/* Getopt for GNU.
   Copyright (C) 1987, 88, 89, 90, 91, 1992 Free Software Foundation, Inc.
   Copyright (C) 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>

   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 2, 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 <stdio.h>
#include <string.h>
#include <getopt.h>

#if __MESC__
#define static
#endif

/* For communication from `getopt' to the caller.
   When `getopt' finds an option that takes an argument,
   the argument value is returned here. */

char *optarg = 0;

/* Index in ARGV of the next element to be scanned.
   This is used for communication to and from the caller
   and for communication between successive calls to `getopt'.

   On entry to `getopt', zero means this is the first call; initialize.

   When `getopt' returns EOF, this is the index of the first of the
   non-option elements that the caller should itself scan.

   Otherwise, `optind' communicates from one call to the next
   how much of ARGV has been scanned so far.  */

int optind = 0;

/* The next char to be scanned in the option-element
   in which the last option character we returned was found.
   This allows us to pick up the scan where we left off.

   If this is zero, or a null string, it means resume the scan
   by advancing to the next ARGV-element.  */

static char *nextchar;

/* Callers store zero here to inhibit the error message
   for unrecognized options.  */

int opterr = 1;


/* Handle permutation of arguments.  */

/* Describe the part of ARGV that contains non-options that have
   been skipped.  `first_nonopt' is the index in ARGV of the first of them;
   `last_nonopt' is the index after the last of them.  */

static int first_nonopt;
static int last_nonopt;


/* Scan elements of ARGV (whose length is ARGC) for option characters
   given in OPTSTRING.

   If an element of ARGV starts with '-', and is not exactly "-" or "--",
   then it is an option element.  The characters of this element
   (aside from the initial '-') are option characters.  If `getopt'
   is called repeatedly, it returns successively each of the option characters
   from each of the option elements.

   If `getopt' finds another option character, it returns that character,
   updating `optind' and `nextchar' so that the next call to `getopt' can
   resume the scan with the following option character or ARGV-element.

   If there are no more option characters, `getopt' returns `EOF'.
   Then `optind' is the index in ARGV of the first ARGV-element
   that is not an option.  (The ARGV-elements have been permuted
   so that those that are not options now come last.)

   OPTSTRING is a string containing the legitimate option characters.
   If an option character is seen that is not listed in OPTSTRING,
   return '?' after printing an error message.  If you set `opterr' to
   zero, the error message is suppressed but we still return '?'.

   If a char in OPTSTRING is followed by a colon, that means it wants an arg,
   so the following text in the same ARGV-element, or the text of the following
   ARGV-element, is returned in `optarg'.  Two colons mean an option that
   wants an optional arg; if there is text in the current ARGV-element,
   it is returned in `optarg', otherwise `optarg' is set to zero.

   If OPTSTRING starts with `-' or `+', it requests different methods of
   handling the non-option ARGV-elements.

   Long-named options begin with `--' instead of `-'.
   Their names may be abbreviated as long as the abbreviation is unique
   or is an exact match for some defined option.  If they have an
   argument, it follows the option name in the same ARGV-element, separated
   from the option name by a `=', or else the in next ARGV-element.
   When `getopt' finds a long-named option, it returns 0 if that option's
   `flag' field is nonzero, the value of the option's `val' field
   if the `flag' field is zero.

   The elements of ARGV aren't really const, because we permute them.
   But we pretend they're const in the prototype to be compatible
   with other systems.

   LONGOPTS is a vector of `struct option' terminated by an
   element containing a name which is zero.

   LONGIND returns the index in LONGOPT of the long-named option found.
   It is only valid when a long-named option has been found by the most
   recent call.

   If LONG_ONLY is nonzero, '-' as well as '--' can introduce
   long-named options.  */

int
_getopt_internal (int argc, char *const
                  *argv, char const *optstring, struct option const *longopts, int *longind, int long_only)
{
  int option_index;

  optarg = 0;

  /* Initialize the internal data when the first call is made.
     Start processing options with ARGV-element 1 (since ARGV-element 0
     is the program name); the sequence of previously skipped
     non-option ARGV-elements is empty.  */

  if (optind == 0)
    {
      first_nonopt = last_nonopt = optind = 1;

      nextchar = NULL;
    }

  if (nextchar == NULL || *nextchar == '\0')
    {
      /* If we have done all the ARGV-elements, stop the scan
         and back over any non-options that we skipped and permuted.  */

      if (optind == argc)
        {
          /* Set the next-arg-index to point at the non-options
             that we previously skipped, so the caller will digest them.  */
          if (first_nonopt != last_nonopt)
            optind = first_nonopt;
          return EOF;
        }

      /* If we have come to a non-option and did not permute it,
         either stop the scan or describe it to the caller and pass it by.  */

      if ((argv[optind][0] != '-' || argv[optind][1] == '\0'))
        return EOF;

      /* We have found another option-ARGV-element.
         Start decoding its characters.  */

      nextchar = (argv[optind] + 1 + (longopts != NULL && argv[optind][1] == '-'));
    }

  if (longopts != NULL && ((argv[optind][0] == '-' && (argv[optind][1] == '-' || long_only))))
    {
      const struct option *p;
      char *s = nextchar;
      int exact = 0;
      int ambig = 0;
      const struct option *pfound = NULL;
      int indfound;

      while (*s && *s != '=')
        s++;

      /* Test all options for either exact match or abbreviated matches.  */
      for (p = longopts, option_index = 0; p->name; p++, option_index++)
        if (!strncmp (p->name, nextchar, s - nextchar))
          {
            if (s - nextchar == strlen (p->name))
              {
                /* Exact match found.  */
                pfound = p;
                indfound = option_index;
                exact = 1;
                break;
              }
            else if (pfound == NULL)
              {
                /* First nonexact match found.  */
                pfound = p;
                indfound = option_index;
              }
            else
              /* Second nonexact match found.  */
              ambig = 1;
          }

      if (ambig && !exact)
        {
          if (opterr)
            fprintf (stderr, "%s: option `%s' is ambiguous\n", argv[0], argv[optind]);
          nextchar += strlen (nextchar);
          optind++;
          return '?';
        }

      if (pfound != NULL)
        {
          option_index = indfound;
          optind++;
          if (*s)
            {
              /* Don't test has_arg with >, because some C compilers don't
                 allow it to be used on enums. */
              if (pfound->has_arg)
                optarg = s + 1;
              else
                {
                  if (opterr)
                    {
                      if (argv[optind - 1][1] == '-')
                        /* --option */
                        fprintf (stderr,
                                 "%s: option `--%s' doesn't allow an argument\n", argv[0], pfound->name);
                      else
                        /* +option or -option */
                        fprintf (stderr,
                                 "%s: option `%c%s' doesn't allow an argument\n",
                                 argv[0], argv[optind - 1][0], pfound->name);
                    }
                  nextchar += strlen (nextchar);
                  return '?';
                }
            }
          else if (pfound->has_arg == 1)
            {
              if (optind < argc)
                optarg = argv[optind++];
              else
                {
                  if (opterr)
                    fprintf (stderr, "%s: option `%s' requires an argument\n", argv[0], argv[optind - 1]);
                  nextchar += strlen (nextchar);
                  return '?';
                }
            }
          nextchar += strlen (nextchar);
          if (longind != NULL)
            *longind = option_index;
          if (pfound->flag)
            {
              *(pfound->flag) = pfound->val;
              return 0;
            }
          return pfound->val;
        }
      /* Can't find it as a long option.  If this is not getopt_long_only,
         or the option starts with '--' or is not a valid short
         option, then it's an error.
         Otherwise interpret it as a short option. */
      if (!long_only || argv[optind][1] == '-' || strchr (optstring, *nextchar) == NULL)
        {
          if (opterr)
            {
              if (argv[optind][1] == '-')
                /* --option */
                fprintf (stderr, "%s: unrecognized option `--%s'\n", argv[0], nextchar);
              else
                /* +option or -option */
                fprintf (stderr, "%s: unrecognized option `%c%s'\n", argv[0], argv[optind][0], nextchar);
            }
          nextchar += strlen (nextchar);
          optind++;
          return '?';
        }
    }

  /* Look at and handle the next option-character.  */

  {
    char c = *nextchar++;
    char *temp = strchr (optstring, c);

    /* Increment `optind' when we start to process its last character.  */
    if (*nextchar == '\0')
      optind++;

    if (temp == NULL || c == ':')
      {
        if (opterr)
          {
            if (c < 040 || c >= 0177)
              fprintf (stderr, "%s: unrecognized option, character code 0%o\n", argv[0], c);
            else
              fprintf (stderr, "%s: unrecognized option `-%c'\n", argv[0], c);
          }
        return '?';
      }
    if (temp[1] == ':')
      {
        if (temp[2] == ':')
          {
            /* This is an option that accepts an argument optionally.  */
            if (*nextchar != '\0')
              {
                optarg = nextchar;
                optind++;
              }
            else
              optarg = 0;
            nextchar = NULL;
          }
        else
          {
            /* This is an option that requires an argument.  */
            if (*nextchar != 0)
              {
                optarg = nextchar;
                /* If we end this ARGV-element by taking the rest as an arg,
                   we must advance to the next element now.  */
                optind++;
              }
            else if (optind == argc)
              {
                if (opterr)
                  fprintf (stderr, "%s: option `-%c' requires an argument\n", argv[0], c);
                c = '?';
              }
            else
              /* We already incremented `optind' once;
                 increment it again when taking next ARGV-elt as argument.  */
              optarg = argv[optind++];
            nextchar = NULL;
          }
      }
    return c;
  }
}

int
getopt (int argc, char *const *argv, char const *options)
{
  return _getopt_internal (argc, argv, options, (const struct option *) 0, (int *) 0, 0);
}

int
getopt_long (int argc, char *const *argv, char const *options,
             struct option const *long_options, int *opt_index)
{
  return _getopt_internal (argc, argv, options, long_options, opt_index, 0);
}

int
getopt_long_only (int argc, char *const *argv, char const *options,
                  struct option const *long_options, int *opt_index)
{
  return _getopt_internal (argc, argv, options, long_options, opt_index, 1);
}