/********************************************************************
 KWin - the KDE window manager
 This file is part of the KDE project.

Copyright 2019 Roman Gilg <subdiff@gmail.com>

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

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 General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*********************************************************************/
#ifndef KWIN_XWL_DRAG_WL
#define KWIN_XWL_DRAG_WL

#include "drag.h"

#include <KWayland/Client/dataoffer.h>

#include <QPoint>
#include <QPointer>
#include <QVector>

namespace KWayland
{
namespace Client
{
class Surface;
}
}
namespace KWaylandServer
{
class DataDeviceInterface;
class DataSourceInterface;
class SurfaceInterface;
}

namespace KWin
{
class Toplevel;
class AbstractClient;

namespace Xwl
{
class X11Source;
enum class DragEventReply;
class Xvisit;

using DnDActions = KWayland::Client::DataDeviceManager::DnDActions;

class WlToXDrag : public Drag
{
    Q_OBJECT

public:
    explicit WlToXDrag();

    DragEventReply moveFilter(Toplevel *target, const QPoint &pos) override;
    bool handleClientMessage(xcb_client_message_event_t *event) override;

    bool end() override;

    KWaylandServer::DataSourceInterface *dataSourceIface() const {
        return m_dsi;
    }

private:
    KWaylandServer::DataSourceInterface *m_dsi;
    Xvisit *m_visit = nullptr;

    Q_DISABLE_COPY(WlToXDrag)
};

// visit to an X window
class Xvisit : public QObject
{
    Q_OBJECT

public:
    // TODO: handle ask action

    Xvisit(WlToXDrag *drag, AbstractClient *target);

    bool handleClientMessage(xcb_client_message_event_t *event);
    bool handleStatus(xcb_client_message_event_t *event);
    bool handleFinished(xcb_client_message_event_t *event);

    void sendPosition(const QPointF &globalPos);
    void leave();

    bool finished() const {
        return m_state.finished;
    }
    AbstractClient *target() const {
        return m_target;
    }

Q_SIGNALS:
    void finish(Xvisit *self);

private:
    void sendEnter();
    void sendDrop(uint32_t time);
    void sendLeave();

    void receiveOffer();
    void enter();

    void retrieveSupportedActions();
    void determineProposedAction();
    void requestDragAndDropAction();
    void setProposedAction();

    void drop();

    void doFinish();
    void stopConnections();

    WlToXDrag *m_drag;
    AbstractClient *m_target;
    uint32_t m_version = 0;

    QMetaObject::Connection m_enterConnection;
    QMetaObject::Connection m_motionConnection;
    QMetaObject::Connection m_actionConnection;
    QMetaObject::Connection m_dropConnection;

    struct {
        bool pending = false;
        bool cached = false;
        QPoint cache;
    } m_pos;

    // Must be QPointer, because KWayland::Client::DataDevice
    // might delete it.
    QPointer<KWayland::Client::DataOffer> m_dataOffer;

    // supported by the Wl source
    DnDActions m_supportedActions = DnDAction::None;
    // preferred by the X client
    DnDAction m_preferredAction = DnDAction::None;
    // decided upon by the compositor
    DnDAction m_proposedAction = DnDAction::None;

    struct {
        bool entered = false;
        bool dropped = false;
        bool finished = false;
    } m_state;

    bool m_accepts = false;

    Q_DISABLE_COPY(Xvisit)
};

} // namespace Xwl
} // namespace KWin

#endif