/**

 * @file hash.c

 * @brief Implements a simple hash table.

 * @note Copyright (C) 2015 Richard Cochran <richardcochran@gmail.com>

 *

 * This program 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.

 *

 * This program 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.,

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

 */

#include <stdlib.h>

#include <string.h>

#include "hash.h"

#define HASH_TABLE_SIZE 200

struct node {

	char *key;

	void *data;

	struct node *next;

};

struct hash {

	struct node *table[HASH_TABLE_SIZE];

};

static unsigned int hash_function(const char* s)

{

	unsigned int i;

	for (i = 0; *s; s++) {

		i = 131 * i + *s;

	}

	return i % HASH_TABLE_SIZE;

}

struct hash *hash_create(void)

{

	struct hash *ht = calloc(1, sizeof(*ht));

	return ht;

}

void hash_destroy(struct hash *ht, void (*func)(void *))

{

	unsigned int i;

	struct node *n, *next, **table = ht->table;

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

		for (n = table[i] ; n; n = next) {

			next = n->next;

			if (func) {

				func(n->data);

			}

			free(n->key);

			free(n);

		}

	}

	free(ht);

}

int hash_insert(struct hash *ht, const char* key, void *data)

{

	unsigned int h;

	struct node *n, **table = ht->table;

	h = hash_function(key);

	for (n = table[h] ; n; n = n->next) {

		if (!strcmp(n->key, key)) {

			/* reject duplicate keys */

			return -1;

		}

	}

	n = calloc(1, sizeof(*n));

	if (!n) {

		return -1;

	}

	n->key = strdup(key);

	if (!n->key) {

		free(n);

		return -1;

	}

	n->data = data;

	n->next = table[h];

	table[h] = n;

	return 0;

}

void *hash_lookup(struct hash *ht, const char* key)

{

	unsigned int h;

	struct node *n, **table = ht->table;

	h = hash_function(key);

	for (n = table[h] ; n; n = n->next) {

		if (!strcmp(n->key, key)) {

			return n->data;

		}

	}

	return NULL;

}