/*  This file is part of the KDE libraries
 *  Copyright (C) 1999 Waldo Bastian <bastian@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 version 2 as published by the Free Software Foundation;
 *
 *  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 KSYCOCAFACTORY_H
#define KSYCOCAFACTORY_H

#include <ksycocaentry.h>

class QString;
class KSycocaDict;
class KSycocaResourceList;
template <typename T> class QList;
template <typename KT, typename VT> class QHash;

typedef QHash<QString, KSycocaEntry::Ptr> KSycocaEntryDict;

/**
 * @internal
 * Base class for sycoca factories
 */
class KDECORE_EXPORT KSycocaFactory
{
public:
    virtual KSycocaFactoryId factoryId() const = 0;

protected: // virtual class
    /**
     * Create a factory which can be used to lookup from/create a database
     * (depending on KSycoca::isBuilding())
     */
    explicit KSycocaFactory( KSycocaFactoryId factory_id );

public:
    virtual ~KSycocaFactory();

    /**
     * @return the position of the factory in the sycoca file
     */
    int offset() const;

    /**
     * @return the dict, for special use by KBuildSycoca
     */
    KSycocaEntryDict * entryDict() { return m_entryDict; }

    /**
     * Construct an entry from a config file.
     * To be implemented in the real factories.
     */
    virtual KSycocaEntry *createEntry(const QString &file, const char *resource) const = 0;

    /**
     * Add an entry
     */
    virtual void addEntry(const KSycocaEntry::Ptr& newEntry);

    /**
     * Remove all entries with the given name.
     * Not very fast (O(N)), use with care.
     */
    void removeEntry(const QString& entryName);

    /**
     * Read an entry from the database
     */
    virtual KSycocaEntry *createEntry(int offset) const = 0;

    /**
     * Get a list of all entries from the database.
     */
    virtual KSycocaEntry::List allEntries() const;

    /**
     * Saves all entries it maintains as well as index files
     * for these entries to the stream 'str'.
     *
     * Also sets mOffset to the starting position.
     *
     * The stream is positioned at the end of the last index.
     *
     * Don't forget to call the parent first when you override
     * this function.
     */
    virtual void save(QDataStream &str);

    /**
     * Writes out a header to the stream 'str'.
     * The baseclass positions the stream correctly.
     *
     * Don't forget to call the parent first when you override
     * this function.
     */
    virtual void saveHeader(QDataStream &str);

    /**
     * @return the resources for which this factory is responsible.
     * @internal to kbuildsycoca
     */
    const KSycocaResourceList * resourceList() const;

    /**
     * @return the sycoca dict, for factories to find entries by name.
     */
    const KSycocaDict *sycocaDict() const;

    /**
     * @return true if the factory is completely empty - no entries defined
     */
    bool isEmpty() const;

protected:
    QDataStream* stream() const;

    KSycocaResourceList *m_resourceList;
    KSycocaEntryDict *m_entryDict;

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

/**
 * This, instead of a typedef, allows to declare "class ..." in header files.
 * @internal
 */
class KDECORE_EXPORT KSycocaFactoryList : public QList<KSycocaFactory*> //krazy:exclude=dpointer (acts as a typedef)
{
public:
    KSycocaFactoryList() { }
};

#include <QThreadStorage>
/**
 * Workaround for the lack of QThreadStorage::setAutoDelete(false).
 * Container for KSycocaFactory that doesn't delete it when it is deleted.
 */
template <typename F> class KSycocaFactoryContainer
{
public:
    KSycocaFactoryContainer(F* factory) : m_factory(factory) {}
    F* factory() { return m_factory; }
private:
    F* m_factory;
};

/**
 * Template for making it easier to define a threadsafe singleton
 * for each factory, with support for kbuildsycoca providing a
 * subclass of the factory.
 *
 * @since 4.3
 * @internal
 */
template <typename F> class KSycocaFactorySingleton
{
public:
    typedef KSycocaFactoryContainer<F> C;
    KSycocaFactorySingleton() {
    }
    ~KSycocaFactorySingleton() {
        // Do not delete the factory here.
        // All factories are owned by KSycoca, and deleted by it.
    }
    void instanceCreated(F* newFactory) {
        // This can also register a subclass created by kbuildsycoca
        Q_ASSERT(!m_factories.hasLocalData());
        Q_ASSERT(newFactory);
        m_factories.setLocalData(new C(newFactory));
    }
    void instanceDestroyed(F* factory) {
        if (m_factories.hasLocalData()) { // could be false on thread exit
            Q_ASSERT(m_factories.localData()->factory() == factory); Q_UNUSED(factory)
            m_factories.setLocalData(0);
        }
    }
    F* self() {
        if (!m_factories.hasLocalData()) {
            new F; // calls instanceCreated, which calls setLocalData
            Q_ASSERT(m_factories.hasLocalData());
        }
        return m_factories.localData()->factory();
    }
private:
    QThreadStorage<C*> m_factories;
};

#endif