/* Iterate over arguments from argv or --files0-from=FILE
   Copyright (C) 2008-2025 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/>.  */

/* Written by Jim Meyering.  */

#include <config.h>
#include "argv-iter.h"

#include <stdlib.h>
#include <string.h>

struct argv_iterator
{
  /* Test FP to determine whether in read-mode or argv-mode. */
  /* file-mode: fp records position */
  FILE *fp;
  size_t item_idx;
  char *tok;
  size_t buf_len;

  /* argv-mode: record just argv and current pointer */
  char **arg_list;
  char **p;
};

struct argv_iterator *
argv_iter_init_argv (char **argv)
{
  struct argv_iterator *ai = malloc (sizeof *ai);
  if (!ai)
    return NULL;
  ai->fp = NULL;
  ai->arg_list = argv;
  ai->p = argv;
  return ai;
}

/* Initialize to read from the stream, FP.
   The input is expected to contain a list of NUL-delimited tokens.  */
struct argv_iterator *
argv_iter_init_stream (FILE *fp)
{
  struct argv_iterator *ai = malloc (sizeof *ai);
  if (!ai)
    return NULL;
  ai->fp = fp;
  ai->tok = NULL;
  ai->buf_len = 0;

  ai->item_idx = 0;
  ai->arg_list = NULL;
  return ai;
}

char *
argv_iter (struct argv_iterator *ai, enum argv_iter_err *err)
{
  if (ai->fp)
    {
      ssize_t len = getdelim (&ai->tok, &ai->buf_len, '\0', ai->fp);
      if (len < 0)
        {
          *err = feof (ai->fp) ? AI_ERR_EOF : AI_ERR_READ;
          return NULL;
        }

      *err = AI_ERR_OK;
      ai->item_idx++;
      return ai->tok;
    }
  else
    {
      if (*(ai->p) == NULL)
        {
          *err = AI_ERR_EOF;
          return NULL;
        }
      else
        {
          *err = AI_ERR_OK;
          return *(ai->p++);
        }
    }
}

size_t
argv_iter_n_args (struct argv_iterator const *ai)
{
  return ai->fp ? ai->item_idx : ai->p - ai->arg_list;
}

void
argv_iter_free (struct argv_iterator *ai)
{
  if (ai->fp)
    free (ai->tok);
  free (ai);
}
