// This file contains the definitions of the public functions used by the shash-hashtable library and is part of the shash library
// Copyright (C) 2023  theboring_XOR

// 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 3 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, see <http://www.gnu.org/licenses/>.

#ifndef _SHASH_H
#define _SHASH_H

#include <stdint.h>
#include <assert.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <time.h>
#include <stdbool.h>

#define WORD 32
#define TRANSFORM_TABLE_MAX_RAND 4294967296
#define DELTA 1

// If set to 1, all strings will be hashed to SIMULATED_COLLISON_HASH
#define SIMULATE_COLLISIONS 0
#define SIMULATED_COLLISION_HASH 20

#ifdef __clang__
#include <builtins.h>
#define rot32_left(x, y) __builtin_rotateleft32(x, y)
#else
#define rot32_left(x, y) (x << y) | (x >> 32 - y)
#endif

typedef struct
{
    char *key;
    unsigned int keylen;
    
    void *data;

    // gets set to 1 if another key, collides with this elemnts location
    uint8_t encountered_collision;
    // On collision, this field stores where in the hash table array the second key (with the same hash) is located
    int next_key_location;

} shash_table_element_t;

// Contains everything the functions for the hashtables need, to work with, including the hash table itself
typedef struct
{
    // stores a transformation table used by the shash_hash function
    unsigned int *transformation_table;
    shash_table_element_t *hash_table;
    unsigned int table_size;
} shash_hashtable_t;

// Initialize an empty hastable in hashtable with a size of table_size. Returns -1 on failure
int shash_init_hashtable(shash_hashtable_t *hashtable, unsigned int table_size);

// Hash the key key of length len so that it fits in hashtable. Returns the calculated hash
unsigned int shash_hash(char *key, unsigned int len, shash_hashtable_t *hashtable);

/* Store the pointer data in hashtable at the key key of length len.
   Returns EXIT_FAILURE when the hashtable is full */
int shash_set(char *key, unsigned int len, void *data, shash_hashtable_t *hashtable);

/* Returns the pointer stored at the key key of length len in hashtable.
   Returns ptr to NULL when the key is not found */ 
void *shash_get(char *key, unsigned int len, shash_hashtable_t *hashtable);

// Free up the space allocated for hashtable. Data inside the hastable is NOT freed
void shash_destroy_hashtable(shash_hashtable_t *hashtable);

#endif