/********************************************************************
Copyright 2014  Martin Gräßlin <mgraesslin@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.), 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/>.
*********************************************************************/
#include "datadevice_interface.h"
#include "datadevicemanager_interface.h"
#include "dataoffer_interface_p.h"
#include "datasource_interface.h"
#include "display.h"
#include "resource_p.h"
#include "pointer_interface.h"
#include "seat_interface.h"
#include "surface_interface.h"
// Wayland
#include <wayland-server.h>

namespace KWayland
{
namespace Server
{

class DataDeviceInterface::Private : public Resource::Private
{
public:
    Private(SeatInterface *seat, DataDeviceInterface *q, DataDeviceManagerInterface *manager, wl_resource *parentResource);
    ~Private();

    DataOfferInterface *createDataOffer(DataSourceInterface *source);

    SeatInterface *seat;
    DataSourceInterface *source = nullptr;
    SurfaceInterface *surface = nullptr;
    SurfaceInterface *icon = nullptr;

    DataSourceInterface *selection = nullptr;
    QMetaObject::Connection selectionUnboundConnection;
    QMetaObject::Connection selectionDestroyedConnection;

    struct Drag {
        SurfaceInterface *surface = nullptr;
        QMetaObject::Connection destroyConnection;
        QMetaObject::Connection posConnection;
        QMetaObject::Connection sourceActionConnection;
        QMetaObject::Connection targetActionConnection;
        quint32 serial = 0;
    };
    Drag drag;

private:
    DataDeviceInterface *q_func() {
        return reinterpret_cast<DataDeviceInterface*>(q);
    }
    void startDrag(DataSourceInterface *dataSource, SurfaceInterface *origin, SurfaceInterface *icon, quint32 serial);
    void setSelection(DataSourceInterface *dataSource);
    static void startDragCallback(wl_client *client, wl_resource *resource, wl_resource *source, wl_resource *origin, wl_resource *icon, uint32_t serial);
    static void setSelectionCallback(wl_client *client, wl_resource *resource, wl_resource *source, uint32_t serial);

    static const struct wl_data_device_interface s_interface;
};

#ifndef DOXYGEN_SHOULD_SKIP_THIS
const struct wl_data_device_interface DataDeviceInterface::Private::s_interface = {
    startDragCallback,
    setSelectionCallback,
    resourceDestroyedCallback
};
#endif

DataDeviceInterface::Private::Private(SeatInterface *seat, DataDeviceInterface *q, DataDeviceManagerInterface *manager, wl_resource *parentResource)
    : Resource::Private(q, manager, parentResource, &wl_data_device_interface, &s_interface)
    , seat(seat)
{
}

DataDeviceInterface::Private::~Private() = default;

void DataDeviceInterface::Private::startDragCallback(wl_client *client, wl_resource *resource, wl_resource *source, wl_resource *origin, wl_resource *icon, uint32_t serial)
{
    Q_UNUSED(client)
    Q_UNUSED(serial)
    // TODO: verify serial
    cast<Private>(resource)->startDrag(DataSourceInterface::get(source), SurfaceInterface::get(origin), SurfaceInterface::get(icon), serial);
}

void DataDeviceInterface::Private::startDrag(DataSourceInterface *dataSource, SurfaceInterface *origin, SurfaceInterface *i, quint32 serial)
{
    const bool pointerGrab = seat->hasImplicitPointerGrab(serial) && seat->focusedPointerSurface() == origin;
    if (!pointerGrab) {
        // Client doesn't have pointer grab.
        const bool touchGrab = seat->hasImplicitTouchGrab(serial) && seat->focusedTouchSurface() == origin;
        if (!touchGrab) {
            // Client neither has pointer nor touch grab. No drag start allowed.
            return;
        }
    }
    // TODO: source is allowed to be null, handled client internally!
    Q_Q(DataDeviceInterface);
    source = dataSource;
    if (dataSource) {
        QObject::connect(dataSource, &Resource::aboutToBeUnbound, q, [this] { source = nullptr; });
    }
    surface = origin;
    icon = i;
    drag.serial = serial;
    emit q->dragStarted();
}

void DataDeviceInterface::Private::setSelectionCallback(wl_client *client, wl_resource *resource, wl_resource *source, uint32_t serial)
{
    Q_UNUSED(client)
    Q_UNUSED(serial)
    // TODO: verify serial
    cast<Private>(resource)->setSelection(DataSourceInterface::get(source));
}

void DataDeviceInterface::Private::setSelection(DataSourceInterface *dataSource)
{
    if (dataSource && dataSource->supportedDragAndDropActions() && wl_resource_get_version(dataSource->resource()) >= WL_DATA_SOURCE_ACTION_SINCE_VERSION) {
        wl_resource_post_error(dataSource->resource(), WL_DATA_SOURCE_ERROR_INVALID_SOURCE, "Data source is for drag and drop");
        return;
    }
    if (selection == dataSource) {
        return;
    }
    Q_Q(DataDeviceInterface);
    QObject::disconnect(selectionUnboundConnection);
    QObject::disconnect(selectionDestroyedConnection);
    if (selection) {
        selection->cancel();
    }
    selection = dataSource;
    if (selection) {
        auto clearSelection = [this] {
            setSelection(nullptr);
        };
        selectionUnboundConnection = QObject::connect(selection, &Resource::unbound, q, clearSelection);
        selectionDestroyedConnection = QObject::connect(selection, &QObject::destroyed, q, clearSelection);
        emit q->selectionChanged(selection);
    } else {
        selectionUnboundConnection = QMetaObject::Connection();
        selectionDestroyedConnection = QMetaObject::Connection();
        emit q->selectionCleared();
    }
}

DataOfferInterface *DataDeviceInterface::Private::createDataOffer(DataSourceInterface *source)
{
    if (!resource) {
        return nullptr;
    }
    if (!source) {
        // a data offer can only exist together with a source
        return nullptr;
    }
    Q_Q(DataDeviceInterface);
    DataOfferInterface *offer = new DataOfferInterface(source, q, resource);
    auto c = q->global()->display()->getConnection(wl_resource_get_client(resource));
    offer->create(c, wl_resource_get_version(resource), 0);
    if (!offer->resource()) {
        // TODO: send error?
        delete offer;
        return nullptr;
    }
    wl_data_device_send_data_offer(resource, offer->resource());
    offer->sendAllOffers();
    return offer;
}

DataDeviceInterface::DataDeviceInterface(SeatInterface *seat, DataDeviceManagerInterface *parent, wl_resource *parentResource)
    : Resource(new Private(seat, this, parent, parentResource))
{
}

DataDeviceInterface::~DataDeviceInterface() = default;

SeatInterface *DataDeviceInterface::seat() const
{
    Q_D();
    return d->seat;
}

DataSourceInterface *DataDeviceInterface::dragSource() const
{
    Q_D();
    return d->source;
}

SurfaceInterface *DataDeviceInterface::icon() const
{
    Q_D();
    return d->icon;
}

SurfaceInterface *DataDeviceInterface::origin() const
{
    Q_D();
    return d->surface;
}

DataSourceInterface *DataDeviceInterface::selection() const
{
    Q_D();
    return d->selection;
}

void DataDeviceInterface::sendSelection(DataDeviceInterface *other)
{
    Q_D();
    auto otherSelection = other->selection();
    if (!otherSelection) {
        sendClearSelection();
        return;
    }
    auto r = d->createDataOffer(otherSelection);
    if (!r) {
        return;
    }
    if (!d->resource) {
        return;
    }
    wl_data_device_send_selection(d->resource, r->resource());
}

void DataDeviceInterface::sendClearSelection()
{
    Q_D();
    if (!d->resource) {
        return;
    }
    wl_data_device_send_selection(d->resource, nullptr);
}

void DataDeviceInterface::drop()
{
    Q_D();
    if (!d->resource) {
        return;
    }
    wl_data_device_send_drop(d->resource);
    if (d->drag.posConnection) {
        disconnect(d->drag.posConnection);
        d->drag.posConnection = QMetaObject::Connection();
    }
    disconnect(d->drag.destroyConnection);
    d->drag.destroyConnection = QMetaObject::Connection();
    d->drag.surface = nullptr;
    client()->flush();
}

void DataDeviceInterface::updateDragTarget(SurfaceInterface *surface, quint32 serial)
{
    Q_D();
    if (d->drag.surface) {
        if (d->resource && d->drag.surface->resource()) {
            wl_data_device_send_leave(d->resource);
        }
        if (d->drag.posConnection) {
            disconnect(d->drag.posConnection);
            d->drag.posConnection = QMetaObject::Connection();
        }
        disconnect(d->drag.destroyConnection);
        d->drag.destroyConnection = QMetaObject::Connection();
        d->drag.surface = nullptr;
        if (d->drag.sourceActionConnection) {
            disconnect(d->drag.sourceActionConnection);
            d->drag.sourceActionConnection = QMetaObject::Connection();
        }
        if (d->drag.targetActionConnection) {
            disconnect(d->drag.targetActionConnection);
            d->drag.targetActionConnection = QMetaObject::Connection();
        }
        // don't update serial, we need it
    }
    if (!surface) {
        if (auto s = d->seat->dragSource()->dragSource()) {
            s->dndAction(DataDeviceManagerInterface::DnDAction::None);
        }
        return;
    }
    auto *source = d->seat->dragSource()->dragSource();
    DataOfferInterface *offer = d->createDataOffer(source);
    d->drag.surface = surface;
    if (d->seat->isDragPointer()) {
        d->drag.posConnection = connect(d->seat, &SeatInterface::pointerPosChanged, this,
            [this] {
                Q_D();
                const QPointF pos = d->seat->dragSurfaceTransformation().map(d->seat->pointerPos());
                wl_data_device_send_motion(d->resource, d->seat->timestamp(),
                                        wl_fixed_from_double(pos.x()), wl_fixed_from_double(pos.y()));
                client()->flush();
            }
        );
    } else if (d->seat->isDragTouch()) {
        d->drag.posConnection = connect(d->seat, &SeatInterface::touchMoved, this,
            [this](qint32 id, quint32 serial, const QPointF &globalPosition) {
                Q_D();
                Q_UNUSED(id);
                if (serial != d->drag.serial) {
                    // different touch down has been moved
                    return;
                }
                const QPointF pos = d->seat->dragSurfaceTransformation().map(globalPosition);
                wl_data_device_send_motion(d->resource, d->seat->timestamp(),
                                        wl_fixed_from_double(pos.x()), wl_fixed_from_double(pos.y()));
                client()->flush();
            }
        );
    }
    d->drag.destroyConnection = connect(d->drag.surface, &QObject::destroyed, this,
        [this] {
            Q_D();
            if (d->resource) {
                wl_data_device_send_leave(d->resource);
            }
            if (d->drag.posConnection) {
                disconnect(d->drag.posConnection);
            }
            d->drag = Private::Drag();
        }
    );

    // TODO: handle touch position
    const QPointF pos = d->seat->dragSurfaceTransformation().map(d->seat->pointerPos());
    wl_data_device_send_enter(d->resource, serial, surface->resource(),
                              wl_fixed_from_double(pos.x()), wl_fixed_from_double(pos.y()), offer ? offer->resource() : nullptr);
    if (offer) {
        offer->d_func()->sendSourceActions();
        auto matchOffers = [source, offer] {
            DataDeviceManagerInterface::DnDAction action{DataDeviceManagerInterface::DnDAction::None};
            if (source->supportedDragAndDropActions().testFlag(offer->preferredDragAndDropAction())) {
                action = offer->preferredDragAndDropAction();
            } else {
                if (source->supportedDragAndDropActions().testFlag(DataDeviceManagerInterface::DnDAction::Copy) &&
                    offer->supportedDragAndDropActions().testFlag(DataDeviceManagerInterface::DnDAction::Copy)) {
                    action = DataDeviceManagerInterface::DnDAction::Copy;
                } else if (source->supportedDragAndDropActions().testFlag(DataDeviceManagerInterface::DnDAction::Move) &&
                    offer->supportedDragAndDropActions().testFlag(DataDeviceManagerInterface::DnDAction::Move)) {
                    action = DataDeviceManagerInterface::DnDAction::Move;
                } else if (source->supportedDragAndDropActions().testFlag(DataDeviceManagerInterface::DnDAction::Ask) &&
                    offer->supportedDragAndDropActions().testFlag(DataDeviceManagerInterface::DnDAction::Ask)) {
                    action = DataDeviceManagerInterface::DnDAction::Ask;
                }
            }
            offer->dndAction(action);
            source->dndAction(action);
        };
        d->drag.targetActionConnection = connect(offer, &DataOfferInterface::dragAndDropActionsChanged, offer, matchOffers);
        d->drag.sourceActionConnection = connect(source, &DataSourceInterface::supportedDragAndDropActionsChanged, source, matchOffers);
    }
    d->client->flush();
}

quint32 DataDeviceInterface::dragImplicitGrabSerial() const
{
    Q_D();
    return d->drag.serial;
}

DataDeviceInterface::Private *DataDeviceInterface::d_func() const
{
    return reinterpret_cast<DataDeviceInterface::Private*>(d.data());
}

}
}
