/***************************************************************
  MPU-STRING.C

       This file contains source code of functions for
       UCS-2 string stream operations.

       PART OF : MPUIO - library .

       USAGE   : Internal only .

       NOTE    : String streams contain UCS-2 characters
                 directly. No UTF-8 conversion is performed.

       Copyright (C) 2000 - 2026  by Andrey V.Kosteltsev.
       All Rights Reserved.
 ***************************************************************/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <libmpuio.h>
#include <mpu-symbols.h>
#include <mpu-libio.h>


/***************************************************************
  Publish a NUL-terminated memory-stream buffer and logical size.
  For fixed caller-owned streams this only maintains the trailing
  NUL; dynamic streams also update the user pointer and length.
 ***************************************************************/
static int __mpu_IO_str_publish_unlocked( mpu_FILE *stream )
{
  __mpu_IO_strfile  *sf;

  sf = (__mpu_IO_strfile *)stream->_cookie;
  if( sf == (__mpu_IO_strfile *)0 )
  {
    errno = EBADF;
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( mpu_EOF );
  }

  if( sf->nul_terminated && sf->buffer != (__mpu_char16_t *)0 &&
      sf->capacity != 0 )
  {
    size_t end = sf->length;
    if( end >= sf->capacity ) end = sf->capacity - 1;
    sf->buffer[end] = (__mpu_char16_t)0;
  }

  if( sf->publish_buffer != (__mpu_char16_t **)0 )
    *sf->publish_buffer = sf->buffer;
  if( sf->publish_size != (size_t *)0 )
    *sf->publish_size = sf->length;

  return( 0 );

} /* End of __mpu_IO_str_publish_unlocked() */


/***************************************************************
  Grow a dynamic UCS-2 memory stream to hold NEED code units.
 ***************************************************************/
static int __mpu_IO_str_grow_unlocked( mpu_FILE *stream, size_t need )
{
  __mpu_IO_strfile  *sf;
  size_t             capacity;
  __mpu_char16_t    *buffer;

  sf = (__mpu_IO_strfile *)stream->_cookie;
  if( sf == (__mpu_IO_strfile *)0 || !sf->dynamic )
  {
    errno = ENOSPC;
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( mpu_EOF );
  }

  capacity = sf->capacity ? sf->capacity : 16;
  while( capacity < need )
  {
    if( capacity > SIZE_MAX / 2 )
    {
      capacity = need;
      break;
    }
    capacity *= 2;
  }

  if( capacity > SIZE_MAX / sizeof(__mpu_char16_t) )
  {
    errno = EOVERFLOW;
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( mpu_EOF );
  }

  buffer = (__mpu_char16_t *)realloc( sf->buffer,
                                  capacity * sizeof(__mpu_char16_t) );
  if( buffer == (__mpu_char16_t *)0 )
  {
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( mpu_EOF );
  }

  sf->buffer = buffer;
  sf->capacity = capacity;
  return( 0 );

} /* End of __mpu_IO_str_grow_unlocked() */


/***************************************************************
  Reject raw-byte underflow on a UCS-2 string stream.
 ***************************************************************/
static int __mpu_IO_str_underflow_unlocked( mpu_FILE *stream )
{
  stream->_flags |= __MPU_IO_ERR_SEEN;
  errno = EINVAL;
  return( mpu_EOF );

} /* End of __mpu_IO_str_underflow_unlocked() */


/***************************************************************
  Reject raw-byte overflow on a UCS-2 string stream.
 ***************************************************************/
static int __mpu_IO_str_overflow_unlocked( mpu_FILE *stream, int c )
{
  (void)c;
  stream->_flags |= __MPU_IO_ERR_SEEN;
  errno = EINVAL;
  return( mpu_EOF );

} /* End of __mpu_IO_str_overflow_unlocked() */


/***************************************************************
  Synchronize a UCS-2 string stream; no external I/O is required.
 ***************************************************************/
static int __mpu_IO_str_sync_unlocked( mpu_FILE *stream )
{
  return( __mpu_IO_str_publish_unlocked( stream ) );

} /* End of __mpu_IO_str_sync_unlocked() */

/***************************************************************
  Finish string-stream backend state before stream destruction.
 ***************************************************************/
static int __mpu_IO_str_finish_unlocked( mpu_FILE *stream )
{
  __mpu_IO_strfile  *sf;

  sf = (__mpu_IO_strfile *)stream->_cookie;
  if( sf != (__mpu_IO_strfile *)0 )
  {
    if( __mpu_IO_str_publish_unlocked( stream ) == mpu_EOF )
      return( mpu_EOF );
    free( sf );
    stream->_cookie = (void *)0;
  }

  return( 0 );

} /* End of __mpu_IO_str_finish_unlocked() */


/***************************************************************
  Reject stdio byte-buffer configuration on UCS-2 string streams.
 ***************************************************************/
static int __mpu_IO_str_setbuf_unlocked( mpu_FILE *stream,
                                         unsigned char *buf,
                                         int mode, size_t size )
{
  (void)stream;
  (void)buf;
  (void)mode;
  (void)size;
  errno = EINVAL;
  return( -1 );

} /* End of __mpu_IO_str_setbuf_unlocked() */


static int __mpu_IO_str_flush_unlocked( mpu_FILE *stream )
{
   return( __mpu_IO_str_publish_unlocked( stream ) );
} /* End of __mpu_IO_str_flush_unlocked() */

static int __mpu_IO_str_close_unlocked( mpu_FILE *stream )
{
  (void)stream;
  return( 0 );
} /* End of __mpu_IO_str_close_unlocked() */

/***************************************************************
  Reposition a UCS-2 memory stream.  Fixed fmemopen streams may
  seek anywhere representable by their caller-owned buffer, while
  dynamic memstreams may seek beyond the current end.  A later
  write fills any resulting gap with NUL code units.
 ***************************************************************/
static int __mpu_IO_str_seek_unlocked( mpu_FILE *stream,
                                       off_t offset, int whence )
{
  __mpu_IO_strfile  *sf;
  uintmax_t          base;
  uintmax_t          magnitude;
  uintmax_t          position;
  uintmax_t          limit;

  sf = (__mpu_IO_strfile *)stream->_cookie;
  if( sf == (__mpu_IO_strfile *)0 )
  {
    errno = EBADF;
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( -1 );
  }

  switch( whence )
  {
    case MPU_SEEK_SET: base = 0; break;
    case MPU_SEEK_CUR: base = (uintmax_t)sf->pos; break;
    case MPU_SEEK_END: base = (uintmax_t)sf->length; break;
    default:
      errno = EINVAL;
      return( -1 );
  }

  if( offset < 0 )
  {
    magnitude = (uintmax_t)(-(offset + 1)) + 1;
    if( magnitude > base )
    {
      errno = EINVAL;
      return( -1 );
    }
    position = base - magnitude;
  }
  else
  {
    if( (uintmax_t)offset > (uintmax_t)SIZE_MAX - base )
    {
      errno = EOVERFLOW;
      return( -1 );
    }
    position = base + (uintmax_t)offset;
  }

  if( sf->dynamic )
    limit = (uintmax_t)SIZE_MAX - 1;
  else if( sf->nul_terminated )
    limit = sf->capacity ? (uintmax_t)sf->capacity - 1 : 0;
  else
    limit = (uintmax_t)sf->capacity;

  if( position > limit )
  {
    errno = EINVAL;
    return( -1 );
  }

  sf->pos = (size_t)position;
  stream->_unget_count = 0;
  stream->_flags &= ~(__MPU_IO_READING | __MPU_IO_WRITING |
                      __MPU_IO_EOF_SEEN);

  return( 0 );
} /* End of __mpu_IO_str_seek_unlocked() */

static off_t __mpu_IO_str_tell_unlocked( mpu_FILE *stream )
{
  __mpu_IO_strfile  *sf = (__mpu_IO_strfile *)stream->_cookie;

  if( sf == (__mpu_IO_strfile *)0 )
  {
    errno = EBADF;
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( (off_t)-1 );
  }

  return( (off_t)sf->pos );
} /* End of __mpu_IO_str_tell_unlocked() */


/***************************************************************
  Seek a UCS-2 string stream and return the resulting position.
 ***************************************************************/
static off_t __mpu_IO_str_seekoff_unlocked( mpu_FILE *stream,
                                             off_t offset, int whence )
{
  if( __mpu_IO_str_seek_unlocked( stream, offset, whence ) != 0 )
    return( (off_t)-1 );
  return( __mpu_IO_str_tell_unlocked( stream ) );

} /* End of __mpu_IO_str_seekoff_unlocked() */


/***************************************************************
  Seek a UCS-2 string stream to an absolute position.
 ***************************************************************/
static off_t __mpu_IO_str_seekpos_unlocked( mpu_FILE *stream,
                                             off_t position )
{
  return( __mpu_IO_str_seekoff_unlocked( stream, position,
                                         MPU_SEEK_SET ) );

} /* End of __mpu_IO_str_seekpos_unlocked() */


static int __mpu_IO_str_get_char_unlocked( mpu_FILE *stream,
                                           __mpu_char16_t *wc )
{
  __mpu_IO_strfile  *sf;

  if( stream->_flags & __MPU_IO_NO_READS )
  {
    errno = EBADF;
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( mpu_EOF );
  }

  sf = (__mpu_IO_strfile *)stream->_cookie;
  if( sf == (__mpu_IO_strfile *)0 )
  {
    errno = EBADF;
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( mpu_EOF );
  }

  /* Keep native UCS-2 streams in the same directional-state model
     as descriptor and cookie streams. */
  stream->_flags &= ~__MPU_IO_WRITING;
  stream->_flags |= __MPU_IO_READING;

  if( sf->pos >= sf->length )
  {
    stream->_flags |= __MPU_IO_EOF_SEEN;
    return( mpu_EOF );
  }

  *wc = sf->buffer[sf->pos++];
  return( 0 );
} /* End of __mpu_IO_str_get_char_unlocked() */

static int __mpu_IO_str_put_char_unlocked( __mpu_char16_t wc,
                                           mpu_FILE *stream )
{
  __mpu_IO_strfile  *sf;

  if( stream->_flags & __MPU_IO_NO_WRITES )
  {
    errno = EBADF;
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( mpu_EOF );
  }

  if( wc >= (__mpu_char16_t)0xd800 && wc <= (__mpu_char16_t)0xdfff )
  {
    errno = EILSEQ;
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( mpu_EOF );
  }

  sf = (__mpu_IO_strfile *)stream->_cookie;
  if( sf == (__mpu_IO_strfile *)0 )
  {
    errno = EBADF;
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( mpu_EOF );
  }

  /* A successful text-output attempt establishes writing direction. */
  stream->_flags &= ~__MPU_IO_READING;
  stream->_flags |= __MPU_IO_WRITING;

  if( (stream->_flags & __MPU_IO_COUNTED) && sf->pos >= sf->capacity )
  {
    ++sf->pos;
    if( sf->pos > sf->length ) sf->length = sf->pos;
    return( 0 );
  }

  /* Append-mode fmemopen writes are always placed at the current
     logical end, even after a successful seek changes the read position. */
  if( stream->_flags & __MPU_IO_APPEND )
    sf->pos = sf->length;

  if( sf->nul_terminated )
  {
    if( sf->dynamic )
    {
      if( sf->pos > SIZE_MAX - 2 ||
          __mpu_IO_str_grow_unlocked( stream, sf->pos + 2 ) == mpu_EOF )
        return( mpu_EOF );
    }
    else if( sf->capacity == 0 || sf->pos + 1 >= sf->capacity )
    {
      errno = ENOSPC;
      stream->_flags |= __MPU_IO_ERR_SEEN;
      return( mpu_EOF );
    }
  }
  else if( sf->pos >= sf->capacity )
  {
    errno = ENOSPC;
    stream->_flags |= __MPU_IO_ERR_SEEN;
    return( mpu_EOF );
  }

  /* A write after seeking beyond the logical end creates a sparse
     text gap.  Materialize it as NUL UCS-2 code units, matching the
     byte-zero gap semantics of libc open_memstream(). */
  if( sf->pos > sf->length && sf->buffer != (__mpu_char16_t *)0 )
  {
    size_t i;
    for( i = sf->length; i < sf->pos; ++i )
      sf->buffer[i] = (__mpu_char16_t)0;
  }

  if( sf->buffer != (__mpu_char16_t *)0 )
    sf->buffer[sf->pos] = wc;

  ++sf->pos;
  if( sf->pos > sf->length ) sf->length = sf->pos;
  if( sf->nul_terminated && sf->buffer != (__mpu_char16_t *)0 )
    sf->buffer[sf->length] = (__mpu_char16_t)0;

  return( 0 );
} /* End of __mpu_IO_str_put_char_unlocked() */

static int __mpu_IO_str_get_byte_unlocked( mpu_FILE *stream )
{
  stream->_flags |= __MPU_IO_ERR_SEEN;
  errno = EINVAL;
  return( mpu_EOF );
} /* End of __mpu_IO_str_get_byte_unlocked() */

static int __mpu_IO_str_put_byte_unlocked( unsigned char c,
                                           mpu_FILE *stream )
{
  (void)c;
  stream->_flags |= __MPU_IO_ERR_SEEN;
  errno = EINVAL;
  return( mpu_EOF );
} /* End of __mpu_IO_str_put_byte_unlocked() */

mpu_FILE *__mpu_IO_str_open( __mpu_char16_t *buffer,
                             size_t capacity,
                             size_t length,
                             unsigned int flags )
{
  struct __mpu_IO_FILE_plus  *plus;
  mpu_FILE                   *stream;
  __mpu_IO_strfile           *sf;

  if( (buffer == (__mpu_char16_t *)0 && capacity != 0) ||
      length > capacity )
  {
    errno = EINVAL;
    return( (mpu_FILE *)0 );
  }

  plus = (struct __mpu_IO_FILE_plus *)calloc( 1, sizeof(*plus) );
  if( plus == (struct __mpu_IO_FILE_plus *)0 )
    return( (mpu_FILE *)0 );

  stream = &plus->file;
  plus->vtable = &__mpu_IO_str_jumps;

  sf = (__mpu_IO_strfile *)calloc( 1, sizeof(__mpu_IO_strfile) );
  if( sf == (__mpu_IO_strfile *)0 )
  {
    free( plus );
    return( (mpu_FILE *)0 );
  }

  sf->buffer   = buffer;
  sf->capacity = capacity;
  sf->length   = length;
  sf->pos      = 0;

  stream->_magic  = __MPU_IO_MAGIC;
  stream->_flags  = flags | __MPU_IO_STRING | __MPU_IO_USER_BUF;
  stream->_fileno = -1;
  stream->_cookie = sf;

  {
    int  lock_error = __mpu_IO_lock_init( &stream->_lock );

    if( lock_error != 0 )
    {
      free( sf );
      free( plus );
      errno = lock_error;
      return( (mpu_FILE *)0 );
    }
  }

  __mpu_IO_link_in( stream );
  return( stream );
} /* End of __mpu_IO_str_open() */

mpu_FILE *__mpu_IO_str_open_readonly( const __mpu_char16_t *buffer,
                                      size_t length )
{
  return( __mpu_IO_str_open( (__mpu_char16_t *)buffer, length, length,
                              __MPU_IO_NO_WRITES | __MPU_IO_NOLIST ) );
} /* End of __mpu_IO_str_open_readonly() */

mpu_FILE *__mpu_IO_str_open_counted( __mpu_char16_t *buffer,
                                    size_t capacity )
{
  mpu_FILE  *stream;

  stream = __mpu_IO_str_open( buffer, capacity, 0,
                              __MPU_IO_COUNTED | __MPU_IO_NOLIST );

  return( stream );

} /* End of __mpu_IO_str_open_counted() */


/***************************************************************
  Return the bounded UCS-2 string length within CAPACITY code
  units.
 ***************************************************************/
static size_t __mpu_IO_strnlen( const __mpu_char16_t *buffer, size_t capacity )
{
  size_t  n;

  for( n = 0; n < capacity; ++n )
    if( buffer[n] == (__mpu_char16_t)0 ) break;

  return( n );

} /* End of __mpu_IO_strnlen() */


/***************************************************************
  Open caller-owned UCS-2 memory as a text stream.  SIZE is the
  number of __mpu_char16_t code units including trailing-NUL
  space.
 ***************************************************************/
mpu_FILE *mpu_fmemopen( __mpu_char16_t *buffer, size_t size,
                        const char *mode )
{
  unsigned int      flags;
  int               oflags;
  mpu_FILE         *stream;
  __mpu_IO_strfile *sf;
  size_t            length;

  if( buffer == (__mpu_char16_t *)0 || size == 0 )
  {
    errno = EINVAL;
    return( (mpu_FILE *)0 );
  }

  if( __mpu_IO_parse_mode( mode, &flags, &oflags, 0 ) < 0 )
    return( (mpu_FILE *)0 );
  (void)oflags;

  length = __mpu_IO_strnlen( buffer, size );
  if( mode[0] == 'w' )
  {
    length = 0;
    buffer[0] = (__mpu_char16_t)0;
  }

  stream = __mpu_IO_str_open( buffer, size, length, flags );
  if( stream == (mpu_FILE *)0 )
    return( (mpu_FILE *)0 );

  sf = (__mpu_IO_strfile *)stream->_cookie;
  sf->nul_terminated = 1;
  if( mode[0] == 'a' ) sf->pos = sf->length;

  return( stream );

} /* End of mpu_fmemopen() */


/***************************************************************
  Open a dynamically growing UCS-2 output memory stream with
  additional internal FLAGS controlling stream-list membership.
 ***************************************************************/
mpu_FILE *__mpu_IO_str_open_memstream( __mpu_char16_t **buffer, size_t *size,
                                       unsigned int flags )
{
  mpu_FILE         *stream;
  __mpu_IO_strfile *sf;
  __mpu_char16_t   *storage;

  if( buffer == (__mpu_char16_t **)0 || size == (size_t *)0 )
  {
    errno = EINVAL;
    return( (mpu_FILE *)0 );
  }

  storage = (__mpu_char16_t *)calloc( 16, sizeof(__mpu_char16_t) );
  if( storage == (__mpu_char16_t *)0 )
    return( (mpu_FILE *)0 );

  stream = __mpu_IO_str_open( storage, 16, 0,
                              __MPU_IO_NO_READS | __MPU_IO_MEMSTREAM |
                              flags );
  if( stream == (mpu_FILE *)0 )
  {
    free( storage );
    return( (mpu_FILE *)0 );
  }

  sf = (__mpu_IO_strfile *)stream->_cookie;
  sf->nul_terminated = 1;
  sf->dynamic = 1;
  sf->publish_buffer = buffer;
  sf->publish_size = size;
  *buffer = storage;
  *size = 0;

  return( stream );

} /* End of __mpu_IO_str_open_memstream() */


/***************************************************************
  Open a public dynamically growing UCS-2 output memory stream.
  *BUFFER and *SIZE are published by fflush() and fclose().
 ***************************************************************/
mpu_FILE *mpu_open_memstream( __mpu_char16_t **buffer, size_t *size )
{
  return( __mpu_IO_str_open_memstream( buffer, size, 0 ) );

} /* End of mpu_open_memstream() */


const struct __mpu_IO_jump_t  __mpu_IO_str_jumps =
{
  .finish    = __mpu_IO_str_finish_unlocked,
  .underflow = __mpu_IO_str_underflow_unlocked,
  .overflow  = __mpu_IO_str_overflow_unlocked,
  .sync      = __mpu_IO_str_sync_unlocked,
  .setbuf    = __mpu_IO_str_setbuf_unlocked,
  .seekoff   = __mpu_IO_str_seekoff_unlocked,
  .seekpos   = __mpu_IO_str_seekpos_unlocked,
  .flush     = __mpu_IO_str_flush_unlocked,
  .close    = __mpu_IO_str_close_unlocked,
  .seek     = __mpu_IO_str_seek_unlocked,
  .tell     = __mpu_IO_str_tell_unlocked,
  .get_byte = __mpu_IO_str_get_byte_unlocked,
  .put_byte = __mpu_IO_str_put_byte_unlocked,
  .xsgetn   = (size_t (*)(mpu_FILE *, void *, size_t))0,
  .xsputn   = (size_t (*)(mpu_FILE *, const void *, size_t))0,
  .get_char = __mpu_IO_str_get_char_unlocked,
  .put_char = __mpu_IO_str_put_char_unlocked
};


/***************************************************************
  Hide internal symbols:
 ***************************************************************/

__mpu_hidden_decl(__mpu_IO_str_jumps);
__mpu_hidden_decl(__mpu_IO_str_open_memstream);
__mpu_hidden_decl(__mpu_IO_str_open);
__mpu_hidden_decl(__mpu_IO_str_open_counted);
__mpu_hidden_decl(__mpu_IO_str_open_readonly);

/*
  End of hide internal symbols.
 ***************************************************************/

/* End of mpu-string.c */