/* SPDX-License-Identifier: GPL-2.0-or-later */
/* SPDX-FileCopyrightText: 2006-2015  Simon Wunderlich <sw@simonwunderlich.de>
 * SPDX-FileCopyrightText: 2006-2015  Marek Lindner <mareklindner@neomailbox.ch>
 */

#ifndef _HASH_H_
#define _HASH_H_

typedef int (*hashdata_compare_cb)(const void *, const void *);
typedef int (*hashdata_choose_cb)(const void *, int);
typedef void (*hashdata_free_cb)(void *);

struct element_t {
	void *data;      /* pointer to the data */
	struct element_t *next;   /* overflow bucket pointer */
};

struct hash_it_t {
	int index;
	struct element_t *bucket;
	struct element_t *prev_bucket;
	struct element_t **first_bucket;
};

struct hashtable_t {
	struct element_t **table;     /* the hashtable itself, with the buckets */
	int elements;        /* number of elements registered */
	int size;         /* size of hashtable */
	hashdata_compare_cb compare;       /* callback to a compare function.
             * should compare 2 element datas for their keys,
             * return 0 if same and not 0 if not same */
	hashdata_choose_cb choose;     /* the hashfunction, should return an index based
             * on the key in the data of the first argument
             * and the size the second */
};

/* clears the hash */
void      hash_init(struct hashtable_t *hash);

/* allocates and clears the hash */
struct hashtable_t *hash_new(int size, hashdata_compare_cb compare, hashdata_choose_cb choose);

/* remove bucket (this might be used in hash_iterate() if you already found the bucket
 * you want to delete and don't need the overhead to find it again with hash_remove().
 * But usually, you don't want to use this function, as it fiddles with hash-internals. */
void     *hash_remove_bucket(struct hashtable_t *hash, struct hash_it_t *hash_it_t);

/* remove the hash structure. if hashdata_free_cb != NULL,
 * this function will be called to remove the elements inside of the hash.
 * if you don't remove the elements, memory might be leaked. */
void      hash_delete(struct hashtable_t *hash, hashdata_free_cb free_cb);

/* free only the hashtable and the hash itself. */
void      hash_destroy(struct hashtable_t *hash);

/* adds data to the hashtable. returns 0 on success, -1 on error */
int      hash_add(struct hashtable_t *hash, void *data);

/* removes data from hash, if found. returns pointer do data on success,
 * so you can remove the used structure yourself, or NULL on error .
 * data could be the structure you use with just the key filled,
 * we just need the key for comparing. */
void     *hash_remove(struct hashtable_t *hash, void *data);

/* adds data to the hashtable. returns 0 on success, -1 on error */
void     *hash_find(struct hashtable_t *hash, void *keydata);

/* resize the hash, returns the pointer to the new hash or NULL on error. removes the old hash on success */
struct hashtable_t *hash_resize(struct hashtable_t *hash, int size);

/* print the hash table for debugging */
void      hash_debug(struct hashtable_t *hash);

/* iterate though the hash. first element is selected with iter_in NULL.
 * use the returned iterator to access the elements until hash_it_t returns NULL. */
struct hash_it_t *hash_iterate(struct hashtable_t *hash, struct hash_it_t *iter_in);

#endif /* _HASH_H_ */
