/*
 * Copyright 2010 Andrea Mazzoleni. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY ANDREA MAZZOLENI AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL ANDREA MAZZOLENI OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "tommyhashdyn.h"
#include "tommylist.h"

#include <string.h> /* for memset */

/******************************************************************************/
/* hashdyn */

void tommy_hashdyn_init(tommy_hashdyn* hashdyn)
{
	/* fixed initial size */
	hashdyn->bucket_bit = TOMMY_HASHDYN_BIT;
	hashdyn->bucket_max = 1 << hashdyn->bucket_bit;
	hashdyn->bucket_mask = hashdyn->bucket_max - 1;
	hashdyn->bucket = tommy_cast(tommy_hashdyn_node**, tommy_malloc(hashdyn->bucket_max * sizeof(tommy_hashdyn_node*)));
	memset(hashdyn->bucket, 0, hashdyn->bucket_max * sizeof(tommy_hashdyn_node*));

	hashdyn->count = 0;
}

void tommy_hashdyn_done(tommy_hashdyn* hashdyn)
{
	tommy_free(hashdyn->bucket);
}

/**
 * Resize the bucket vector.
 */
static void tommy_hashdyn_resize(tommy_hashdyn* hashdyn, unsigned new_bucket_bit)
{
	unsigned bucket_bit;
	unsigned bucket_max;
	unsigned new_bucket_max;
	unsigned new_bucket_mask;
	tommy_hashdyn_node** new_bucket;

	bucket_bit = hashdyn->bucket_bit;
	bucket_max = hashdyn->bucket_max;

	new_bucket_max = 1 << new_bucket_bit;
	new_bucket_mask = new_bucket_max - 1;
	new_bucket = tommy_cast(tommy_hashdyn_node**, tommy_malloc(new_bucket_max * sizeof(tommy_hashdyn_node*)));

	/* reinsert all the elements */
	if (new_bucket_bit > bucket_bit) {
		unsigned i;

		/* grow */
		for(i=0;i<bucket_max;++i) {
			tommy_hashdyn_node* j;

			/* setup the new two buckets */
			new_bucket[i] = 0;
			new_bucket[i + bucket_max] = 0;

			/* reinsert the bucket */
			j = hashdyn->bucket[i];
			while (j) {
				tommy_hashdyn_node* j_next = j->next;
				unsigned index = j->key & new_bucket_mask;
				if (new_bucket[index])
					tommy_list_insert_tail_not_empty(new_bucket[index], j);
				else
					tommy_list_insert_first(&new_bucket[index], j);
				j = j_next;
			}
		}
	} else {
		unsigned i;

		/* shrink */
		for(i=0;i<new_bucket_max;++i) {
			/* setup the new bucket with the lower bucket*/
			new_bucket[i] = hashdyn->bucket[i];

			/* concat the upper bucket */
			tommy_list_concat(&new_bucket[i], &hashdyn->bucket[i + new_bucket_max]);
		}
	}

	tommy_free(hashdyn->bucket);

	/* setup */
	hashdyn->bucket_bit = new_bucket_bit;
	hashdyn->bucket_max = new_bucket_max;
	hashdyn->bucket_mask = new_bucket_mask;
	hashdyn->bucket = new_bucket;
}

/**
 * Grow.
 */
tommy_inline void hashdyn_grow_step(tommy_hashdyn* hashdyn)
{
	/* grow if more than 50% full */
	if (hashdyn->count >= hashdyn->bucket_max / 2) {
		tommy_hashdyn_resize(hashdyn, hashdyn->bucket_bit + 1);
	}
}

/**
 * Shrink.
 */
tommy_inline void hashdyn_shrink_step(tommy_hashdyn* hashdyn)
{
	/* shrink if less than 12.5% full */
	if (hashdyn->count <= hashdyn->bucket_max / 8 && hashdyn->bucket_bit > TOMMY_HASHDYN_BIT) {
		tommy_hashdyn_resize(hashdyn, hashdyn->bucket_bit - 1);
	}
}

void tommy_hashdyn_insert(tommy_hashdyn* hashdyn, tommy_hashdyn_node* node, void* data, tommy_hash_t hash)
{
	unsigned pos = hash & hashdyn->bucket_mask;

	tommy_list_insert_tail(&hashdyn->bucket[pos], node, data);

	node->key = hash;

	++hashdyn->count;

	hashdyn_grow_step(hashdyn);
}

void* tommy_hashdyn_remove_existing(tommy_hashdyn* hashdyn, tommy_hashdyn_node* node)
{
	unsigned pos = node->key & hashdyn->bucket_mask;

	tommy_list_remove_existing(&hashdyn->bucket[pos], node);

	--hashdyn->count;

	hashdyn_shrink_step(hashdyn);

	return node->data;
}

void* tommy_hashdyn_remove(tommy_hashdyn* hashdyn, tommy_compare_func* cmp, const void* cmp_arg, tommy_hash_t hash)
{
	unsigned pos = hash % hashdyn->bucket_max;
	tommy_hashdyn_node* i = hashdyn->bucket[pos];

	while (i) {
		/* we first check if the hash matches, as in the same bucket we may have multiples hash values */
		if (i->key == hash && cmp(cmp_arg, i->data) == 0) {
			tommy_list_remove_existing(&hashdyn->bucket[pos], i);

			--hashdyn->count;

			hashdyn_shrink_step(hashdyn);

			return i->data;
		}
		i = i->next;
	}

	return 0;
}

tommy_size_t tommy_hashdyn_memory_usage(tommy_hashdyn* hashdyn)
{
	return hashdyn->bucket_max * (tommy_size_t)sizeof(hashdyn->bucket[0])
		+ tommy_hashdyn_count(hashdyn) * (tommy_size_t)sizeof(tommy_hashdyn_node);
}