/** Shared host-side FFT for Android/JNI and desktop/ctypes; no GUI dependencies. */
#ifndef SET_SPECTRUM_H
#define SET_SPECTRUM_H
#include "pcan_abi.h"
#ifdef __cplusplus
extern "C" {
#endif

#define SET_SPECTRUM_MAX 16384U
enum { SET_WINDOW_RECT, SET_WINDOW_HANN, SET_WINDOW_HAMMING, SET_WINDOW_BLACKMAN, SET_WINDOW_FLATTOP };
enum { SET_FILTER_NONE, SET_FILTER_LOW_PASS, SET_FILTER_HIGH_PASS, SET_FILTER_BAND_PASS, SET_FILTER_NOTCH };
enum { SET_SPECTRUM_OK, SET_SPECTRUM_SHORT, SET_SPECTRUM_INVALID, SET_SPECTRUM_TIMING,
       SET_SPECTRUM_CUTOFF, SET_SPECTRUM_MEMORY };

/** Analyze the last power-of-two block (16 <= N <= max_size).
 * times are seconds, strictly increasing; values must be finite. Fs is measured
 * from timestamps, never taken from the requested acquisition rate. Interval
 * deviations >50% of the mean are rejected; smaller jitter is linearly resampled.
 * Filter: second-order Butterworth LP/HP, their cascade for band pass, notch Q=30.
 * low_hz: HP/band lower cutoff or notch center; high_hz: LP/band upper cutoff.
 * Each block starts the causal filters at steady state for its first sample.
 * Processing order: resample, optional mean removal, filter, periodic window, FFT.
 * Output: one-sided PEAK amplitude, normalized by window sum, DC/Nyquist not doubled.
 * Caller supplies max_size/2+1 amplitudes; meta = {N, Fs, max relative jitter}.
 * Inputs are immutable. Scratch memory is bounded by 2*N doubles, allocated here.
 */
PCAN_ABI_API int set_spectrum_analyze(const double *times, const double *values, size_t count,
    size_t max_size, int window, int filter, double low_hz, double high_hz, int remove_mean,
    double *amplitudes, size_t capacity, double *meta);

/** Find the strongest non-DC local maximum above both the absolute floor and
 * relative_threshold * median(non-DC amplitudes). The caller supplies scratch
 * storage of at least count-1 doubles. peak = {frequency_hz, amplitude}.
 * Returns 1 when found, 0 when no narrow-band peak exists, -1 on invalid input.
 */
PCAN_ABI_API int set_spectrum_dominant_peak(const double *amplitudes, size_t count,
    double bin_hz, double relative_threshold, double absolute_floor,
    double *scratch, size_t scratch_capacity, double *peak, size_t peak_capacity);

#ifdef __cplusplus
}
#endif
#endif