project-kyoku/include/tools/bpmcalculator.h

#pragma once

#include "tools/music.h"
#include "tools/beatutils.h"
#include <memory>

class BPMCalculator
{
public:
    explicit BPMCalculator(const std::shared_ptr<Music>& music);

    void setMusic(const std::shared_ptr<Music>& music);
    std::shared_ptr<Music> music() const;

    void start();
    void stop();
    void click();

    bool calculating() const;

    const beat_utils::BeatInfo& fetchApproximatedInfo();
    microsec fetchTimeUntilNextBeat();

    microsec getStartingOffset() const;
    void setStartingOffset(microsec offset);
    void moveStartingOffsetBy(microsec shift);

private:
    bool _need_recalculate;
    bool _calculating;

    std::shared_ptr<Music> _music;
    std::vector<microsec> _deltas;
    microsec _previous_click_offset;
    microsec _first_click_offset;

    beat_utils::BeatInfo _approximated_info;

    inline void reset();
};