/* Copyright (C) 2008  Emmanuel Varoquaux

   This file is part of XOS.

   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 "common.h"

#include <getopt.h>
#include <error.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/utsname.h>
#include <errno.h>

struct toprint_struct {
  unsigned kernel_name : 1;
  unsigned kernel_release : 1;
  unsigned kernel_version : 1;
  unsigned machine : 1;
};

static void print_name(const struct utsname *name, const struct toprint_struct *toprint)
{
  int print_separator;

  print_separator = 0;
  if (toprint->kernel_name) {
    if (print_separator)
      putchar(' ');
    fputs(name->sysname, stdout);
    print_separator = 1;
  }
  if (toprint->kernel_release) {
    if (print_separator)
      putchar(' ');
    fputs(name->release, stdout);
    print_separator = 1;
  }
  if (toprint->kernel_version) {
    if (print_separator)
      putchar(' ');
    fputs(name->version, stdout);
    print_separator = 1;
  }
  if (toprint->machine) {
    if (print_separator)
      putchar(' ');
    fputs(name->machine, stdout);
    print_separator = 1;
  }
  if (print_separator)
    putchar('\n');
}

static void print_system_info(const struct toprint_struct *toprint)
{
  struct utsname name;

  if (uname(&name) == -1)
    error(EXIT_FAILURE, errno, "cannot get system name");
  print_name(&name, toprint);
}

static void __attribute__ ((noreturn)) die_bad_usage()
{
  fprintf(stderr, "Try `%s --help' for more information.\n", program_invocation_name);
  exit(EXIT_FAILURE);
}

static void print_help()
{
  printf("Usage: %s [OPTION]...\n", program_invocation_name);
  puts("Print certain system information.  With no OPTION, same as -s.");
  putchar('\n');
  puts("  -a, --all             print all information, in the following order:");
  puts("  -s, --kernel-name     print the kernel name");
  puts("  -r, --kernel-release  print the kernel release");
  puts("  -v, --kernel-version  print the kernel version");
  puts("  -m, --machine         print the machine hardware name");
  puts("  -h, --help            display this help and exit");
}

int main(int argc, char **argv)
{
  static const struct toprint_struct print_none = {
    .kernel_name = 0,
    .kernel_release = 0,
    .kernel_version = 0,
    .machine = 0,
  };
  static const struct toprint_struct print_all = {
    .kernel_name = 1,
    .kernel_release = 1,
    .kernel_version = 1,
    .machine = 1,
  };
  static const struct toprint_struct default_toprint = {
    .kernel_name = 1,
    .kernel_release = 0,
    .kernel_version = 0,
    .machine = 0,
  };
  static const struct option longopts[] = {
    {"all", no_argument, NULL, 'a'},
    {"kernel-name", no_argument, NULL, 's'},
    {"kernel-release", no_argument, NULL, 'r'},
    {"kernel-version", no_argument, NULL, 'v'},
    {"machine", no_argument, NULL, 'm'},
    {"help", no_argument, NULL, 'h'},
    {NULL, 0, NULL, 0}
  };

  struct toprint_struct toprint;
  int c;

  atexit(close_stdout);

  toprint = print_none;
  while ((c = getopt_long(argc, argv, "asrvmh", longopts, NULL)) != -1)
    switch (c) {
    case 'a':
      toprint = print_all;
      break;
    case 's':
      toprint.kernel_name = 1;
      break;
    case 'r':
      toprint.kernel_release = 1;
      break;
    case 'v':
      toprint.kernel_version = 1;
      break;
    case 'm':
      toprint.machine = 1;
      break;
    case 'h':
      print_help();
      return EXIT_SUCCESS;
    case '?':
      die_bad_usage();
    }
  if (optind < argc) {
    error(0, 0, "extra operand `%s'", argv[optind]);
    die_bad_usage();
  }
  if (!toprint.kernel_name
      && !toprint.kernel_release
      && !toprint.kernel_version
      && !toprint.machine)
    toprint = default_toprint;

  print_system_info(&toprint);
  return EXIT_SUCCESS;
}