#ifndef FX_EQUALIZER_H
#define FX_EQUALIZER_H

#include <stdbool.h>

#define FX_EQ_NUM_BANDS 10U

typedef struct
{
    float freq_hz;   /* frequence centrale de la bande */
    float gain_db;   /* -24.0 a +24.0 dB */
    float q;         /* facteur de qualite, typiquement 0.5 a 5.0 */
} FxEqBand;

typedef struct
{
    bool     enabled;
    FxEqBand bands[FX_EQ_NUM_BANDS];
} FxEqualizerParams;

typedef struct
{
    /* coefficients biquad mis en cache, recalcules seulement si les parametres changent */
    float b0, b1, b2, a1, a2;
    /* dernieres valeurs de parametres utilisees pour calculer les coefficients ci-dessus */
    float last_freq_hz;
    float last_gain_db;
    float last_q;
} FxEqBandState;

typedef struct
{
    FxEqBandState band_state[FX_EQ_NUM_BANDS];
    /* etat du filtre (direct form 1), par bande */
    float x1[FX_EQ_NUM_BANDS];
    float x2[FX_EQ_NUM_BANDS];
    float y1[FX_EQ_NUM_BANDS];
    float y2[FX_EQ_NUM_BANDS];
} FxEqualizerState;

void  FxEqualizer_Init(FxEqualizerState *state, FxEqualizerParams *params);
float FxEqualizer_Process(FxEqualizerState *state, const FxEqualizerParams *params, float input);

#endif /* FX_EQUALIZER_H */