/* Hierarchial argument parsing, layered over getopt

   Copyright (C) 1995 Free Software Foundation, Inc.

   Written by Miles Bader <miles@gnu.ai.mit.edu>

   This file is part of the GNU Hurd.

   The GNU Hurd 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.

   The GNU Hurd 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */

#include <stdlib.h>
#include <string.h>
#include <limits.h>		/* for CHAR_BIT */
#include <getopt.h>
#include <cthreads.h>

#include "argp.h"

#define EOF (-1)

/* The number of bits we steal in a long-option value for our own use.  */
#define GROUP_BITS CHAR_BIT

/* The number of bits available for the user value.  */
#define USER_BITS ((sizeof ((struct option *)0)->val * CHAR_BIT) - GROUP_BITS)
#define USER_MASK ((1 << USER_BITS) - 1)

/* ---------------------------------------------------------------- */

#define OPT_HELP	-1

static struct argp_option argp_default_options[] =
{
  {"help",	OPT_HELP, 0, 0, "Give this help list"},
  {0, 0}
};

static error_t
argp_default_parser (int key, char *arg, struct argp_state *state)
{
  unsigned usage_flags = ARGP_HELP_STD_HELP;
  switch (key)
    {
    case OPT_HELP:
      if (state->flags & ARGP_NO_EXIT)
	usage_flags &= ~ARGP_HELP_EXIT;
      argp_help (state->argp, stdout, usage_flags);
      return 0;
    default:
      return EINVAL;
    }
}

static struct argp argp_default_argp =
  {argp_default_options, &argp_default_parser};


/* ---------------------------------------------------------------- */

/* Returns the offset into the getopt long options array LONG_OPTIONS of a
   long option with called NAME, or -1 if none is found.  Passing NULL as
   NAME will return the number of options.  */
static int
find_long_option (struct option *long_options, const char *name)
{
  struct option *l = long_options;
  while (l->name != NULL)
    if (name != NULL && strcmp (l->name, name) == 0)
      return l - long_options;
    else
      l++;
  if (name == NULL)
    return l - long_options;
  else
    return -1;
}

/* ---------------------------------------------------------------- */

/* Used to regulate access to the getopt routines, which are non-reentrant.  */
static struct mutex getopt_lock = MUTEX_INITIALIZER;

/* The state of a `group' during parsing.  Each group corresponds to a
   particular argp structure from the tree of such descending from the top
   level argp passed to argp_parse.  */
struct group
{
  /* This group's parsing function.  */
  argp_parser_t parser;

  /* Points to the point in SHORT_OPTS corresponding to the end of the short
     options for this group.  We use it to determine from which group a
     particular short options is from.  */
  char *short_end;

  /* True if this group has successfully processed a non-option argument;
     used to determine who to call with ARGP_KEY_NO_ARGS.  */
  int processed_arg;
};

/* Parse the options strings in ARGC & ARGV according to the argp in
   ARGP.  FLAGS is one of the ARGP_ flags above.  If OPTIND is
   non-NULL, the index in ARGV of the first unparsed option is returned in
   it.  If an unknown option is present, EINVAL is returned; if some parser
   routine returned a non-zero value, it is returned; otherwise 0 is
   returned.  */
error_t
argp_parse (struct argp *argp, int argc, char **argv, unsigned flags,
	    int *end_index)
{
  int opt;
  error_t err = 0;
  /* SHORT_OPTS is the getopt short options string for the union of all the
     groups of options.  */
  char *short_opts;
  /* LONG_OPTS is the array of getop long option structures for the union of
     all the groups of options.  */
  struct option *long_opts;
  /* States of the various parsing groups.  */
  struct group *groups;
  /* The end of the GROUPS array.  */
  struct group *egroup;
  /* A pointer for people to use for iteration over GROUPS.  */
  struct group *group;
  /* State block supplied to parsing routines.  */
  struct argp_state state = { argp, argc, argv, 0, flags };

  if (! (state.flags & ARGP_NO_HELP))
    /* Add our own options.  */
    {
      struct argp **plist = alloca (3 * sizeof (struct argp *));
      struct argp *top_argp = alloca (sizeof (struct argp));

      /* TOP_ARGP has no options, it just serves to group the user & default
	 argps.  */
      bzero (top_argp, sizeof (*top_argp));
      top_argp->parents = plist;

      plist[0] = state.argp;
      plist[1] = &argp_default_argp;
      plist[2] = 0;

      state.argp = top_argp;
    }

  /* Find the merged set of getopt options, with keys appropiately prefixed. */
  {
    char *short_end;
    unsigned short_len = (state.flags & ARGP_NO_ARGS) ? 0 : 1;
    struct option *long_end;
    unsigned long_len = 0;
    unsigned num_groups = 0;

    /* For ARGP, increments NUM_GROUPS by the total number of argp structures
       descended from it, and SHORT_LEN & LONG_LEN by the maximum lengths of
       the resulting merged getopt short options string and long-options
       array, respectively.  */
    void calc_lengths (struct argp *argp)
      {
	struct argp **parents = argp->parents;
	struct argp_option *opt = argp->options;

	if (opt || argp->parser)
	  {
	    num_groups++;
	    if (opt)
	      {
		int num_opts = 0;
		while (!_option_is_end (opt++))
		  num_opts++;
		short_len += num_opts * 3; /* opt + up to 2 `:'s */
		long_len += num_opts;
	      }
	  }

	if (parents)
	  while (*parents)
	    calc_lengths (*parents++);
      }

    /* Converts all options in ARGP (which is put in GROUP) and ancestors
       into getopt options stored in SHORT_OPTS and LONG_OPTS; SHORT_END and
       LONG_END are the points at which new options are added.  Returns the
       next unused group entry.  */
    struct group *convert_options (struct argp *argp, struct group *group)
      {
	/* REAL is the most recent non-alias value of OPT.  */
	struct argp_option *real = argp->options;
	struct argp **parents = argp->parents;

	if (real || argp->parser)
	  {
	    struct argp_option *opt;

	    if (real)
	      for (opt = real; !_option_is_end (opt); opt++)
		{
		  if (! (opt->flags & OPTION_ALIAS))
		    /* OPT isn't an alias, so we can use values from it.  */
		    real = opt;

		  if (_option_is_short (opt))
		    /* OPT can be used as a short option.  */
		    {
		      *short_end++ = opt->key;
		      if (real->arg)
			{
			  *short_end++ = ':';
			  if (! (real->flags & OPTION_ARG_OPTIONAL))
			    *short_end++ = ':';
			}
		      *short_end = '\0'; /* keep 0 terminated */
		    }

		  if (opt->name && find_long_option (long_opts, opt->name) < 0)
		    /* OPT can be used as a long option.  */
		    {
		      long_end->name = opt->name;
		      long_end->has_arg =
			(real->arg
			 ? (real->flags & OPTION_ARG_OPTIONAL
			    ? optional_argument
			    : required_argument)
			 : no_argument);
		      long_end->flag = 0;
		      /* we add a disambiguating code to all the user's
			 values (which is removed before we actually call
			 the function to parse the value); this means that
			 the user loses use of the high 8 bits in all his
			 values (the sign of the lower bits is preserved
			 however)...  */
		      long_end->val =
			(opt->key & USER_MASK)
			  + (((group - groups) + 1) << USER_BITS);

		      /* Keep the LONG_OPTS list terminated.  */
		      (++long_end)->name = NULL;
		    }
		  }

	    group->parser = argp->parser;
	    group->short_end = short_end;
	    group->processed_arg = 0;

	    group++;
	  }

	if (parents)
	  while (*parents)
	    group = convert_options (*parents++, group);

	return group;
      }

    calc_lengths (state.argp);

    short_opts = short_end = alloca (short_len + 1);
    if (state.flags & ARGP_IN_ORDER)
      *short_end++ = '-';
    else if (! (state.flags & ARGP_NO_ARGS))
      *short_end++ = '-';
    *short_end = '\0';

    long_opts = long_end = alloca ((long_len + 1) * sizeof (struct option));
    long_end->name = NULL;

    groups = alloca ((num_groups + 1) * sizeof (struct group));

    egroup = convert_options (state.argp, groups);
  }

  /* Getopt is (currently) non-reentrant.  */
  mutex_lock (&getopt_lock);

  /* Tell getopt to initialize.  */
  optind = state.index = 0;

  if (state.flags & ARGP_NO_ERRS)
    {
      opterr = 0;
      if (state.flags & ARGP_PARSE_ARGV0)
	/* getopt always skips ARGV[0], so we have to fake it out.  As long
	   as opterr is 0, then it shouldn't actually try to access it.  */
	state.argv--, state.argc++;
    }
  else
    opterr = 1;			/* Print error messages.  */

  /* Now use getopt on our coalesced options lists.  */
  while ((opt = getopt_long (state.argc, state.argv, short_opts, long_opts, 0)) != EOF)
    {
      /* The group key encoded in the high bits; 0 for short opts or
	 group_number + 1 for long opts.  */
      int group_key = opt >> USER_BITS;

      err = EINVAL;		/* until otherwise asserted */

      state.index = optind;	/* Store OPTIND in STATE while calling user
				   functions.  */

      if (opt == 1)
	/* A non-option argument; try each parser in turn.  */
	{
	  for (group = groups; group < egroup && err == EINVAL; group++)
	    if (group->parser)
	      err = (*group->parser)(ARGP_KEY_ARG, optarg, &state);
	  if (err == EINVAL)
	    /* No parser understood this argument, return immediately.  */
	    {
	      if (end_index)
		/* As long as there's some way for the user to deal with the
		   remaining arguments, don't complain.  */
		err = 0;
	      break;
	    }
	  else if (state.index >= optind)
	    /* Remember that we successfully processed a non-option
	       argument -- but only if the user hasn't gotten tricky and set
	       the clock back.  */
	    (--group)->processed_arg = 1;
	}
      else if (group_key == 0)
	/* A short option.  */
	{
	  /* By comparing OPT's position in SHORT_OPTS to the various
	     starting positions in each group's SHORT_END field, we can
	     determine which group OPT came from.  */
	  char *short_index = index (short_opts, opt);
	  if (short_index)
	    for (group = groups; group < egroup; group++)
	      if (group->short_end > short_index && group->parser)
		{
		  err = (*group->parser)(opt, optarg, &state);
		  break;
		}
	}
      else
	/* A long option.  We use shifts instead of masking for extracting
	   the user value in order to preserve the sign.  */
	err =
	  (*groups[group_key - 1].parser)(((opt << GROUP_BITS) >> GROUP_BITS),
					  optarg, &state);

      optind = state.index;	/* Put it back in OPTIND for getopt.  */

      if (err)
	break;
    }

  if (opt == EOF)
    state.index = optind;	/* Only update INDEX if getopt just failed. */

  mutex_unlock (&getopt_lock);

  if (!err && !state.argv[state.index])
    /* We successfully parsed all arguments!  Call all the parsers again,
       just a few more times... */
    {
      for (group = groups; group < egroup && (!err || err == EINVAL); group++)
	if (!group->processed_arg && group->parser)
	  err = (*group->parser)(ARGP_KEY_NO_ARGS, 0, &state);
      for (group = groups; group < egroup && (!err || err == EINVAL); group++)
	if (group->parser)
	  err = (*group->parser)(ARGP_KEY_END, 0, &state);
      if (err == EINVAL)
	/* EINVAL here just means that ARGP_KEY_END wasn't understood. */
	err = 0;
    }

  if (end_index)
    *end_index = state.index;

  if (err && !(state.flags & ARGP_NO_HELP))
    {
      unsigned usage_flags = ARGP_HELP_STD_ERR;
      if (state.flags & ARGP_NO_EXIT)
	usage_flags &= ~ARGP_HELP_EXIT;
      argp_help (state.argp, stderr, usage_flags);
    }

  return err;
}