/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is Mozilla Communicator client code.
 *
 * The Initial Developer of the Original Code is Netscape Communications
 * Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s): Rick Potts <rpotts@netscape.com>
 *                 David Matiskella <davidm@netscape.com>
 *                 David Hyatt <hyatt@netscape.com>
 *                 Suresh Duddi <dp@netscape.com>
 *                 Scott Collins <scc@netscape.com>
 *                 Dan Matejka <danm@netscape.com>
 *                 Doug Turner <dougt@netscape.com>
 *                 Ray Whitmer <rayw@netscape.com>
 *                 Dan Mosedale <dmose@mozilla.org>
 */

#include "nsISupports.idl"
#include "nsIEventQueue.idl"

%{C++
#include "prthread.h"
#include "plevent.h"

/* be761f00-a3b0-11d2-996c-0080c7cb1080 */
#define NS_EVENTQUEUESERVICE_CID \
{ 0xbe761f00, 0xa3b0, 0x11d2, \
  {0x99, 0x6c, 0x00, 0x80, 0xc7, 0xcb, 0x10, 0x80} }

#define NS_EVENTQUEUESERVICE_CONTRACTID "@mozilla.org/event-queue-service;1"
#define NS_EVENTQUEUESERVICE_CLASSNAME "Event Queue Service"

#define NS_CURRENT_THREAD    ((PRThread*)0)
#define NS_CURRENT_EVENTQ    ((nsIEventQueue*)0)

#define NS_UI_THREAD         ((PRThread*)1)
#define NS_UI_THREAD_EVENTQ  ((nsIEventQueue*)1)

%}

/* a forward decl */
interface nsIThread;

[scriptable, uuid(a6cf90dc-15b3-11d2-932e-00805f8add32)]
interface nsIEventQueueService : nsISupports
{
  /**
   * Creates and holds a native event queue for the current thread.
   * "Native" queues have an associated callback mechanism which is
   * automatically triggered when an event is posted. See plevent.c for 
   * details.
   * @return NS_OK on success, or a host of failure indications
   */
  void createThreadEventQueue();

  /**
   * Creates and hold a monitored event queue for the current thread.
   * "Monitored" queues have no callback processing mechanism.
   * @return NS_OK on success, or a host of failure indications
   */
  void createMonitoredThreadEventQueue();

  /**
   * Somewhat misnamed, this method releases the service's hold on the event
   * queue(s) for this thread. Subsequent attempts to access this thread's
   * queue (GetThreadEventQueue, for example) may fail, though the queue itself
   * will be destroyed only after all references to it are released and the
   * queue itself is no longer actively processing events.
   * @return nonsense.
   */
  void destroyThreadEventQueue();

  nsIEventQueue createFromIThread(in nsIThread aThread, 
				  in boolean aNative);
                               
  [noscript] nsIEventQueue createFromPLEventQueue(in PLEventQueuePtr 
						  aPLEventQueue);

  // Add a new event queue for the current thread, making it the "current"
  // queue. Return that queue, addrefed.
  nsIEventQueue pushThreadEventQueue();

  // release and disable the queue
  void popThreadEventQueue(in nsIEventQueue aQueue);

  [noscript] nsIEventQueue getThreadEventQueue(in PRThreadPtr aThread);

  /**
   * @deprecated in favor of getSpecialEventQueue, since that's
   * scriptable and this isn't.
   *
   * Check for any "magic" event queue constants (NS_CURRENT_EVENTQ,
   * NS_UI_THREAD_EVENTQ) and return the real event queue that they
   * represent, AddRef()ed.  Otherwise, return the event queue passed
   * in, AddRef()ed.  This is not scriptable because the arguments in
   * question may be magic constants rather than real nsIEventQueues.
   *
   * @arg queueOrConstant    either a real event queue or a magic
   *                         constant to be resolved
   *
   * @return                 a real event queue, AddRef()ed
   */
  [noscript] nsIEventQueue resolveEventQueue(in nsIEventQueue queueOrConstant);

  /**
   * Returns the appropriate special event queue, AddRef()ed.  Really
   * just a scriptable version of ResolveEventQueue.
   *
   * @arg aQueue    Either CURRENT_THREAD_EVENT_QUEUE or
   *                UI_THREAD_EVENT_QUEUE
   * @return        The requested nsIEventQueue, AddRef()ed
   * @exception NS_ERROR_NULL_POINTER   Zero pointer passed in for return value
   * @exception NS_ERROR_ILLEGAL_VALUE  Bogus constant passed in aQueue
   * @exception NS_ERROR_FAILURE        Error while calling 
   *                                    GetThreadEventQueue()
   */
  nsIEventQueue getSpecialEventQueue(in long aQueue);

  const long CURRENT_THREAD_EVENT_QUEUE = 0;
  const long UI_THREAD_EVENT_QUEUE = 1;

};