/* GNU's uptime.
   Copyright (C) 1992-2023 Free Software Foundation, Inc.

   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 <https://www.gnu.org/licenses/>.  */

/* Created by hacking who.c by Kaveh Ghazi ghazi@caip.rutgers.edu.  */

#include <config.h>

#include <stdckdint.h>
#include <stdio.h>
#include <sys/types.h>

#include "system.h"

#include "long-options.h"
#include "quote.h"
#include "readutmp.h"
#include "fprintftime.h"

/* The official name of this program (e.g., no 'g' prefix).  */
#define PROGRAM_NAME "uptime"

#define AUTHORS \
  proper_name ("Joseph Arceneaux"), \
  proper_name ("David MacKenzie"), \
  proper_name ("Kaveh Ghazi")

static int
print_uptime (idx_t n, struct gl_utmp const *utmp_buf)
{
  int status = EXIT_SUCCESS;
  time_t boot_time = 0;

  /* Loop through all the utmp entries we just read and count up the valid
     ones, also in the process possibly gleaning boottime. */
  idx_t entries = 0;
  for (idx_t i = 0; i < n; i++)
    {
      struct gl_utmp const *this = &utmp_buf[i];
      entries += IS_USER_PROCESS (this);
      if (UT_TYPE_BOOT_TIME (this))
        boot_time = this->ut_ts.tv_sec;
    }
  /* The gnulib module 'readutmp' is supposed to provide a BOOT_TIME entry
     on all platforms.  */
  if (boot_time == 0)
    {
      error (0, errno, _("couldn't get boot time"));
      status = EXIT_FAILURE;
    }

  time_t time_now = time (nullptr);
  struct tm *tmn = time_now == (time_t) -1 ? nullptr : localtime (&time_now);
  /* procps' version of uptime also prints the seconds field, but
     previous versions of coreutils don't. */
  if (tmn)
    /* TRANSLATORS: This prints the current clock time. */
    fprintftime (stdout, _(" %H:%M:%S  "), tmn, 0, 0);
  else
    {
      printf (_(" ??:????  "));
      status = EXIT_FAILURE;
    }

  intmax_t uptime;
  if (time_now == (time_t) -1 || boot_time == 0
      || ckd_sub (&uptime, time_now, boot_time) || uptime < 0)
    {
      printf (_("up ???? days ??:??,  "));
      status = EXIT_FAILURE;
    }
  else
    {
      intmax_t updays = uptime / 86400;
      int uphours = uptime % 86400 / 3600;
      int upmins = uptime % 86400 % 3600 / 60;
      if (0 < updays)
        printf (ngettext ("up %"PRIdMAX" day %2d:%02d,  ",
                          "up %"PRIdMAX" days %2d:%02d,  ",
                          select_plural (updays)),
                updays, uphours, upmins);
      else
        printf (_("up  %2d:%02d,  "), uphours, upmins);
    }

  printf (ngettext ("%td user", "%td users", select_plural (entries)),
          entries);

  double avg[3];
  int loads = getloadavg (avg, 3);

  if (loads == -1)
    putchar ('\n');
  else
    {
      if (loads > 0)
        printf (_(",  load average: %.2f"), avg[0]);
      if (loads > 1)
        printf (", %.2f", avg[1]);
      if (loads > 2)
        printf (", %.2f", avg[2]);
      if (loads > 0)
        putchar ('\n');
    }

  return status;
}

/* Display the system uptime and the number of users on the system,
   according to utmp file FILENAME.  Use read_utmp OPTIONS to read the
   utmp file.  */

static _Noreturn void
uptime (char const *filename, int options)
{
  idx_t n_users;
  struct gl_utmp *utmp_buf;
  int read_utmp_status = (read_utmp (filename, &n_users, &utmp_buf, options) < 0
                          ? EXIT_FAILURE : EXIT_SUCCESS);
  if (read_utmp_status != EXIT_SUCCESS)
    {
      error (0, errno, "%s", quotef (filename));
      n_users = 0;
      utmp_buf = nullptr;
    }

  int print_uptime_status = print_uptime (n_users, utmp_buf);
  exit (MAX (read_utmp_status, print_uptime_status));
}

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    emit_try_help ();
  else
    {
      printf (_("Usage: %s [OPTION]... [FILE]\n"), program_name);
      printf (_("\
Print the current time, the length of time the system has been up,\n\
the number of users on the system, and the average number of jobs\n\
in the run queue over the last 1, 5 and 15 minutes."));
#ifdef __linux__
      /* It would be better to introduce a configure test for this,
         but such a test is hard to write.  For the moment then, we
         have a hack which depends on the preprocessor used at compile
         time to tell us what the running kernel is.  Ugh.  */
      printf (_("  \
Processes in\n\
an uninterruptible sleep state also contribute to the load average.\n"));
#else
      printf (_("\n"));
#endif
      printf (_("\
If FILE is not specified, use %s.  %s as FILE is common.\n\
\n"),
              UTMP_FILE, WTMP_FILE);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      emit_ancillary_info (PROGRAM_NAME);
    }
  exit (status);
}

int
main (int argc, char **argv)
{
  initialize_main (&argc, &argv);
  set_program_name (argv[0]);
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  parse_gnu_standard_options_only (argc, argv, PROGRAM_NAME, PACKAGE_NAME,
                                   Version, true, usage, AUTHORS,
                                   (char const *) nullptr);

  switch (argc - optind)
    {
    case 0:			/* uptime */
      uptime (UTMP_FILE, READ_UTMP_CHECK_PIDS);
      break;

    case 1:			/* uptime <utmp file> */
      uptime (argv[optind], 0);
      break;

    default:			/* lose */
      error (0, 0, _("extra operand %s"), quote (argv[optind + 1]));
      usage (EXIT_FAILURE);
    }
}