#include <string.h>
#include <stdio.h>

#include "sdbm.h"
#include "hashtable.h"

bool hashtable_expand(hashtable* table) {
	size_t oldcapacity = table->capacity;
	size_t newcapacity = oldcapacity << 1;
	hashtable_item* olditems = table->items;
	hashtable_item* newitems = calloc(newcapacity, sizeof(hashtable_item));
	if (newitems == NULL)
		return false;
	hashtable temptable;
	temptable.capacity = newcapacity;
	temptable.filled = 0;
	temptable.items = newitems;
	for (size_t i = 0; i < oldcapacity; i++) {
		if (olditems[i].name == NULL || olditems[i].name == (void*)1)
			continue;
		size_t_optional index = hashtable_insert(&temptable, olditems[i].name);
		if (!index.exists) {
			hashtable_item* array = temptable.items;
			for (size_t i = 0; i < temptable.capacity; i++)
				free(array[i].name);
			return false;
		}
		newitems[index.sizet].data = olditems[i].data;
	}
	table->capacity = newcapacity;
	table->filled = temptable.filled;
	table->items = newitems;
	return true;
}

hashtable* hashtable_create(void) {
	hashtable* table = malloc(sizeof(hashtable));
	if (table == NULL)
		return NULL;
	table->capacity = 16;
	table->items = calloc(16, sizeof(hashtable_item));
	return table;
}

size_t_optional hashtable_key(hashtable* table, char* name) {
	size_t index = sdbm(name) & (table->capacity - 1);
	hashtable_item* array = table->items;
	while (1) {
		if (array[index].name == NULL) 
			return (size_t_optional) { false, 0 }; 
		if (array[index].name != (void*)(1))
			if (!strcmp(name, array[index].name))
				return (size_t_optional) { true, index };
		index = (index + 1) & (table->capacity - 1);
	}
}

size_t_optional hashtable_insert(hashtable* table, char* name) {
	size_t index = sdbm(name) & (table->capacity - 1);
	hashtable_item* array = table->items;
	if ((table->capacity >> 2) * 3 < table->filled) {
		hashtable_expand(table);
	}
	while (1) {
		if (array[index].name == NULL || array[index].name == (void*)1) {
			array[index].name = malloc(strlen(name) + sizeof(name));
			strcpy(array[index].name, name);
			table->filled++;
			return (size_t_optional) {true, index};
		}
		else
			if (!strcmp(array[index].name, name))
				return (size_t_optional) {true, index};
			else
				index = (index + 1) & (table->capacity - 1);
	}
}

void hashtable_destroy(hashtable* table) {
	hashtable_item* array = table->items;
	for (size_t i = 0; i < table->capacity; i++)
		free(array[i].name);
	free(table);
}

void* hashtable_get(hashtable* table, char* name) {
	size_t_optional index = hashtable_key(table, name);
	if (!index.exists)
		return NULL;
	return table->items[index.sizet].data;
}

void hashtable_set(hashtable* table, char* name, void* data) {
	size_t_optional index = hashtable_insert(table, name);
	if (index.exists)
		table->items[index.sizet].data = data;
}

void hashtable_delete(hashtable* table, char* name) {
	size_t_optional index = hashtable_key(table, name);
	if (index.exists) {
		table->items[index.sizet].name = (void*)1;
		table->filled--;
	}
}

void hashtable_forall(hashtable* table, void (*callback)(char*, void*)) {
	size_t capacity = table->capacity;
	hashtable_item* items = table->items;
	for (size_t i = 0; i < capacity; i++)
		callback(items[i].name, items[i].data);
}