/****************************************************************************
**
** Copyright (C) 2020 Uwe Kindler
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt Creator.
**
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or (at your option) any later version.
** The licenses are as published by the Free Software Foundation
** and appearing in the file LICENSE.LGPLv21 included in the packaging
** of this file. Please review the following information to ensure
** the GNU Lesser General Public License version 2.1 requirements
** will be met: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 or (at your option) any later version
** approved by the KDE Free Qt Foundation. The licenses are as published by
** the Free Software Foundation and appearing in the file LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-3.0.html.
**
****************************************************************************/

#pragma once

#include "ads_globals.h"
#include "dockwidget.h"

#include <QFrame>

class QXmlStreamWriter;
class QAbstractButton;

namespace ADS {

struct DockAreaWidgetPrivate;
class DockManager;
class DockContainerWidget;
class DockContainerWidgetPrivate;
class DockAreaTitleBar;

/**
 * DockAreaWidget manages multiple instances of DockWidgets.
 * It displays a title tab, which is clickable and will switch to
 * the contents associated to the title when clicked.
 */
class ADS_EXPORT DockAreaWidget : public QFrame
{
    Q_OBJECT
private:
    DockAreaWidgetPrivate *d; ///< private data (pimpl)
    friend struct DockAreaWidgetPrivate;
    friend class DockContainerWidget;
    friend class DockContainerWidgetPrivate;
    friend class DockWidgetTab;
    friend struct DockWidgetPrivate;
    friend class DockWidget;
    friend struct DockManagerPrivate;
    friend class DockManager;

    void onTabCloseRequested(int index);

    /**
     * Reorder the index position of DockWidget at fromIndx to toIndex
     * if a tab in the tabbar is dragged from one index to another one
     */
    void reorderDockWidget(int fromIndex, int toIndex);

protected:
    /**
     * Inserts a dock widget into dock area.
     * All dockwidgets in the dock area tabified in a stacked layout with tabs.
     * The index indicates the index of the new dockwidget in the tabbar and
     * in the stacked layout. If the Activate parameter is true, the new
     * DockWidget will be the active one in the stacked layout
     */
    void insertDockWidget(int index, DockWidget *dockWidget, bool activate = true);

    /**
     * Add a new dock widget to dock area.
     * All dockwidgets in the dock area tabified in a stacked layout with tabs
     */
    void addDockWidget(DockWidget *dockWidget);

    /**
     * Removes the given dock widget from the dock area
     */
    void removeDockWidget(DockWidget *dockWidget);

    /**
     * Called from dock widget if it is opened or closed
     */
    void toggleDockWidgetView(DockWidget *dockWidget, bool open);

    /**
     * This is a helper function to get the next open dock widget to activate
     * if the given DockWidget will be closed or removed.
     * The function returns the next widget that should be activated or
     * nullptr in case there are no more open widgets in this area.
     */
    DockWidget *nextOpenDockWidget(DockWidget *dockWidget) const;

    /**
     * Returns the index of the given DockWidget in the internal layout
     */
    int indexOf(DockWidget *dockWidget);

    /**
     * Call this function, if you already know, that the dock does not
     * contain any visible content (any open dock widgets).
     */
    void hideAreaWithNoVisibleContent();

    /**
     * Updates the dock area layout and components visibility
     */
    void updateTitleBarVisibility();

    /**
     * This is the internal private function for setting the current widget.
     * This function is called by the public setCurrentDockWidget() function
     * and by the dock manager when restoring the state
     */
    void internalSetCurrentDockWidget(DockWidget *dockWidget);

    /**
     * Marks tabs menu to update
     */
    void markTitleBarMenuOutdated();

    void toggleView(bool open);

public:
    using Super = QFrame;

    /**
     * Default Constructor
     */
    DockAreaWidget(DockManager *dockManager, DockContainerWidget *parent);

    /**
     * Virtual Destructor
     */
    virtual ~DockAreaWidget() override;

    /**
     * Returns the dock manager object this dock area belongs to
     */
    DockManager *dockManager() const;

    /**
     * Returns the dock container widget this dock area widget belongs to or 0
     * if there is no
     */
    DockContainerWidget *dockContainer() const;

    /**
     * Returns the rectangle of the title area
     */
    QRect titleBarGeometry() const;

    /**
     * Returns the rectangle of the content
     */
    QRect contentAreaGeometry() const;

    /**
     * Returns the number of dock widgets in this area
     */
    int dockWidgetsCount() const;

    /**
     * Returns a list of all dock widgets in this dock area.
     * This list contains open and closed dock widgets.
     */
    QList<DockWidget *> dockWidgets() const;

    /**
     * Returns the number of open dock widgets in this area
     */
    int openDockWidgetsCount() const;

    /**
     * Returns a list of dock widgets that are not closed.
     */
    QList<DockWidget *> openedDockWidgets() const;

    /**
     * Returns a dock widget by its index
     */
    DockWidget *dockWidget(int indexOf) const;

    /**
     * Returns the index of the current active dock widget or -1 if there
     * are is no active dock widget (ie.e if all dock widgets are closed)
     */
    int currentIndex() const;

    /**
     * Returns the index of the first open dock widgets in the list of
     * dock widgets.
     * This function is here for performance reasons. Normally it would
     * be possible to take the first dock widget from the list returned by
     * openedDockWidgets() function. But that function enumerates all
     * dock widgets while this functions stops after the first open dock widget.
     * If there are no open dock widgets, the function returns -1.
     */
    int indexOfFirstOpenDockWidget() const;

    /**
     * Returns the current active dock widget or a nullptr if there is no
     * active dock widget (i.e. if all dock widgets are closed)
     */
    DockWidget *currentDockWidget() const;

    /**
     * Shows the tab with the given dock widget
     */
    void setCurrentDockWidget(DockWidget *dockWidget);

    /**
     * Saves the state into the given stream
     */
    void saveState(QXmlStreamWriter &stream) const;

    /**
     * This functions returns the dock widget features of all dock widget in
     * this area.
     * A bitwise and is used to combine the flags of all dock widgets. That
     * means, if only one single dock widget does not support a certain flag,
     * the whole dock are does not support the flag. I.e. if one single
     * dock widget in this area is not closable, the whole dock are is not
     * closable.
     */
    DockWidget::DockWidgetFeatures features(eBitwiseOperator mode = BitwiseAnd) const;

    /**
     * Returns the title bar button corresponding to the given title bar
     * button identifier
     */
    QAbstractButton *titleBarButton(eTitleBarButton which) const;

    /**
     * Update the close button if visibility changed
     */
    virtual void setVisible(bool visible) override;

    /**
     * Configures the areas of this particular dock area that are allowed for docking
     */
    void setAllowedAreas(DockWidgetAreas areas);

    /**
     * Returns flags with all allowed drop areas of this particular dock area
     */
    DockWidgetAreas allowedAreas() const;

    /**
     * Returns the title bar of this dock area
     */
    DockAreaTitleBar *titleBar() const;

    /**
     * This activates the tab for the given tab index.
     * If the dock widget for the given tab is not visible, the this function
     * call will make it visible.
     */
    void setCurrentIndex(int indexOf);

    /**
     * Closes the dock area and all dock widgets in this area
     */
    void closeArea();

    /**
     * This function closes all other areas except of this area
     */
    void closeOtherAreas();

signals:
    /**
     * This signal is emitted when user clicks on a tab at an index.
     */
    void tabBarClicked(int indexOf);

    /**
    * This signal is emitted when the tab bar's current tab is about to be changed. The new
    * current has the given index, or -1 if there isn't a new one.
    * @param index
    */
    void currentChanging(int indexOf);

    /**
     * This signal is emitted when the tab bar's current tab changes. The new
     * current has the given index, or -1 if there isn't a new one
     * @param index
     */
    void currentChanged(int indexOf);

    /**
     * This signal is emitted if the visibility of this dock area is toggled
     * via toggle view function
     */
    void viewToggled(bool open);
}; // class DockAreaWidget

} // namespace ADS
