disableBlacklistTableUpdates();
    this.disableWhitelistTableUpdates();
  }
}

/**
 * Deal with a user changing the pref that says whether we should 
 * enable the phishing warden (i.e., that SafeBrowsing is active)
 *
 * @param prefName Name of the pref holding the value indicating whether
 *                 we should enable the phishing warden
 */
PROT_PhishingWarden.prototype.onPhishWardenEnabledPrefChanged = function(
                                                                    prefName) {
  // Just to be safe, ignore changes to sub prefs.
  if (prefName != "browser.safebrowsing.enabled")
    return;

  this.phishWardenEnabled_ = 
    this.prefs_.getPref(prefName, this.phishWardenEnabled_);
  this.maybeToggleUpdateChecking();
}