Juce Oversampling

#pragma once

#include <JuceHeader.h>

namespace hot {

    template<typename SampleType>
    class Oversampling
        : public dsp::Oversampling<double>
    {
    public:
        Oversampling(size_t newNumChannels, size_t newFactor)
            : dsp::Oversampling(newNumChannels)
        {
            jassert(isPositiveAndBelow(newFactor, 5) && numChannels > 0);

            clearOversamplingStages();

            if (newFactor == 0)
            {
                addDummyOversamplingStage();
            }
            else // newFactor >= 1: At least one stage
            {
                bool isMaximumQuality;
                int n{0};
                float twUp, twDown, gaindBStartUp, gaindBStartDown, gaindBFactorUp, gaindBFactorDown;

                // 1st stage (2x), HQ Half Band Polyphase
                isMaximumQuality = true;
                twUp = 0.05f;
                twDown = 0.06f;

                gaindBStartUp = -90.0;
                gaindBStartDown = -75.0f;
                gaindBFactorUp = 10.0f;
                gaindBFactorDown = 10.0f;

                addOversamplingStage(FilterType::filterHalfBandPolyphaseIIR,
                    twUp, gaindBStartUp + gaindBFactorUp * n,
                    twDown, gaindBStartDown + gaindBFactorDown * n);

                if (newFactor >= 2)
                {
                    // 2nd stage (4x), HQ Half Band Polyphase
                    isMaximumQuality = true;
                    n++;

                    twUp = (isMaximumQuality ? 0.10f : 0.12f);
                    twDown = (isMaximumQuality ? 0.12f : 0.15f);

                    gaindBStartUp = (isMaximumQuality ? -90.0f : -70.0f);
                    gaindBStartDown = (isMaximumQuality ? -75.0f : -60.0f);
                    gaindBFactorUp = (isMaximumQuality ? 10.0f : 8.0f);
                    gaindBFactorDown = (isMaximumQuality ? 10.0f : 8.0f);

                    addOversamplingStage(FilterType::filterHalfBandPolyphaseIIR,
                        twUp, gaindBStartUp + gaindBFactorUp * n,
                        twDown, gaindBStartDown + gaindBFactorDown * n);
                }
                if (newFactor >= 3)
                {
                    // 3rd stage (8x), filterHalfBandFIREquiripple
                    isMaximumQuality = false;
                    n++;

                    twUp = (isMaximumQuality ? 0.10f : 0.12f);
                    twDown = (isMaximumQuality ? 0.12f : 0.15f);

                    gaindBStartUp = (isMaximumQuality ? -90.0f : -70.0f);
                    gaindBStartDown = (isMaximumQuality ? -75.0f : -60.0f);
                    gaindBFactorUp = (isMaximumQuality ? 10.0f : 8.0f);
                    gaindBFactorDown = (isMaximumQuality ? 10.0f : 8.0f);

                    addOversamplingStage(FilterType::filterHalfBandFIREquiripple,
                        twUp, gaindBStartUp + gaindBFactorUp * n,
                        twDown, gaindBStartDown + gaindBFactorDown * n);
                }
                if (newFactor >= 4)
                {
                    // 4th stage (16x), filterHalfBandFIREquiripple
                    isMaximumQuality = false;
                    n++;

                    twUp = (isMaximumQuality ? 0.10f : 0.12f);
                    twDown = (isMaximumQuality ? 0.12f : 0.15f);

                    gaindBStartUp = (isMaximumQuality ? -90.0f : -70.0f);
                    gaindBStartDown = (isMaximumQuality ? -75.0f : -60.0f);
                    gaindBFactorUp = (isMaximumQuality ? 10.0f : 8.0f);
                    gaindBFactorDown = (isMaximumQuality ? 10.0f : 8.0f);

                    addOversamplingStage(FilterType::filterHalfBandFIREquiripple,
                        twUp, gaindBStartUp + gaindBFactorUp * n,
                        twDown, gaindBStartDown + gaindBFactorDown * n);
                }
            }
        }

        ~Oversampling()
        {

        }

    };

}