/****************************************************************************
** GeomIO Library
** Copyright FougSys (2 Mar. 2015)
** contact@fougsys.fr
**
** This software is a reusable library whose purpose is to provide complete
** I/O support for various CAD file formats (eg. STL)
**
** This software is governed by the CeCILL-B license under French law and
** abiding by the rules of distribution of free software.  You can  use,
** modify and/ or redistribute the software under the terms of the CeCILL-B
** license as circulated by CEA, CNRS and INRIA at the following URL
** "http://www.cecill.info/licences/Licence_CeCILL-B_V1-en.html".
****************************************************************************/

#include "stream.h"

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

#if defined(GMIO_HAVE_SYS_TYPES_H) && defined(GMIO_HAVE_SYS_STAT_H)

/* Activate 64bit variants of stat(), fstat(), ...
 * See:
 *   http://linux.die.net/man/2/fstat64
 *   https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man2/fstat.2.html
 */
#  ifdef GMIO_OS_LINUX
#    if defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS != 64
#      undef _FILE_OFFSET_BITS
#    endif
#    if !defined(_FILE_OFFSET_BITS)
#      define _FILE_OFFSET_BITS=64
#    endif
#    if !defined(_POSIX_C_SOURCE)
       /* This enables fileno() */
#      define _POSIX_C_SOURCE
#    endif
#    define GMIO_FSTAT64_OVERRIDE
#  endif /* Linux */

#  ifdef GMIO_OS_MAC
#    if !defined(_DARWIN_USE_64_BIT_INODE)
#      define _DARWIN_USE_64_BIT_INODE
#    endif
#    define GMIO_FSTAT64_OVERRIDE
#  endif /* Apple */

#  include <sys/types.h>
#  include <sys/stat.h>

/* Define wrapper around the stat structure and the fstat() function */
#  ifdef GMIO_HAVE_WIN__FSTAT64_FUNC
typedef struct __stat64 gmio_stat_t;
GMIO_INLINE int gmio_fstat(int fd, gmio_stat_t* buf)
{ return _fstat64(fd, buf); }
#  elif defined(GMIO_FSTAT64_OVERRIDE) || !defined(GMIO_HAVE_POSIX_FSTAT64_FUNC)
typedef struct stat gmio_stat_t;
GMIO_INLINE int gmio_fstat(int fd, gmio_stat_t* buf)
{ return fstat(fd, buf); }
#  elif defined(GMIO_HAVE_POSIX_FSTAT64_FUNC)
typedef struct stat64 gmio_stat_t;
GMIO_INLINE int gmio_fstat(int fd, gmio_stat_t* buf)
{ return fstat64(fd, buf); }
#  endif

#endif /* GMIO_HAVE_SYS_TYPES_H && GMIO_HAVE_SYS_STAT_H */

gmio_stream_t gmio_stream_null()
{
    gmio_stream_t null_stream = { 0 };
    return null_stream;
}

static gmio_bool_t gmio_stream_stdio_at_end(void* cookie)
{
    return feof((FILE*) cookie);
}

static int gmio_stream_stdio_error(void* cookie)
{
    return ferror((FILE*) cookie);
}

static size_t gmio_stream_stdio_read(
        void* cookie, void* ptr, size_t item_size, size_t item_count)
{
    return fread(ptr, item_size, item_count, (FILE*) cookie);
}

static size_t gmio_stream_stdio_write(
        void* cookie, const void* ptr, size_t item_size, size_t item_count)
{
    return fwrite(ptr, item_size, item_count, (FILE*) cookie);
}

static size_t gmio_stream_stdio_size(void* cookie)
{
    FILE* file = (FILE*) cookie;

#if defined(GMIO_HAVE_SYS_TYPES_H) \
    && defined(GMIO_HAVE_SYS_STAT_H) \
    && defined(GMIO_HAVE_POSIX_FILENO_FUNC)

    const int fd = fileno(file);
    if (fd != -1) {
        gmio_stat_t buf;
        if (gmio_fstat(fd, &buf) == 0)
            return buf.st_size;
    }
    return 0;

#else

    /* Excerpted from: https://www.securecoding.cert.org
     *                 item FIO19-C
     *
     * Subclause 7.21.9.2 of the C Standard [ISO/IEC 9899:2011] specifies the
     * following behavior for fseek() when opening a binary file in binary mode:
     *     A binary stream need not meaningfully support fseek calls with a
     *     whence value of SEEK_END.
     *
     * In addition, footnote 268 of subclause 7.21.3 says:
     *     Setting the file position indicator to end-of-file, as with
     *     fseek(file, 0, SEEK_END), has undefined behavior for a binary stream
     *     (because of possible trailing null characters) or for any stream with
     *     state-dependent encoding that does not assuredly end in the initial
     *     shift state.
     *
     * Subclause 7.21.9.4 of the C Standard [ISO/IEC 9899:2011] specifies the
     * following behavior for ftell() when opening a text file in text mode:
     *     For a text stream, its file position indicator contains unspecified
     *     information, usable by the fseek function for returning the file
     *     position indicator for the stream to its position at the time of the
     *     ftell call.
     * Consequently, the return value of ftell() for streams opened in text mode
     * should never be used for offset calculations other than in calls to
     * fseek().
     */

    long size = 0L;
    const long old_pos = ftell(file);

    fseek(file, 0L, SEEK_END);
    size = ftell(file);
    fseek(file, old_pos, SEEK_SET);

    return size;

#endif
}

static void gmio_stream_stdio_rewind(void* cookie)
{
    rewind((FILE*) cookie);
}

gmio_stream_t gmio_stream_stdio(FILE* file)
{
    gmio_stream_t stream = { 0 };
    stream.cookie = file;
    stream.at_end_func = gmio_stream_stdio_at_end;
    stream.error_func = gmio_stream_stdio_error;
    stream.read_func = gmio_stream_stdio_read;
    stream.write_func = gmio_stream_stdio_write;
    stream.size_func = gmio_stream_stdio_size;
    stream.rewind_func = gmio_stream_stdio_rewind;
    return stream;
}