/****************************************************************************
 **
 ** Copyright (C) 1992-2009 Nokia. All rights reserved.
 **
 ** This file is part of Qt Jambi.
 **
 ** ** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at qt-sales@nokia.com.


 **
 ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 **
 ****************************************************************************/

package com.trolltech.qt.core;

import java.util.*;

/**
 * The QMessageHandler class provides a means of receiving notifications when the C++ side
 * of Qt Jambi enters a state where it produces warnings and debug messages and similar.
 */
public abstract class QMessageHandler {

    static {
        try {
            // Make sure we load dependent libraries...
            Class.forName("com.trolltech.qt.QtJambi_LibraryInitializer");
        } catch (ClassNotFoundException e) { }
    }

    /**
     * Implement this method to be notified about debug messages.
     */
    public abstract void debug(String message);

    /**
     * Implement this method to be notified about warnings.
     */
    public abstract void warning(String message);

    /**
     * Implement this method to be notified about critical messages
     */
    public abstract void critical(String message);

    /**
     * Implement this method to be notified about fatal messages. After receiving a fatal
     * message the application will immediatly shut down.
     */
    public abstract void fatal(String message);

    /**
     * Installs the specified message handler as a receiver for message notification.
     */
    public static void installMessageHandler(QMessageHandler handler) {
        if (handlers == null) {
            handlers = new ArrayList<QMessageHandler>();
            installMessageHandlerProxy();
        }
        handlers.add(handler);
    }

    /**
     * Removes the specified message handler as a receiver for message notification.
     */
    public static void removeMessageHandler(QMessageHandler handler) {
        if (handlers != null){
            handlers.remove(handler);
            if(handlers.isEmpty()){
                removeMessageHandlerProxy();
                handlers = null;
            }
        }
    }

    private static boolean process(int id, String message) {
        if (handlers == null)
            return false;
        switch (id) {
            case 0: for (QMessageHandler h : handlers) h.debug(message); break;
            case 1: for (QMessageHandler h : handlers) h.warning(message); break;
            case 2: for (QMessageHandler h : handlers) h.critical(message); break;
            case 3: for (QMessageHandler h : handlers) h.fatal(message); break;
        }
        return true;
    }

    private static native void installMessageHandlerProxy();
    private static native void removeMessageHandlerProxy();

    private static List<QMessageHandler> handlers;
}
