/* -*- 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 1.0 (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.
 */

#include "prmon.h"
#include "nsIEventQueue.h"
#include "nsPIEventQueueChain.h"

static NS_DEFINE_IID(kIEventQueueIID, NS_IEVENTQUEUE_IID);

class nsEventQueueImpl : public nsIEventQueue,
                         public nsPIEventQueueChain
{
public:
    nsEventQueueImpl();
    virtual ~nsEventQueueImpl();

  // nsISupports interface...
    NS_DECL_ISUPPORTS

  // nsIEventQueue interface...
    NS_IMETHOD_(PRStatus) PostEvent(PLEvent* aEvent);
    NS_IMETHOD PostSynchronousEvent(PLEvent* aEvent, void** aResult);

    NS_IMETHOD ProcessPendingEvents();
    NS_IMETHOD EventLoop();

    NS_IMETHOD EventAvailable(PRBool& aResult);
    NS_IMETHOD GetEvent(PLEvent** aResult);
    NS_IMETHOD HandleEvent(PLEvent* aEvent);

    NS_IMETHOD_(PRInt32) GetEventQueueSelectFD();

    NS_IMETHOD Init();
    NS_IMETHOD InitFromPLQueue(PLEventQueue* aQueue);

    NS_IMETHOD EnterMonitor();
    NS_IMETHOD ExitMonitor();

    NS_IMETHOD RevokeEvents(void* owner);

    NS_IMETHOD GetPLEventQueue(PLEventQueue** aEventQueue);
    
    NS_IMETHOD IsQueueOnCurrentThread(PRBool *aResult);

    NS_IMETHOD StopAcceptingEvents();

    // Helpers
    static NS_METHOD Create(nsISupports* outer, const nsIID& aIID, void* *aInstancePtr);

    static const nsCID& CID() { static nsCID cid = NS_EVENTQUEUE_CID; return cid; }

    // nsPIEventQueueChain interface
    NS_IMETHOD AppendQueue(nsIEventQueue *aQueue);
    NS_IMETHOD Unlink();
    NS_IMETHOD GetYoungest(nsIEventQueue **aQueue);
    NS_IMETHOD GetYoungestActive(nsIEventQueue **aQueue);
    NS_IMETHOD SetYounger(nsPIEventQueueChain *aQueue);
    NS_IMETHOD SetElder(nsPIEventQueueChain *aQueue);

private:
  PLEventQueue  *mEventQueue;
  PRBool        mAcceptingEvents, // accept new events or pass them on?
                mCouldHaveEvents; // accepting new ones, or still have old ones?
  nsPIEventQueueChain *mYoungerQueue,
                      *mElderQueue;

  void NotifyObservers(const char *aTopic);

  void CheckForDeactivation() {
         if (mCouldHaveEvents && !mAcceptingEvents && !PL_EventAvailable(mEventQueue)) {
            mCouldHaveEvents = PR_FALSE;
            Release();
         }
       }
};