/*

 * hashtable.c

 * really simple hash table implementation

 *

 * Copyright (c) 2011-2016 Nikias Bassen, All Rights Reserved.

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 */

#include "hashtable.h"

hashtable_t* hash_table_new(hash_func_t hash_func, compare_func_t compare_func, free_func_t free_func)

{

  hashtable_t* ht = (hashtable_t*)malloc(sizeof(hashtable_t));

  int i;

  for (i = 0; i < 4096; i++) {

    ht->entries[i] = NULL;

  }

  ht->count = 0;

  ht->hash_func = hash_func;

  ht->compare_func = compare_func;

  ht->free_func = free_func;

  return ht;

}

void hash_table_destroy(hashtable_t *ht)

{

  if (!ht) return;

  int i = 0;

  for (i = 0; i < 4096; i++) {

    if (ht->entries[i]) {

      hashentry_t* e = ht->entries[i];

      while (e) {

        if (ht->free_func) {

          ht->free_func(e->value);

        }

        hashentry_t* old = e;

        e = e->next;

        free(old);

      }

    }

  }

  free(ht);

}

void hash_table_insert(hashtable_t* ht, void *key, void *value)

{

  if (!ht || !key) return;

  unsigned int hash = ht->hash_func(key);

  int idx0 = hash & 0xFFF;

  // get the idx0 list

  hashentry_t* e = ht->entries[idx0];

  while (e) {

    if (ht->compare_func(e->key, key)) {

      // element already present. replace value.

      e->value = value;

      return;

    }

    e = e->next;

  }

  // if we get here, the element is not yet in the list.

  // make a new entry.

  hashentry_t* entry = (hashentry_t*)malloc(sizeof(hashentry_t));

  entry->key = key;

  entry->value = value;

  if (!ht->entries[idx0]) {

    // first entry

    entry->next = NULL;

  } else {

    // add to list

    entry->next = ht->entries[idx0];

  }

  ht->entries[idx0] = entry;

  ht->count++;

}

void* hash_table_lookup(hashtable_t* ht, void *key)

{

  if (!ht || !key) return NULL;

  unsigned int hash = ht->hash_func(key);

  int idx0 = hash & 0xFFF;

  hashentry_t* e = ht->entries[idx0];

  while (e) {

    if (ht->compare_func(e->key, key)) {

      return e->value;

    }

    e = e->next;

  }

  return NULL;

}

void hash_table_remove(hashtable_t* ht, void *key)

{

  if (!ht || !key) return;

  unsigned int hash = ht->hash_func(key);

  int idx0 = hash & 0xFFF;

  // get the idx0 list

  hashentry_t* e = ht->entries[idx0];

  hashentry_t* last = e;

  while (e) {

    if (ht->compare_func(e->key, key)) {

      // found element, remove it from the list

      hashentry_t* old = e;

      if (e == ht->entries[idx0]) {

        ht->entries[idx0] = e->next;

      } else {

        last->next = e->next;

      }

      if (ht->free_func) {

        ht->free_func(old->value);

      }

      free(old);

      return;

    }

    last = e;

    e = e->next;

  }

}