/* active_list.h - the opkg package management system

   Tick Chen <tick@openmoko.com>

   Copyright (C) 2008 Openmoko Inc.

   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, 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.
*/

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

#include "libbb/libbb.h"

void active_list_init(struct active_list *ptr)
{
	INIT_LIST_HEAD(&ptr->node);
	INIT_LIST_HEAD(&ptr->depend);
	ptr->depended = NULL;
}

/**
 */
struct active_list *active_list_next(struct active_list *head,
				     struct active_list *ptr)
{
	struct active_list *next = NULL;
	if (!head) {
		opkg_msg(ERROR, "Internal error: head=%p, ptr=%p\n", head, ptr);
		return NULL;
	}
	if (!ptr)
		ptr = head;
	next = list_entry(ptr->node.next, struct active_list, node);
	if (next == head) {
		return NULL;
	}
	if (ptr->depended && &ptr->depended->depend == ptr->node.next) {
		return ptr->depended;
	}
	while (next->depend.next != &next->depend) {
		next = list_entry(next->depend.next, struct active_list, node);
	}
	return next;
}

struct active_list *active_list_prev(struct active_list *head,
				     struct active_list *ptr)
{
	struct active_list *prev = NULL;
	if (!head) {
		opkg_msg(ERROR, "Internal error: head=%p, ptr=%p\n", head, ptr);
		return NULL;
	}
	if (!ptr)
		ptr = head;
	if (ptr->depend.prev != &ptr->depend) {
		prev = list_entry(ptr->depend.prev, struct active_list, node);
		return prev;
	}
	if (ptr->depended && ptr->depended != head
	    && &ptr->depended->depend == ptr->node.prev) {
		prev =
		    list_entry(ptr->depended->node.prev, struct active_list,
			       node);
	} else
		prev = list_entry(ptr->node.prev, struct active_list, node);
	if (prev == head)
		return NULL;
	return prev;
}

struct active_list *active_list_move_node(struct active_list *old_head,
					  struct active_list *new_head,
					  struct active_list *node)
{
	struct active_list *prev;
	if (!old_head || !new_head || !node)
		return NULL;
	if (old_head == new_head)
		return node;
	prev = active_list_prev(old_head, node);
	active_list_add(new_head, node);
	return prev;
}

static void list_head_clear(struct list_head *head)
{
	struct active_list *next;
	struct list_head *n, *ptr;
	if (!head)
		return;
	list_for_each_safe(ptr, n, head) {
		next = list_entry(ptr, struct active_list, node);
		if (next->depend.next != &next->depend) {
			list_head_clear(&next->depend);
		}
		active_list_init(next);
	}
}

void active_list_clear(struct active_list *head)
{
	list_head_clear(&head->node);
	if (head->depend.next != &head->depend) {
		list_head_clear(&head->depend);
	}
	active_list_init(head);
}

void active_list_add(struct active_list *head, struct active_list *node)
{
	list_del_init(&node->node);
	list_add_tail(&node->node, &head->node);
	node->depended = head;
}

struct active_list *active_list_head_new(void)
{
	struct active_list *head = xcalloc(1, sizeof(struct active_list));
	active_list_init(head);
	return head;
}

void active_list_head_delete(struct active_list *head)
{
	active_list_clear(head);
	free(head);
}