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// FFT
#pragma once
#include <complex>
#include <memory>
#include <vector>
namespace RIT {
// Fast Fourier Transform
class FFT {
private:
int mSize;
std::vector<int> order;
std::vector<std::complex<double>> expLUT;
bool mFlagHalfOnly;
public:
FFT(int size, bool halfOnly = false);
std::vector<std::complex<double>> operator()(const std::vector<std::complex<double>> &v) const;
FFT& SetHalfOnly(bool enable);
private:
void reorder(const std::vector<std::complex<double>>& src, std::vector<std::complex<double>>& dst) const;
void fft_recursive(std::vector<std::complex<double>>::iterator X, int N) const;
void fft_half(std::vector<std::complex<double>>::iterator X, int N) const;
}; // class FFT
// Inverse FFT
class IFFT {
public:
IFFT(int size);
IFFT(std::shared_ptr<FFT> fft);
~IFFT();
std::vector<std::complex<double>> operator()(const std::vector<std::complex<double>> &v) const;
private:
struct Impl;
std::unique_ptr<Impl> mImpl;
}; // class IFFT
} // namespace RIT
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