#ifndef QUEUE_H_
#define QUEUE_H_

#include <stdbool.h>
#include <string.h>

#ifdef __cplusplus
extern "C" {
#endif

#define QUEUE_CONTAINER(t, m, v)                                               \
	((void *)((v) ? (uintptr_t)(v) - (offsetof(t, m)) : 0))

#define QUEUE_INIT ((struct queue) {.q_first = NULL, .q_last = NULL})
#define QUEUE_ENTRY_INIT                                                       \
	((struct queue_entry) {.qe_next = NULL, .qe_prev = NULL})

#define queue_foreach(iter_type, iter_name, queue_name, node_member)           \
	for (iter_type *iter_name = (iter_type *)QUEUE_CONTAINER(              \
		     iter_type,                                                \
		     node_member,                                              \
		     queue_first(queue_name));                                 \
	     iter_name;                                                        \
	     iter_name = (iter_type *)QUEUE_CONTAINER(                         \
		     iter_type,                                                \
		     node_member,                                              \
		     queue_next(&((iter_name)->node_member))))

#define queue_foreach_r(iter_type, iter_name, queue_name, node_member)         \
	for (iter_type *iter_name = (iter_type *)QUEUE_CONTAINER(              \
		     iter_type,                                                \
		     node_member,                                              \
		     queue_last(queue_name));                                  \
	     iter_name;                                                        \
	     iter_name = (iter_type *)QUEUE_CONTAINER(                         \
		     iter_type,                                                \
		     node_member,                                              \
		     queue_prev(&((iter_name)->node_member))))

struct queue_entry {
	struct queue_entry *qe_next;
	struct queue_entry *qe_prev;
};

struct queue {
	struct queue_entry *q_first;
	struct queue_entry *q_last;
};

static inline void queue_init(struct queue *q)
{
	memset(q, 0x00, sizeof *q);
}
static inline bool queue_empty(struct queue *q)
{
	return q->q_first == NULL;
}

static inline struct queue_entry *queue_first(struct queue *q)
{
	return q->q_first;
}
static inline struct queue_entry *queue_last(struct queue *q)
{
	return q->q_last;
}
static inline struct queue_entry *queue_next(struct queue_entry *entry)
{
	return entry->qe_next;
}
static inline struct queue_entry *queue_prev(struct queue_entry *entry)
{
	return entry->qe_prev;
}

extern size_t queue_length(struct queue *q);

extern void queue_insert_before(
	struct queue *q,
	struct queue_entry *entry,
	struct queue_entry *before);
extern void queue_insert_after(
	struct queue *q,
	struct queue_entry *entry,
	struct queue_entry *after);

extern void queue_push_front(struct queue *q, struct queue_entry *entry);
extern void queue_push_back(struct queue *q, struct queue_entry *entry);

extern struct queue_entry *queue_pop_front(struct queue *q);
extern struct queue_entry *queue_pop_back(struct queue *q);

extern void queue_delete(struct queue *q, struct queue_entry *entry);
extern void queue_delete_all(struct queue *q);

#ifdef __cplusplus
}
#endif

#endif