/***************************************************************************
    qgslegendfilterbutton.h - QToolButton for legend filter by map content
     --------------------------------------
    Date                 : June 2015
    Copyright            : (C) 2015 by Hugo Mercier at Oslandia
    Email                : hugo dot mercier at oslandia dot 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.                                   *
 *                                                                         *
 ***************************************************************************/
#ifndef QGS_LEGEND_FILTER_BUTTON_H
#define QGS_LEGEND_FILTER_BUTTON_H

#include <QToolButton>
#include "qgis_gui.h"
#include "qgsexpressioncontext.h"

class QgsVectorLayer;
class QgsExpressionContextGenerator;

/**
 * \ingroup gui
 * \class QgsLegendFilterButton
 * \brief A tool button that allows enabling or disabling legend filter by contents of the map.
 * An additional pop down menu allows defining a boolean expression to refine the filtering.
 * \since QGIS 2.14
 */

class GUI_EXPORT QgsLegendFilterButton: public QToolButton
{
    Q_OBJECT

  public:

    /**
     * Construct a new filter legend button
     *
     * \param parent The parent QWidget
     */
    QgsLegendFilterButton( QWidget *parent = nullptr );

    /**
     * Returns the current text used as filter expression
     */
    QString expressionText() const;

    /**
     * Sets the current text used as filter expression.
     * This will update the menu
     */
    void setExpressionText( const QString &expression );

    /**
     * Register an expression context generator class that will be used to retrieve
     * an expression context for the button when required.
     * \since QGIS 3.32
     */
    void registerExpressionContextGenerator( QgsExpressionContextGenerator *generator );

    /**
     * Returns the current associated vectorLayer
     * May be NULLPTR
     */
    QgsVectorLayer *vectorLayer() const;

    /**
     * Sets the associated vectorLayer
     * May be NULLPTR
     */
    void setVectorLayer( QgsVectorLayer *layer );

  signals:

    /**
     * Emitted when the expression text changes
     */
    void expressionTextChanged();

  private:
    QMenu *mMenu = nullptr;
    QAction *mSetExpressionAction = nullptr;
    QAction *mClearExpressionAction = nullptr;
    QString mExpression;
    QgsExpressionContextGenerator *mExpressionContextGenerator = nullptr;

    void updateMenu();

    QgsVectorLayer *mLayer = nullptr;
  private slots:
    void onSetLegendFilterExpression();
    void onClearFilterExpression();
    void onToggle( bool );
};

#endif // QGS_FILTER_LEGEND_BUTTON_H
