// NativeMixer.cpp — xem NativeMixer.h cho cong thuc mirror.
#include "NativeMixer.h"

namespace sonicforge {

namespace {

// Mirror _clamp(v, lo, hi, default) cua mastering_engine.py: NaN -> default.
float clampDb (float v, float lo, float hi, float def)
{
    if (!(v == v)) // NaN
        return def;
    if (v < lo)
        return lo;
    if (v > hi)
        return hi;
    return v;
}

} // namespace

TrackGainPan TrackGainPan::fromDbPan (float gainDb, float pan)
{
    TrackGainPan t;
    t.gainLin = std::pow (10.0f, gainDb / 20.0f);
    float p = pan;
    if (p < -1.0f)
        p = -1.0f;
    else if (p > 1.0f)
        p = 1.0f;
    if (p == 0.0f)
    {
        t.panL = 1.0f;
        t.panR = 1.0f;
    }
    else
    {
        const float theta = ((p + 1.0f) / 2.0f) * (3.14159265358979323846f / 2.0f);
        t.panL = std::cos (theta);
        t.panR = std::sin (theta);
    }
    return t;
}

void NativeMixer::setLimiter (bool active, float thresholdDb)
{
    m_limActive = active;
    if (!active)
    {
        m_limK = 1.0f;
        m_limTk = 1.0f;
        return;
    }
    const float t = clampDb (thresholdDb, -24.0f, 0.0f, -1.0f);
    const float tLin = std::pow (10.0f, t / 20.0f);
    m_limK = 1.0f / (tLin > 0.02f ? tLin : 0.02f);
    m_limTk = std::tanh (m_limK);
}

void NativeMixer::processInPlace (float* outL, float* outR, int32 frames) const
{
    if (!outL || !outR || frames <= 0)
        return;
    const float gl = m_track.gainLin * m_track.panL;
    const float gr = m_track.gainLin * m_track.panR;
    for (int32 i = 0; i < frames; ++i)
    {
        float l = outL[i] * gl;
        float r = outR[i] * gr;
        if (m_limActive)
        {
            l = std::tanh (l * m_limK) / m_limTk;
            r = std::tanh (r * m_limK) / m_limTk;
            // Hard clip [-1,1] — mirror render_project sau apply_mastering
            // (chi khi mastering on; limiter off => khong clip).
            if (l > 1.0f)
                l = 1.0f;
            else if (l < -1.0f)
                l = -1.0f;
            if (r > 1.0f)
                r = 1.0f;
            else if (r < -1.0f)
                r = -1.0f;
        }
        outL[i] = l;
        outR[i] = r;
    }
}

} // namespace sonicforge