/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is libguac.
 *
 * The Initial Developer of the Original Code is
 * Michael Jumper.
 * Portions created by the Initial Developer are Copyright (C) 2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include <stdlib.h>
#include <string.h>

#include "pool.h"

guac_pool* guac_pool_alloc(int size) {

    guac_pool* pool = malloc(sizeof(guac_pool));

    /* If unable to allocate, just return NULL. */
    if (pool == NULL)
        return NULL;

    /* Initialize empty pool */
    pool->min_size = size;
    pool->__next_value = 0;
    pool->__head = NULL;
    pool->__tail = NULL;

    return pool;

}

void guac_pool_free(guac_pool* pool) {

    /* Free all ints in pool */
    guac_pool_int* current = pool->__head;
    while (current != NULL) {

        guac_pool_int* old = current;
        current = current->__next;

        free(old);
    }

    /* Free pool */
    free(pool);

}

int guac_pool_next_int(guac_pool* pool) {

    int value;

    /* If more integers are needed, or we are out of integers, return a new one. */
    if (pool->__head == NULL || pool->__next_value < pool->min_size)
        return pool->__next_value++;

    /* Otherwise, remove first integer. */
    value = pool->__head->value;

    /* If only one element exists, reset pool to empty. */
    if (pool->__tail == pool->__head) {
        free(pool->__head);
        pool->__head = NULL;
        pool->__tail = NULL;
    }

    /* Otherwise, advance head. */
    else {
        guac_pool_int* old_head = pool->__head;
        pool->__head = old_head->__next;
        free(old_head);
    }

    /* Return retrieved value. */
    return value;
}

void guac_pool_free_int(guac_pool* pool, int value) {

    /* Allocate and initialize new returned value */
    guac_pool_int* pool_int = malloc(sizeof(guac_pool_int));
    pool_int->value = value;
    pool_int->__next = NULL;

    /* If pool empty, store as sole entry. */
    if (pool->__tail == NULL)
        pool->__head = pool->__tail = pool_int;

    /* Otherwise, append to end of pool. */
    else {
        pool->__tail->__next = pool_int;
        pool->__tail = pool_int;
    }

}