#!/usr/bin/python
#    Copyright 2011 Jeff Epler <jepler@unpythonic.net>
#
#    This program 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 2 of the License, 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 General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, write to the Free Software
#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
import email
import glob
import os
import mimetypes
import sys
import tempfile
import shutil
import subprocess
import re

def convert_tnef_to_mime(message, part):
    content_type = part.get_content_type()
    print >>sys.stderr, "subpart", content_type
    if content_type != 'application/ms-tnef': return 0
    print >>sys.stderr, "should convert this subpart"
    tempdir = tempfile.mkdtemp()
    print >>sys.stderr, "temporary directory", tempdir
    try:
        pipe = subprocess.Popen(['tnef', '-C', tempdir], stdin=subprocess.PIPE,
                stdout=sys.stderr)
        pipe.communicate(part.get_payload(decode=True))
        pipe.wait()
        if pipe.returncode:
            print >>sys.stderr, "tnef exited with code %r" % pipe.returncode
        extracted = glob.glob(os.path.join(tempdir, "*"))
        print >>sys.stderr, "extracted", tempdir, extracted
        if extracted:
            payload = []
            for fn in extracted:
                safename = re.sub("[^-a-zA-Z0-9_. ]", "", os.path.basename(fn))
                mtype = mimetypes.guess_type(fn)
                if mtype: mtype = mtype[0]
                else: mtype = 'application/octet-stream'
                newsubpart = email.message.Message()
                newsubpart.set_type("%s; name=\"%s\"" % (mtype, safename))
                newsubpart.set_payload(open(fn).read().encode("base64"))
                newsubpart.add_header("content-transfer-encoding", "base64")
                message.attach(newsubpart)
                print >>sys.stderr, "newsubpart:", safename
            return len(extracted)
        else:
            print >>sys.stderr, "tnef attachment appeared to have no contents"
            print >>sys.stderr, "left unchanged"
            return 0
    finally:
        pass
        #shutil.rmtree(tempdir)
    
mdata = sys.stdin.read()
try:
    message = email.message_from_string(mdata)
    new_parts = 0
    for part in message.walk(): new_parts += convert_tnef_to_mime(message, part)
    if new_parts:
        print >>sys.stderr, "Changed %d tnef attachment(s) to mime" % new_parts
        del message['content-length']
        mdata = message.as_string(True)
    sys.stdout.write(mdata)
except:
    sys.stdout.write(mdata)
    print >>sys.stderr, "Error encountered.  Original message written on stdout"
    raise