/* NeoStats - IRC Statistical Services 
** Copyright (c) 1999-2004 Adam Rutter, Justin Hammond
** http://www.neostats.net/
**
**  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 2 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, write to the Free Software
**  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
**  USA
**
** Portions borrowed from kazlib. Header follows:
*/


/*
 * List Abstract Data Type
 * Copyright (C) 1997 Kaz Kylheku <kaz@ashi.footprints.net>
 *
 * Free Software License:
 *
 * All rights are reserved by the author, with the following exceptions:
 * Permission is granted to freely reproduce and distribute this software,
 * possibly in exchange for a fee, provided that this copyright notice appears
 * intact. Permission is also granted to adapt this software to produce
 * derivative works, as long as the modified versions carry this copyright
 * notice and additional notices stating that the work has been modified.
 * This source code may be translated into executable form and incorporated
 * into proprietary software; there is no requirement for such software to
 * contain a copyright notice related to this source.
 *
 * $Id$
 * $Name:  $
 */


#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <assert.h>
#define LIST_IMPLEMENTATION
#include "list.h"
#include "log.h"

#define next list_next
#define prev list_prev
#define data list_data

#define pool list_pool
#define fre list_free
#define size list_size

#define nilnode list_nilnode
#define nodecount list_nodecount
#define maxcount list_maxcount

#define list_nil(L)		(&(L)->nilnode)
#define list_first_priv(L)	((L)->nilnode.next)
#define list_last_priv(L)	((L)->nilnode.prev)
#define lnode_next(N)		((N)->next)
#define lnode_prev(N)		((N)->prev)

#ifdef KAZLIB_RCSID
static const char rcsid[] = "$Id$";
#endif

/*
 * Initialize a list object supplied by the client such that it becomes a valid
 * empty list. If the list is to be ``unbounded'', the maxcount should be
 * specified as LISTCOUNT_T_MAX, or, alternately, as -1. The value zero
 * is not permitted.
 */

list_t *
list_init (list_t * list, listcount_t maxcount)
{
	nassert (maxcount != 0);
	list->nilnode.next = &list->nilnode;
	list->nilnode.prev = &list->nilnode;
	list->nodecount = 0;
	list->maxcount = maxcount;
	return list;
}

/*
 * Dynamically allocate a list object using malloc(), and initialize it so that
 * it is a valid empty list. If the list is to be ``unbounded'', the maxcount
 * should be specified as LISTCOUNT_T_MAX, or, alternately, as -1.
 */

list_t *
list_create (listcount_t maxcount)
{
	list_t *new = malloc (sizeof *new);
	if (new) {
		nassert (maxcount != 0);
		new->nilnode.next = &new->nilnode;
		new->nilnode.prev = &new->nilnode;
		new->nodecount = 0;
		new->maxcount = maxcount;
	}
	return new;
}

/*
 * Destroy a dynamically allocated list object.
 * The client must remove the nodes first.
 */

void
list_destroy (list_t * list)
{
	nassert (list_isempty (list));
	free (list);
}

/*
 * Free all of the nodes of a list. The list must contain only 
 * dynamically allocated nodes. After this call, the list
 * is empty.
 */

void
list_destroy_nodes (list_t * list)
{
	lnode_t *lnode = list_first_priv (list), *nil = list_nil (list), *tmp;

	while (lnode != nil) {
		tmp = lnode->next;
		lnode->next = NULL;
		lnode->prev = NULL;
		lnode_destroy (lnode);
		lnode = tmp;
	}

	list_init (list, list->maxcount);
}

/*
 * Return all of the nodes of a list to a node pool. The nodes in
 * the list must all have come from the same pool.
 */

void
list_return_nodes (list_t * list, lnodepool_t * pool)
{
	lnode_t *lnode = list_first_priv (list), *tmp, *nil = list_nil (list);

	while (lnode != nil) {
		tmp = lnode->next;
		lnode->next = NULL;
		lnode->prev = NULL;
		lnode_return (pool, lnode);
		lnode = tmp;
	}

	list_init (list, list->maxcount);
}

/*
 * Insert the node ``new'' into the list immediately after ``this'' node.
 */

void
list_ins_after (list_t * list, lnode_t * new, lnode_t * this)
{
	lnode_t *that = this->next;

	nassert (new != NULL);
	nassert (!list_contains (list, new));
	nassert (!lnode_is_in_a_list (new));
	nassert (this == list_nil (list) || list_contains (list, this));
	nassert (list->nodecount + 1 > list->nodecount);

	new->prev = this;
	new->next = that;
	that->prev = new;
	this->next = new;
	list->nodecount++;

	nassert (list->nodecount <= list->maxcount);
}

/*
 * Insert the node ``new'' into the list immediately before ``this'' node.
 */

void
list_ins_before (list_t * list, lnode_t * new, lnode_t * this)
{
	lnode_t *that = this->prev;

	nassert (new != NULL);
	nassert (!list_contains (list, new));
	nassert (!lnode_is_in_a_list (new));
	nassert (this == list_nil (list) || list_contains (list, this));
	nassert (list->nodecount + 1 > list->nodecount);

	new->next = this;
	new->prev = that;
	that->next = new;
	this->prev = new;
	list->nodecount++;

	nassert (list->nodecount <= list->maxcount);
}

/*
 * Delete the given node from the list.
 */

lnode_t *
list_delete (list_t * list, lnode_t * del)
{
	lnode_t *next = del->next;
	lnode_t *prev = del->prev;

	nassert (list_contains (list, del));

	prev->next = next;
	next->prev = prev;
	list->nodecount--;

	del->next = del->prev = NULL;

	return del;
}

/*
 * For each node in the list, execute the given function. The list,
 * current node and the given context pointer are passed on each
 * call to the function.
 */

void
list_process (list_t * list, void *context, void (*function) (list_t * list, lnode_t * lnode, void *context))
{
	lnode_t *node = list_first_priv (list), *next, *nil = list_nil (list);

	while (node != nil) {
		/* check for callback function deleting */
		/* the next node from under us          */
		nassert (list_contains (list, node));
		next = node->next;
		function (list, node, context);
		node = next;
	}
}

/*
 * Dynamically allocate a list node and assign it the given piece of data.
 */

lnode_t *
lnode_create (void *data)
{
	lnode_t *new = malloc (sizeof *new);
	if (new) {
		new->data = data;
		new->next = NULL;
		new->prev = NULL;
	}
	return new;
}

/*
 * Initialize a user-supplied lnode.
 */

lnode_t *
lnode_init (lnode_t * lnode, void *data)
{
	lnode->data = data;
	lnode->next = NULL;
	lnode->prev = NULL;
	return lnode;
}

/*
 * Destroy a dynamically allocated node.
 */

void
lnode_destroy (lnode_t * lnode)
{
	nassert (!lnode_is_in_a_list (lnode));
	free (lnode);
}

/*
 * Initialize a node pool object to use a user-supplied set of nodes.
 * The ``nodes'' pointer refers to an array of lnode_t objects, containing
 * ``n'' elements.
 */

lnodepool_t *
lnode_pool_init (lnodepool_t * pool, lnode_t * nodes, listcount_t n)
{
	listcount_t i;

	nassert (n != 0);

	pool->pool = nodes;
	pool->fre = nodes;
	pool->size = n;
	for (i = 0; i < n - 1; i++) {
		nodes[i].next = nodes + i + 1;
	}
	nodes[i].next = NULL;
	nodes[i].prev = nodes;	/* to make sure node is marked ``on list'' */
	return pool;
}

/*
 * Create a dynamically allocated pool of n nodes.
 */

lnodepool_t *
lnode_pool_create (listcount_t n)
{
	lnodepool_t *pool;
	lnode_t *nodes;

	nassert (n != 0);

	pool = malloc (sizeof *pool);
	if (!pool)
		return NULL;
	nodes = malloc (n * sizeof *nodes);
	if (!nodes) {
		free (pool);
		return NULL;
	}
	lnode_pool_init (pool, nodes, n);
	return pool;
}

/*
 * Determine whether the given pool is from this pool.
 */

int
lnode_pool_isfrom (lnodepool_t * pool, lnode_t * node)
{
	listcount_t i;

	/* this is carefully coded this way because ANSI C forbids pointers
	   to different objects from being subtracted or compared other
	   than for exact equality */

	for (i = 0; i < pool->size; i++) {
		if (pool->pool + i == node)
			return 1;
	}
	return 0;
}

/*
 * Destroy a dynamically allocated pool of nodes.
 */

void
lnode_pool_destroy (lnodepool_t * p)
{
	free (p->pool);
	free (p);
}

/*
 * Borrow a node from a node pool. Returns a null pointer if the pool
 * is exhausted. 
 */

lnode_t *
lnode_borrow (lnodepool_t * pool, void *data)
{
	lnode_t *new = pool->fre;
	if (new) {
		pool->fre = new->next;
		new->data = data;
		new->next = NULL;
		new->prev = NULL;
	}
	return new;
}

/*
 * Return a node to a node pool. A node must be returned to the pool
 * from which it came.
 */

void
lnode_return (lnodepool_t * pool, lnode_t * node)
{
	nassert (lnode_pool_isfrom (pool, node));
	nassert (!lnode_is_in_a_list (node));

	node->next = pool->fre;
	node->prev = node;
	pool->fre = node;
}

/*
 * Determine whether the given list contains the given node.
 * According to this function, a list does not contain its nilnode.
 */

int
list_contains (list_t * list, lnode_t * node)
{
	lnode_t *n, *nil = list_nil (list);

	for (n = list_first_priv (list); n != nil; n = lnode_next (n)) {
		if (node == n)
			return 1;
	}

	return 0;
}

/*
 * A more generalized variant of list_transfer. This one removes a
 * ``slice'' from the source list and appends it to the destination
 * list.
 */

void
list_extract (list_t * dest, list_t * source, lnode_t * first, lnode_t * last)
{
	listcount_t moved = 1;

	nassert (first == NULL || list_contains (source, first));
	nassert (last == NULL || list_contains (source, last));

	if (first == NULL || last == NULL)
		return;

	/* adjust the destination list so that the slice is spliced out */

	first->prev->next = last->next;
	last->next->prev = first->prev;

	/* graft the splice at the end of the dest list */

	last->next = &dest->nilnode;
	first->prev = dest->nilnode.prev;
	dest->nilnode.prev->next = first;
	dest->nilnode.prev = last;

	while (first != last) {
		first = first->next;
		nassert (first != list_nil (source));	/* oops, last before first! */
		moved++;
	}

	/* nassert no overflows */
	nassert (source->nodecount - moved <= source->nodecount);
	nassert (dest->nodecount + moved >= dest->nodecount);

	/* nassert no weirdness */
	nassert (moved <= source->nodecount);

	source->nodecount -= moved;
	dest->nodecount += moved;

	/* nassert list sanity */
	nassert (list_verify (source));
	nassert (list_verify (dest));
}


/*
 * Split off a trailing sequence of nodes from the source list and relocate
 * them to the tail of the destination list. The trailing sequence begins
 * with node ``first'' and terminates with the last node of the source
 * list. The nodes are added to the end of the new list in their original
 * order.
 */

void
list_transfer (list_t * dest, list_t * source, lnode_t * first)
{
	listcount_t moved = 1;
	lnode_t *last;

	nassert (first == NULL || list_contains (source, first));

	if (first == NULL)
		return;

	last = source->nilnode.prev;

	source->nilnode.prev = first->prev;
	first->prev->next = &source->nilnode;

	last->next = &dest->nilnode;
	first->prev = dest->nilnode.prev;
	dest->nilnode.prev->next = first;
	dest->nilnode.prev = last;

	while (first != last) {
		first = first->next;
		moved++;
	}

	/* nassert no overflows */
	nassert (source->nodecount - moved <= source->nodecount);
	nassert (dest->nodecount + moved >= dest->nodecount);

	/* nassert no weirdness */
	nassert (moved <= source->nodecount);

	source->nodecount -= moved;
	dest->nodecount += moved;

	/* nassert list sanity */
	nassert (list_verify (source));
	nassert (list_verify (dest));
}

void
list_merge (list_t * dest, list_t * sour, int compare (const void *, const void *))
{
	lnode_t *dn, *sn, *tn;
	lnode_t *d_nil = list_nil (dest), *s_nil = list_nil (sour);

	/* Nothing to do if source and destination list are the same. */
	if (dest == sour)
		return;

	/* overflow check */
	nassert (list_count (sour) + list_count (dest) >= list_count (sour));

	/* lists must be sorted */
	nassert (list_is_sorted (sour, compare));
	nassert (list_is_sorted (dest, compare));

	dn = list_first_priv (dest);
	sn = list_first_priv (sour);

	while (dn != d_nil && sn != s_nil) {
		if (compare (lnode_get (dn), lnode_get (sn)) >= 0) {
			tn = lnode_next (sn);
			list_delete (sour, sn);
			list_ins_before (dest, sn, dn);
			sn = tn;
		} else {
			dn = lnode_next (dn);
		}
	}

	if (dn != d_nil)
		return;

	if (sn != s_nil)
		list_transfer (dest, sour, sn);
}

void
list_sort (list_t * list, int compare (const void *, const void *))
{
	list_t extra;
	listcount_t middle;
	lnode_t *node;

	if (list_count (list) > 1) {
		middle = list_count (list) / 2;
		node = list_first_priv (list);

		list_init (&extra, list_count (list) - middle);

		while (middle--)
			node = lnode_next (node);

		list_transfer (&extra, list, node);
		list_sort (list, compare);
		list_sort (&extra, compare);
		list_merge (list, &extra, compare);
	}
	nassert (list_is_sorted (list, compare));
}

lnode_t *
list_find (list_t * list, const void *key, int compare (const void *, const void *))
{
	lnode_t *node;

	for (node = list_first_priv (list); node != list_nil (list); node = node->next) {
		if (compare (lnode_get (node), key) == 0)
			return node;
	}

	return 0;
}


/*
 * Return 1 if the list is in sorted order, 0 otherwise
 */

int
list_is_sorted (list_t * list, int compare (const void *, const void *))
{
	lnode_t *node, *next, *nil;

	next = nil = list_nil (list);
	node = list_first_priv (list);

	if (node != nil)
		next = lnode_next (node);

	for (; next != nil; node = next, next = lnode_next (next)) {
		if (compare (lnode_get (node), lnode_get (next)) > 0)
			return 0;
	}

	return 1;
}

/*
 * Get rid of macro functions definitions so they don't interfere
 * with the actual definitions
 */

#undef list_isempty
#undef list_isfull
#undef lnode_pool_isempty
#undef list_append
#undef list_prepend
#undef list_first
#undef list_last
#undef list_next
#undef list_prev
#undef list_count
#undef list_del_first
#undef list_del_last
#undef lnode_put
#undef lnode_get

/*
 * Return 1 if the list is empty, 0 otherwise
 */

int
list_isempty (list_t * list)
{
	return list->nodecount == 0;
}

/*
 * Return 1 if the list is full, 0 otherwise
 * Permitted only on bounded lists. 
 */

int
list_isfull (list_t * list)
{
	return list->nodecount == list->maxcount;
}

/*
 * Check if the node pool is empty.
 */

int
lnode_pool_isempty (lnodepool_t * pool)
{
	return (pool->fre == NULL);
}

/*
 * Add the given node at the end of the list
 */

void
list_append (list_t * list, lnode_t * node)
{
	list_ins_before (list, node, &list->nilnode);
}

/*
 * Add the given node at the beginning of the list.
 */

void
list_prepend (list_t * list, lnode_t * node)
{
	list_ins_after (list, node, &list->nilnode);
}

/*
 * Retrieve the first node of the list
 */

lnode_t *
list_first (list_t * list)
{
	if (list->nilnode.next == &list->nilnode)
		return NULL;
	return list->nilnode.next;
}

/*
 * Retrieve the last node of the list
 */

lnode_t *
list_last (list_t * list)
{
	if (list->nilnode.prev == &list->nilnode)
		return NULL;
	return list->nilnode.prev;
}

/*
 * Retrieve the count of nodes in the list
 */

listcount_t
list_count (list_t * list)
{
	return list->nodecount;
}

/*
 * Remove the first node from the list and return it.
 */

lnode_t *
list_del_first (list_t * list)
{
	return list_delete (list, list->nilnode.next);
}

/*
 * Remove the last node from the list and return it.
 */

lnode_t *
list_del_last (list_t * list)
{
	return list_delete (list, list->nilnode.prev);
}


/*
 * Associate a data item with the given node.
 */

void
lnode_put (lnode_t * lnode, void *data)
{
	lnode->data = data;
}

/*
 * Retrieve the data item associated with the node.
 */

void *
lnode_get (lnode_t * lnode)
{
	return lnode->data;
}

/*
 * Retrieve the node's successor. If there is no successor, 
 * NULL is returned.
 */

lnode_t *
list_next (list_t * list, lnode_t * lnode)
{
	nassert (list_contains (list, lnode));

	if (lnode->next == list_nil (list))
		return NULL;
	return lnode->next;
}

/*
 * Retrieve the node's predecessor. See comment for lnode_next().
 */

lnode_t *
list_prev (list_t * list, lnode_t * lnode)
{
	nassert (list_contains (list, lnode));

	if (lnode->prev == list_nil (list))
		return NULL;
	return lnode->prev;
}

/*
 * Return 1 if the lnode is in some list, otherwise return 0.
 */

int
lnode_is_in_a_list (lnode_t * lnode)
{
	return (lnode->next != NULL || lnode->prev != NULL);
}


int
list_verify (list_t * list)
{
	lnode_t *node = list_first_priv (list), *nil = list_nil (list);
	listcount_t count = list_count (list);

	if (node->prev != nil) {
		return 0;
	}
	if (count > list->maxcount) {
		return 0;
	}

	while (node != nil && count--) {
		if (node->next->prev != node) {
			return 0;
		}
		node = node->next;
	}

	if (count != 0 || node != nil) {
		return 0;
	}

	return 1;
}

int
comparef (const void *key1, const void *key2)
{
	return strcasecmp (key1, key2);
}