#include "storage.h"
#include "hardware/flash.h"
#include "pico/flash.h"
#include <stddef.h>
#include <string.h>

#define MAGIC   0x53425831u   /* "SBX1" */
#define VERSION 3             /* 3: KEYS GEN. Older records are ignored. */
#define OFFSET  (PICO_FLASH_SIZE_BYTES - FLASH_SECTOR_SIZE)
#define BUFSZ   512

typedef struct {
  uint32_t magic, version;
  uint32_t seed, salts[2];
  int32_t gen, keys, bpm, scale, root, mono_ch, mono_oct;
  uint8_t on[SB_NT];
  pad_t learn[NKIT];
  slot_t slots[NSLOTS];
  uint32_t crc;
} record_t;
_Static_assert(sizeof(record_t) <= BUFSZ, "record too big");

static uint32_t crc(const record_t *r){
  const uint8_t *p = (const uint8_t *)r;
  uint32_t h = 0x811C9DC5u;
  size_t i;
  for(i = 0; i < offsetof(record_t, crc); i++) h = (h ^ p[i]) * 0x01000193u;
  return h;
}

/* defaults from app.js DEF and app */
void storage_defaults(live_t *L, slot_t *slots){
  int t;
  memset(L, 0, sizeof *L);
  L->state.seed = 0x5EEDB0C5u;
  L->gen = 0; L->keys = 0; L->scale = -1; L->root = -1; L->energy = 64; L->drift = 32; L->bpm = 165;
  for(t = 0; t < SB_NT; t++) L->on[t] = 1;
  L->mono_ch = 1; L->mono_oct = 0; L->clock = 1;
  memset(slots, 0, sizeof(slot_t) * NSLOTS);
}

int storage_load(live_t *L, slot_t *slots){
  const record_t *r = (const record_t *)(XIP_BASE + OFFSET);
  int t;
  storage_defaults(L, slots);
  if(r->magic != MAGIC || r->version != VERSION || r->crc != crc(r)) return 0;
  L->state.seed = r->seed; L->state.salts[0] = r->salts[0]; L->state.salts[1] = r->salts[1];
  L->gen = r->gen; L->keys = r->keys; L->bpm = r->bpm; L->scale = r->scale; L->root = r->root; L->mono_ch = r->mono_ch; L->mono_oct = r->mono_oct;
  for(t = 0; t < SB_NT; t++) L->on[t] = r->on[t] ? 1 : 0;
  memcpy(L->learn, r->learn, sizeof L->learn);
  memcpy(slots, r->slots, sizeof r->slots);
  return 1;
}

static void do_write(void *buf){
  flash_range_erase(OFFSET, FLASH_SECTOR_SIZE);
  flash_range_program(OFFSET, (const uint8_t *)buf, BUFSZ);
}

int storage_save(const live_t *L, const slot_t *slots){
  static uint8_t buf[BUFSZ] __attribute__((aligned(4)));
  record_t *r = (record_t *)buf;
  memset(buf, 0xFF, sizeof buf);
  memset(r, 0, sizeof *r);
  r->magic = MAGIC; r->version = VERSION;
  r->seed = L->state.seed; r->salts[0] = L->state.salts[0]; r->salts[1] = L->state.salts[1];
  r->gen = L->gen; r->keys = L->keys; r->bpm = L->bpm; r->scale = L->scale; r->root = L->root; r->mono_ch = L->mono_ch; r->mono_oct = L->mono_oct;
  memcpy(r->on, L->on, sizeof r->on);
  memcpy(r->learn, L->learn, sizeof r->learn);
  memcpy(r->slots, slots, sizeof r->slots);
  r->crc = crc(r);
  return flash_safe_execute(do_write, buf, 500) == PICO_OK;
}