#pragma once

/**
 * @file oscillation.hpp
 * @brief FFT-based oscillation detection (Phase 25).
 */

#include <vector>

namespace fces {

class OscillationDetector {
public:
    static constexpr int WINDOW_SIZE = 64;
    static constexpr float POWER_THRESHOLD = 0.5f;
    static constexpr int MIN_PERIOD = 4;
    static constexpr int MAX_PERIOD = 16;

    void update(float loss);
    bool detect() const;
    float get_score() const;
    float get_variance_50() const;
    void reset();

private:
    std::vector<float> loss_history_;
    static std::vector<float> detrend(const std::vector<float>& signal);
    static std::vector<float> compute_power_spectrum(const std::vector<float>& signal);
};

}  // namespace fces