#include <fx/core/queue.h>

struct fx_queue_iterator_p {
	size_t i;
	fx_queue_entry *entry;
	fx_queue *_q;
};

size_t fx_queue_length(const struct fx_queue *q)
{
	size_t i = 0;
	struct fx_queue_entry *x = q->q_first;
	while (x) {
		i++;
		x = x->qe_next;
	}

	return i;
}

void fx_queue_insert_before(
	struct fx_queue *q, struct fx_queue_entry *entry, struct fx_queue_entry *before)
{
	struct fx_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 fx_queue_insert_after(
	struct fx_queue *q, struct fx_queue_entry *entry, struct fx_queue_entry *after)
{
	struct fx_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 fx_queue_push_front(struct fx_queue *q, struct fx_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 fx_queue_push_back(struct fx_queue *q, struct fx_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 fx_queue_entry *fx_queue_pop_front(struct fx_queue *q)
{
	struct fx_queue_entry *x = q->q_first;
	if (x) {
		fx_queue_delete(q, x);
	}

	return x;
}

struct fx_queue_entry *fx_queue_pop_back(struct fx_queue *q)
{
	struct fx_queue_entry *x = q->q_last;
	if (x) {
		fx_queue_delete(q, x);
	}

	return x;
}

void fx_queue_move(fx_queue *q, fx_queue_entry *dest, fx_queue_entry *src)
{
	if (src->qe_next) {
		src->qe_next->qe_prev = dest;
	}

	if (src->qe_prev) {
		src->qe_prev->qe_next = dest;
	}

	if (q->q_first == src) {
		q->q_first = dest;
	}

	if (q->q_last == src) {
		q->q_last = dest;
	}

	memmove(dest, src, sizeof *src);
}

void fx_queue_delete(struct fx_queue *q, struct fx_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 fx_queue_delete_all(struct fx_queue *q)
{
	struct fx_queue_entry *x = q->q_first;
	while (x) {
		struct fx_queue_entry *next = x->qe_next;
		x->qe_next = x->qe_prev = NULL;
		x = next;
	}

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

fx_iterator *fx_queue_begin(struct fx_queue *q)
{
	fx_queue_iterator *it_obj = fx_object_create(FX_TYPE_QUEUE_ITERATOR);
	struct fx_queue_iterator_p *it
		= fx_object_get_private(it_obj, FX_TYPE_QUEUE_ITERATOR);

	it->_q = (struct fx_queue *)q;
	it->entry = q->q_first;
	it->i = 0;

	if (!it->entry) {
		fx_iterator_set_status(it_obj, FX_ERR_NO_DATA);
	}

	return it_obj;
}

static enum fx_status iterator_move_next(const fx_iterator *obj)
{
	struct fx_queue_iterator_p *it
		= fx_object_get_private(obj, FX_TYPE_QUEUE_ITERATOR);

	if (!it->entry) {
		return FX_ERR_NO_DATA;
	}

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

	return (it->entry != NULL) ? FX_SUCCESS : FX_ERR_NO_DATA;
}

static enum fx_status iterator_erase(fx_iterator *obj)
{
	struct fx_queue_iterator_p *it
		= fx_object_get_private(obj, FX_TYPE_QUEUE_ITERATOR);

	if (!it->entry) {
		return FX_ERR_OUT_OF_BOUNDS;
	}

	struct fx_queue_entry *next = it->entry->qe_next;
	fx_queue_delete(it->_q, it->entry);
	it->entry = next;

	return FX_SUCCESS;
}

static fx_iterator_value iterator_get_value(fx_iterator *obj)
{
	struct fx_queue_iterator_p *it
		= fx_object_get_private(obj, FX_TYPE_QUEUE_ITERATOR);

	return FX_ITERATOR_VALUE_PTR(it->entry);
}

static const fx_iterator_value iterator_get_cvalue(const fx_iterator *obj)
{
	struct fx_queue_iterator_p *it
		= fx_object_get_private(obj, FX_TYPE_QUEUE_ITERATOR);

	return FX_ITERATOR_VALUE_CPTR(it->entry);
}

FX_TYPE_CLASS_DEFINITION_BEGIN(fx_queue_iterator)
	FX_TYPE_CLASS_INTERFACE_BEGIN(fx_object, FX_TYPE_OBJECT)
		FX_INTERFACE_ENTRY(to_string) = NULL;
	FX_TYPE_CLASS_INTERFACE_END(fx_object, FX_TYPE_OBJECT)

	FX_TYPE_CLASS_INTERFACE_BEGIN(fx_iterator, FX_TYPE_ITERATOR)
		FX_INTERFACE_ENTRY(it_move_next) = iterator_move_next;
		FX_INTERFACE_ENTRY(it_erase) = iterator_erase;
		FX_INTERFACE_ENTRY(it_get_value) = iterator_get_value;
		FX_INTERFACE_ENTRY(it_get_cvalue) = iterator_get_cvalue;
	FX_TYPE_CLASS_INTERFACE_END(fx_iterator, FX_TYPE_ITERATOR)
FX_TYPE_CLASS_DEFINITION_END(fx_queue_iterator)

FX_TYPE_DEFINITION_BEGIN(fx_queue_iterator)
	FX_TYPE_ID(0x560dc263, 0xff98, 0x4812, 0x9b29, 0xa1218bd70881);
	FX_TYPE_EXTENDS(FX_TYPE_ITERATOR);
	FX_TYPE_CLASS(fx_queue_iterator_class);
	FX_TYPE_INSTANCE_PRIVATE(struct fx_queue_iterator_p);
FX_TYPE_DEFINITION_END(fx_queue_iterator)