/* 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));
extern char *base_name __P ((char const *));

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 ostream; // output file/decoding 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 = base_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) ) == 0 ) {
						if ( ( ret = stream_open(fstream, filename, 0,  MU_STREAM_READ) ) == 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, fstream;
	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(&fstream) ) == 0 ) {
			if ( ( ret = stream_open(fstream, fname, 0,  MU_STREAM_WRITE|MU_STREAM_CREAT) ) == 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->ostream, fstream, content_encoding, MU_FILTER_DECODE, MU_STREAM_READ);
			}
		}
	}
	if ( info->ostream && istream ) {
		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(info->ostream, info->buf, info->nbytes, info->ooffset, &nbytes ) ) != 0 )
					break;
				info->nbytes -= nbytes;
				info->ooffset += nbytes;
			}
		}
	}
	if ( ret != EAGAIN && info ) {
		stream_close(info->ostream);
		stream_destroy(&info->ostream, 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(content_type)) != 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;
}