/*
 *   Copyright (C) 2005 by Aaron Seigo <aseigo@kde.org>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library General Public License version 2 as
 *   published by the Free Software Foundation
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this program; if not, write to the
 *   Free Software Foundation, Inc.,
 *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#ifndef PLASMA_APPLET_H
#define PLASMA_APPLET_H

#include <QtGui/QGraphicsItemGroup>
#include <QtGui/QWidget>

#include <ksharedconfig.h>

#include <Plasma/Plasma>
#include <Plasma/DataEngine>

namespace Plasma
{
/**
 * @short the base Applet class
 *
 *
 */
class PLASMA_EXPORT Applet : public QWidget, public QGraphicsItemGroup
{
    Q_OBJECT

    public:
        typedef QList<Applet*> List;

        /**
         * @arg parent the QGraphicsItem this applet is parented to
         * @arg servideId the name of the .desktop file containing the
         *      information about the widget
         * @arg appletId a unique id used to differentiate between multiple
         *      instances of the same Applet type
         */
        Applet( QGraphicsItem* parent,
                const QString& serviceId,
                int appletId );
        ~Applet();

        /**
        * Returns the KConfig object to access the applets configuration.
        *
        * For unique applets this config object will write to a config file
        * named \<appletname\>rc in the user's local %KDE directory.
        *
        * For normal applets this config object will write to an instance
        * specific config file named \<appletname\>\<instanceid\>rc
        * in the user's local %KDE directory.
        **/
        KSharedConfig::Ptr appletConfig() const;

        /**
         * Returns a KConfig object to be shared by all applets of this type
         * For unique applets, this will return the same config object as
         * appletConfig()
         */
        KSharedConfig::Ptr globalAppletConfig() const;

        /**
         * Ensures that the DataEngine named name is loaded and ready to be used
         *
         * @return returns true on success, false on failure
         */
        bool loadDataEngine( const QString& name );

        /**
         * called when any of the geometry constraints have been updated
         * this is always called prior to painting and should be used as an
         * opportunity to layout the widget, calculate sizings, etc.
         * @property constraint
         */
        virtual void constraintsUpdated();

    public Q_SLOTS:
        virtual void updated(const QString& source, const Plasma::DataEngine::Data&) = 0;

    Q_SIGNALS:
        void requestFocus( bool focus );

    protected:

        QString globalName() const;
        QString instanceName() const;

        /**
        * Register widgets that can receive keyboard focus with this this method
        * This call results in an eventFilter being places on the widget.
        * @param widget the widget to watch for keyboard focus
        * @param watch whether to start watching the widget, or to stop doing so
        */
        void watchForFocus( QObject *widget, bool watch = true );

        /**
        * Call this whenever focus is needed or not needed. You do not have to
        * call this method for widgets that have been registered with
        * watchForFocus
        * @see watchForFocus
        * @param focus whether to or not to request focus
        */
        void needsFocus( bool focus );


        bool eventFilter( QObject *o, QEvent *e );

    private:
        class Private;
        Private* const d;
};

#define K_EXPORT_PLASMA_APPLET(libname, classname)                       \
        K_EXPORT_COMPONENT_FACTORY(                                      \
                        plasmaapplet_##libname,                          \
                        KGenericFactory<classname>("libplasmaapplet_" #libname))


} // Plasma namespace

#endif // multiple inclusion guard