/*-

 * Copyright (c) 2019 Christos Zoulas

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS

 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED

 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS

 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

 * POSSIBILITY OF SUCH DAMAGE.

 */

/*

 * Parse CSV object serialization format (RFC-4180, RFC-7111)

 */

#ifndef TEST

#include "file.h"

#ifndef lint

FILE_RCSID("@(#)$File: is_csv.c,v 1.13 2023/07/17 16:08:17 christos Exp $")

#endif

#include <string.h>

#include "magic.h"

#else

#include <sys/types.h>

#endif

#ifdef DEBUG

#include <stdio.h>

#define DPRINTF(fmt, ...) printf(fmt, __VA_ARGS__)

#else

#define DPRINTF(fmt, ...)

#endif

/*

 * if CSV_LINES == 0:

 *  check all the lines in the buffer

 * otherwise:

 *  check only up-to the number of lines specified

 *

 * the last line count is always ignored if it does not end in CRLF

 */

#ifndef CSV_LINES

#define CSV_LINES 10

#endif

static int csv_parse(const unsigned char *, const unsigned char *);

static const unsigned char *

eatquote(const unsigned char *uc, const unsigned char *ue)

{

  int quote = 0;

  while (uc < ue) {

    unsigned char c = *uc++;

    if (c != '"') {

      // We already got one, done.

      if (quote) {

        return --uc;

      }

      continue;

    }

    if (quote) {

      // quote-quote escapes

      quote = 0;

      continue;

    }

    // first quote

    quote = 1;

  }

  return ue;

}

static int

csv_parse(const unsigned char *uc, const unsigned char *ue)

{

  size_t nf = 0, tf = 0, nl = 0;

  while (uc < ue) {

    switch (*uc++) {

    case '"':

      // Eat until the matching quote

      uc = eatquote(uc, ue);

      break;

    case ',':

      nf++;

      break;

    case '\n':

      DPRINTF("%zu %zu %zu\n", nl, nf, tf);

      nl++;

#if CSV_LINES

      if (nl == CSV_LINES)

        return tf != 0 && tf == nf;

#endif

      if (tf == 0) {

        // First time and no fields, give up

        if (nf == 0) 

          return 0;

        // First time, set the number of fields

        tf = nf;

      } else if (tf != nf) {

        // Field number mismatch, we are done.

        return 0;

      }

      nf = 0;

      break;

    default:

      break;

    }

  }

  return tf && nl >= 2;

}

#ifndef TEST

int

file_is_csv(struct magic_set *ms, const struct buffer *b, int looks_text,

    const char *code)

{

  const unsigned char *uc = CAST(const unsigned char *, b->fbuf);

  const unsigned char *ue = uc + b->flen;

  int mime = ms->flags & MAGIC_MIME;

  if (!looks_text)

    return 0;

  if ((ms->flags & (MAGIC_APPLE|MAGIC_EXTENSION)) != 0)

    return 0;

  if (!csv_parse(uc, ue))

    return 0;

  if (mime == MAGIC_MIME_ENCODING)

    return 1;

  if (mime) {

    if (file_printf(ms, "text/csv") == -1)

      return -1;

    return 1;

  }

  if (file_printf(ms, "CSV %s%stext", code ? code : "",

      code ? " " : "") == -1)

    return -1;

  return 1;

}

#else

#include <sys/types.h>

#include <sys/stat.h>

#include <stdio.h>

#include <fcntl.h>

#include <unistd.h>

#include <stdlib.h>

#include <stdint.h>

#include <err.h>

int

main(int argc, char *argv[])

{

  int fd;

  struct stat st;

  unsigned char *p;

  if ((fd = open(argv[1], O_RDONLY)) == -1)

    err(EXIT_FAILURE, "Can't open `%s'", argv[1]);

  if (fstat(fd, &st) == -1)

    err(EXIT_FAILURE, "Can't stat `%s'", argv[1]);

  if ((p = CAST(char *, malloc(st.st_size))) == NULL)

    err(EXIT_FAILURE, "Can't allocate %jd bytes",

        (intmax_t)st.st_size);

  if (read(fd, p, st.st_size) != st.st_size)

    err(EXIT_FAILURE, "Can't read %jd bytes",

        (intmax_t)st.st_size);

  printf("is csv %d\n", csv_parse(p, p + st.st_size));

  return 0;

}

#endif