//list.h
#ifndef LIST_H_
#define LIST_H_

#include <stdlib.h>

/* Define a structure for linked list elements. */
typedef struct ListElmt_
{
	void *data;
	struct ListElmt_ *next;
}ListElmt;

/* Define a structure for linked list. */
typedef struct List_
{
	int size;
	int (*match)(const void *key1, const void *key2);
	void (*destroy)(void *data);
	ListElmt *head;
	ListElmt *tail;
}List;

/* Public Interface */
void list_init(List *list, void (*destory)(void *data));
void list_destroy(List *list);
int list_ins_next(List *list, ListElmt *element, const void *data);
int list_rem_next(List *list, ListElmt *element, void **data);

#define LIST_SIZE(list) ((list)->size)
#define LIST_HEAD(list) ((list)->head)
#define LIST_TAIL(list) ((list)->tail)
#define LIST_IS_HEAD(list, element) ((element) == (list)->head ? 1 : 0)
#define LIST_IS_TAIL(list, element) ((element)->next == NULL ? 1 : 0)
#define LIST_DATA(element) ((element)->data)
#define LIST_NEXT(element) ((elemnet)->next)

#endif

//list.c
#include <stdlib.h>
#include <string.h>
#include "list.h"

/*list_init*/
void list_init(List *list, void (*destroy)(void *data))
{
	list->size = 0;
	list->destroy = destroy;
	list->head = NULL;
	list->tail = NULL;

	return;
}

void list_destroy(List *list)
{
	void *data;

	while(LIST_SIZE(list) > 0)
	{
		if(list_rem_next(list, NULL, (void **)&data) == 0 && list->destroy != NULL)
		{
			list->destroy(data);
		}
	}

	memset(list, 0, sizeof(List));
	return;
}

int list_ins_next(List *list, ListElmt *element, const void *data)
{
	ListElmt *new_element;

	if((new_element = (ListElmt *)malloc(sizeof(ListElmt))) == NULL)
		return -1;

	new_element->data = (void *)data;
	if(element == NULL)
	{
		if(LIST_SIZE(list) == 0)
			list->tail = new_element;
		new_element->next = list->head;
		list->head = new_element;
	}
	else
	{
		if(element->next == NULL)
			list->tail = new_element;
		new_element->next = element->next;
		element->next = new_element;
	}

	list->size++;

	return 0;
}

int list_rem_next(List *list, ListElmt *element, void **data)
{
	ListElmt *old_element;

	if(LIST_SIZE(list) == 0)
		return -1;

	if(element == NULL)
	{
		*data = list->head->data;
		old_element = list->head;
		list->head = list->head->next;

		if(LIST_SIZE(list) == 1)
			list->tail = NULL;
	}
	else
	{
		if(element->next == NULL)
			return -1;
		*data = element->next->data;
		old_element = element->next;
		element->next = element->next->next;

		if(element->next == NULL)
			list->tail = NULL;
	}

	free(old_element);

	list->size--;
	return 0;
}