/*
    This file is part of the KDE project
    SPDX-FileCopyrightText: 1999 Simon Hausmann <hausmann@kde.org>
    SPDX-FileCopyrightText: 1999 David Faure <faure@kde.org>

    SPDX-License-Identifier: LGPL-2.0-or-later
*/

#ifndef __kpartmanager_h__
#define __kpartmanager_h__

#include <kparts/kparts_export.h>

#include <QWidget>
#include <memory>

namespace KParts
{
class Part;

class PartManagerPrivate;

/**
 * @class PartManager partmanager.h <KParts/PartManager>
 *
 * @short The part manager is an object which knows about a collection of parts
 * (even nested ones) and handles activation/deactivation.
 *
 * Applications that want to embed parts without merging GUIs
 * only use a KParts::PartManager. Those who want to merge GUIs use a
 * KParts::MainWindow for example, in addition to a part manager.
 *
 * Parts know about the part manager to add nested parts to it.
 * See also KParts::Part::manager() and KParts::Part::setManager().
 */
class KPARTS_EXPORT PartManager : public QObject
{
    Q_OBJECT
    Q_PROPERTY(SelectionPolicy selectionPolicy READ selectionPolicy WRITE setSelectionPolicy)
    Q_PROPERTY(bool allowNestedParts READ allowNestedParts WRITE setAllowNestedParts)
    Q_PROPERTY(bool ignoreScrollBars READ ignoreScrollBars WRITE setIgnoreScrollBars)
public:
    /// Selection policy. The default policy of a PartManager is Direct.
    enum SelectionPolicy { Direct, TriState };
    Q_ENUM(SelectionPolicy)

    /**
     * This extends QFocusEvent::Reason with the non-focus-event reasons for partmanager to activate a part.
     * To test for "any focusin reason", use < ReasonLeftClick
     * NoReason usually means: explicit activation with @ref setActivePart.
     */
    enum Reason { ReasonLeftClick = 100, ReasonMidClick, ReasonRightClick, NoReason };

    /**
     * Constructs a part manager.
     *
     * @param parent The toplevel widget (window / dialog) the
     *               partmanager should monitor for activation/selection
     *               events
     */
    PartManager(QWidget *parent);
    /**
     * Constructs a part manager.
     *
     * @param topLevel The toplevel widget (window / dialog ) the
     *                 partmanager should monitor for activation/selection
     *                 events
     * @param parent   The parent QObject.
     */
    PartManager(QWidget *topLevel, QObject *parent);
    ~PartManager() override;

    /**
     * Sets the selection policy of the partmanager.
     */
    void setSelectionPolicy(SelectionPolicy policy);
    /**
     * Returns the current selection policy.
     */
    SelectionPolicy selectionPolicy() const;

    /**
     * Specifies whether the partmanager should handle/allow nested parts
     * or not.
     *
     *  This is a property the shell has to set/specify. Per
     * default we assume that the shell cannot handle nested
     * parts. However in case of a KOffice shell for example we allow
     * nested parts.  A Part is nested (a child part) if its parent
     * object inherits KParts::Part.  If a child part is activated and
     * nested parts are not allowed/handled, then the top parent part in
     * the tree is activated.
     */
    void setAllowNestedParts(bool allow);
    /**
     * @see setAllowNestedParts
     */
    bool allowNestedParts() const;

    /**
     * Specifies whether the partmanager should ignore mouse click events for
     * scrollbars or not. If the partmanager ignores them, then clicking on the
     * scrollbars of a non-active/non-selected part will not change the selection
     * or activation state.
     *
     * The default value is false (read: scrollbars are NOT ignored).
     */
    void setIgnoreScrollBars(bool ignore);
    /**
     * @see setIgnoreScrollBars
     */
    bool ignoreScrollBars() const;

    /**
     * Specifies which mouse buttons the partmanager should react upon.
     * By default it reacts on all mouse buttons (LMB/MMB/RMB).
     * @param buttonMask a combination of Qt::ButtonState values e.g. Qt::LeftButton | Qt::MiddleButton
     */
    void setActivationButtonMask(short int buttonMask);
    /**
     * @see setActivationButtonMask
     */
    short int activationButtonMask() const;

    /**
     * @internal
     */
    bool eventFilter(QObject *obj, QEvent *ev) override;

    /**
     * Adds a part to the manager.
     *
     * Sets it to the active part automatically if @p setActive is true (default).
     */
    virtual void addPart(Part *part, bool setActive = true);

    /**
     * Removes a part from the manager (this does not delete the object) .
     *
     * Sets the active part to 0 if @p part is the activePart() .
     */
    virtual void removePart(Part *part);

    /**
     * Replaces @p oldPart with @p newPart, and sets @p newPart as active if
     * @p setActive is true.
     * This is an optimised version of removePart + addPart
     */
    virtual void replacePart(Part *oldPart, Part *newPart, bool setActive = true);

    /**
     * Sets the active part.
     *
     * The active part receives activation events.
     *
     * @p widget can be used to specify which widget was responsible for the activation.
     * This is important if you have multiple views for a document/part , like in KOffice .
     */
    virtual void setActivePart(Part *part, QWidget *widget = nullptr);

    /**
     * Returns the active part.
     **/
    virtual Part *activePart() const;

    /**
     * Returns the active widget of the current active part (see activePart ).
     */
    virtual QWidget *activeWidget() const;

    /**
     * Returns the list of parts being managed by the partmanager.
     */
    const QList<Part *> parts() const;

    /**
     * Adds the @p topLevel widget to the list of managed toplevel widgets.
     * Usually a PartManager only listens for events (for activation/selection)
     * for one toplevel widget (and its children) , the one specified in the
     * constructor. Sometimes however (like for example when using the KDE dockwidget
     * library) , it is necessary to extend this.
     */
    void addManagedTopLevelWidget(const QWidget *topLevel);
    /**
     * Removes the @p topLevel widget from the list of managed toplevel widgets.
     * @see addManagedTopLevelWidget
     */
    void removeManagedTopLevelWidget(const QWidget *topLevel);

    /**
     * @return the reason for the last activePartChanged signal emitted.
     * @see Reason
     */
    int reason() const;

Q_SIGNALS:
    /**
     * Emitted when a new part has been added.
     * @see addPart()
     **/
    void partAdded(KParts::Part *part);
    /**
     * Emitted when a part has been removed.
     * @see removePart()
     **/
    void partRemoved(KParts::Part *part);
    /**
     * Emitted when the active part has changed.
     * @see setActivePart()
     **/
    void activePartChanged(KParts::Part *newPart);

protected:
    /**
     * Sets whether the PartManager ignores explicit set focus requests
     * from the part.
     *
     * By default this option is set to false. Set it to true to prevent
     * the part from sending explicit set focus requests to the client
     * application.
     *
     * @since 4.10
     */
    void setIgnoreExplictFocusRequests(bool);

protected Q_SLOTS:
    /**
     * Removes a part when it is destroyed.
     **/
    void slotObjectDestroyed();

    /**
     * @internal
     */
    void slotWidgetDestroyed();

    /**
     * @internal
     */
    void slotManagedTopLevelWidgetDestroyed();

private:
    KPARTS_NO_EXPORT Part *findPartFromWidget(QWidget *widget, const QPoint &pos);
    KPARTS_NO_EXPORT Part *findPartFromWidget(QWidget *widget);

private:
    std::unique_ptr<PartManagerPrivate> const d;
};

}

#endif