/* GNU Mailutils -- a suite of utilities for electronic mail
   Copyright (C) 2009, 2010 Free Software Foundation, Inc.

   GNU Mailutils 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, or (at your option)
   any later version.

   GNU Mailutils 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 GNU Mailutils.  If not, see <http://www.gnu.org/licenses/>. */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <string.h>
#include <stdlib.h>
#include <limits.h>
#ifndef SIZE_MAX
# define SIZE_MAX (~((size_t)0))
#endif

#include <mailutils/types.h>
#include <mailutils/alloc.h>
#include <mailutils/error.h>
#include <mailutils/errno.h>
#include <mailutils/nls.h>
#include <mailutils/stream.h>
#include <mailutils/sys/stream.h>

static int
_stream_seterror (struct _mu_stream *stream, int code, int perm)
{
  stream->last_err = code;
  switch (code)
    {
    case 0:
    case EAGAIN:
    case EINPROGRESS:
      break;

    default:
      if (perm)
	stream->flags |= _MU_STR_ERR;
    }
  return code;
}

#define _stream_cleareof(s) ((s)->flags &= ~_MU_STR_EOF)
#define _stream_advance_buffer(s,n) ((s)->cur += n, (s)->level -= n)
#define _stream_buffer_offset(s) ((s)->cur - (s)->buffer)
#define _stream_orig_level(s) ((s)->level + _stream_buffer_offset (s))

static int
_stream_fill_buffer (struct _mu_stream *stream)
{
  size_t n;
  size_t rdn;
  int rc = 0;
  char c;
    
  switch (stream->buftype)
    {
    case mu_buffer_none:
      return 0;
	
    case mu_buffer_full:
      rc = mu_stream_read_unbuffered (stream,
				      stream->buffer, stream->bufsize,
				      0,
				      &stream->level);
      break;
	
    case mu_buffer_line:
      for (n = 0;
	   n < stream->bufsize
	     && (rc = mu_stream_read_unbuffered (stream,
						 &c, 1, 0, &rdn)) == 0
	     && rdn; n++)
	{
	  stream->buffer[n] = c;
	  if (c == '\n')
	    break;
	}
      stream->level = n;
      break;
    }
  stream->cur = stream->buffer;
  return rc;
}

#define BUFFER_FULL_P(s) \
  ((s)->cur + (s)->level == (s)->buffer + (s)->bufsize)

static int
_stream_buffer_full_p (struct _mu_stream *stream)
{
    switch (stream->buftype)
      {
      case mu_buffer_none:
	break;
	
      case mu_buffer_line:
	return BUFFER_FULL_P (stream)
	       || memchr (stream->cur, '\n', stream->level) != NULL;

      case mu_buffer_full:
	return BUFFER_FULL_P (stream);
      }
    return 0;
}

static int
_stream_flush_buffer (struct _mu_stream *stream, int all)
{
  int rc;
  char *end;
		  
  if (stream->flags & _MU_STR_DIRTY)
    {
      if ((stream->flags & MU_STREAM_SEEK)
	  && (rc = mu_stream_seek (stream, stream->offset, MU_SEEK_SET, NULL)))
	return rc;

      switch (stream->buftype)
	{
	case mu_buffer_none:
	    abort(); /* should not happen */
	    
	case mu_buffer_full:
	  if ((rc = mu_stream_write_unbuffered (stream, stream->cur,
						stream->level, 1, NULL)))
	    return rc;
	  if (all)
	    _stream_advance_buffer (stream, stream->level);
	  break;
	    
	case mu_buffer_line:
	  if (stream->level == 0)
	    break;
	  for (end = memchr (stream->cur, '\n', stream->level);
	       end;
	       end = memchr (stream->cur, '\n', stream->level))
	    {
	      size_t size = end - stream->cur + 1;
	      rc = mu_stream_write_unbuffered (stream,
					       stream->cur,
					       size, 1, NULL);
	      if (rc)
		return rc;
	      _stream_advance_buffer (stream, size);
	    }
	  if ((all && stream->level) || BUFFER_FULL_P (stream))
	    {
	      rc = mu_stream_write_unbuffered (stream,
					       stream->cur,
					       stream->level,
					       1, NULL);
	      if (rc)
		return rc;
	      _stream_advance_buffer (stream, stream->level);
	    }
	}
    }
  else if (all)
    _stream_advance_buffer (stream, stream->level);
  
  if (stream->level)
    {
      if (stream->cur > stream->buffer)
	memmove (stream->buffer, stream->cur, stream->level);
    }
  else
    {
      stream->flags &= ~_MU_STR_DIRTY;
      stream->level = 0;
    }
  stream->cur = stream->buffer;
  return 0;
}


mu_stream_t
_mu_stream_create (size_t size, int flags)
{
  struct _mu_stream *str;
  if (size < sizeof (str))
    abort ();
  str = mu_zalloc (size);
  str->flags = flags;
  mu_stream_ref (str);
  return str;
}

void
mu_stream_destroy (mu_stream_t *pstream)
{
  if (pstream)
    {
      mu_stream_t str = *pstream;
      if (str && (str->ref_count == 0 || --str->ref_count == 0))
	{
	  mu_stream_close (str);
	  if (str->done)
	    str->done (str);
	  free (str);
	  *pstream = NULL;
	}
    }
}

void
mu_stream_get_flags (mu_stream_t str, int *pflags)
{
  *pflags = str->flags & ~_MU_STR_INTERN_MASK;
}
  
void
mu_stream_ref (mu_stream_t stream)
{
  stream->ref_count++;
}

void
mu_stream_unref (mu_stream_t stream)
{
  mu_stream_destroy (&stream);
}

int
mu_stream_open (mu_stream_t stream)
{
  int rc;

  if (stream->open && (rc = stream->open (stream)))
    return _stream_seterror (stream, rc, 1);
  stream->bytes_in = stream->bytes_out = 0;
  return 0;
}

const char *
mu_stream_strerror (mu_stream_t stream, int rc)
{
  const char *str;

  if (stream->error_string)
    str = stream->error_string (stream, rc);
  else
    str = mu_strerror (rc);
  return str;
}

int
mu_stream_err (mu_stream_t stream)
{
  return stream->flags & _MU_STR_ERR;
}

int
mu_stream_last_error (mu_stream_t stream)
{
  return stream->last_err;
}

void
mu_stream_clearerr (mu_stream_t stream)
{
  stream->last_err = 0;
  stream->flags &= ~_MU_STR_ERR;
}

int
mu_stream_eof (mu_stream_t stream)
{
  return stream->flags & _MU_STR_EOF;
}

int
mu_stream_seek (mu_stream_t stream, mu_off_t offset, int whence,
		mu_off_t *pres)
{    
  int rc;
  mu_off_t size;
  
  if (!stream->seek)
    return _stream_seterror (stream, ENOSYS, 0);

  if (!(stream->flags & MU_STREAM_SEEK))
    return _stream_seterror (stream, EACCES, 1);

  switch (whence)
    {
    case MU_SEEK_SET:
      break;

    case MU_SEEK_CUR:
      if (offset == 0)
	{
	  *pres = stream->offset + _stream_buffer_offset (stream);
	  return 0;
	}
      offset += stream->offset;
      break;

    case MU_SEEK_END:
      rc = mu_stream_size (stream, &size);
      if (rc)
	return _stream_seterror (stream, rc, 1);
      offset += size;
      break;

    default:
      return _stream_seterror (stream, EINVAL, 1);
    }

  if (stream->buftype == mu_buffer_none
      || offset < stream->offset
      || offset > stream->offset + _stream_buffer_offset (stream))
    {
      if ((rc = _stream_flush_buffer (stream, 1)))
	return rc;
      rc = stream->seek (stream, offset, MU_SEEK_SET, &stream->offset);
      if (rc)
	return _stream_seterror (stream, rc, 1);
      _stream_cleareof (stream);
    }
  
  if (pres)
    *pres = stream->offset + _stream_buffer_offset (stream);
  return 0;
}

int
mu_stream_set_buffer (mu_stream_t stream, enum mu_buffer_type type,
		      size_t size)
{
  if (size == 0)
    type = mu_buffer_none;

  if (stream->buffer)
    {
      mu_stream_flush (stream);
      free (stream->buffer);
    }

  stream->buftype = type;
  if (type == mu_buffer_none)
    {
      stream->buffer = NULL;
      return 0;
    }

  stream->buffer = mu_alloc (size);
  if (stream->buffer == NULL)
    {
      stream->buftype = mu_buffer_none;
      return _stream_seterror (stream, ENOMEM, 1);
    }
  stream->bufsize = size;
  stream->cur = stream->buffer;
  stream->level = 0;
    
  return 0;
}

int
mu_stream_read_unbuffered (mu_stream_t stream, void *buf, size_t size,
			   int full_read,
			   size_t *pnread)
{
  int rc;
  size_t nread;
    
  if (!stream->read) 
    return _stream_seterror (stream, ENOSYS, 0);

  if (!(stream->flags & MU_STREAM_READ)) 
    return _stream_seterror (stream, EACCES, 1);
    
  if (stream->flags & _MU_STR_ERR)
    return stream->last_err;
    
  if ((stream->flags & _MU_STR_EOF) || size == 0)
    {
      if (pnread)
	*pnread = 0;
      return 0;
    }
    
    if (full_read)
      {
	size_t rdbytes;

	nread = 0;
	while (size > 0
	       && (rc = stream->read (stream, buf, size, &rdbytes)) == 0)
	  {
	    if (rdbytes == 0)
	      {
		stream->flags |= _MU_STR_EOF;
		break;
	      }
	    buf += rdbytes;
	    nread += rdbytes;
	    size -= rdbytes;
	    stream->bytes_in += rdbytes;
	    
	  }
	if (size && rc)
	  rc = _stream_seterror (stream, rc, 0);
      }
    else
      {
	rc = stream->read (stream, buf, size, &nread);
	if (rc == 0)
	  {
	    if (nread == 0)
	      stream->flags |= _MU_STR_EOF;
	    stream->bytes_in += nread;
	  }
	_stream_seterror (stream, rc, rc != 0);
      }
    stream->offset += nread;
    if (pnread)
      *pnread = nread;
    
    return rc;
}

int
mu_stream_write_unbuffered (mu_stream_t stream,
			    const void *buf, size_t size,
			    int full_write,
			    size_t *pnwritten)
{
  int rc;
  size_t nwritten;
  
  if (!stream->write) 
    return _stream_seterror (stream, ENOSYS, 0);

  if (!(stream->flags & MU_STREAM_WRITE)) 
    return _stream_seterror (stream, EACCES, 1);

  if (stream->flags & _MU_STR_ERR)
    return stream->last_err;

  if (size == 0)
    {
      if (pnwritten)
	*pnwritten = 0;
      return 0;
    }
    
  if (full_write)
    {
      size_t wrbytes;
      const char *bufp = buf;

      nwritten = 0;
      while (size > 0
	     && (rc = stream->write (stream, bufp, size, &wrbytes))
	             == 0)
	{
	  if (wrbytes == 0)
	    {
	      rc = EIO;
	      break;
	    }
	  bufp += wrbytes;
	  nwritten += wrbytes;
	  size -= wrbytes;
	  stream->bytes_out += wrbytes;
	}
    }
  else
    {
      rc = stream->write (stream, buf, size, &nwritten);
      if (rc == 0)
	stream->bytes_out += nwritten;
    }
  stream->flags |= _MU_STR_WRT;
  stream->offset += nwritten;
  if (pnwritten)
    *pnwritten = nwritten;
  _stream_seterror (stream, rc, rc != 0);
  return rc;
}

int
mu_stream_read (mu_stream_t stream, void *buf, size_t size, size_t *pread)
{
  if (stream->buftype == mu_buffer_none)
    return mu_stream_read_unbuffered (stream, buf, size, !pread, pread);
  else
    {
      char *bufp = buf;
      size_t nbytes = 0;
      while (size)
	{
	  size_t n;
	  int rc;
	  
	  if (stream->level == 0)
	    {
	      if ((rc = _stream_fill_buffer (stream)))
		{
		  if (nbytes)
		    break;
		  return rc;
		}
	      if (stream->level == 0)
		break;
	    }
	  
	  n = size;
	  if (n > stream->level)
	    n = stream->level;
	  memcpy (bufp, stream->cur, n);
	  _stream_advance_buffer (stream, n);
	  nbytes += n;
	  bufp += n;
	  size -= n;
	  if (stream->buftype == mu_buffer_line && bufp[-1] == '\n')
	    break;
	}
      
      if (pread)
	*pread = nbytes;
    }
  return 0;
}

int
_stream_scandelim (mu_stream_t stream, char *buf, size_t size, int delim,
		   size_t *pnread)
{
  int rc = 0;
  size_t nread = 0;
  
  size--;
  while (size)
    {
      char *p;
      size_t len;
      
      if (stream->level == 0)
	{
	  if ((rc = _stream_fill_buffer (stream)) || stream->level == 0)
	    break;
	}
      
      p = memchr (stream->cur, delim, stream->level);
      len = p ? p - stream->cur + 1 : stream->level;
      if (len > size)
	len = size;
      memcpy (buf, stream->cur, len);
      _stream_advance_buffer (stream, len);
      buf += len;
      size -= len;
      nread += len;
    }
  *buf = 0;
  *pnread = nread;
  return rc;
}

static int
_stream_readdelim (mu_stream_t stream, char *buf, size_t size,
		   int delim, size_t *pread)
{
  int rc;
  char c;
  size_t n = 0, rdn;
    
  size--;
  for (n = 0;
       n < size && (rc = mu_stream_read (stream, &c, 1, &rdn)) == 0 && rdn;)
    {
      *buf++ = c;
      n++;
      if (c == delim)
	break;
    }
  *buf = 0;
  if (pread)
    *pread = n;
  return rc;
}

int
mu_stream_readdelim (mu_stream_t stream, char *buf, size_t size,
		     int delim, size_t *pread)
{
  int rc;
  
  if (size == 0)
    return EINVAL;
    
  if (stream->readdelim)
    rc = stream->readdelim (stream, buf, size, delim, pread);
  else if (stream->buftype != mu_buffer_none)
    rc = _stream_scandelim (stream, buf, size, delim, pread);
  else
    rc = _stream_readdelim (stream, buf, size, delim, pread);
  return rc;
}

int
mu_stream_readline (mu_stream_t stream, char *buf, size_t size, size_t *pread)
{
  return mu_stream_readdelim (stream, buf, size, '\n', pread);
}

int
mu_stream_getdelim (mu_stream_t stream, char **pbuf, size_t *psize,
		    int delim, size_t *pread)
{
  int rc;
  char *lineptr = *pbuf;
  size_t n = *psize;
  size_t cur_len = 0;
    
  if (lineptr == NULL || n == 0)
    {
      char *new_lineptr;
      n = 120;
      new_lineptr = mu_realloc (lineptr, n);
      if (new_lineptr == NULL) 
	return ENOMEM;
      lineptr = new_lineptr;
    }
    
  for (;;)
    {
      size_t rdn;

      /* Make enough space for len+1 (for final NUL) bytes.  */
      if (cur_len + 1 >= n)
	{
	  size_t needed_max =
	    SSIZE_MAX < SIZE_MAX ? (size_t) SSIZE_MAX + 1 : SIZE_MAX;
	  size_t needed = 2 * n + 1;   /* Be generous. */
	  char *new_lineptr;
	  
	  if (needed_max < needed)
	    needed = needed_max;
	  if (cur_len + 1 >= needed)
	    {
	      rc = EOVERFLOW;
	      break;
	    }
	    
	  new_lineptr = mu_realloc (lineptr, needed);
	  if (new_lineptr == NULL)
	    {
	      rc = ENOMEM;
	      break;
	    }
	    
	  lineptr = new_lineptr;
	  n = needed;
	}

      if (stream->readdelim)
	rc = stream->readdelim (stream, lineptr + cur_len, n - cur_len, delim,
				&rdn);
      else if (stream->buftype != mu_buffer_none)
	rc = _stream_scandelim (stream, lineptr + cur_len, n - cur_len, delim,
				&rdn);
      else
	rc = mu_stream_read (stream, lineptr + cur_len, 1, &rdn);

      if (rc || rdn == 0)
	break;
      cur_len += rdn;
      
      if (lineptr[cur_len - 1] == delim)
	break;
    }
  lineptr[cur_len] = '\0';
    
  *pbuf = lineptr;
  *psize = n;
  
  if (pread)
    *pread = cur_len;
  return rc;
}

int
mu_stream_getline (mu_stream_t stream, char **pbuf, size_t *psize,
		   size_t *pread)
{
    return mu_stream_getdelim (stream, pbuf, psize, '\n', pread);
}

int
mu_stream_write (mu_stream_t stream, const void *buf, size_t size,
		 size_t *pnwritten)
{
  int rc = 0;
  
  if (stream->buftype == mu_buffer_none)
    rc = mu_stream_write_unbuffered (stream, buf, size,
				     !pnwritten, pnwritten);
  else
    {
      size_t nbytes = 0;
      const char *bufp = buf;
	
      while (1)
	{
	  size_t n;
	  
	  if (_stream_buffer_full_p (stream)
	      && (rc = _stream_flush_buffer (stream, 0)))
	    break;

	  if (size == 0)
	    break;
	    
	  n = stream->bufsize - stream->level;
	  if (n > size)
	    n = size;
	  memcpy (stream->cur + stream->level, bufp, n);
	  stream->level += n;
	  nbytes += n;
	  bufp += n;
	  size -= n;
	  stream->flags |= _MU_STR_DIRTY;
	}
      if (pnwritten)
	*pnwritten = nbytes;
    }
  return rc;
}

int
mu_stream_writeline (mu_stream_t stream, const char *buf, size_t size)
{
  int rc;
  if ((rc = mu_stream_write (stream, buf, size, NULL)) == 0)
    rc = mu_stream_write (stream, "\r\n", 2, NULL);
  return rc;
}

int
mu_stream_flush (mu_stream_t stream)
{
  int rc;
  
  if (!stream)
    return EINVAL;
  rc = _stream_flush_buffer (stream, 1);
  if (rc)
    return rc;
  if ((stream->flags & _MU_STR_WRT) && stream->flush)
    return stream->flush (stream);
  stream->flags &= ~_MU_STR_WRT;
  return 0;
}

int
mu_stream_close (mu_stream_t stream)
{
  int rc = 0;
    
  if (!stream)
    return EINVAL;
  mu_stream_flush (stream);
  /* Do close the stream only if it is not used by anyone else */
  if (stream->ref_count > 1)
    return 0;
  if (stream->close)
    rc = stream->close (stream);
  return rc;
}

int
mu_stream_size (mu_stream_t stream, mu_off_t *psize)
{
  int rc;
    
  if (!stream->size)
    return _stream_seterror (stream, ENOSYS, 0);
  rc = stream->size (stream, psize);
  return _stream_seterror (stream, rc, rc != 0);
}

mu_off_t
mu_stream_bytes_in (mu_stream_t stream)
{
  return stream->bytes_in;
}

mu_off_t
mu_stream_bytes_out (mu_stream_t stream)
{
  return stream->bytes_out;
}

int
mu_stream_ioctl (mu_stream_t stream, int code, void *ptr)
{
  if (stream->ctl == NULL)
    return ENOSYS;
  return stream->ctl (stream, code, ptr);
}

int
mu_stream_wait (mu_stream_t stream, int *pflags, struct timeval *tvp)
{
  int flg = 0;
  if (stream == NULL)
    return EINVAL;
  
  /* Take to acount if we have any buffering.  */
  /* FIXME: How about MU_STREAM_READY_WR? */
  if ((*pflags) & MU_STREAM_READY_RD 
      && stream->buftype != mu_buffer_none
      && stream->level > 0)
    {
      flg = MU_STREAM_READY_RD;
      *pflags &= ~MU_STREAM_READY_RD;
    }

  if (stream->wait)
    {
      int rc = stream->wait (stream, pflags, tvp);
      if (rc == 0)
	*pflags |= flg;
      return rc;
    }
  
  return ENOSYS;
}

int
mu_stream_truncate (mu_stream_t stream, mu_off_t size)
{
  if (stream->truncate)
    return stream->truncate (stream, size);
  return ENOSYS;
}

int
mu_stream_shutdown (mu_stream_t stream, int how)
{
  if (stream->shutdown)
    return stream->shutdown (stream, how);
  return ENOSYS;
}

int
mu_stream_set_flags (mu_stream_t stream, int fl)
{
  if (stream == NULL)
    return EINVAL;
  stream->flags |= (fl & ~_MU_STR_INTERN_MASK);
  return 0;
}

int
mu_stream_clr_flags (mu_stream_t stream, int fl)
{
  if (stream == NULL)
    return EINVAL;
  stream->flags &= ~(fl & ~_MU_STR_INTERN_MASK);
  return 0;
}