#include <stdlib.h>
#include <string.h>

#include "wscm.h"

St syms = {0, 0, NULL};

static S *findsym(const char *str, Z len, U32 hash) {
  if (syms.capacity == 0)
    return NULL;

  Z ix = hash % syms.capacity;
  for (Z i = 0; i < syms.capacity; i++) {
    S *s = syms.data[ix];
    if (!s)
      return NULL;
    if (s->hash == hash && s->len == len)
      return s;
    ix = (ix + 1) % syms.capacity;
  }
  return NULL;
}

static void symtabresize(void) {
  Z cap = syms.capacity;
  if (cap == 0) {
    syms.capacity = 16;
  } else {
    syms.capacity *= 2;
  }
  S **nb = calloc(syms.capacity, sizeof(S *));
  for (Z i = 0; i < cap; i++) {
    if (syms.data[i]) {
      S *s = syms.data[i];
      Z ix = s->hash % syms.capacity;
      while (nb[ix])
        ix = (ix + 1) % syms.capacity;
      nb[ix] = s;
    }
  }
  if (syms.data != NULL)
    free(syms.data);
  syms.data = nb;
}

U32 hashstring(const char *data, I len) {
  U32 hash = 2166136261u;
  for (I i = 0; i < len; i++) {
    hash ^= (uint8_t)data[i];
    hash *= 16777619u;
  }
  return hash;
}

S *intern(const char *str, I len) {
  if (len < 0)
    len = strlen(str);

  U32 hash = hashstring(str, len);
  S *s = findsym(str, len, hash);
  if (s)
    return s;

  s = malloc(sizeof(S));
  s->data = malloc(len);
  memcpy(s->data, str, len);
  s->len = len;
  s->hash = hash;

  if (syms.count + 1 > syms.capacity)
    symtabresize();

  Z ix = hash % syms.capacity;
  while (syms.data[ix])
    ix = (ix + 1) % syms.capacity;

  syms.data[ix] = s;
  syms.count++;

  return s;
}