fftw

#include <fftw3.h>
#include "include/fft.h"
#include <vector>
#include <iostream>

#include <cmath>


class DctCalculator::Impl {
public:
    fftw_plan plan;
    size_t width;
    std::vector<double>* input;
    std::vector<double>* output;

    Impl(size_t width, std::vector<double> *input, std::vector<double> *output)
        : input(input), output(output), width(width) {
        if (!(input->size() == output->size() && input->size() == width * width)) {
            throw std::invalid_argument("Wrong arrays");
        }
        plan = fftw_plan_r2r_2d(width, width, input->data(), output->data(), FFTW_REDFT01, FFTW_REDFT01, FFTW_ESTIMATE);
    }

    ~Impl() {
        fftw_destroy_plan(plan);
    }

    void Inverse() {
        double two_sqrt = std::sqrt(2);

        for (size_t i = 0; i < width * width; ++i) {
            (*input)[i] *= 4 * (i < width ? two_sqrt : 1) * (i % width == 0 ? two_sqrt : 1);
        }
        fftw_execute(plan);
        // for (size_t i = 0; i < output->size(); ++i) {
        //     output->at(i) /= (width * width);
        // }
    }
};

DctCalculator::DctCalculator(size_t width, std::vector<double> *input, std::vector<double> *output)
    : impl_(new Impl(width, input, output)) {
}

void DctCalculator::Inverse() {
    impl_->Inverse();
}

DctCalculator::~DctCalculator() = default;