/////////////////////////////////////////////////////////////////////////////

// Name:        wx/unix/private/timer.h

// Purpose:     wxTimer for wxBase (unix)

// Author:      Lukasz Michalski

// Created:     15/01/2005

// Copyright:   (c) Lukasz Michalski

// Licence:     wxWindows licence

/////////////////////////////////////////////////////////////////////////////

#ifndef _WX_UNIX_PRIVATE_TIMER_H_

#define _WX_UNIX_PRIVATE_TIMER_H_

#if wxUSE_TIMER

#include "wx/private/timer.h"

#include <list>

// the type used for milliseconds is large enough for microseconds too but

// introduce a synonym for it to avoid confusion

typedef wxMilliClock_t wxUsecClock_t;

// ----------------------------------------------------------------------------

// wxTimer implementation class for Unix platforms

// ----------------------------------------------------------------------------

// NB: we have to export at least this symbol from the shared library, because

//     it's used by wxDFB's wxCore

class WXDLLIMPEXP_BASE wxUnixTimerImpl : public wxTimerImpl

{

public:

    wxUnixTimerImpl(wxTimer *timer);

    virtual ~wxUnixTimerImpl();

    virtual bool IsRunning() const override;

    virtual bool Start(int milliseconds = -1, bool oneShot = false) override;

    virtual void Stop() override;

    // for wxTimerScheduler only: resets the internal flag indicating that the

    // timer is running

    void MarkStopped()

    {

        wxASSERT_MSG( m_isRunning, wxT("stopping non-running timer?") );

        m_isRunning = false;

    }

private:

    bool m_isRunning;

};

// ----------------------------------------------------------------------------

// wxTimerSchedule: information about a single timer, used by wxTimerScheduler

// ----------------------------------------------------------------------------

struct wxTimerSchedule

{

    wxTimerSchedule(wxUnixTimerImpl *timer, wxUsecClock_t expiration)

        : m_timer(timer),

          m_expiration(expiration)

    {

    }

    // the timer itself (we don't own this pointer)

    wxUnixTimerImpl *m_timer;

    // the time of its next expiration, in usec

    wxUsecClock_t m_expiration;

};

// the linked list of all active timers, we keep it sorted by expiration time

using wxTimerList = std::list<wxTimerSchedule>;

// ----------------------------------------------------------------------------

// wxTimerScheduler: class responsible for updating all timers

// ----------------------------------------------------------------------------

class wxTimerScheduler

{

public:

    // get the unique timer scheduler instance

    static wxTimerScheduler& Get()

    {

        if ( !ms_instance )

            ms_instance = new wxTimerScheduler;

        return *ms_instance;

    }

    // must be called on shutdown to delete the global timer scheduler

    static void Shutdown()

    {

        if ( ms_instance )

        {

            delete ms_instance;

            ms_instance = nullptr;

        }

    }

    // adds timer which should expire at the given absolute time to the list

    void AddTimer(wxUnixTimerImpl *timer, wxUsecClock_t expiration);

    // remove timer from the list, called automatically from timer dtor

    void RemoveTimer(wxUnixTimerImpl *timer);

    // the functions below are used by the event loop implementation to monitor

    // and notify timers:

    // if this function returns true, the time remaining until the next time

    // expiration is returned in the provided parameter (always positive or 0)

    //

    // it returns false if there are no timers

    bool GetNext(wxUsecClock_t *remaining) const;

    // trigger the timer event for all timers which have expired, return true

    // if any did

    bool NotifyExpired();

private:

    // ctor and dtor are private, this is a singleton class only created by

    // Get() and destroyed by Shutdown()

    wxTimerScheduler() = default;

    ~wxTimerScheduler() = default;

    // add the given timer schedule to the list in the right place

    void DoAddTimer(const wxTimerSchedule& s);

    // the list of all currently active timers sorted by expiration

    wxTimerList m_timers;

    static wxTimerScheduler *ms_instance;

};

#endif // wxUSE_TIMER

#endif // _WX_UNIX_PRIVATE_TIMER_H_