/* MIT License

 *

 * Copyright (c) 2024 Brad House

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice (including the next

 * paragraph) shall be included in all copies or substantial portions of the

 * Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 * SOFTWARE.

 *

 * SPDX-License-Identifier: MIT

 */

/* Some systems might default to something low like 256 (NetBSD), lets define

 * this to assist.  Really, no one should be using select, but lets be safe

 * anyhow */

#define FD_SETSIZE 4096

#include "ares_private.h"

#include "ares_event.h"

/* All systems have select(), but not all have a way to wake, so we require

 * pipe() to wake the select() */

#if defined(HAVE_PIPE) && defined(CARES_THREADS)

#ifdef HAVE_SYS_SELECT_H

#  include <sys/select.h>

#endif

static ares_bool_t ares_evsys_select_init(ares_event_thread_t *e)

{

  e->ev_signal = ares_pipeevent_create(e);

  if (e->ev_signal == NULL) {

    return ARES_FALSE; /* LCOV_EXCL_LINE: UntestablePath */

  }

  return ARES_TRUE;

}

static void ares_evsys_select_destroy(ares_event_thread_t *e)

{

  (void)e;

}

static ares_bool_t ares_evsys_select_event_add(ares_event_t *event)

{

  (void)event;

  return ARES_TRUE;

}

static void ares_evsys_select_event_del(ares_event_t *event)

{

  (void)event;

}

static void ares_evsys_select_event_mod(ares_event_t      *event,

                                        ares_event_flags_t new_flags)

{

  (void)event;

  (void)new_flags;

}

static size_t ares_evsys_select_wait(ares_event_thread_t *e,

                                     unsigned long        timeout_ms)

{

  size_t          num_fds = 0;

  ares_socket_t  *fdlist  = ares_htable_asvp_keys(e->ev_sock_handles, &num_fds);

  int             rv;

  size_t          cnt = 0;

  size_t          i;

  fd_set          read_fds;

  fd_set          write_fds;

  fd_set          except_fds;

  int             nfds = 0;

  struct timeval  tv;

  struct timeval *tout = NULL;

  FD_ZERO(&read_fds);

  FD_ZERO(&write_fds);

  FD_ZERO(&except_fds);

  for (i = 0; i < num_fds; i++) {

    const ares_event_t *ev =

      ares_htable_asvp_get_direct(e->ev_sock_handles, fdlist[i]);

    if (ev->flags & ARES_EVENT_FLAG_READ) {

      FD_SET(ev->fd, &read_fds);

    }

    if (ev->flags & ARES_EVENT_FLAG_WRITE) {

      FD_SET(ev->fd, &write_fds);

    }

    FD_SET(ev->fd, &except_fds);

    if (ev->fd + 1 > nfds) {

      nfds = ev->fd + 1;

    }

  }

  if (timeout_ms) {

    tv.tv_sec  = (int)(timeout_ms / 1000);

    tv.tv_usec = (int)((timeout_ms % 1000) * 1000);

    tout       = &tv;

  }

  rv = select(nfds, &read_fds, &write_fds, &except_fds, tout);

  if (rv > 0) {

    for (i = 0; i < num_fds; i++) {

      ares_event_t      *ev;

      ares_event_flags_t flags = 0;

      ev = ares_htable_asvp_get_direct(e->ev_sock_handles, fdlist[i]);

      if (ev == NULL || ev->cb == NULL) {

        continue; /* LCOV_EXCL_LINE: DefensiveCoding */

      }

      if (FD_ISSET(fdlist[i], &read_fds) || FD_ISSET(fdlist[i], &except_fds)) {

        flags |= ARES_EVENT_FLAG_READ;

      }

      if (FD_ISSET(fdlist[i], &write_fds)) {

        flags |= ARES_EVENT_FLAG_WRITE;

      }

      if (flags == 0) {

        continue;

      }

      cnt++;

      ev->cb(e, fdlist[i], ev->data, flags);

    }

  }

  ares_free(fdlist);

  return cnt;

}

const ares_event_sys_t ares_evsys_select = {

  "select",

  ares_evsys_select_init,

  ares_evsys_select_destroy,   /* NoOp */

  ares_evsys_select_event_add, /* NoOp */

  ares_evsys_select_event_del, /* NoOp */

  ares_evsys_select_event_mod, /* NoOp */

  ares_evsys_select_wait

};

#endif