// SPDX-License-Identifier: MIT

#include "list.h"

/* Unlink a node from a list. */
void list_del(list_t* node)
{
	node->prev->next = node->next;
	node->next->prev = node->prev;
	
	node->next = node->prev = node;
}

/* Add an element after another in a list. */
void list_add(list_t* node, list_t* to_add)
{
	to_add->next = node->next;
	to_add->prev = node;
	
	node->next->prev = to_add;
	node->next = to_add;
}

void list_add_tail(list_t* node, list_t* to_add)
{
	to_add->next = node;
	to_add->prev = node->prev;
	
	node->prev->next = to_add;
	node->prev = to_add;
}

list_t* list_pop(list_t* head)
{
	list_t* node;
	if (list_empty(head))
		return NULL;
	
	node = head->next;
	list_del(node);
	
	return node;
}

list_t* list_pop_tail(list_t* head)
{
	list_t* node;
	if (list_empty(head))
		return NULL;
	
	node = head->prev;
	list_del(node);
	
	return node;
}


/* Move the root of a list to a different location. */
void list_move(list_t* dst, list_t* src)
{
	dst->next = dst->prev = dst;
	
	if (list_empty(src))
		return;
	
	*dst = *src;
	src->next = src->prev = src;
	dst->next->prev = dst;
	dst->prev->next = dst;
}