/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */

#include "nsISupports.idl"

webidl EventTarget;

interface nsIArray;

/**
 * Contains an event target along with a count of event listener changes
 * affecting accessibility.
 */
[scriptable, uuid(07222b02-da12-4cf4-b2f7-761da007a8d8)]
interface nsIEventListenerChange : nsISupports
{
  readonly attribute EventTarget target;

  [noscript]
  readonly attribute uint32_t countOfEventListenerChangesAffectingAccessibility;
};

[scriptable, function, uuid(aa7c95f6-d3b5-44b3-9597-1d9f19b9c5f2)]
interface nsIListenerChangeListener : nsISupports
{
  void listenersChanged(in nsIArray aEventListenerChanges);
};

/**
 * An instance of this interface describes how an event listener
 * was added to an event target.
 */
[scriptable, uuid(11ba5fd7-8db2-4b1a-9f67-342cfa11afad)]
interface nsIEventListenerInfo : nsISupports
{
  /**
   * The type of the event for which the listener was added.
   * Null if the listener is for all the events.
   */
  readonly attribute AString type;
  readonly attribute boolean capturing;
  readonly attribute boolean allowsUntrusted;
  readonly attribute boolean inSystemEventGroup;

  /**
   * Changing the enabled state works only with listeners implemented in
   * JS. An error is thrown for native listeners.
   */
  attribute boolean enabled;

  /**
   * The underlying JS object of the event listener, if this listener
   * has one.  Null otherwise.
   */
  [implicit_jscontext]
  readonly attribute jsval listenerObject;

  /**
   * Tries to serialize event listener to a string.
   * Returns null if serialization isn't possible
   * (for example with C++ listeners).
   */
  AString toSource();
};

[scriptable, uuid(77aab5f7-213d-4db4-9f22-e46dfb774f15)]
interface nsIEventListenerService : nsISupports
{
  /**
   * Returns an array of nsIEventListenerInfo objects.
   * If aEventTarget doesn't have any listeners, this returns null.
   */
  Array<nsIEventListenerInfo> getListenerInfoFor(in EventTarget aEventTarget);

  /**
   * Returns an array of event targets.
   * aEventTarget will be at index 0.
   * The objects are the ones that would be used as DOMEvent.currentTarget while
   * dispatching an event to aEventTarget
   * @note Some events, especially 'load', may actually have a shorter
   *       event target chain than what this methods returns.
   */
  [can_run_script]
  Array<EventTarget> getEventTargetChainFor(in EventTarget aEventTarget,
                                            in boolean composed);

  /**
   * Returns true if a event target has any listener for the given type.
   */
  boolean hasListenersFor(in EventTarget aEventTarget,
                          in AString aType);

  /**
   * Add a system-group eventlistener to a event target.
   */
  [implicit_jscontext]
  void addSystemEventListener(in EventTarget target,
                              in AString type,
                              in jsval listener,
                              in boolean useCapture);

  /**
   * Remove a system-group eventlistener from a event target.
   */
  [implicit_jscontext]
  void removeSystemEventListener(in EventTarget target,
                                 in AString type,
                                 in jsval listener,
                                 in boolean useCapture);

  [implicit_jscontext]
  void addListenerForAllEvents(in EventTarget target,
                               in jsval listener,
                               [optional] in boolean aUseCapture,
                               [optional] in boolean aWantsUntrusted,
                               [optional] in boolean aSystemEventGroup);

  [implicit_jscontext]
  void removeListenerForAllEvents(in EventTarget target,
                                  in jsval listener,
                                  [optional] in boolean aUseCapture,
                                  [optional] in boolean aSystemEventGroup);

  void addListenerChangeListener(in nsIListenerChangeListener aListener);
  void removeListenerChangeListener(in nsIListenerChangeListener aListener);
};