/****************************************************************************

**

** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

** All rights reserved.

** Contact: Nokia Corporation (qt-info@nokia.com)

**

** This file is part of the Qt Mobility Components.

**

** $QT_BEGIN_LICENSE:LGPL$

** 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 Technology Preview License Agreement accompanying

** this package.

**

** GNU Lesser General Public License Usage

** Alternatively, this file may be used under the terms of the GNU Lesser

** General Public License version 2.1 as published by the Free Software

** Foundation and appearing in the file LICENSE.LGPL included in the

** packaging of this file.  Please review the following information to

** ensure the GNU Lesser General Public License version 2.1 requirements

** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.

**

** In addition, as a special exception, Nokia gives you certain additional

** rights.  These rights are described in the Nokia Qt LGPL Exception

** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.

**

** If you have questions regarding the use of this file, please contact

** Nokia at qt-info@nokia.com.

**

**

**

**

**

**

**

**

** $QT_END_LICENSE$

**

****************************************************************************/

#include "qvaluespacesubscriber.h"

#include "qvaluespace_p.h"

#include "qvaluespacemanager_p.h"

#include <QSet>

#include <QCoreApplication>

#include <QUuid>

#include <QSharedData>

#include <QMutex>

QTM_BEGIN_NAMESPACE

/*!

    \class QValueSpaceSubscriber

    \brief The QValueSpaceSubscriber class allows applications to read and subscribe to Value Space

           paths.

    \ingroup publishsubscribe

    By default QValueSpaceSubscriber can read values from and report change notifications for all

    available Value Space layers.  Only data from the layer with the highest order and that

    contains the specific key is returned by this class.

    The layers that QValueSpaceSubscriber accesses can be limited by specifying either a

    \l {QValueSpace::LayerOptions}{filter} or a QUuid at construction time.

    Applications subscribe to a particular path in the Value Space.  If anything under that path

    changes the contextChanged() signal is emitted.  For example given the schema:

    \code

    /Device/Buttons = 3

    /Device/Buttons/1/Name = Menu

    /Device/Buttons/1/Usable = true

    /Device/Buttons/2/Name = Select

    /Device/Buttons/2/Usable = false

    /Device/Buttons/3/Name = Back

    /Device/Buttons/3/Usable = true

    \endcode

    The code:

    \code

        QValueSpaceSubscriber *buttons = new QValueSpaceSubscriber("/Device/Buttons");

        QObject::connect(buttons, SIGNAL(contentsChanged()), this, SLOT(buttonInfoChanged()));

    \endcode

    will invoke the \c {buttonInfoChanged()} slot whenever any value under \c {/Device/Buttons}

    changes.  This includes the value of \c {/Device/Buttons} itself, a change of a subpath such as

    \c {/Device/Buttons/2/Name} or the creation or removal of a subpath.

*/

/*!

    \fn QValueSpaceSubscriber::contentsChanged()

    Emitted whenever any value under the current path changes.

    \bold {Note:} that if a value changes multiple times in quick succession, only the most recent

    value may be accessible via the value() function.

*/

/*!

    \property QValueSpaceSubscriber::path

    This property holds the current path that the QValueSpaceSubscriber refers to.

    Settings this property causes the QValueSpaceSubscriber to disconnect and reconnect to the

    Value Space with the new path.  As a result all signal/slot connections are disconnected.

*/

/*!

    \property QValueSpaceSubscriber::value

    This property holds the value of the path that this QValueSpaceSubscriber refers to.

*/

class QValueSpaceSubscriberPrivateProxy : public QObject

{

    Q_OBJECT

signals:

    void changed();

public slots:

    void handleChanged(quintptr handle)

    {

        QAbstractValueSpaceLayer *layer = qobject_cast<QAbstractValueSpaceLayer *>(sender());

        for (int i = 0; i < readers.count(); ++i) {

            if (readers.at(i).first == layer && readers.at(i).second == handle) {

                emit changed();

                return;

            }

        }

    }

public:

    QList<QPair<QAbstractValueSpaceLayer *, QAbstractValueSpaceLayer::Handle> > readers;

    QHash<const QValueSpaceSubscriber *,int> connections;

};

typedef QList<QPair<QAbstractValueSpaceLayer *, QAbstractValueSpaceLayer::Handle> > LayerList;

class QValueSpaceSubscriberPrivate : public QSharedData

{

public:

    QValueSpaceSubscriberPrivate(const QString &_path,

                           QValueSpace::LayerOptions filter = QValueSpace::UnspecifiedLayer);

    QValueSpaceSubscriberPrivate(const QString &_path, const QUuid &uuid);

    ~QValueSpaceSubscriberPrivate();

    void connect(const QValueSpaceSubscriber *space) const;

    bool disconnect(QValueSpaceSubscriber * space);

    const QString path;

    const LayerList readers;

    mutable QMutex lock;

    mutable QValueSpaceSubscriberPrivateProxy *connections;

};

static LayerList matchLayers(const QString &path, QValueSpace::LayerOptions filter)

{

    LayerList list;

    QValueSpaceManager *manager = QValueSpaceManager::instance();

    if (!manager)

        return list;

    // Invalid filter combination.

    if ((filter & QValueSpace::PermanentLayer &&

         filter & QValueSpace::TransientLayer) ||

        (filter & QValueSpace::WritableLayer &&

         filter & QValueSpace::ReadOnlyLayer)) {

        return list;

    }

    const QList<QAbstractValueSpaceLayer *> &readerList = manager->getLayers();

    for (int ii = 0; ii < readerList.count(); ++ii) {

        QAbstractValueSpaceLayer *read = readerList.at(ii);

        if (filter != QValueSpace::UnspecifiedLayer &&

            !(read->layerOptions() & filter)) {

            continue;

        }

        QAbstractValueSpaceLayer::Handle handle =

            read->item(QAbstractValueSpaceLayer::InvalidHandle, path);

        if (QAbstractValueSpaceLayer::InvalidHandle != handle) {

            list.append(qMakePair(read, handle));

            read->notifyInterest(handle, true);

        }

    }

    return list;

}

QValueSpaceSubscriberPrivate::QValueSpaceSubscriberPrivate(const QString &path,

                                                           QValueSpace::LayerOptions filter)

:   path(qCanonicalPath(path)), readers(matchLayers(this->path, filter)), connections(0)

{

}

static LayerList matchLayers(const QString &path, const QUuid &uuid)

{

    LayerList list;

    QValueSpaceManager *manager = QValueSpaceManager::instance();

    if (!manager)

        return list;

    const QList<QAbstractValueSpaceLayer *> &readerList = manager->getLayers();

    for (int ii = 0; ii < readerList.count(); ++ii) {

        QAbstractValueSpaceLayer *read = readerList.at(ii);

        if (read->id() != uuid)

            continue;

        QAbstractValueSpaceLayer::Handle handle =

            read->item(QAbstractValueSpaceLayer::InvalidHandle, path);

        if (QAbstractValueSpaceLayer::InvalidHandle != handle) {

            list.append(qMakePair(read, handle));

            read->notifyInterest(handle, true);

        }

    }

    return list;

}

QValueSpaceSubscriberPrivate::QValueSpaceSubscriberPrivate(const QString &path, const QUuid &uuid)

:   path(qCanonicalPath(path)), readers(matchLayers(this->path, uuid)), connections(0)

{

}

QValueSpaceSubscriberPrivate::~QValueSpaceSubscriberPrivate()

{

    for (int ii = 0; ii < readers.count(); ++ii) {

        readers[ii].first->notifyInterest(readers[ii].second, false);

        readers[ii].first->removeHandle(readers[ii].second);

    }

    if (connections)

        delete connections;

}

void QValueSpaceSubscriberPrivate::connect(const QValueSpaceSubscriber *space) const

{

    QMutexLocker locker(&lock);

    if (!connections) {

        qRegisterMetaType<quintptr>("quintptr");

        connections = new QValueSpaceSubscriberPrivateProxy;

        connections->readers = readers;

        connections->connections.insert(space,1);

        QObject::connect(connections, SIGNAL(changed()),

                         space, SIGNAL(contentsChanged()));

        for (int ii = 0; ii < readers.count(); ++ii) {

            readers.at(ii).first->setProperty(readers.at(ii).second,

                                              QAbstractValueSpaceLayer::Publish);

            QObject::connect(readers.at(ii).first, SIGNAL(handleChanged(quintptr)),

                             connections, SLOT(handleChanged(quintptr)));

        }

    } else if (!connections->connections.contains(space)) {

        connections->connections[space] = 1;

        QObject::connect(connections, SIGNAL(changed()),

                         space, SIGNAL(contentsChanged()));

    } else {

        ++connections->connections[space];

    }

}

bool QValueSpaceSubscriberPrivate::disconnect(QValueSpaceSubscriber * space)

{

    QMutexLocker locker(&lock);

    if (connections) {

        QHash<const QValueSpaceSubscriber *, int>::Iterator iter =

            connections->connections.find(space);

        if (iter != connections->connections.end()) {

            --(*iter);

            if (!*iter) {

                QObject::disconnect(connections, SIGNAL(changed()),

                                    space, SIGNAL(contentsChanged()));

                connections->connections.erase(iter);

            }

            return true;

        }

    }

    return false;

}

/*!

    Constructs a QValueSpaceSubscriber with the specified \a parent that refers to the root path.

    The constructed Value Space subscriber will access all available

    \l {QAbstractValueSpaceLayer}{layers}.

*/

QValueSpaceSubscriber::QValueSpaceSubscriber(QObject *parent)

:   QObject(parent)

{

    d = new QValueSpaceSubscriberPrivate(QLatin1String("/"));

}

/*!

    Constructs a QValueSpaceSubscriber with the specified \a parent that refers to \a path.

    The constructed Value Space subscriber will access all available

    \l {QAbstractValueSpaceLayer}{layers}.

*/

QValueSpaceSubscriber::QValueSpaceSubscriber(const QString &path, QObject *parent)

:   QObject(parent)

{

    d = new QValueSpaceSubscriberPrivate(path);

}

/*!

    Constructs a QValueSpaceSubscriber with the specified \a parent that refers to \a path.  The

    \a filter parameter is used to limit which layers this QValueSpaceSubscriber will access.

    If a layer matching \a filter is not found, the constructed QValueSpaceSubscriber will be

    unconnected.

    \sa isConnected()

*/

QValueSpaceSubscriber::QValueSpaceSubscriber(QValueSpace::LayerOptions filter,

                                             const QString &path,

                                             QObject *parent)

:   QObject(parent)

{

    d = new QValueSpaceSubscriberPrivate(path, filter);

}

/*!

    Constructs a QValueSpaceSubscriber with the specified \a parent that refers to \a path.  This

    QValueSpaceSubscriber will only use the layer identified by \a uuid.

    Use of this constructor is not platform agnostic.  If possible use one of the constructors that

    take a QAbstractValueSpaceLayer::LayerOptions parameter instead.

    If a layer with a matching \a uuid is not found, the constructed QValueSpaceSubscriber will be

    unconnected.

    \sa QAbstractValueSpaceLayer::id(), QValueSpace, isConnected()

*/

QValueSpaceSubscriber::QValueSpaceSubscriber(const QUuid &uuid,

                                             const QString &path,

                                             QObject *parent)

:   QObject(parent)

{

    d = new QValueSpaceSubscriberPrivate(path, uuid);

}

/*!

    Destroys the QValueSpaceSubscriber.

*/

QValueSpaceSubscriber::~QValueSpaceSubscriber()

{

    d->disconnect(this);

}

/*!

    Sets the path to \a path.

    Calling this function causes the QValueSpaceSubscriber to disconnect and reconnect to the value

    space with the new \a path.

    Calling this function disconnects all signal/slot connections.

*/

void QValueSpaceSubscriber::setPath(const QString &path)

{

    if (d->path == path)

        return;

    d->disconnect(this);

    disconnect();

    d = new QValueSpaceSubscriberPrivate(path);

}

/*!

    Sets the path to the same path as \a subscriber.

    Calling this function causes the QValueSpaceSubscriber to disconnect and reconnect to the value

    space with the specified \a path.

    Calling this function disconnects all signal/slot connections.

*/

void QValueSpaceSubscriber::setPath(QValueSpaceSubscriber *subscriber)

{

    d->disconnect(this);

    disconnect();

    d = subscriber->d;

}

QString QValueSpaceSubscriber::path() const

{

    return d->path;

}

/*!

    Changes the path to the absolute path if \a path starts with a '/'; otherwise changes to the

    sub path of the current path.

*/

void QValueSpaceSubscriber::cd(const QString &path)

{

    if (path.startsWith(QLatin1Char('/')))

        setPath(path);

    else

        setPath(d->path + QLatin1Char('/') + path);

}

/*!

    Sets the path to parent of the current path.

*/

void QValueSpaceSubscriber::cdUp()

{

    if (d->path == QLatin1String("/"))

        return;

    QString p(d->path);

    int index = p.lastIndexOf(QLatin1Char('/'));

    p.truncate(index);

    setPath(p);

}

/*!

    Returns true if this QValueSpaceSubscriber is connected to at least one available layer;

    otherwise returns false.  An unconnected QValueSpaceSubscriber is constructed if the filtering

    parameters passed to the constructor eliminate all available layers.

*/

bool QValueSpaceSubscriber::isConnected() const

{

    return !d->readers.isEmpty();

}

/*!

    Returns the value of the \a subPath under this subscriber path, or the value of this subscriber

    path if \a subPath is empty.  If the value does not exists \a def is returned.

    The following code shows how the subscriber path and \a subPath relate.

    \code

        QValueSpaceSubscriber base("/Settings");

        QValueSpaceSubscriber equiv("/Settings/Nokia/General/Mappings);

        // Is true

        equiv.value() == base.value("Nokia/General/Mapping");

    \endcode

*/

QVariant QValueSpaceSubscriber::value(const QString & subPath, const QVariant &def) const

{

    QVariant value;

    if (subPath.isEmpty()) {

        for (int ii = d->readers.count(); ii > 0; --ii) {

            if (d->readers[ii - 1].first->value(d->readers[ii - 1].second, &value))

                return value;

        }

    } else {

        const QString vpath(qCanonicalPath(subPath));

        for (int ii = d->readers.count(); ii > 0; --ii) {

            if (d->readers[ii - 1].first->value(d->readers[ii - 1].second, vpath, &value))

                return value;

        }

    }

    return def;

}

QVariant QValueSpaceSubscriber::valuex(const QVariant &def) const

{

    QMutexLocker locker(&d->lock);

    if (!d->connections || d->connections->connections.value(this) == 0) {

        locker.unlock();

        d->connect(this);

    }

    return value(QString(), def);

}

/*!

    \internal

    Registers for change notifications in response to connection to the contentsChanged()

    \a signal.

*/

void QValueSpaceSubscriber::connectNotify(const char *signal)

{

    if (QLatin1String(signal) == SIGNAL(contentsChanged()))

        d->connect(this);

    else

        QObject::connectNotify(signal);

}

/*!

    \internal

    Unregisters for change notifications in response to disconnection from the contentsChanged()

    \a signal.

*/

void QValueSpaceSubscriber::disconnectNotify(const char *signal)

{

    if (QLatin1String(signal) == SIGNAL(contentsChanged()))

        d->disconnect(this);

    else

        QObject::disconnectNotify(signal);

}

/*!

    Returns a list of sub-paths under the current path.  For example, given a Value Space tree

    containing:

    \code

    /Settings/Nokia/Device

    /Settings/Nokia/Other

    /Settings/Qt

    /Device/Buttons

    \endcode