/* This file is part of the KDE project
   Copyright (C) 2001 Simon Hausmann <hausmann@kde.org>

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library 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 Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this library; see the file COPYING.LIB.  If not, write to the
   Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.
*/
#ifndef KPARTS_GENERICFACTORY_H
#define KPARTS_GENERICFACTORY_H

#include <kparts/factory.h>
#include <kparts/part.h>
#include <kgenericfactory.h>
#include <kaboutdata.h>
#include <kdebug.h>

namespace KParts
{

/**
 * @internal
 */
template <class T>
class GenericFactoryBase : public KParts::Factory
{
public:
    GenericFactoryBase()
    {
        if (s_self) {
            kWarning() << "KParts::GenericFactory instantiated more than once!";
        }
        s_self = this;
    }
    virtual ~GenericFactoryBase()
    {
        delete s_aboutData;
        delete s_componentData;
        s_aboutData = 0;
        s_componentData = 0;
        s_self = 0;
    }

    static const KComponentData &componentData();
    static K4AboutData *aboutData();
    virtual KComponentData partComponentData()
    {
        return componentData();
    }

protected:
    virtual KComponentData *createComponentData()
    {
        return new KComponentData(aboutData());
    }

private:
    static GenericFactoryBase<T> *s_self;
    static KComponentData *s_componentData;
    static K4AboutData *s_aboutData;
};

/**
 * A template for a KParts::Factory implementation. It implements the pure virtual
 * createPartObject method by instantiating the template argument when requested
 * through the className field. In addition it is a container for a part's KComponentData
 * object, by providing a static KComponentData componentData() method.
 *
 * The template argument has to inherit from KParts::Part and has to implement two methods:
 *  1) There needs to be a public constructor with the following signature:
 *         MyPart( QWidget *parentWidget, QObject *parent, const QStringList& args )
 *
 *  2) It needs to provide one static method to create a K4AboutData object per
 *     request, holding information about the component's name, its authors, license, etc.
 *     The signature of that static method has to be
 *         K4AboutData *createAboutData()
 *
 * The template will take care of memory management of the KComponentData and the K4AboutData object,
 * meaning ownership of what createAboutData returns is passed to the caller (this template) .
 *
 * For advanced use you can also inherit from the template and re-implement additionally the
 * virtual KComponentData createComponentData() method, for example in case you want to extend the
 * paths of your instance's KStandardDirs object.
 *
 * If a KParts::ReadOnlyPart is requested through this factory and the template argument
 * implements a KParts::ReadWritePart then setReadWrite( false ) will automatically be
 * called in createPartObject.
 *
 * Use the factory through the K_EXPORT_COMPONENT_FACTORY macro, like that:
 * \code
 * typedef KParts::GenericFactory&lt;YourKPart&gt; YourKPartFactory;
 * K_EXPORT_COMPONENT_FACTORY( yourlibrary, YourKPartFactory )
 * \endcode
 * yourlibrary is the library name that you compiled your KPart into.
 */
template <class T>
class KDELIBS4SUPPORT_DEPRECATED GenericFactory : public GenericFactoryBase<T>
{
public:
    GenericFactory() { }

    virtual KParts::Part *createPartObject(QWidget *parentWidget,
                                           QObject *parent,
                                           const char *className,
                                           const QStringList &args)
    {
        T *part = KDEPrivate::ConcreteFactory<T>::create(parentWidget,
                  parent,
                  className,
                  args);

        if (part && !qstrcmp(className, "KParts::ReadOnlyPart")) {
            KParts::ReadWritePart *rwp = dynamic_cast<KParts::ReadWritePart *>(part);
            if (rwp) {
                rwp->setReadWrite(false);
            }
        }
        return part;
    }
};

template <class T1, class T2>
class GenericFactory< KTypeList<T1, T2> > : public GenericFactoryBase<T1>
{
public:
    GenericFactory() { }

    virtual KParts::Part *createPartObject(QWidget *parentWidget,
                                           QObject *parent,
                                           const char *className,
                                           const QStringList &args)
    {
        QObject *object = KDEPrivate::MultiFactory< KTypeList<T1, T2> >::create(parentWidget,
                          parent,
                          className,
                          args);

        // (this cast is guaranteed to work...)
        KParts::Part *part = dynamic_cast<KParts::Part *>(object);

        if (part && !qstrcmp(className, "KParts::ReadOnlyPart")) {
            KParts::ReadWritePart *rwp = dynamic_cast<KParts::ReadWritePart *>(part);
            if (rwp) {
                rwp->setReadWrite(false);
            }
        }
        return part;
    }
};

/**
 * @internal
 */
template <class T>
GenericFactoryBase<T> *GenericFactoryBase<T>::s_self = 0;

/**
 * @internal
 */
template <class T>
KComponentData *GenericFactoryBase<T>::s_componentData = 0;

/**
 * @internal
 */
template <class T>
K4AboutData *GenericFactoryBase<T>::s_aboutData = 0;

/**
 * @internal
 */
template <class T>
const KComponentData &GenericFactoryBase<T>::componentData()
{
    if (!s_componentData) {
        if (s_self) {
            s_componentData = s_self->createComponentData();
        } else {
            s_componentData = new KComponentData(aboutData());
        }
    }
    return *s_componentData;
}

/**
 * @internal
 */
template <class T>
K4AboutData *GenericFactoryBase<T>::aboutData()
{
    if (!s_aboutData) {
        s_aboutData = T::createAboutData();
    }
    return s_aboutData;
}

}

#endif

