/* Seedbox engine: C port of sim/engine.js. Portable C99, no SDK, no allocation, integer-only.
   sim/engine.js is the reference; this file must reproduce test/vectors bit for bit.
   Not reentrant: render from one core only (scratch buffers are static). */
#ifndef SEEDBOX_ENGINE_H
#define SEEDBOX_ENGINE_H

#include <stdint.h>

#define SB_TPB          840   /* ticks per quarter */
#define SB_TPS          210   /* ticks per 16th */
#define SB_CLOCK_TICKS  35    /* MIDI clock every 35 ticks */
#define SB_PHRASE_BARS  4
#define SB_NT           11    /* tracks */
#define SB_NSCALES      21
#define SB_MAX_EVENTS   128   /* per bar and per scratch list; the vectors peak at 54 */

enum { SB_T_KICK, SB_T_KICK2, SB_T_SNARE, SB_T_GHOST, SB_T_HAT, SB_T_HAT16, SB_T_PERC,
       SB_T_BASS, SB_T_MELA, SB_T_MELB, SB_T_PAD };
enum { SB_GEN_EUCLID, SB_GEN_SKELETON, SB_GEN_SUBDIV, SB_GEN_AUTOMATA, SB_GEN_AMENIZER, SB_NGEN };
enum { SB_KEYS_MOTIF, SB_KEYS_303, SB_KEYS_TURING, SB_KEYS_ARP, SB_NKEYS };

/* hash and RNG */
uint32_t sb_mix(uint32_t a, uint32_t b);
typedef struct { uint32_t s; } sb_rng;
void     sb_rng_init(sb_rng *r, uint32_t seed);
uint32_t sb_rng_next(sb_rng *r);
int      sb_rng_below(sb_rng *r, int n);
int      sb_rng_chance(sb_rng *r, int p);

/* genome: field names follow engine.js */
typedef struct {
  int steps;
  int form_idx;            /* index into FORMS; form[] is a copy */
  int form[4];
  int scale, root;
  int dens[2];
  int fillP, monoLen, monoRange, rot, hocket, bassDeg;
  int prog_idx;            /* index into PROGS; prog[] is a copy */
  int prog[4];
  int swing, arc, motifLen, accentCycle, layback, frame, freeK, freeRot;
} sb_genome;
typedef struct { uint32_t seed; uint32_t salts[2]; } sb_state;
/* shared part from the seed; kit and keys parts also take their salt (ROLL KIT / ROLL KEYS) */
void sb_genome_make(const sb_state *st, sb_genome *g);
const char *sb_form_name(int form_idx);

typedef struct { int gen, keys, energy, drift, fill, scale, root; } sb_params;   /* scale, root: -1 = AUTO (the seed picks) */

/* one output row: [t, lane, v, vel, len, tr] */
typedef struct { int16_t t, len; uint8_t lane, v, vel, tr; } sb_event;

typedef struct {
  int bar, pos, phrase, sec, fill, variants[2], barTicks, steps;
  int overflow;            /* nonzero if any list hit SB_MAX_EVENTS (should never happen) */
  int n;
  sb_event ev[SB_MAX_EVENTS];
} sb_bar;

/* ROOT / SCALE pages: overrides the genome's scale and root when they're >= 0 (app.js applyKey). */
void sb_apply_key(sb_genome *g, const sb_params *p);
const char *sb_scale_name(int scale);
const char *sb_keys_name(int keys);     /* MOTIF, 303, TURING, ARP */   /* screen name, at most 10 characters */

void sb_render_bar(const sb_state *st, const sb_params *p, int bar, sb_bar *out);

/* FNV-1a over rows, each field & 0xFFFF. Feed a whole case's events in order, starting from SB_FNV_INIT. */
#define SB_FNV_INIT 0x811C9DC5u
uint32_t sb_checksum_event(uint32_t h, const sb_event *e);

#endif