/* Copyright (c) 2008, 2009
 *      Juergen Weigert (jnweiger@immd4.informatik.uni-erlangen.de)
 *      Michael Schroeder (mlschroe@immd4.informatik.uni-erlangen.de)
 *      Micah Cowan (micah@cowan.name)
 *      Sadrul Habib Chowdhury (sadrul@users.sourceforge.net)
 * Copyright (c) 1993-2002, 2003, 2005, 2006, 2007
 *      Juergen Weigert (jnweiger@immd4.informatik.uni-erlangen.de)
 *      Michael Schroeder (mlschroe@immd4.informatik.uni-erlangen.de)
 * Copyright (c) 1987 Oliver Laumann
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (see the file COPYING); if not, see
 * https://www.gnu.org/licenses/, or contact Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02111-1301  USA
 *
 ****************************************************************
 */

#include <sys/types.h>
#if !defined(sun) && !defined(B43) && !defined(ISC) && !defined(pyr) && !defined(_CX_UX)
# include <time.h>
#endif
#include <sys/time.h>

#include "config.h"
#include "screen.h"
#include "extern.h"

static struct event *evs;
static struct event *tevs;
static struct event *nextev;
static int calctimeout;

static struct event *calctimo __P((void));
#if (defined(sgi) && defined(SVR4)) || defined(__osf__) || defined(M_UNIX)
static int sgihack __P((void));
#endif

void
evenq(struct event *ev)
{
	struct event *evp, **evpp;
	debug3("New event fd %d type %d queued %d\n", ev -> fd, ev -> type, ev -> queued);
	if (ev->queued)
		return;
	evpp = &evs;
	if (ev->type == EV_TIMEOUT) {
		calctimeout = 1;
		evpp = &tevs;
	}
	for (; (evp = *evpp); evpp = &evp->next)
		if (ev->pri > evp->pri)
			break;
	ev->next = evp;
	*evpp = ev;
	ev->queued = 1;
}

void
evdeq(struct event *ev)
{
	struct event *evp, **evpp;
	debug3("Deq event fd %d type %d queued %d\n", ev -> fd, ev -> type, ev -> queued);
	if (!ev->queued)
		return;
	evpp = &evs;
	if (ev->type == EV_TIMEOUT) {
		calctimeout = 1;
		evpp = &tevs;
	}
	for (; (evp = *evpp); evpp = &evp->next)
		if (evp == ev)
			break;
	ASSERT(evp);
	*evpp = ev->next;
	ev->queued = 0;
	if (ev == nextev)
		nextev = nextev->next;
}

static struct event *
calctimo()
{
	struct event *ev, *min;
	long mins;

	if ((min = tevs) == 0)
		return 0;
	mins = min->timeout.tv_sec;
	for (ev = tevs->next; ev; ev = ev->next) {
		ASSERT(ev->type == EV_TIMEOUT);
		if (mins < ev->timeout.tv_sec)
			continue;
		if (mins > ev->timeout.tv_sec || min->timeout.tv_usec > ev->timeout.tv_usec) {
			min = ev;
			mins = ev->timeout.tv_sec;
		}
	}
	return min;
}

void
sched()
{
	struct event *ev;
	fd_set r, w, *set;
	struct event *timeoutev = 0;
	struct timeval timeout;
	int nsel;

	for (;;) {
		if (calctimeout)
			timeoutev = calctimo();
		if (timeoutev) {
			gettimeofday(&timeout, NULL);
			/* tp - timeout */
			timeout.tv_sec = timeoutev->timeout.tv_sec - timeout.tv_sec;
			timeout.tv_usec = timeoutev->timeout.tv_usec - timeout.tv_usec;

			if (timeout.tv_usec < 0) {
				timeout.tv_usec += 1000000;
				timeout.tv_sec--;
			}
			if (timeout.tv_sec < 0) {
				timeout.tv_usec = 0;
				timeout.tv_sec = 0;
			}
		}
#ifdef DEBUG
		debug("waiting for events");
		if (timeoutev)
			debug2(" timeout %d secs %d usecs", timeout.tv_sec, timeout.tv_usec);
		debug(":\n");
		for (ev = evs; ev; ev = ev->next)
			debug3(" - fd %d type %d pri %d\n", ev->fd, ev->type, ev->pri);
		if (tevs)
			debug("timed events:\n");
		for (ev = tevs; ev; ev = ev->next)
			debug3(" - pri %d sec %d usec %d\n", ev->pri,
			    ev->timeout.tv_sec, ev->timeout.tv_usec);
#endif

		FD_ZERO(&r);
		FD_ZERO(&w);
		for (ev = evs; ev; ev = ev->next) {
			if (ev->condpos && *ev->condpos <= (ev->condneg ? *ev->condneg : 0)) {
				debug2(" - cond ev fd %d type %d failed\n", ev->fd, ev->type);
				continue;
			}
			if (ev->type == EV_READ)
				FD_SET(ev->fd, &r);
			else if (ev->type == EV_WRITE)
				FD_SET(ev->fd, &w);
		}

#ifdef DEBUG
		debug("readfds:");
		for (nsel = 0; nsel < FD_SETSIZE; nsel++)
			if (FD_ISSET(nsel, &r))
				debug1(" %d", nsel);
		debug("\n");
		debug("writefds:");
		for (nsel = 0; nsel < FD_SETSIZE; nsel++)
			if (FD_ISSET(nsel, &w))
				debug1(" %d", nsel);
		debug("\n");
#endif

		nsel = select(FD_SETSIZE, &r, &w, (fd_set *)0, timeoutev ? &timeout : (struct timeval *)0);
		if (nsel < 0) {
			if (errno != EINTR) {
#if defined(sgi) && defined(SVR4)
				if (errno == EIO && sgihack())
					continue;
#endif
#if defined(__osf__) || defined(M_UNIX)
				/* OSF/1 3.x, SCO bug: EBADF */
				/* OSF/1 4.x bug: EIO */
				if ((errno == EIO || errno == EBADF) && sgihack())
					continue;
#endif
				Panic(errno, "select");
			}
			nsel = 0;
		} else if (nsel == 0) {		/* timeout */
			debug("TIMEOUT!\n");
			ASSERT(timeoutev);
			evdeq(timeoutev);
			timeoutev->handler(timeoutev, timeoutev->data);
		}
#ifdef SELECT_BROKEN
      /*
       * Sequents select emulation counts a descriptor which is
       * readable and writeable only as one hit. Waaaaa.
       */
		if (nsel)
			nsel = 2 * FD_SETSIZE;
#endif

		for (ev = evs; ev; ev = nextev) {
			nextev = ev->next;
			if (ev->type != EV_ALWAYS) {
				set = ev->type == EV_READ ? &r : &w;
				if (nsel == 0 || !FD_ISSET(ev->fd, set))
					continue;
				nsel--;
			}
			if (ev->condpos &&
			    *ev->condpos <= (ev->condneg ? *ev->condneg : 0))
				continue;
			debug2(" + hit ev fd %d type %d!\n", ev->fd, ev->type);
			ev->handler(ev, ev->data);
		}
	}
}

void
SetTimeout(struct event *ev, int timo)
{
	ASSERT(ev->type == EV_TIMEOUT);
	debug2("event %x new timeout %d ms\n", ev, timo);
	gettimeofday(&ev->timeout, NULL);
	ev->timeout.tv_sec += timo / 1000;
	ev->timeout.tv_usec += (timo % 1000) * 1000;

	if (ev->timeout.tv_usec > 1000000) {
		ev->timeout.tv_usec -= 1000000;
		ev->timeout.tv_sec++;
	}
	if (ev->queued)
		calctimeout = 1;
}

#if (defined(sgi) && defined(SVR4)) || defined(__osf__) || defined(M_UNIX)
/* do we still need it?
                    @anaumov */
extern struct display *display, *displays;
static int
sgihack()
{
	fd_set r, w;
	struct timeval tv;

	debug("IRIX5.2 workaround: searching for bad display\n");
	for (display = displays; display;) {
		FD_ZERO(&r);
		FD_ZERO(&w);
		FD_SET(D_userfd, &r);
		FD_SET(D_userfd, &w);
		tv.tv_sec = tv.tv_usec = 0;
		if (select(FD_SETSIZE, &r, &w, (fd_set *)0, &tv) == -1) {
			if (errno == EINTR)
				continue;
			Hangup();	/* goodbye display */
			return 1;
		}
		display = display->d_next;
	}
	return 0;
}

#endif