/*
   Unix SMB/CIFS implementation.
   Timed event library.
   Copyright (C) Andrew Tridgell 1992-1998
   Copyright (C) Volker Lendecke 2005-2007

   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 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "lib/tevent/tevent_internal.h"
#include "../lib/util/select.h"
#include "system/select.h"

struct tevent_poll_private {
	/*
	 * Index from file descriptor into the pollfd array
	 */
	int *pollfd_idx;

	/*
	 * Cache for s3_event_loop_once to avoid reallocs
	 */
	struct pollfd *pfds;
};

static struct tevent_poll_private *tevent_get_poll_private(
	struct tevent_context *ev)
{
	struct tevent_poll_private *state;

	state = (struct tevent_poll_private *)ev->additional_data;
	if (state == NULL) {
		state = talloc_zero(ev, struct tevent_poll_private);
		ev->additional_data = (void *)state;
		if (state == NULL) {
			DEBUG(10, ("talloc failed\n"));
		}
	}
	return state;
}

static void count_fds(struct tevent_context *ev,
		      int *pnum_fds, int *pmax_fd)
{
	struct tevent_fd *fde;
	int num_fds = 0;
	int max_fd = 0;

	for (fde = ev->fd_events; fde != NULL; fde = fde->next) {
		if (fde->flags & (TEVENT_FD_READ|TEVENT_FD_WRITE)) {
			num_fds += 1;
			if (fde->fd > max_fd) {
				max_fd = fde->fd;
			}
		}
	}
	*pnum_fds = num_fds;
	*pmax_fd = max_fd;
}

bool event_add_to_poll_args(struct tevent_context *ev, TALLOC_CTX *mem_ctx,
			    struct pollfd **pfds, int *pnum_pfds,
			    int *ptimeout)
{
	struct tevent_poll_private *state;
	struct tevent_fd *fde;
	int i, num_fds, max_fd, num_pollfds, idx_len;
	struct pollfd *fds;
	struct timeval now, diff;
	int timeout;

	state = tevent_get_poll_private(ev);
	if (state == NULL) {
		return false;
	}
	count_fds(ev, &num_fds, &max_fd);

	idx_len = max_fd+1;

	if (talloc_array_length(state->pollfd_idx) < idx_len) {
		state->pollfd_idx = talloc_realloc(
			state, state->pollfd_idx, int, idx_len);
		if (state->pollfd_idx == NULL) {
			DEBUG(10, ("talloc_realloc failed\n"));
			return false;
		}
	}

	fds = *pfds;
	num_pollfds = *pnum_pfds;

	if (talloc_array_length(fds) < num_pollfds + num_fds) {
		fds = talloc_realloc(mem_ctx, fds, struct pollfd,
					   num_pollfds + num_fds);
		if (fds == NULL) {
			DEBUG(10, ("talloc_realloc failed\n"));
			return false;
		}
	}

	memset(&fds[num_pollfds], 0, sizeof(struct pollfd) * num_fds);

	/*
	 * This needs tuning. We need to cope with multiple fde's for a file
	 * descriptor. The problem is that we need to re-use pollfd_idx across
	 * calls for efficiency. One way would be a direct bitmask that might
	 * be initialized quicker, but our bitmap_init implementation is
	 * pretty heavy-weight as well.
	 */
	for (i=0; i<idx_len; i++) {
		state->pollfd_idx[i] = -1;
	}

	for (fde = ev->fd_events; fde; fde = fde->next) {
		struct pollfd *pfd;

		if ((fde->flags & (TEVENT_FD_READ|TEVENT_FD_WRITE)) == 0) {
			continue;
		}

		if (state->pollfd_idx[fde->fd] == -1) {
			/*
			 * We haven't seen this fd yet. Allocate a new pollfd.
			 */
			state->pollfd_idx[fde->fd] = num_pollfds;
			pfd = &fds[num_pollfds];
			num_pollfds += 1;
		} else {
			/*
			 * We have already seen this fd. OR in the flags.
			 */
			pfd = &fds[state->pollfd_idx[fde->fd]];
		}

		pfd->fd = fde->fd;

		if (fde->flags & TEVENT_FD_READ) {
			pfd->events |= (POLLIN|POLLHUP);
		}
		if (fde->flags & TEVENT_FD_WRITE) {
			pfd->events |= POLLOUT;
		}
	}
	*pfds = fds;
	*pnum_pfds = num_pollfds;

	if (ev->immediate_events != NULL) {
		*ptimeout = 0;
		return true;
	}
	if (ev->timer_events == NULL) {
		*ptimeout = MIN(*ptimeout, INT_MAX);
		return true;
	}

	now = timeval_current();
	diff = timeval_until(&now, &ev->timer_events->next_event);
	timeout = timeval_to_msec(diff);

	if (timeout < *ptimeout) {
		*ptimeout = timeout;
	}

	return true;
}

bool run_events_poll(struct tevent_context *ev, int pollrtn,
		     struct pollfd *pfds, int num_pfds)
{
	struct tevent_poll_private *state;
	int *pollfd_idx;
	struct tevent_fd *fde;

	if (ev->signal_events &&
	    tevent_common_check_signal(ev)) {
		return true;
	}

	if (ev->immediate_events &&
	    tevent_common_loop_immediate(ev)) {
		return true;
	}

	if (pollrtn <= 0) {
		struct timeval tval;

		tval = tevent_common_loop_timer_delay(ev);
		if (tevent_timeval_is_zero(&tval)) {
			return true;
		}

		/*
		 * No fd ready
		 */
		return false;
	}

	state = (struct tevent_poll_private *)ev->additional_data;
	pollfd_idx = state->pollfd_idx;

	for (fde = ev->fd_events; fde; fde = fde->next) {
		struct pollfd *pfd;
		uint16_t flags = 0;

		if ((fde->flags & (TEVENT_FD_READ|TEVENT_FD_WRITE)) == 0) {
			continue;
		}

		if (pollfd_idx[fde->fd] >= num_pfds) {
			DEBUG(1, ("internal error: pollfd_idx[fde->fd] (%d) "
				  ">= num_pfds (%d)\n", pollfd_idx[fde->fd],
				  num_pfds));
			return false;
		}
		pfd = &pfds[pollfd_idx[fde->fd]];

		if (pfd->fd != fde->fd) {
			DEBUG(1, ("internal error: pfd->fd (%d) "
				  "!= fde->fd (%d)\n", pollfd_idx[fde->fd],
                                  num_pfds));
			return false;
		}

		if (pfd->revents & (POLLHUP|POLLERR)) {
			/* If we only wait for TEVENT_FD_WRITE, we
			   should not tell the event handler about it,
			   and remove the writable flag, as we only
			   report errors when waiting for read events
			   to match the select behavior. */
			if (!(fde->flags & TEVENT_FD_READ)) {
				TEVENT_FD_NOT_WRITEABLE(fde);
				continue;
			}
			flags |= TEVENT_FD_READ;
		}

		if (pfd->revents & POLLIN) {
			flags |= TEVENT_FD_READ;
		}
		if (pfd->revents & POLLOUT) {
			flags |= TEVENT_FD_WRITE;
		}
		if (flags & fde->flags) {
			DLIST_DEMOTE(ev->fd_events, fde, struct tevent_fd);
			fde->handler(ev, fde, flags, fde->private_data);
			return true;
		}
	}

	return false;
}

struct timeval *get_timed_events_timeout(struct tevent_context *ev,
					 struct timeval *to_ret)
{
	struct timeval now;

	if ((ev->timer_events == NULL) && (ev->immediate_events == NULL)) {
		return NULL;
	}
	if (ev->immediate_events != NULL) {
		*to_ret = timeval_zero();
		return to_ret;
	}

	now = timeval_current();
	*to_ret = timeval_until(&now, &ev->timer_events->next_event);

	DEBUG(10, ("timed_events_timeout: %d/%d\n", (int)to_ret->tv_sec,
		(int)to_ret->tv_usec));

	return to_ret;
}

static int s3_event_loop_once(struct tevent_context *ev, const char *location)
{
	struct tevent_poll_private *state;
	int timeout;
	int num_pfds;
	int ret;
	int poll_errno;

	timeout = INT_MAX;

	state = tevent_get_poll_private(ev);
	if (state == NULL) {
		errno = ENOMEM;
		return -1;
	}

	if (run_events_poll(ev, 0, NULL, 0)) {
		return 0;
	}

	num_pfds = 0;
	if (!event_add_to_poll_args(ev, state,
				    &state->pfds, &num_pfds, &timeout)) {
		return -1;
	}

	tevent_trace_point_callback(ev, TEVENT_TRACE_BEFORE_WAIT);
	ret = poll(state->pfds, num_pfds, timeout);
	poll_errno = errno;
	tevent_trace_point_callback(ev, TEVENT_TRACE_AFTER_WAIT);
	errno = poll_errno;

	if (ret == -1 && errno != EINTR) {
		tevent_debug(ev, TEVENT_DEBUG_FATAL,
			     "poll() failed: %d:%s\n",
			     errno, strerror(errno));
		return -1;
	}

	run_events_poll(ev, ret, state->pfds, num_pfds);
	return 0;
}

static int s3_event_context_init(struct tevent_context *ev)
{
	return 0;
}

void dump_event_list(struct tevent_context *ev)
{
	struct tevent_timer *te;
	struct tevent_fd *fe;
	struct timeval evt, now;

	if (!ev) {
		return;
	}

	now = timeval_current();

	DEBUG(10,("dump_event_list:\n"));

	for (te = ev->timer_events; te; te = te->next) {

		evt = timeval_until(&now, &te->next_event);

		DEBUGADD(10,("Timed Event \"%s\" %p handled in %d seconds (at %s)\n",
			   te->handler_name,
			   te,
			   (int)evt.tv_sec,
			   http_timestring(talloc_tos(), te->next_event.tv_sec)));
	}

	for (fe = ev->fd_events; fe; fe = fe->next) {

		DEBUGADD(10,("FD Event %d %p, flags: 0x%04x\n",
			   fe->fd,
			   fe,
			   fe->flags));
	}
}

static const struct tevent_ops s3_event_ops = {
	.context_init		= s3_event_context_init,
	.add_fd			= tevent_common_add_fd,
	.set_fd_close_fn	= tevent_common_fd_set_close_fn,
	.get_fd_flags		= tevent_common_fd_get_flags,
	.set_fd_flags		= tevent_common_fd_set_flags,
	.add_timer		= tevent_common_add_timer,
	.schedule_immediate	= tevent_common_schedule_immediate,
	.add_signal		= tevent_common_add_signal,
	.loop_once		= s3_event_loop_once,
	.loop_wait		= tevent_common_loop_wait,
};

static bool s3_tevent_init(void)
{
	static bool initialized;
	if (initialized) {
		return true;
	}
	initialized = tevent_register_backend("s3", &s3_event_ops);
	tevent_set_default_backend("s3");
	return initialized;
}

struct tevent_context *s3_tevent_context_init(TALLOC_CTX *mem_ctx)
{
	struct tevent_context *ev;

	s3_tevent_init();

	ev = tevent_context_init_byname(mem_ctx, "s3");
	if (ev) {
		samba_tevent_set_debug(ev, "s3_tevent");
	}

	return ev;
}

struct idle_event {
	struct tevent_timer *te;
	struct timeval interval;
	char *name;
	bool (*handler)(const struct timeval *now, void *private_data);
	void *private_data;
};

static void smbd_idle_event_handler(struct tevent_context *ctx,
				    struct tevent_timer *te,
				    struct timeval now,
				    void *private_data)
{
	struct idle_event *event =
		talloc_get_type_abort(private_data, struct idle_event);

	TALLOC_FREE(event->te);

	DEBUG(10,("smbd_idle_event_handler: %s %p called\n",
		  event->name, event->te));

	if (!event->handler(&now, event->private_data)) {
		DEBUG(10,("smbd_idle_event_handler: %s %p stopped\n",
			  event->name, event->te));
		/* Don't repeat, delete ourselves */
		TALLOC_FREE(event);
		return;
	}

	DEBUG(10,("smbd_idle_event_handler: %s %p rescheduled\n",
		  event->name, event->te));

	event->te = tevent_add_timer(ctx, event,
				     timeval_sum(&now, &event->interval),
				     smbd_idle_event_handler, event);

	/* We can't do much but fail here. */
	SMB_ASSERT(event->te != NULL);
}

struct idle_event *event_add_idle(struct tevent_context *event_ctx,
				  TALLOC_CTX *mem_ctx,
				  struct timeval interval,
				  const char *name,
				  bool (*handler)(const struct timeval *now,
						  void *private_data),
				  void *private_data)
{
	struct idle_event *result;
	struct timeval now = timeval_current();

	result = talloc(mem_ctx, struct idle_event);
	if (result == NULL) {
		DEBUG(0, ("talloc failed\n"));
		return NULL;
	}

	result->interval = interval;
	result->handler = handler;
	result->private_data = private_data;

	if (!(result->name = talloc_asprintf(result, "idle_evt(%s)", name))) {
		DEBUG(0, ("talloc failed\n"));
		TALLOC_FREE(result);
		return NULL;
	}

	result->te = tevent_add_timer(event_ctx, result,
				      timeval_sum(&now, &interval),
				      smbd_idle_event_handler, result);
	if (result->te == NULL) {
		DEBUG(0, ("event_add_timed failed\n"));
		TALLOC_FREE(result);
		return NULL;
	}

	DEBUG(10,("event_add_idle: %s %p\n", result->name, result->te));
	return result;
}

