#ifndef _LIB_LIST_H
#define _LIB_LIST_H

#include <stddef.h>

struct list_head {
    struct list_head *next, *prev;
};

#define LIST_HEAD_INIT(name) { &(name), &(name) }
#define LIST_HEAD(name) struct list_head name = LIST_HEAD_INIT(name)

static inline void INIT_LIST_HEAD(struct list_head *list) {
    list->next = list;
    list->prev = list;
}

static inline void __list_add(struct list_head *new_node,
                              struct list_head *prev,
                              struct list_head *next) {
    next->prev = new_node;
    new_node->next = next;
    new_node->prev = prev;
    prev->next = new_node;
}

static inline void list_add(struct list_head *new_node, struct list_head *head) {
    __list_add(new_node, head, head->next);
}

static inline void list_add_tail(struct list_head *new_node, struct list_head *head) {
    __list_add(new_node, head->prev, head);
}

static inline void list_del(struct list_head *entry) {
    entry->next->prev = entry->prev;
    entry->prev->next = entry->next;
    entry->next = NULL;
    entry->prev = NULL;
}

static inline int list_empty(const struct list_head *head) {
    return head->next == head;
}

#define list_entry(ptr, type, member) \
    ((type *)((char *)(ptr) - offsetof(type, member)))

#define list_for_each(pos, head) \
    for (pos = (head)->next; pos != (head); pos = pos->next)

#define list_for_each_safe(pos, n, head) \
    for (pos = (head)->next, n = pos->next; pos != (head); \
        pos = n, n = pos->next)

#define list_for_each_entry(pos, head, member) \
    for (pos = list_entry((head)->next, typeof(*pos), member); \
         &pos->member != (head); \
         pos = list_entry(pos->member.next, typeof(*pos), member))

#endif // _LIB_LIST_H