/* GNU mailutils - a suite of utilities for electronic mail
   Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Library Public License as published by
   the Free Software Foundation; either version 2, 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 Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

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

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>

#ifdef HAVE_ALLOCA_H
# include <alloca.h>
#endif

#ifdef HAVE_LIBGEN_H
# include <libgen.h>
#endif

#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif

#include <mailutils/message.h>
#include <mailutils/filter.h>
#include <mailutils/stream.h>

#define MAX_HDR_LEN 256
#define BUF_SIZE	2048

/* FIXME: this should be in a public header.  */
extern int message_attachment_filename __P ((message_t, const char **filename));

struct _msg_info
{
  char *buf;
  size_t nbytes;
  char *header_buf;
  int header_len;
  int header_size;
  header_t hdr;
  message_t msg;
  int ioffset;
  int ooffset;
  stream_t stream;		/* output file/decoding stream for saving attachment */
  stream_t fstream;		/* output file stream for saving attachment */
};

#define MSG_HDR "Content-Type: %s; name=%s\nContent-Transfer-Encoding: %s\nContent-Disposition: attachment; filename=%s\n\n"

int
message_create_attachment (const char *content_type, const char *encoding,
			   const char *filename, message_t * newmsg)
{
  header_t hdr;
  body_t body;
  stream_t fstream = NULL, tstream = NULL;
  char *header, *name = NULL, *fname = NULL;
  int ret;

  if (filename == NULL || newmsg == NULL)
    return EINVAL;

  if ((ret = message_create (newmsg, NULL)) == 0)
    {
      if (content_type == NULL)
	content_type = "text/plain";
      if (encoding == NULL)
	encoding = "7bit";
      if ((fname = strdup (filename)) != NULL)
	{
	  name = strrchr (fname, '/');
	  if (name)
	    name++;
	  else
	    name = fname;
	  if ((header =
	       alloca (strlen (MSG_HDR) + strlen (content_type) +
		       strlen (name) * 2 + strlen (encoding) + 1)) == NULL)
	    ret = ENOMEM;
	  else
	    {
	      sprintf (header, MSG_HDR, content_type, name, encoding, name);
	      if ((ret =
		   header_create (&hdr, header, strlen (header),
				  *newmsg)) == 0)
		{
		  message_get_body (*newmsg, &body);
		  if ((ret =
		       file_stream_create (&fstream, filename,
					   MU_STREAM_READ)) == 0)
		    {
		      if ((ret = stream_open (fstream)) == 0)
			{
			  if ((ret =
			       filter_create (&tstream, fstream, encoding,
					      MU_FILTER_ENCODE,
					      MU_STREAM_READ)) == 0)
			    {
			      body_set_stream (body, tstream, *newmsg);
			      message_set_header (*newmsg, hdr, NULL);
			    }
			}
		    }
		}
	    }
	}
    }
  if (ret)
    {
      if (*newmsg)
	message_destroy (newmsg, NULL);
      if (hdr)
	header_destroy (&hdr, NULL);
      if (fstream)
	stream_destroy (&fstream, NULL);
      if (fname)
	free (fname);
    }
  return ret;
}


static int
_attachment_setup (struct _msg_info **info, message_t msg, stream_t * stream,
		   void **data)
{
  int sfl, ret;
  body_t body;

  if ((ret = message_get_body (msg, &body)) != 0 ||
      (ret = body_get_stream (body, stream)) != 0)
    return ret;
  stream_get_flags (*stream, &sfl);
  if (data == NULL && (sfl & MU_STREAM_NONBLOCK))
    return EINVAL;
  if (data)
    *info = *data;
  if (*info == NULL)
    {
      if ((*info = calloc (1, sizeof (struct _msg_info))) == NULL)
	return ENOMEM;
    }
  if (((*info)->buf = malloc (BUF_SIZE)) == NULL)
    {
      free (*info);
      return ENOMEM;
    }
  return 0;
}

static void
_attachment_free (struct _msg_info *info, int free_message)
{
  if (info->buf)
    free (info->buf);
  if (info->header_buf)
    free (info->header_buf);
  if (free_message)
    {
      if (info->msg)
	message_destroy (&(info->msg), NULL);
      else if (info->hdr)
	header_destroy (&(info->hdr), NULL);
    }
  free (info);
}

#define _ISSPECIAL(c) ( \
    ((c) == '(') || ((c) == ')') || ((c) == '<') || ((c) == '>') \
    || ((c) == '@') || ((c) == ',') || ((c) == ';') || ((c) == ':') \
    || ((c) == '\\') || ((c) == '.') || ((c) == '[') \
    || ((c) == ']') )

static char *
_header_get_param (char *field_body, const char *param, size_t * len)
{
  char *str, *p, *v, *e;
  int quoted = 0, was_quoted = 0;

  if (len == NULL || (str = field_body) == NULL)
    return NULL;

  p = strchr (str, ';');
  while (p)
    {
      p++;
      while (isspace ((unsigned) *p))	/* walk upto start of param */
	p++;
      if ((v = strchr (p, '=')) == NULL)
	break;
      *len = 0;
      v = e = v + 1;
      while (*e && (quoted || (!_ISSPECIAL (*e) && !isspace ((unsigned) *e))))
	{			/* skip pass value and calc len */
	  if (*e == '\"')
	    quoted = ~quoted, was_quoted = 1;
	  else
	    (*len)++;
	  e++;
	}
      if (strncasecmp (p, param, strlen (param)))
	{			/* no match jump to next */
	  p = strchr (e, ';');
	  continue;
	}
      else
	return was_quoted ? v + 1 : v;	/* return unquoted value */
    }
  return NULL;
}

int
message_attachment_filename (message_t msg, const char **filename)
{
  char *pTmp, *fname = NULL;
  header_t hdr;
  int ret = EINVAL;
  size_t size = 0;

  if (filename != NULL && (ret = message_get_header (msg, &hdr)) == 0)
    {
      *filename = NULL;
      header_get_value (hdr, "Content-Disposition", NULL, 0, &size);
      if (size)
	{
	  if ((pTmp = alloca (size + 1)) == NULL)
	    ret = ENOMEM;
	  header_get_value (hdr, "Content-Disposition", pTmp, size + 1, 0);
	  if (strstr (pTmp, "attachment") != NULL)
	    fname = _header_get_param (pTmp, "filename", &size);
	}
      if (fname == NULL)
	{
	  size = 0;
	  header_get_value (hdr, "Content-Type", NULL, 0, &size);
	  if (size)
	    {
	      if ((pTmp = alloca (size + 1)) == NULL)
		ret = ENOMEM;
	      header_get_value (hdr, "Content-Type", pTmp, size + 1, 0);
	      fname = _header_get_param (pTmp, "name", &size);
	    }
	}
      if (fname)
	{
	  fname[size] = '\0';
	  if ((*filename = strdup (fname)) == NULL)
	    ret = ENOMEM;
	}
      else
	ret = ENOENT;
    }
  return ret;
}

int
message_save_attachment (message_t msg, const char *filename, void **data)
{
  stream_t istream;
  struct _msg_info *info = NULL;
  int ret;
  size_t size;
  size_t nbytes;
  header_t hdr;
  char *content_encoding;
  const char *fname = NULL;

  if (msg == NULL || filename == NULL)
    return EINVAL;

  if ((ret = _attachment_setup (&info, msg, &istream, data)) != 0)
    return ret;

  if (ret == 0 && (ret = message_get_header (msg, &hdr)) == 0)
    {
      if (filename == NULL)
	ret = message_attachment_filename (msg, &fname);
      else
	fname = filename;
      if (fname
	  && (ret =
	      file_stream_create (&info->fstream, fname,
				  MU_STREAM_WRITE | MU_STREAM_CREAT)) == 0)
	{
	  if ((ret = stream_open (info->fstream)) == 0)
	    {
	      header_get_value (hdr, "Content-Transfer-Encoding", NULL, 0,
				&size);
	      if (size)
		{
		  if ((content_encoding = alloca (size + 1)) == NULL)
		    ret = ENOMEM;
		  header_get_value (hdr, "Content-Transfer-Encoding",
				    content_encoding, size + 1, 0);
		}
	      else
		content_encoding = (char *) "7bit";
	      ret =
		filter_create (&info->stream, istream, content_encoding,
			       MU_FILTER_DECODE, MU_STREAM_READ);
	    }
	}
    }
  if (info->stream && istream)
    {
      if (info->nbytes)
	memmove (info->buf, info->buf + (BUF_SIZE - info->nbytes),
		 info->nbytes);
      while ((ret == 0 && info->nbytes)
	     ||
	     ((ret =
	       stream_read (info->stream, info->buf, BUF_SIZE, info->ioffset,
			    &info->nbytes)) == 0 && info->nbytes))
	{
	  info->ioffset += info->nbytes;
	  while (info->nbytes)
	    {
	      if ((ret =
		   stream_write (info->fstream, info->buf, info->nbytes,
				 info->ooffset, &nbytes)) != 0)
		break;
	      info->nbytes -= nbytes;
	      info->ooffset += nbytes;
	    }
	}
    }
  if (ret != EAGAIN && info)
    {
      stream_close (info->fstream);
      stream_destroy (&info->stream, NULL);
      stream_destroy (&info->fstream, NULL);
      _attachment_free (info, ret);
    }
  return ret;
}

int
message_encapsulate (message_t msg, message_t * newmsg, void **data)
{
  stream_t istream, ostream;
  const char *header;
  struct _msg_info *info = NULL;
  int ret = 0;
  size_t nbytes;
  body_t body;

  if (msg == NULL || newmsg == NULL)
    return EINVAL;

  if ((ret = _attachment_setup (&info, msg, &ostream, data)) != 0)
    return ret;

  if (info->msg == NULL && (ret = message_create (&(info->msg), NULL)) == 0)
    {
      header =
	"Content-Type: message/rfc822\nContent-Transfer-Encoding: 7bit\n\n";
      if ((ret =
	   header_create (&(info->hdr), header, strlen (header), msg)) == 0)
	ret = message_set_header (info->msg, info->hdr, NULL);
    }
  if (ret == 0 && (ret = message_get_stream (msg, &istream)) == 0)
    {
      if ((ret = message_get_body (info->msg, &body)) == 0 &&
	  (ret = body_get_stream (body, &ostream)) == 0)
	{
	  if (info->nbytes)
	    memmove (info->buf, info->buf + (BUF_SIZE - info->nbytes),
		     info->nbytes);
	  while ((ret == 0 && info->nbytes)
		 ||
		 ((ret =
		   stream_read (istream, info->buf, BUF_SIZE, info->ioffset,
				&info->nbytes)) == 0 && info->nbytes))
	    {
	      info->ioffset += info->nbytes;
	      while (info->nbytes)
		{
		  if ((ret =
		       stream_write (ostream, info->buf, info->nbytes,
				     info->ooffset, &nbytes)) != 0)
		    break;
		  info->nbytes -= nbytes;
		  info->ooffset += nbytes;
		}
	    }
	}
    }
  if (ret == 0)
    *newmsg = info->msg;
  if (ret != EAGAIN && info)
    _attachment_free (info, ret);
  return ret;
}

int
message_unencapsulate (message_t msg, message_t * newmsg, void **data)
{
  size_t size, nbytes;
  int ret = 0;
  char *content_type;
  header_t hdr;
  stream_t istream, ostream;
  struct _msg_info *info = NULL;

  if (msg == NULL || newmsg == NULL)
    return EINVAL;

  if ((data == NULL || *data == NULL)
      && (ret = message_get_header (msg, &hdr)) == 0)
    {
      header_get_value (hdr, "Content-Type", NULL, 0, &size);
      if (size)
	{
	  if ((content_type = alloca (size + 1)) == NULL)
	    return ENOMEM;
	  header_get_value (hdr, "Content-Type", content_type, size + 1, 0);
	  if (strncasecmp
	      (content_type, "message/rfc822",
	       strlen ("message/rfc822")) != 0)
	    return EINVAL;
	}
      else
	return EINVAL;
    }
  if ((ret = _attachment_setup (&info, msg, &istream, data)) != 0)
    return ret;
  if (info->msg == NULL)
    ret = message_create (&(info->msg), NULL);
  if (ret == 0)
    {
      message_get_stream (info->msg, &ostream);
      if (info->nbytes)
	memmove (info->buf, info->buf + (BUF_SIZE - info->nbytes),
		 info->nbytes);
      while ((ret == 0 && info->nbytes)
	     ||
	     ((ret =
	       stream_read (istream, info->buf, BUF_SIZE, info->ioffset,
			    &info->nbytes)) == 0 && info->nbytes))
	{
	  info->ioffset += info->nbytes;
	  while (info->nbytes)
	    {
	      if ((ret =
		   stream_write (ostream, info->buf, info->nbytes,
				 info->ooffset, &nbytes)) != 0)
		break;
	      info->nbytes -= nbytes;
	      info->ooffset += nbytes;
	    }
	}
    }
  if (ret == 0)
    *newmsg = info->msg;
  if (ret != EAGAIN && info)
    _attachment_free (info, ret);
  return ret;
}