# Copyright (C) 1998,1999,2000,2001 by the Free Software Foundation, Inc.
#
# 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.

"""Parse RFC 1894 (i.e. DSN) bounce formats."""

import string
import multifile
import mimetools

from Mailman.pythonlib.StringIO import StringIO



def parseaddr(val):
    try:
        atype, addr = string.split(val, ';')
    except ValueError:
        # Bogus format for Original-Recipient: or Final-Recipient: fields
        return None
    if string.lower(string.strip(atype)) <> 'rfc822':
        return None
    addr = string.strip(addr)
    if not addr:
        return None
    # strip off <>
    if addr[0] == '<' and addr[-1] == '>':
        addr = addr[1:-1]
    return addr



def process(msg):
    ctype = msg.gettype() or ''
    param = msg.getparam('report-type') or ''
    if string.lower(ctype) <> 'multipart/report' or \
       string.lower(param) <> 'delivery-status':
        # then
        return None
    boundary = msg.getparam('boundary')
    msg.fp.seek(0)
    mfile = multifile.MultiFile(msg.fp)
    mfile.push(boundary)
    # find the subpart with message/delivery-status information
    while 1:
        try:
            more = mfile.next()
        except multifile.Error:
            # the message *looked* like a DSN, but it really wasn't :(
            return None
        except TypeError:
            # This message has serious problems, pass it on.  Seen in the
            # wild: it is a MIME document with no boundary parameter in its
            # Content-Type: header.
            return None
        if not more:
            # we didn't find it
            return None
        try:
            s = StringIO(mfile.read())
        except multifile.Error:
            # It is a mis-formated or incomplete message
            return None
        msg2 = mimetools.Message(s)
        if msg2.gettype() == 'message/delivery-status':
            # hmm, could there be more than one DSN per message?
            break
    # now parse out the per-recipient fields, which are separated by blank
    # lines.  the first block is actually the per-notification fields, but
    # those can be safely ignored
    #
    # we try to dig out the Original-Recipient (which is optional) and
    # Final-Recipient (which is mandatory, but may not exactly match an addr
    # on our list).  Some MTA's also use X-Actual-Recipeint as a synonym for
    # Original-Recipeint, but some apparently use that for other purposes :(
    #
    # Also grok out Action so we can do something with that too.
    blocks = []
    headers = {}
    while 1:
        line = msg2.fp.readline()
        if not line:
            break
        line = string.strip(line)
        if not line:
            # a new recipient block
            blocks.append(headers)
            headers = {}
        try:
            hdr, val = string.split(line, ':', 1)
        except ValueError:
            continue
        headers[string.lower(hdr)] = string.strip(val)
    # now go through all the blocks, finding the recip address that is being
    # reported.
    addrs = []
    for headers in blocks:
        if string.lower(headers.get('action', '')) <> 'failed':
            # ignore this block
            continue
        # preference order is original-recipient, final-recipient
##        val = headers.get('original-recipient',
##                          headers.get('x-actual-recipient',
##                                      headers.get('final-recipient')))
        val = headers.get('original-recipient',
                          headers.get('final-recipient'))
        if val:
            addrs.append(parseaddr(val))
    return filter(None, addrs) or None
