/* ============================================================
 *
 * This file is a part of digiKam project
 * http://www.digikam.org
 *
 * Date        : 2011-01-02
 * Description : Sample implementations for drag and drop handling
 *
 * Copyright (C) 2009-2011 by Marcel Wiesweg <marcel dot wiesweg at gmx dot de>
 *
 * 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, 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.
 *
 * ============================================================ */

#ifndef DRAGDROPIMPLEMENTATIONS_H
#define DRAGDROPIMPLEMENTATIONS_H

// Qt includes

#include <QAbstractItemView>

// Local includes

#include "digikam_export.h"
#include "abstractitemdragdrophandler.h"

namespace Digikam
{

class DIGIKAM_EXPORT DragDropModelImplementation
{
public:

    /**
     * A class providing a sample implementation for a QAbstractItemModel
     * redirecting drag-and-drop support to a handler.
     * Include the macro DECLARE_DRAG_DROP_METHODS in your derived QAbstractItemModel class.
     */

    DragDropModelImplementation();
    virtual ~DragDropModelImplementation() {}

    /**
     * Implements the relevant QAbstractItemModel methods for drag and drop.
     * All functionality is redirected to the handler.
     * dropMimeData() always returns false, leaving implementation to the view.
     */
    Qt::DropActions supportedDropActions() const;
    QStringList     mimeTypes() const;
    bool            dropMimeData(const QMimeData*, Qt::DropAction, int, int, const QModelIndex&);
    QMimeData*      mimeData(const QModelIndexList& indexes) const;

    /**
     * Call from your flags() method, adding the relevant drag drop flags.
     * Default implementation enables both drag and drop on the index
     * if a drag drop handler is set.
     * Reimplement to fine-tune. Note: There is an alternative below.
     */
    virtual Qt::ItemFlags dragDropFlags(const QModelIndex& index) const;

    /**
     * This is an alternative approach to dragDropFlags().
     * dragDropFlagsV2 calls the virtual methods isDragEnabled()
     * and isDropEnabled() which you then reimplement.
     * Use simple dragDropFlags() if you need not customization,
     * or reimplement dragDropFlags() if you fine-tune it yourself.
     */
    Qt::ItemFlags dragDropFlagsV2(const QModelIndex& index) const;
    virtual bool  isDragEnabled(const QModelIndex& index) const;
    virtual bool  isDropEnabled(const QModelIndex& index) const;

    /// Set a drag drop handler.
    void setDragDropHandler(AbstractItemDragDropHandler* handler);
    AbstractItemDragDropHandler* dragDropHandler() const;

    #define DECLARE_MODEL_DRAG_DROP_METHODS \
    virtual Qt::DropActions supportedDropActions() const \
        { return DragDropModelImplementation::supportedDropActions(); } \
    virtual QStringList mimeTypes() const \
        { return DragDropModelImplementation::mimeTypes(); } \
    virtual bool dropMimeData(const QMimeData* d, Qt::DropAction a, int r, int c, const QModelIndex& p) \
        { return DragDropModelImplementation::dropMimeData(d, a, r, c, p); } \
    virtual QMimeData* mimeData(const QModelIndexList& indexes) const \
        { return DragDropModelImplementation::mimeData(indexes); }

protected:

    AbstractItemDragDropHandler* m_dragDropHandler;
};

// --------------------------------------------------------------------------------------------

class DIGIKAM_EXPORT DragDropViewImplementation
{
public:

    virtual ~DragDropViewImplementation() {}

    virtual void cut();
    virtual void copy();
    virtual void paste();

protected:

    /// This one is implemented by DECLARE_DRAG_DROP_METHODS
    virtual QAbstractItemView* asView() = 0;

    /// You need to implement these three methods
    /// Returns the drag drop handler
    virtual AbstractItemDragDropHandler* dragDropHandler() const = 0;

    /**
     * Maps the given index of the view's model to an index of the handler's model,
     * which can be a source model of the view's model.
     */
    virtual QModelIndex mapIndexForDragDrop(const QModelIndex& index) const = 0;

    /**
     * Creates a pixmap for dragging the given indexes.
     */
    virtual QPixmap     pixmapForDrag(const QList<QModelIndex>& indexes) const = 0;

    /**
     * Implements the relevant QAbstractItemView methods for drag and drop.
     */
    void dragEnterEvent(QDragEnterEvent* event);
    void dragMoveEvent(QDragMoveEvent* e);
    void dropEvent(QDropEvent* e);
    void startDrag(Qt::DropActions supportedActions);

    #define DECLARE_VIEW_DRAG_DROP_METHODS(ParentViewClass) \
    virtual QAbstractItemView* asView() { return this; } \
    void dragEnterEvent(QDragEnterEvent* e) \
        { DragDropViewImplementation::dragEnterEvent(e); } \
    void dragMoveEvent(QDragMoveEvent* e) \
        { ParentViewClass::dragMoveEvent(e); \
          DragDropViewImplementation::dragMoveEvent(e); } \
    void dropEvent(QDropEvent* e) \
        { ParentViewClass::dropEvent(e); \
          DragDropViewImplementation::dropEvent(e); } \
    void startDrag(Qt::DropActions supportedActions) \
        { DragDropViewImplementation::startDrag(supportedActions); } \

    void encodeIsCutSelection(QMimeData* mime, bool isCutSelection);
    bool decodeIsCutSelection(const QMimeData* mimeData);
};

} // namespace Digikam

#endif // DRAGDROPIMPLEMENTATIONS_H
