/*  This file is part of the KDE project
    Copyright (C) 2007-2008 Matthias Kretz <kretz@kde.org>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) version 3, or any
    later version accepted by the membership of KDE e.V. (or its
    successor approved by the membership of KDE e.V.), Nokia Corporation 
    (or its successors, if any) and the KDE Free Qt Foundation, which shall
    act as a proxy defined in Section 6 of version 3 of the license.

    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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public 
    License along with this library.  If not, see <http://www.gnu.org/licenses/>.

*/

#ifndef PHONON_AUDIOOUTPUTINTERFACE_H
#define PHONON_AUDIOOUTPUTINTERFACE_H

#include "phononnamespace.h"
#include "objectdescription.h"
#include "phonondefs.h"
#include <QtCore/QtGlobal>

QT_BEGIN_HEADER
QT_BEGIN_NAMESPACE

namespace Phonon
{
/** \class AudioOutputInterface audiooutputinterface.h Phonon/AudioOutputInterface
 * \short Interface for AudioOutput objects
 *
 * The implementation can make use of the signals
 * \code
     void volumeChanged(qreal newVolume);
     void audioDeviceFailed();
 * \endcode
 * to notify the frontend whenever the volume has changed or when an audioDeviceFailed (e.g. USB
 * unplug or sound server failure).
 *
 * \author Matthias Kretz <kretz@kde.org>
 */
class AudioOutputInterface40
{
    public:
        virtual ~AudioOutputInterface40() {}

        /**
         * Returns the current software volume.
         *
         * A value of 0.0 means muted, 1.0 means unchanged, 2.0 means double voltage (i.e. all
         * samples are multiplied by 2).
         */
        virtual qreal volume() const = 0;
        /**
         * Sets the new current software volume.
         *
         * A value of 0.0 means muted, 1.0 means unchanged, 2.0 means double voltage (i.e. all
         * samples are multiplied by 2).
         *
         * Everytime the volume in the backend changes it should emit volumeChanged(qreal), also
         * inside this function.
         */
        virtual void setVolume(qreal) = 0;

        /**
         * Returns the index of the device that is used. The index is the number returned from
         * BackendInterface::objectDescriptionIndexes(AudioOutputDeviceType).
         */
        virtual int outputDevice() const = 0;
        /**
         * \deprecated
         *
         * Requests to change the current output device to the one identified by the passed index.
         *
         * The index is the number returned from
         * BackendInterface::objectDescriptionIndexes(AudioOutputDeviceType).
         *
         * \returns \c true if the requested device works and is used after this call.
         * \returns \c false if something failed and the device is not used after this call.
         */
        virtual bool setOutputDevice(int) = 0;
};

class AudioOutputInterface42 : public AudioOutputInterface40
{
    public:
        /**
         * Requests to change the current output device.
         *
         * \returns \c true if the requested device works and is used after this call.
         * \returns \c false if something failed and the device is not used after this call.
         */
        virtual bool setOutputDevice(const Phonon::AudioOutputDevice &) = 0;

        using AudioOutputInterface40::setOutputDevice;

        /**
         * Helper function for backends to get a list of (driver, handle) pairs for
         * AudioOutputDevice objects that are listed by the platform plugin.
         *
         * Example:
         * \code
           typedef QPair<QByteArray, QString> PhononDeviceAccess;
           const QList<PhononDeviceAccess> &deviceAccessList = deviceAccessListFor(deviceDesc);
           foreach (const PhononDeviceAccess &access, deviceAccessList) {
               const QByteArray &driver = access.first;
               const QString &handle = access.second;
               if (openDevice(driver, handle)) {
                   // we found the first pair in the list that works. done.
                   return;
               }
               // continue trying the other (driver, handle) pairs
           }
           // none of the (driver, handle) pairs worked, that means the whole AudioOutputDevice is
           // inaccessible and the frontend needs to know (either by emitting audioDeviceFailed or
           // returning false when called from setOutputDevice)
         * \endcode
         *
         * At the time of this writing the following driver strings are known to be in use:
         * \li \c alsa: The handle is the string to pass to snd_pcm_open (e.g. "dmix:CARD=0,DEV=1")
         * \li \c oss: The handle is the device file (e.g. "/dev/dsp")
         * \li \c pulseaudio: The handle contains the server string and the sink/source name
         * separated by a newline character.
         * (e.g. unix:/tmp/pulse-mkretz/native\nalsa_output.pci_8086_293e_sound_card_0_alsa_playback_0)
         */
        PHONON_EXPORT QList<QPair<QByteArray, QString> > deviceAccessListFor(const Phonon::AudioOutputDevice &) const;
};

} // namespace Phonon

#ifdef PHONON_BACKEND_VERSION_4_2
namespace Phonon { typedef AudioOutputInterface42 AudioOutputInterface; }
Q_DECLARE_INTERFACE(Phonon::AudioOutputInterface40, "AudioOutputInterface2.phonon.kde.org")
Q_DECLARE_INTERFACE(Phonon::AudioOutputInterface,   "3AudioOutputInterface.phonon.kde.org")
#else
namespace Phonon { typedef AudioOutputInterface40 AudioOutputInterface; }
Q_DECLARE_INTERFACE(Phonon::AudioOutputInterface,   "AudioOutputInterface2.phonon.kde.org")
Q_DECLARE_INTERFACE(Phonon::AudioOutputInterface42, "3AudioOutputInterface.phonon.kde.org")
#endif

QT_END_NAMESPACE
QT_END_HEADER

#endif // PHONON_AUDIOOUTPUTINTERFACE_H
