/*
 * hash.c -- Hash Table Library
 * (C)Copyright 1999 by Hiroshi Takekawa
 * This file is not part of any package
 *
 * Last Modified: Mon Oct 18 21:13:13 1999.
 * $Id: hash.c,v 1.7 1999/10/18 12:26:03 sian Exp $
 *
 * Enfle is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Enfle is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "dlist.h"
#include "hash.h"

Hash *
hash_create(int size)
{
  int i;
  Hash *h;
  Hash_data *d;

  if ((h = (Hash *)malloc(sizeof(Hash))) == NULL)
    return NULL;

  if ((h->data = (Hash_data **)malloc(sizeof(Hash_data *) * size)) == NULL) {
    free(h);
    return NULL;
  }

  if ((d = (Hash_data *)calloc(size, sizeof(Hash_data))) == NULL) {
    free(h->data);
    free(h);
    return NULL;
  }

  if ((h->keys = dlist_create()) == NULL) {
    free(h->data);
    free(h);
    free(d);
    return NULL;
  }

  for (i = 0; i < size; i++)
    h->data[i] = d++;

  h->size = size;

  return h;
}

Dlist *
hash_get_keys(Hash *h)
{
  return h->keys;
}

static int
calculate_hash_function(unsigned char *k, int size, int n)
{
  int i, index = 0;

  for (i = 0; i < strlen(k); i++)
    index = (index << 3) + (index >> 28) + k[i] * n;
  index = (index > 0 ? index : -index) % size;

  return index;
}

static int
lookup(Hash *h, unsigned char *k)
{
  int n = 1, index;

  do {
    index = calculate_hash_function(k, h->size, n++);
  } while (h->data[index]->key != NULL && (strcmp(h->data[index]->key->data, k) != 0));

  return index;
}

int
hash_register(Hash *h, unsigned char *k, void *d)
{
  int index = lookup(h, k);

  if (h->data[index]->key != NULL)
    return -1; /* already registered */

  if (dlist_stradd(h->keys, k) == NULL)
    return 0;

  h->data[index]->key = dlist_gethead(h->keys);
  h->data[index]->datum = d;

  return 1;
}

void *
hash_lookup(Hash *h, unsigned char *k)
{
  int index = lookup(h, k);

  return (h->data[index]->key == NULL) ? NULL : h->data[index]->datum;
}

static void
destroy_datum(Hash *h, int index, int f)
{
  Hash_data *d = h->data[index];

  if (d->key != NULL) {
    dlist_delete(h->keys, d->key, f);
    d->key = NULL;
  }
  if (f && d->datum != NULL)
    free(d->datum);
}

int
hash_destroy_key(Hash *h, unsigned char *k, int f)
{
  int index = lookup(h, k);

  if (h->data[index]->key == NULL)
    return 0;

  destroy_datum(h, index, f);

  return 1;
}

void
hash_destroy(Hash *h, int f)
{
  int i;

  for (i = 0; i < h->size; i++)
    destroy_datum(h, i, f);

  free(h->data[0]);
  free(h->data);
  free(h);
}