#include <blue/core/queue.h>

size_t b_queue_length(struct b_queue *q)
{
	size_t i = 0;
	struct b_queue_entry *x = q->q_first;
	while (x) {
		i++;
		x = x->qe_next;
	}

	return i;
}

void b_queue_insert_before(
	struct b_queue *q, struct b_queue_entry *entry, struct b_queue_entry *before)
{
	struct b_queue_entry *x = before->qe_prev;
	if (x) {
		x->qe_next = entry;
	} else {
		q->q_first = entry;
	}

	entry->qe_prev = x;

	before->qe_prev = entry;
	entry->qe_next = before;
}

void b_queue_insert_after(
	struct b_queue *q, struct b_queue_entry *entry, struct b_queue_entry *after)
{
	struct b_queue_entry *x = after->qe_next;
	if (x) {
		x->qe_prev = entry;
	} else {
		q->q_last = entry;
	}

	entry->qe_next = x;

	after->qe_next = entry;
	entry->qe_prev = after;
}

void b_queue_push_front(struct b_queue *q, struct b_queue_entry *entry)
{
	if (q->q_first) {
		q->q_first->qe_prev = entry;
	}

	entry->qe_next = q->q_first;
	entry->qe_prev = NULL;

	q->q_first = entry;

	if (!q->q_last) {
		q->q_last = entry;
	}
}

void b_queue_push_back(struct b_queue *q, struct b_queue_entry *entry)
{
	if (q->q_last) {
		q->q_last->qe_next = entry;
	}

	entry->qe_prev = q->q_last;
	entry->qe_next = NULL;

	q->q_last = entry;

	if (!q->q_first) {
		q->q_first = entry;
	}
}

struct b_queue_entry *b_queue_pop_front(struct b_queue *q)
{
	struct b_queue_entry *x = q->q_first;
	if (x) {
		b_queue_delete(q, x);
	}

	return x;
}

struct b_queue_entry *b_queue_pop_back(struct b_queue *q)
{
	struct b_queue_entry *x = q->q_last;
	if (x) {
		b_queue_delete(q, x);
	}

	return x;
}

void b_queue_delete(struct b_queue *q, struct b_queue_entry *entry)
{
	if (!entry) {
		return;
	}

	if (entry == q->q_first) {
		q->q_first = q->q_first->qe_next;
	}

	if (entry == q->q_last) {
		q->q_last = q->q_last->qe_prev;
	}

	if (entry->qe_next) {
		entry->qe_next->qe_prev = entry->qe_prev;
	}

	if (entry->qe_prev) {
		entry->qe_prev->qe_next = entry->qe_next;
	}

	entry->qe_next = entry->qe_prev = NULL;
}

void b_queue_delete_all(struct b_queue *q)
{
	struct b_queue_entry *x = q->q_first;
	while (x) {
		struct b_queue_entry *next = x->qe_next;
		x->qe_next = x->qe_prev = NULL;
		x = next;
	}

	q->q_first = q->q_last = NULL;
}

static bool queue_iterator_next(struct b_iterator *it)
{
	return b_queue_iterator_next((struct b_queue_iterator *)it);
}

static b_status queue_iterator_erase(struct b_iterator *it)
{
	return b_queue_iterator_erase((struct b_queue_iterator *)it);
}

static bool queue_iterator_is_valid(const struct b_iterator *it)
{
	return b_queue_iterator_is_valid((const struct b_queue_iterator *)it);
}

static const b_iterator_ops queue_iterator_ops = {
	.it_next = queue_iterator_next,
	.it_erase = queue_iterator_erase,
	.it_close = NULL,
	.it_is_valid = queue_iterator_is_valid,
};

int b_queue_iterator_begin(const struct b_queue *q, struct b_queue_iterator *it)
{
	it->_q = (struct b_queue *)q;
	it->_base.it_ops = &queue_iterator_ops;
	it->entry = q->q_first;
	it->i = 0;

	return 0;
}

bool b_queue_iterator_next(struct b_queue_iterator *it)
{
	if (!it->entry) {
		return false;
	}

	it->entry = it->entry->qe_next;
	it->i++;

	return it->entry != NULL;
}

b_status b_queue_iterator_erase(struct b_queue_iterator *it)
{
	if (!it->entry) {
		return B_ERR_OUT_OF_BOUNDS;
	}

	struct b_queue_entry *next = it->entry->qe_next;
	b_queue_delete(it->_q, it->entry);
	it->entry = next;

	return B_SUCCESS;
}

bool b_queue_iterator_is_valid(const struct b_queue_iterator *it)
{
	return it->entry != NULL;
}