// SPDX-License-Identifier: ISC

#define _GNU_SOURCE /* for ppoll */

#include <libbasis/deadline.h>
#include <libbasis/misc.h>
#include <libbasis/timespec.h>

#include <errno.h>
#include <unistd.h>

struct dl dl_now = DL_NOW;

int init_dl(struct dl *dl, clockid_t clock, unsigned long ms)
{
	dl->clock = clock;

	if (clock_gettime(clock, &dl->time) < 0)
		return -1;

	timespec_add_msec(&dl->time, &dl->time, ms);

	return 0;
}

bool passed_dl(const struct dl *dl)
{
	struct timespec now;

	if (!dl)
		return false;

	/* shortcut for dl_now, so we do not need dl->clock */
	if (!dl->time.tv_sec && !dl->time.tv_nsec)
		return true;

	if (clock_gettime(dl->clock, &now) < 0)
		return true;

	if (timespec_is_less(&dl->time, &now)) {
		errno = ETIMEDOUT;
		return true;
	}

	return false;
}

int sleep_dl(const struct dl *dl)
{
	struct timespec now, diff;
	int r;

	if (!dl)
		return 0;

	/* shortcut for dl_now, so we do not need dl->clock */
	if (!dl->time.tv_sec && !dl->time.tv_nsec)
		return 0;

	if (clock_gettime(dl->clock, &now) < 0)
		return -1;

	if (!timespec_sub(&diff, &dl->time, &now))
		return 0;

	while ((r = nanosleep(&diff, &diff)) < 0 && errno == EINTR)
		;

	if (r < 0)
		return -1;

	return 1;
}

static int poll_timeout_fixup(int ret) {
	if (!ret) {
		errno = ETIMEDOUT;
		return -1;
	}
	return ret;
}

int poll_dl(struct pollfd *fds, nfds_t nfds, const struct dl *dl)
{
	struct timespec now, diff;

	/* should never return timeout, so poll_timeout_fixup is not needed */
	if (!dl)
		return poll(fds, nfds, -1);

	/* shortcut for dl_now, so we do not need dl->clock */
	if (!dl->time.tv_sec && !dl->time.tv_nsec)
		return poll_timeout_fixup(poll(fds, nfds, 0));

	if (clock_gettime(dl->clock, &now) < 0)
		return -1;

	/* return timeout if we already passed the deadline */
	if (!timespec_sub(&diff, &dl->time, &now)) {
		errno = ETIMEDOUT;
		return -1;
	}

	return poll_timeout_fixup(ppoll(fds, nfds, &diff, NULL));
}

const struct dl *next_dl(const struct dl *lhs, const struct dl *rhs)
{
	if (!lhs)
		return rhs;
	if (!rhs)
		return lhs;
	if (timespec_is_less(&lhs->time, &rhs->time))
		return lhs;
	return rhs;
}