/*
 * This file is part of the KDE project
 * Copyright (C) 2007 Rafael Fernández López <ereslibre@kde.org>
 * Copyright (C) 2007 John Tapsell <tapsell@kde.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#ifndef KCATEGORIZEDSORTFILTERPROXYMODEL_H
#define KCATEGORIZEDSORTFILTERPROXYMODEL_H

#include <QSortFilterProxyModel>

#include <kitemviews_export.h>
class KCategorizedSortFilterProxyModelPrivate;

class QItemSelection;

/**
  * This class lets you categorize a view. It is meant to be used along with
  * KCategorizedView class.
  *
  * In general terms all you need to do is to reimplement subSortLessThan() and
  * compareCategories() methods. In order to make categorization work, you need
  * to also call setCategorizedModel() class to enable it, since the categorization
  * is disabled by default.
  *
  * @see KCategorizedView
  *
  * @author Rafael Fernández López <ereslibre@kde.org>
  */
class KITEMVIEWS_EXPORT KCategorizedSortFilterProxyModel
    : public QSortFilterProxyModel
{
public:
    enum AdditionalRoles {
        // Note: use printf "0x%08X\n" $(($RANDOM*$RANDOM))
        // to define additional roles.
        CategoryDisplayRole = 0x17CE990A,  ///< This role is used for asking the category to a given index

        CategorySortRole    = 0x27857E60   ///< This role is used for sorting categories. You can return a
                              ///< string or a long long value. Strings will be sorted alphabetically
                              ///< while long long will be sorted by their value. Please note that this
                              ///< value won't be shown on the view, is only for sorting purposes. What will
                              ///< be shown as "Category" on the view will be asked with the role
                              ///< CategoryDisplayRole.
    };

    KCategorizedSortFilterProxyModel(QObject *parent = 0);
    virtual ~KCategorizedSortFilterProxyModel();

    /**
      * Overridden from QSortFilterProxyModel. Sorts the source model using
      * @p column for the given @p order.
      */
    void sort(int column, Qt::SortOrder order = Qt::AscendingOrder) Q_DECL_OVERRIDE;

    /**
      * @return whether the model is categorized or not. Disabled by default.
      */
    bool isCategorizedModel() const;

    /**
      * Enables or disables the categorization feature.
      *
      * @param categorizedModel whether to enable or disable the categorization feature.
      */
    void setCategorizedModel(bool categorizedModel);

    /**
      * @return the column being used for sorting.
      */
    int sortColumn() const;

    /**
      * @return the sort order being used for sorting.
      */
    Qt::SortOrder sortOrder() const;

    /**
      * Set if the sorting using CategorySortRole will use a natural comparison
      * in the case that strings were returned. If enabled, QCollator
      * will be used for sorting.
      *
      * @param sortCategoriesByNaturalComparison whether to sort using a natural comparison or not.
      */
    void setSortCategoriesByNaturalComparison(bool sortCategoriesByNaturalComparison);

    /**
      * @return whether it is being used a natural comparison for sorting. Enabled by default.
      */
    bool sortCategoriesByNaturalComparison() const;

    /**
      * Does a natural comparing of the strings. A negative value is returned if \a a
      * is smaller than \a b. A positive value is returned if \a a is greater than \a b. 0
      * is returned if both values are equal.
      * @deprecated
      * Use QCollator instead.
      */
#ifndef KITEMVIEWS_NO_DEPRECATED
    KITEMVIEWS_DEPRECATED static int naturalCompare(const QString &a, const QString &b);
#endif

protected:
    /**
      * Overridden from QSortFilterProxyModel. If you are subclassing
      * KCategorizedSortFilterProxyModel, you will probably not need to reimplement this
      * method.
      *
      * It calls compareCategories() to sort by category.  If the both items are in the
      * same category (i.e. compareCategories returns 0), then subSortLessThan is called.
      *
      * @return Returns true if the item @p left is less than the item @p right when sorting.
      *
      * @warning You usually won't need to reimplement this method when subclassing
      *          from KCategorizedSortFilterProxyModel.
      */
    bool lessThan(const QModelIndex &left, const QModelIndex &right) const Q_DECL_OVERRIDE;

    /**
      * This method has a similar purpose as lessThan() has on QSortFilterProxyModel.
      * It is used for sorting items that are in the same category.
      *
      * @return Returns true if the item @p left is less than the item @p right when sorting.
      */
    virtual bool subSortLessThan(const QModelIndex &left, const QModelIndex &right) const;

    /**
      * This method compares the category of the @p left index with the category
      * of the @p right index.
      *
      * Internally and if not reimplemented, this method will ask for @p left and
      * @p right models for role CategorySortRole. In order to correctly sort
      * categories, the data() metod of the model should return a qlonglong (or numeric) value, or
      * a QString object. QString objects will be sorted with QString::localeAwareCompare if
      * sortCategoriesByNaturalComparison() is true.
      *
      * @note Please have present that:
      *       QString(QChar(QChar::ObjectReplacementCharacter)) >
      *       QString(QChar(QChar::ReplacementCharacter)) >
      *       [ all possible strings ] >
      *       QString();
      *
      *       This means that QString() will be sorted the first one, while
      *       QString(QChar(QChar::ObjectReplacementCharacter)) and
      *       QString(QChar(QChar::ReplacementCharacter)) will be sorted in last
      *       position.
      *
      * @warning Please note that data() method of the model should return always
      *          information of the same type. If you return a QString for an index,
      *          you should return always QStrings for all indexes for role CategorySortRole
      *          in order to correctly sort categories. You can't mix by returning
      *          a QString for one index, and a qlonglong for other.
      *
      * @note If you need a more complex layout, you will have to reimplement this
      *       method.
      *
      * @return A negative value if the category of @p left should be placed before the
      *         category of @p right. 0 if @p left and @p right are on the same category, and
      *         a positive value if the category of @p left should be placed after the
      *         category of @p right.
      */
    virtual int compareCategories(const QModelIndex &left, const QModelIndex &right) const;

private:
    KCategorizedSortFilterProxyModelPrivate *const d;
};

#endif // KCATEGORIZEDSORTFILTERPROXYMODEL_H
