#include "tools/bpmcalculator.h"
#include <cmath>
#include <numeric>
#include <iostream>

constexpr microsec MICROSECONDS_IN_MINUTE = 60000000;

BPMCalculator::BPMCalculator(const std::shared_ptr<Music>& music) :
    _music(music),
    _previous_click_offset(0)
{}

void BPMCalculator::setMusic(const std::shared_ptr<Music>& music)
{
    _music = music;
}

void BPMCalculator::startListening(const microsec &offset)
{
    _deltas.clear();
    _previous_click_offset = 0;
    _music->setOffset(offset);
    _music->play();
}

void BPMCalculator::stopListening()
{
    _music->stop();
}

void BPMCalculator::click()
{
    const microsec click_offset = _music->fetchOffset();

    if (_previous_click_offset == 0)
    {
        _previous_click_offset = click_offset;
        return;
    }

    const microsec delta = click_offset - _previous_click_offset;
    _deltas.emplace_back(delta);

    _previous_click_offset = click_offset;
}

int BPMCalculator::getCurrentApproximation() const
{
    const microsec sum = std::accumulate(_deltas.begin(), _deltas.end(), 0);

    return (sum == 0)
         ?  0.
         :  static_cast<int>(static_cast<float>(MICROSECONDS_IN_MINUTE) / (static_cast<float>(sum) / static_cast<float>(_deltas.size())));
}