#include "aquila/global.h"
#include "aquila/source/generator/SineGenerator.h"
#include "aquila/transform/FftFactory.h"
#include "aquila/tools/TextPlot.h"
#include <algorithm>
#include <functional>
#include <memory>

int main()
{
    // input signal parameters
    const std::size_t SIZE = 64;
    const Aquila::FrequencyType sampleFreq = 2000;
    const Aquila::FrequencyType f1 = 96, f2 = 813;
    const Aquila::FrequencyType f_lp = 500;

    Aquila::SineGenerator sineGenerator1(sampleFreq);
    sineGenerator1.setAmplitude(32).setFrequency(f1).generate(SIZE);
    Aquila::SineGenerator sineGenerator2(sampleFreq);
    sineGenerator2.setAmplitude(8).setFrequency(f2).setPhase(0.75).generate(SIZE);
    auto sum = sineGenerator1 + sineGenerator2;

    Aquila::TextPlot plt("Signal waveform before filtration");
    plt.plot(sum);

    // calculate the FFT
    auto fft = Aquila::FftFactory::getFft(SIZE);
    Aquila::SpectrumType spectrum = fft->fft(sum.toArray());
    plt.setTitle("Signal spectrum before filtration");
    plt.plotSpectrum(spectrum);

    // generate a low-pass filter spectrum
    Aquila::SpectrumType filterSpectrum(SIZE);
    for (std::size_t i = 0; i < SIZE; ++i)
    {
        if (i < (SIZE * f_lp / sampleFreq))
        {
            // passband
            filterSpectrum[i] = 1.0;
        }
        else
        {
            // stopband
            filterSpectrum[i] = 0.0;
        }
    }
    plt.setTitle("Filter spectrum");
    plt.plotSpectrum(filterSpectrum);

    // the following call does the multiplication of two spectra
    // (which is complementary to convolution in time domain)
    std::transform(
        std::begin(spectrum),
        std::end(spectrum),
        std::begin(filterSpectrum),
        std::begin(spectrum),
        [] (Aquila::ComplexType x, Aquila::ComplexType y) { return x * y; }
    );
    plt.setTitle("Signal spectrum after filtration");
    plt.plotSpectrum(spectrum);

    // Inverse FFT moves us back to time domain
    double x1[SIZE];
    fft->ifft(spectrum, x1);
    plt.setTitle("Signal waveform after filtration");
    plt.plot(x1, SIZE);

    return 0;
}

Signal waveform before filtration
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Signal spectrum before filtration
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Filter spectrum
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Signal spectrum after filtration
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Signal waveform after filtration
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