#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "hashtable.h"

const unsigned int fnvPrime = 16777619;
const unsigned int fnvOffset = 2166136261U;

pair_t init_pair(char* key, void* value) {
	pair_t p;
	if (key != NULL) {
		char* kp = malloc((strlen(key) + 1) * sizeof(char));
		strcpy(kp, key);
		p.key = kp;
	}
	else {
		p.key = NULL;
	}
	p.value = value;
	return p;
}
hashtable_t* init_hashtable(unsigned int capacity, hashtable_t* parent) {
	hashtable_t* ht = malloc(sizeof(hashtable_t));
	ht->pairs = calloc(capacity, sizeof(pair_t));
	ht->capacity = capacity;
	ht->parent = parent;
	return ht;
}
void destroy_hashtable(hashtable_t* hashtable) {
	/* TODO: optimize this */
	for (int i = 0; i < hashtable->capacity; i++) {
		if (hashtable->pairs[i].key != NULL) {
			free(hashtable->pairs[i].key);
		}
	}
	free(hashtable->pairs);
	free(hashtable);
}
//FNV-1a hash
unsigned int get_hash(char* str) {
	unsigned int hash = fnvOffset;
	while (*str != '\0') {
		hash = (hash ^ *str) * fnvPrime;
		str++;
	}
	return hash;
}
unsigned int hashtable_add_pair(hashtable_t* hashtable, pair_t pair) {
	unsigned int hash = get_hash(pair.key);
	for (int i = 0; i < hashtable->capacity; i++) {
		pair_t p = hashtable->pairs[hash % hashtable->capacity];
		if (p.key == NULL || p.key == pair.key) {
			hashtable->pairs[hash % hashtable->capacity] = pair;
			return hash;
		}
	}
	return 0;
}
pair_t hashtable_get_pair(hashtable_t* hashtable, char* key) {
	unsigned int hash = get_hash(key);
	for (int i = 0; i < hashtable->capacity; i++) {
		pair_t p = hashtable->pairs[hash % hashtable->capacity];
		if (p.key == key) {
			return p;
		}
		else if (p.key == NULL) {
			return init_pair(NULL, NULL);
		}
	}
	return hashtable->pairs[(hash) % hashtable->capacity];
}
pair_t hashtable_get_pair_recurse(hashtable_t* origin, char* key) {
	pair_t pair = hashtable_get_pair(origin, key);
	if (pair.key != NULL) {
		return pair;
	}
	if (origin->parent != NULL) {
		return hashtable_get_pair_recurse(origin->parent, key);
	}
	return pair;
}