/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

/*

 * This file is part of the LibreOffice project.

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/.

 *

 * This file incorporates work covered by the following license notice:

 *

 *   Licensed to the Apache Software Foundation (ASF) under one or more

 *   contributor license agreements. See the NOTICE file distributed

 *   with this work for additional information regarding copyright

 *   ownership. The ASF licenses this file to you under the Apache

 *   License, Version 2.0 (the "License"); you may not use this file

 *   except in compliance with the License. You may obtain a copy of

 *   the License at http://www.apache.org/licenses/LICENSE-2.0 .

 */

#ifndef INCLUDED_VCL_SVAPP_HXX

#define INCLUDED_VCL_SVAPP_HXX

#include <sal/config.h>

#include <sal/types.h>

#include <cassert>

#include <vector>

#include <comphelper/solarmutex.hxx>

#include <LibreOfficeKit/LibreOfficeKitTypes.h>

#include <osl/mutex.hxx>

#include <rtl/ustring.hxx>

#include <osl/thread.h>

#include <tools/link.hxx>

#include <tools/long.hxx>

#include <vcl/dllapi.h>

#include <vcl/IDialogRenderable.hxx>

#include <vcl/Platform.hxx>

#include <vcl/Toolkit.hxx>

#include <vcl/inputtypes.hxx>

#include <i18nlangtag/lang.h>

#include <o3tl/typed_flags_set.hxx>

class AbsoluteScreenPixelRectangle;

class Bitmap;

namespace tools { class JsonWriter; }

namespace weld

{

    class Builder;

    class MessageDialog;

    class Widget;

    class Window;

}

class LocaleDataWrapper;

class AllSettings;

class DataChangedEvent;

class Accelerator;

class Help;

class OutputDevice;

namespace vcl {

    class KeyCode;

    class Window;

}

class NotifyEvent;

class KeyEvent;

class MouseEvent;

class GestureEventPan;

class VclSimpleEvent;

class VclWindowEvent;

struct ImplSVEvent;

struct ConvertData;

namespace basegfx { class SystemDependentDataManager; }

namespace rtl { template <class reference_type> class Reference; }

enum class DesktopType;

enum class ExceptionCategory;

enum class VclButtonsType;

enum class VclEventId;

enum class VclMessageType;

namespace com::sun::star::uno {

    template <class interface_type> class Reference;

    class XComponentContext;

}

namespace com::sun::star::ui::dialogs {

    class XFilePicker2;

    class XFolderPicker2;

}

namespace com::sun::star::awt {

    class XToolkit;

    class XWindow;

}

VCL_DLLPUBLIC OUString LocalizeDigitsInString( const OUString&, LanguageType,

                                               sal_Int32 nStart, sal_Int32& nLen );

inline OUString LocalizeDigitsInString( const OUString& sStr, LanguageType eTextLanguage )

{

    sal_Int32 nLen = sStr.getLength();

    return LocalizeDigitsInString(sStr, eTextLanguage, 0, nLen);

}

enum class SystemWindowFlags {

    NOAUTOMODE    = 0x0001,

    DIALOG        = 0x0002

};

namespace o3tl

{

    template<> struct typed_flags<SystemWindowFlags> : is_typed_flags<SystemWindowFlags, 0x03> {};

}

typedef long (*VCLEventHookProc)( NotifyEvent& rEvt, void* pData );

/** An application can be notified of a number of different events:

    - Type::Accept       - listen for connection to the application (a connection

                          string is passed via the event)

    - Type::Unaccept     - stops listening for a connection to the app (determined by

                          a connection string passed via the event)

    - Type::Appear       - brings the app to the front (i.e. makes it "appear")

    - Type::Version      - display the app version

    - Type::Help         - opens a help topic (help topic passed as string)

    - Type::OpenHELP_URL - opens a help URL (URL passed as a string)

    - Type::ShowDialog   - shows a dialog (dialog passed as a string)

    - Type::Open         - opens a document or group of documents (documents passed

                          as an array of strings)

    - Type::Print        - print a document or group of documents (documents passed

                          as an array of strings

    - Type::PrivateDoShutdown - shutdown the app

*/

class VCL_DLLPUBLIC ApplicationEvent

{

public:

    enum class Type {

        Accept,                ///< Listen for connections

        Appear,                ///< Make application appear

        Open,                  ///< Open a document

        OpenHelpUrl,           ///< Open a help URL

        Print,                 ///< Print document

        PrivateDoShutdown,    ///< Shutdown application

        QuickStart,            ///< Start QuickStart

        ShowDialog,            ///< Show a dialog

        Unaccept               ///< Stop listening for connections

    };

    /** Explicit constructor for ApplicationEvent.

     @attention Type::Appear, Type::PrivateDoShutdown and

        Type::QuickStart are the \em only events that don't need to include

        a data string with the event. No other events should use this

        constructor!

    */

    explicit ApplicationEvent(Type type): aEvent(type)

    {

        assert(type == Type::Appear || type == Type::PrivateDoShutdown || type == Type::QuickStart);

    }

    /** Constructor for ApplicationEvent, accepts a string for the data

     associated with the event.

     @attention Type::Accept, Type::OpenHelpUrl, Type::ShowDialog

        and Type::Unaccept are the \em only events that accept a single

        string as event data. No other events should use this constructor!

    */

    ApplicationEvent(Type type, OUString const & data): aEvent(type)

    {

        assert(

            type == Type::Accept || type == Type::OpenHelpUrl

            || type == Type::ShowDialog || type == Type::Unaccept);

        aData.push_back(data);

    }

    /** Constructor for ApplicationEvent, accepts an array of strings for

     the data associated with the event.

     @attention Type::Open and Type::Print can apply to multiple documents,

        and are the \em only events that accept an array of strings. No other

        events should use this constructor.

    */

    ApplicationEvent(Type type, std::vector<OUString>&& data):

        aEvent(type), aData(std::move(data))

    {

        assert(type == Type::Open || type == Type::Print);

    }

    /** Get the type of event.

     @returns The type of event.

    */

    Type GetEvent() const

    {

        return aEvent;

    }

    /** Gets the application event's data string.

     @attention The \em only events that need a single string Type::Accept,

        Type::OpenHelpUrl, Type::ShowDialog and Type::Unaccept

     @returns The event's data string.

    */

    OUString const & GetStringData() const

    {

        assert(

            aEvent == Type::Accept

            || aEvent == Type::OpenHelpUrl || aEvent == Type::ShowDialog

            || aEvent == Type::Unaccept);

        assert(aData.size() == 1);

        return aData[0];

    }

    /** Gets the event's array of strings.

     @attention The \em only events that need an array of strings

        are Type::Open and Type::Print.

    */

    std::vector<OUString> const & GetStringsData() const

    {

        assert(aEvent == Type::Open || aEvent == Type::Print);

        return aData;

    }

private:

    Type aEvent;

    std::vector<OUString> aData;

};

enum class DialogCancelMode {

    Off,      ///< do not automatically cancel dialogs

    Silent,   ///< silently cancel any dialogs

    LOKSilent, ///< silently cancel any dialogs (LOK case)

    Fatal     ///< cancel any dialogs by std::abort

};

/**

 @brief Base class used mainly for the LibreOffice Desktop class.

 The Application class is a base class mainly used by the Desktop

 class. It is really meant to be subclassed, and the Main() function

 should be overridden. Many of the ImplSVData members should be

 moved to this class.

 The reason Application exists is because the VCL used to be a

 standalone framework, long since abandoned by anything other than

 our application.

 @see   Desktop, ImplSVData

 */

class VCL_DLLPUBLIC Application : public vcl::ILibreOfficeKitNotifier

{

public:

    /** @name Initialization

        The following functions perform initialization and deinitialization

        of the application.

    */

    ///@{

    /** Default constructor for Application class.

    Initializes the LibreOffice global instance data structure if needed,

    and then sets itself to be the Application class. Also initializes any

    platform specific data structures.

    @attention The initialization of the application itself is done in Init()

    */

                                Application();

    /** Virtual destructor for Application class.

     Deinitializes the LibreOffice global instance data structure, then

     deinitializes any platform specific data structures.

    */

    virtual                     ~Application();

    /** Initialize the application itself.

     @attention Note that the global data structures and platform specific

        initialization is done in the constructor.

     @see InitFinished, DeInit

    */

    virtual void                Init();

    /** Finish initialization of the application.

     @see Init, DeInit

    */

    virtual void                InitFinished();

    /** Deinitialized the application itself.

     @attention Note that the global data structures and platform specific

         deinitialization is done in the destructor.

     @see Init, InitFinished

    */

    virtual void                DeInit();

    ///@}

    /** @brief Pure virtual entrypoint to the application.

     Main() is the pure virtual entrypoint to your application. You

     inherit your class from Application and subclass this function to

     implement an application.

     The Main() function does not pass in command line parameters,

     you must use the functions GetCommandLineParamCount() and

     GetCommandLineParam() to get these values as these are platform

     independent ways of getting the command line (use GetAppFileName()

     to get the invoked executable filename).

     Once in this function, you create windows, etc. then call on

     Execute() to start the application's main event loop.

     An example code snippet follows (it won't compile, this just gives the

     general flavour of the framework and is adapted from an old HelloWorld

     example program that Star Division used to provide as part of their

     library).

     \code{.cpp}

        class TheApplication : public Application

        {

            public:

                virtual void Main();

        };

        class TheWindow : public WorkWindow

        {

            public:

                TheWindow(vcl::Window *parent, WinBits windowStyle) :

                        WorkWindow(parent, windowStyle) {}

                virtual void Paint(const Rectangle &);

        };

        void TheWindow::Paint(const Rectangle&)

        {

                DrawText(Point(100,100), String("Hello World!"));

        }

        void TheApplication::Main()

        {

                TheWindow aWindow(NULL, WB_APP | WB_STDWORK);

                    aWindow.Show();

                        Execute();

        }

        TheApplication anApplication;

    \endcode

    Some examples in the source tree can be found here:

    vcl/workben/svdem.cxx

    This is an example of how to use the Application and WorkWindow. Unfortunately, it

    no longer compiles.

    vcl/fpicker/test/svdem.cxx

    */

    SAL_DLLPRIVATE virtual int  Main();

    /** Exit from the application

     @returns true if exited successfully, false if not able to fully exit

    */

    virtual bool                QueryExit();

    virtual void                Shutdown();

    /** @name Change Notification Functions

        Functions that notify when changes occur in the application.

    */

    ///@{

    /** Notify all windows that the application has changed data.

     @param rDCEvt     Reference to a DataChangedEvent object

     @see DataChanged

    */

    static void                 NotifyAllWindows( DataChangedEvent& rDCEvt );

    ///@}

    /** @name Command Line Processing

        Command line processing is done via the following functions. They

        give the number of parameters, the parameters themselves and a way

        to get the name of the invoking application.

    */

    ///@{

    /** Gets the number of command line parameters passed to the application

     @return sal_uInt16 - the number of parameters

     @see GetCommandLineParam, GetAppFileName

    */

    static sal_uInt16           GetCommandLineParamCount();

    /** Gets a particular command line parameter

     @param  nParam      The index of the parameter to return.

     @return The command line parameter as an OUString

     @see GetCommandLineParamCount, GetAppFileName

    */

    static OUString             GetCommandLineParam( sal_uInt16 nParam );

    /** Get the name of the file used to start the application

     @return The filename as an OUString

     @see GetCommandLineParamCount, GetCommandLineParam

    */

    static OUString             GetAppFileName();

    ///@}

    /** @name Error Handling

        \em Very rudimentary error handling is done by these

        functions.

        @{

    */

    /** Handles an error.

     @param nCategory    The error category, see include/vcl/exceptiontypes.hxx

     @see Abort

    */

    virtual void          Exception( ExceptionCategory nCategory );

    /** Ends the program prematurely with an error message.

     If the \code --norestore \endcode command line argument is given (assuming

     this process is run by developers who are interested in cores,

     vs. end users who are not) then it does a coredump.

     @param rErrorText  The error message to report.

     @see Exception

    */

    static void                 Abort( const OUString& rErrorText );

    ///@}

    /** @name Event Loop Functions

        Functions that handle the LibreOffice main event loop are here,

        including a global lock called the Solar Mutex.

    */

    ///@{

    /** Run the main event processing loop until it is quit by Quit().

     @see Quit, Reschedule, Yield, EndYield, GetSolarMutex,

          IsMainThread, ReleaseSolarMutex, AcquireSolarMutex,

    */

    static void                 Execute();

    /** Quit the program

     @see Execute, Reschedule, Yield, EndYield, GetSolarMutex,

          IsMainThread, ReleaseSolarMutex, AcquireSolarMutex,

    */

    static void                 Quit();

    /** Has Quit() been called?

    */

    static bool                 IsQuit();

    /** Attempt to process current pending event(s)

     It doesn't sleep if no events are available for processing.

     This doesn't process any events generated after invoking the function.

     So in contrast to Scheduler::ProcessEventsToIdle, this cannot become

     busy-locked by an event-generating event in the event queue.

     @param bHandleAllCurrentEvents  If set to true, then try to process all

        the current events. If set to false, then only process one event.

        Defaults to false.

     @returns true if any event was processed.

     @see Yield, Scheduler::ProcessEventsToIdle

     */

    static bool                 Reschedule( bool bHandleAllCurrentEvents = false );

    /** Process the next event.

     It sleeps if no event is available for processing and just returns

     if an event was processed.

     @see Execute, Quit, Reschedule, EndYield, GetSolarMutex,

          IsMainThread, ReleaseSolarMutex, AcquireSolarMutex,

    */

    static void                 Yield();

    /**

     @see Execute, Quit, Reschedule, Yield, GetSolarMutex,

          IsMainThread, ReleaseSolarMutex, AcquireSolarMutex,

    */

    static void                 EndYield();

    /** @brief Get the Solar Mutex for this thread.

     Get the Solar Mutex that prevents other threads from accessing VCL

     concurrently.

     @returns SolarMutex reference

     @see Execute, Quit, Reschedule, Yield, EndYield,

          IsMainThread, ReleaseSolarMutex, AcquireSolarMutex,

    */

    static comphelper::SolarMutex& GetSolarMutex();

    /** Queries whether we are in main thread.

     @returns true if we are in main thread, false if not

     @see Execute, Quit, Reschedule, Yield, EndYield, GetSolarMutex,

          ReleaseSolarMutex, AcquireSolarMutex,

    */

    static bool                 IsMainThread();

    /** @brief Release Solar Mutex(es) for this thread

     Release the Solar Mutex(es) that prevents other threads from accessing

     VCL concurrently.

     @returns The number of mutexes that were acquired by this thread.

     @see Execute, Quit, Reschedule, Yield, EndYield, GetSolarMutex,

          IsMainThread, AcquireSolarMutex,

    */

    static sal_uInt32           ReleaseSolarMutex();

    /** @brief Acquire Solar Mutex(es) for this thread.

     Acquire the Solar Mutex(es) that prevents other threads from accessing

     VCL concurrently.

     @see Execute, Quit, Reschedule, Yield, EndYield, GetSolarMutex,

          IsMainThread, ReleaseSolarMutex,

    */

    static void                 AcquireSolarMutex( sal_uInt32 nCount );

    /** Queries whether the application is in "main", i.e. not yet in

        the event loop

     @returns   true if in main, false if not in main

     @see IsInExecute, IsInModalMode

    */

    static bool                 IsInMain();

    /** Queries whether the application is in the event loop

     @returns   true if in the event loop, false if not

     @see IsInMain, IsInModalMode

    */

    static bool                 IsInExecute();

    /** Queries whether application has a modal dialog active.

     @returns   true if a modal dialog is active, false if not

     @see IsInMain, IsInExecute

    */

    static bool                 IsInModalMode();

    /** Return how many events are being dispatched.

     @returns   the number of events currently being dispatched

    */

    static sal_uInt16           GetDispatchLevel();

    /** Determine if there are any pending input events.

     @param     nType   input identifier, defined in include/vcl/inputtypes.hxx

                        The default is VCL_INPUT_ANY.

     @returns   true if there are pending events, false if not.

     @see GetLastInputInterval

    */

    static bool                 AnyInput( VclInputFlags nType = VCL_INPUT_ANY );

    /** The interval from the last time that input was received.

     @returns   system ticks - last input time

     @see AnyInput

    */

    static sal_uInt64           GetLastInputInterval();

    ///@}

    /* Determines if the UI is captured.

     The UI is considered captured if a system dialog is open (e.g. printer setup),

     a floating window, menu or toolbox dropdown is open, or a window has been

     captured by the mouse.

     @returns   true if UI is captured, false if not

     */

    static bool                 IsUICaptured();

    /** @name Settings

        The following functions set system settings (e.g. tab color, etc.). There are functions

        that set settings objects, and functions that set and get the actual system settings for

        the application.

    */

    ///@{

    /** Sets user settings in settings object to override system settings

     The system settings that can be overridden are:

        - window dragging options (on or off, including live scrolling!)

        - style settings (e.g. checkbox color, border color, 3D colors,

          button rollover colors, etc.)

        - mouse settings

        - menu options, including the mouse follows the menu and whether menu

          icons are used

     @param      rSettings      Reference to the settings object to change.

     @see MergeSystemSettings, SetSettings, GetSettings

    */

    virtual void                OverrideSystemSettings( AllSettings& rSettings );

    /** Set the settings object to the platform/desktop environment system

     settings.

     @param     rSettings       Reference to the settings object to change.

     @see OverrideSystemSettings, SetSettings, GetSettings

    */

    static void                 MergeSystemSettings( AllSettings& rSettings );

    /** Sets the application's settings and notifies all windows of the

     change.

     @param     rSettings       const reference to settings object used to

                                change the application's settings.

     @param     bTemporary      this is a temporary change (used in GraphicExporter::filter),

                                do not notify change listeners

     @see OverrideSystemSettings, MergeSystemSettings, GetSettings

    */

    static void                 SetSettings( const AllSettings& rSettings, bool bTemporary = false );

    /** Gets the application's settings. If the application hasn't initialized

     it's settings, then it does so (lazy initialization).

     @returns AllSettings instance that contains the current settings of the

        application.

     @see OverrideSystemSettings, MergeSystemSettings, SetSettings

    */

    static const AllSettings&   GetSettings();

    /** Get the application's locale data wrapper.

     @returns reference to a LocaleDataWrapper object

    */

    SAL_DLLPRIVATE static const LocaleDataWrapper& GetAppLocaleDataWrapper();

    ///@}

    /** @name Event Listeners/Handlers

        A set of event listeners and callers. Note that in this code there is

        platform specific functions - namely for zoom and scroll events.

    */

    ///@{

    /** Add a VCL event listener to the application. If no event listener exists,

     then initialize the application's event listener with a new one, then add

     the event listener.

     @param     rEventListener  Const reference to the event listener to add.

     @see RemoveEventListener, AddKeyListener, RemoveKeyListener

    */

    static void                 AddEventListener( const Link<VclSimpleEvent&,void>& rEventListener );

    /** Remove a VCL event listener from the application.

     @param     rEventListener  Const reference to the event listener to be removed

     @see AddEventListener, AddKeyListener, RemoveKeyListener

    */

    static void                 RemoveEventListener( const Link<VclSimpleEvent&,void>& rEventListener );

    /** Add a keypress listener to the application. If keypress listener exists,

     then initialize the application's keypress event listener with a new one, then

     add the keypress listener.

     @param     rKeyListener    Const reference to the keypress event listener to add

     @see AddEventListener, RemoveEventListener, RemoveKeyListener

    */

    static void                 AddKeyListener( const Link<VclWindowEvent&,bool>& rKeyListener );

    /** Remove a keypress listener from the application.

     @param     rKeyListener    Const reference to the keypress event listener to be removed

     @see AddEventListener, RemoveEventListener, AddKeyListener

    */

    static void                 RemoveKeyListener( const Link<VclWindowEvent&,bool>& rKeyListener );

    /** Send event to all VCL application event listeners

     @param     pWin            Pointer to window to send event

     @param     pData           Pointer to data to send with event

     @see ImplCallEventListeners(VclSimpleEvent* pEvent)

    */

    SAL_DLLPRIVATE static void  ImplCallEventListenersApplicationDataChanged( void* pData );

    /** Send event to all VCL application event listeners

     @param     rEvent          Reference to VclSimpleEvent

     @see ImplCallEventListeners(sal_uLong nEvent, Windows* pWin, void* pData);

    */

    SAL_DLLPRIVATE static void  ImplCallEventListeners( VclSimpleEvent& rEvent );

    /** Handle keypress event

     @param     nEvent          Event ID for keypress

     @param     pWin            Pointer to window that receives the event

     @param     pKeyEvent       Received key event

     @see PostKeyEvent

    */

    SAL_DLLPRIVATE static bool HandleKey( VclEventId nEvent, vcl::Window *pWin, KeyEvent* pKeyEvent );

    /** Send keypress event

     @param     nEvent          Event ID for keypress

     @param     pWin            Pointer to window to which the event is sent

     @param     pKeyEvent       Key event to send

     @see HandleKey

    */

    static ImplSVEvent *        PostKeyEvent( VclEventId nEvent, vcl::Window *pWin, KeyEvent const * pKeyEvent );

    static bool                 LOKHandleMouseEvent( VclEventId nEvent, vcl::Window *pWin, const MouseEvent* pEvent );

    /** Send mouse event

     @param     nEvent          Event ID for mouse event

     @param     pWin            Pointer to window to which the event is sent

     @param     pMouseEvent     Mouse event to send

    */

    static ImplSVEvent *        PostMouseEvent( VclEventId nEvent, vcl::Window *pWin, MouseEvent const * pMouseEvent );

    static ImplSVEvent* PostGestureEvent(VclEventId nEvent, vcl::Window* pWin,

                                         GestureEventPan const * pGestureEvent);

    /** Remove mouse and keypress events from a window... any also zoom and scroll events

     if the platform supports it.

     @param     pWin            Window to remove events from

     @see HandleKey, PostKeyEvent, PostMouseEvent

    */

    static void                 RemoveMouseAndKeyEvents( vcl::Window *pWin );

    /** Post a user event to the default window.

     User events allow for the deferral of work to later in the main-loop - at idle.

     Execution of the deferred work is thread-safe which means all the tasks are executed

     serially, so no thread-safety locks between tasks are necessary.

     @param     rLink           Link to event callback function

     @param     pCaller         Pointer to data sent to the event by the caller. Optional.

     @param     bReferenceLink  If true - hold a VclPtr<> reference on the Link's instance.

                                Taking the reference is guarded by a SolarMutexGuard.

     @return the event ID used to post the event.

    */

    static ImplSVEvent * PostUserEvent( const Link<void*,void>& rLink, void* pCaller = nullptr,

                                        bool bReferenceLink = false );

    /** Remove user event based on event ID

     @param     nUserEvent      User event to remove

    */

    static void                 RemoveUserEvent( ImplSVEvent * nUserEvent );

    /** @deprecated AppEvent is used only in the Desktop class now. However, it is

     intended to notify the application that an event has occurred. It was in oldsv.cxx,

     but is still needed by a number of functions.

     @param     rAppEvent       const reference to ApplicationEvent event

    */

    virtual void                AppEvent( const ApplicationEvent& rAppEvent );

    ///@}

    /** @name Application Window Functions

        Functions that deal with the application's windows

    */

    ///@{

    /** Get the currently focused window.

     @returns Pointer to focused window.

     @see GetDefaultDevice

    */

    static vcl::Window*              GetFocusWindow();

    /** Get the default "device" (in this case the default window).

     @returns Pointer to an OutputDevice. However, it is a Window object -

             Window class subclasses OutputDevice.

     @see GetFocusWindow

    */

    static OutputDevice*        GetDefaultDevice();

    /** access the DataManager for buffering system-dependent data

     @returns the global instance of the SystemDependentDataManager

    */

    static basegfx::SystemDependentDataManager& GetSystemDependentDataManager();

    /** Get the first top-level window of the application.

     @returns Pointer to top-level window (a Window object)

     @see GetNextTopLevelWindow, GetTopWindowCount, GetTopWindow,

          GetActiveTopWindow

    */

    static vcl::Window*              GetFirstTopLevelWindow();

    /** Get the next top level window.

     @param     pWindow     Pointer to Window object you wish to get the next

                            window from.

     @returns Pointer to next top window.

    */

    static vcl::Window*              GetNextTopLevelWindow( vcl::Window const * pWindow );

    /** Return the number of top-level windows being used by the application

     @returns the number of top-level windows

     @see GetFirstTopLevelWindow, GetNextTopLevelWindow, GetTopWindow,

          GetActiveTopWindow

    */

    static tools::Long                 GetTopWindowCount();

    /** Get the nth top window.

     @remark Top windows are actually implemented in a one-way linked list.

         This iterates through top level windows n times.

     @param    nIndex      The index of the top-level window

     @returns The nth top-level window of the application

     @see GetFirstTopLevelWindow, GetNextTopLevelWindow, GetTopWindowCount,

          GetActiveTopWindow

    */

    static vcl::Window*              GetTopWindow( tools::Long nIndex );

    /** Get the "active" top window.

     An "active" top window is one that has a child window that has the

     application's focus.

     @returns the active top window

     @see GetFirstTopLevelWindow, GetNextTopLevelWindow, GetTopWindowCount,

          GetTopWindow

    */

    static vcl::Window*              GetActiveTopWindow();

    ///@}

    /** Set the application's name.

     @param     rUniqueName     What to set the application name to

     @see       GetAppName

    */

    static void                 SetAppName( const OUString& rUniqueName );

    /** @name Application Name, Branding

    */

    ///@{

    /** Get the application's name.

     @returns The application name.

    */

    static const OUString &     GetAppName();

    /**

     * Get the OS version based on the OS specific implementation.

     *

     * @return OUString version string or "-" in case of problems

     */

    static OUString             GetOSVersion();

    /** Get useful OS, Hardware and configuration information,

     * cf. Help->About, and User-Agent

     * bSelection = 0 to return all info, 1 for environment only,

     *   and 2 for VCL/render related infos

     */

    static OUString             GetHWOSConfInfo(const int bSelection = 0, bool bLocalize = true);

    /** Load a localized branding PNG file as a bitmap.

     @param     pName           Name of the bitmap to load.

     @param     rBitmap         Reference to Bitmap object to load PNG into

     @returns true if the PNG could be loaded, otherwise returns false.

    */

    static bool                 LoadBrandBitmap (std::u16string_view pName, Bitmap& rBitmap);

    ///@}

    /** @name Display and Screen

    */

    ///@{

    /** Set the default name of the application for message dialogs and printing.

     @param     rDisplayName    const reference to string to set the Display name to.

     @see GetDisplayName

    */

    static void                 SetDisplayName( const OUString& rDisplayName );

    /** Get the default name of the application for message dialogs and printing.

     @returns The display name of the application.

    */

    static OUString             GetDisplayName();

    /** Get the platform. */

    static Platform GetPlatform();

    /** Get the toolkit. */

    static Toolkit GetToolkit();

    /** Get the toolkit's name. e.g. gtk3

     @returns The toolkit name.

    */

    static OUString GetToolkitName();

    /** Get the number of screens available for the display.

     @returns The number of screens available.

     @see GetScreenPosSizePixel

    */

    static unsigned int         GetScreenCount();

    /** Get a screen's rectangular area.

     @param     nScreen         The number of the screen requested.

     @returns The area of the screen in a Rectangle object.

     @see GetScreenCount

    */

    static AbsoluteScreenPixelRectangle GetScreenPosSizePixel( unsigned int nScreen );

    /** Get the "best" screen.

     @returns the return value will be nearest screen of the target rectangle.

    */

    SAL_DLLPRIVATE static unsigned int GetBestScreen( const AbsoluteScreenPixelRectangle& );

    /** Get the built-in screen.

     @return

       This returns the LCD screen number for a laptop, or the primary

       external VGA display for a desktop machine - it is where a presenter

       console should be rendered if there are other (non-built-in) screens

       present.

     @see IsUnifiedDisplay, GetBestScreen

    */

    static unsigned int         GetDisplayBuiltInScreen();

    /** Get the display's external screen.

     Practically, this means - Get the screen we should run a presentation on.

     @returns 0 or 1 currently, will fallback to the first available screen if

        there are more than one external screens. May be changed in the future.

    */

    static unsigned int         GetDisplayExternalScreen();

    ///@}

    /** @name Accelerators and Mnemonics

     Accelerators allow a user to hold down Ctrl+key (or CMD+key on macOS)

     combination to gain quick access to functionality.

     Mnemonics are underline letters in things like menus and dialog boxes

     that allow a user to type in the letter to activate the menu or option.

    */

    ///@{

    /** Insert accelerator

     @param     pAccel          Pointer to an Accelerator object to insert

     @returns true if successful, false if otherwise

     @see RemoveAccel

    */

    SAL_DLLPRIVATE static bool  InsertAccel( Accelerator* pAccel );

    /** Remove accelerator

     @param     pAccel          Pointer to Accelerator object to remove

     @see InsertAccel

    */

    SAL_DLLPRIVATE static void  RemoveAccel( Accelerator const * pAccel );

    /** Get the number of reserved key codes used by the application.

     @returns number of reserved key codes

     @see GetReservedKeyCode

    */

    static size_t               GetReservedKeyCodeCount();

    /** Get the reserved key code.

     @param     i               The keycode number to retrieve

     @returns Const pointer to a KeyCode object

     @see GetReservedKeyCodeCount

    */

    static const vcl::KeyCode*  GetReservedKeyCode( size_t i );

    ///@}

    /** @name Application Help

     Deals with the help system, and "auto-help", where a user hovers a mouse above

     a UI element and a tooltip with an explanation pops up.

    */

    ///@{

    /** Sets up help

     @param     pHelp           Pointer to a Help object (optional, can by NULL)

     @see GetHelp

    */

    static void                 SetHelp( Help* pHelp = nullptr );

    /** Gets the application's help

     @returns Pointer to application's help object. Note that the application may

        not have a help object, so it might return NULL.

     @see SetHelp

    */

    static Help*                GetHelp();

    ///@}

    /** @name Dialogs

        @remark "Dialog cancel mode" tells a headless install whether to

                cancel dialogs when they appear. See the DialogCancelMode

                enumerator.

    */

    ///@{

    /** Get the default parent window for dialog boxes.

     @remark This is almost always a terrible method to use to get a parent

             for a dialog, try hard to instead pass a specific parent window

             to dialogs.

             GetDefDialogParent does all sorts of things to try and find a useful

             parent window for dialogs. It first uses the topmost parent of the

             active window to avoid using floating windows or other dialog boxes.

             If there are no active windows, then it will take a random stab and

             choose the first visible top window. Otherwise, it defaults to

             the desktop.

     @returns Pointer to the default window.

    */

    static weld::Window*        GetDefDialogParent();

    /** Gets the dialog cancel mode for headless environments.

     @return DialogCancelMode value

     @see SetDialogCancelMode, IsDialogCancelEnabled

    */

    static DialogCancelMode     GetDialogCancelMode();