// NativeMixer.h — track gain/pan + master brickwall limiter (T13).
//
// MIRROR server render pipeline (`app/core/render_engine.py` track volume/pan
// + `app/core/mastering_engine.py` _apply_limiter):
// - track gain: 10^(dB/20)
// - pan constant-power: theta = ((pan+1)/2)*pi/2, L *= cos(theta), R *= sin(theta)
//   (pan == 0 -> unity, khong nhan — dung nhu render_engine.py)
// - master: tong cac track (processInPlace ap dung gain/pan roi limiter)
// - brickwall limiter: t_lin = 10^(thresholdDb/20) (clamp -24..0, default -1);
//   k = 1/max(0.02, t_lin); tk = tanh(k); out = tanh(x*k)/tk; roi hard clip [-1,1]
//   (clip giong render_project sau apply_mastering).
//
// Audio thread an toan: chi setTrack/setLimiter tu UI thread truoc khi
// AudioStart; processInPlace doc state da set, khong lock, khong cap phat.
#pragma once
#include <cstdint>
#include <cmath>

namespace sonicforge {

using int32 = int32_t;

struct TrackGainPan
{
    float gainLin = 1.0f; // 10^(dB/20)
    float panL = 1.0f;    // cos(theta)
    float panR = 1.0f;    // sin(theta)

    static TrackGainPan fromDbPan (float gainDb, float pan);
};

class NativeMixer
{
public:
    // gainDb: -inf..+inf dB; pan: -1..+1 (clamp). Mirrors render_engine.py.
    void setTrack (const TrackGainPan& t) { m_track = t; }

    // thresholdDb clamp -24..0, NaN -> -1 (mirror _clamp trong mastering_engine).
    void setLimiter (bool active, float thresholdDb);

    // Ap track gain/pan vao buffer roi (neu active) limiter + hard clip [-1,1]
    // ngay tai buffer (in-place). frames > 0.
    void processInPlace (float* outL, float* outR, int32 frames) const;

    bool limiterActive () const { return m_limActive; }

private:
    TrackGainPan m_track;
    bool m_limActive = false;
    float m_limK = 1.0f;   // 1/max(0.02, t_lin)
    float m_limTk = 1.0f;  // tanh(k)
};

} // namespace sonicforge