#include "Distortion.h"

namespace serum
{

void DistortionUnit::prepare (double sampleRate, int)
{
    sr = sampleRate;
    lpL.setSampleRate (sr); lpR.setSampleRate (sr);
    lpL.setLowpass (8000.0, 0.7071); lpR.setLowpass (8000.0, 0.7071);
    reset();
}

void DistortionUnit::reset()
{
    lpL.clear(); lpR.clear();
}

float DistortionUnit::shape (float x, float shapeParam) noexcept
{
    if (shapeParam < 0.33f)                        return std::tanh (x);
    if (shapeParam < 0.66f)                        return juce::jlimit (-1.0f, 1.0f, x);
    return std::sin (x * 1.5707963267948966f);     // sine fold
}

void DistortionUnit::process (float* l, float* r, int numSamples, const float p[4])
{
    const float drive  = 1.0f + p[0] * 24.0f;
    const float shapeP = p[1];
    const float output = 0.4f + p[3] * 1.2f;

    // Tone: re-tune the lowpass from 800..16000 Hz.
    const double toneHz = 800.0 + p[2] * 15200.0;
    lpL.setLowpass (toneHz, 0.7071);
    lpR.setLowpass (toneHz, 0.7071);

    for (int i = 0; i < numSamples; ++i)
    {
        l[i] = lpL.process (shape (l[i] * drive, shapeP) * output);
        r[i] = lpR.process (shape (r[i] * drive, shapeP) * output);
    }
}

} // namespace serum