# Copyright (C) 2000-2009 by the Free Software Foundation, Inc.
#
# This file is part of GNU Mailman.
#
# GNU Mailman 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 of the License, or (at your option)
# any later version.
#
# GNU Mailman 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 Mailman.  If not, see <http://www.gnu.org/licenses/>.

"""NNTP queue runner."""

import re
import email
import socket
import logging
import nntplib

from cStringIO import StringIO

from mailman import Utils
from mailman.config import config
from mailman.interfaces.nntp import NewsModeration
from mailman.queue import Runner

COMMASPACE = ', '
log = logging.getLogger('mailman.error')


# Matches our Mailman crafted Message-IDs.  See Utils.unique_message_id()
# XXX The move to email.utils.make_msgid() breaks this.
mcre = re.compile(r"""
    <mailman.                                     # match the prefix
    \d+.                                          # serial number
    \d+.                                          # time in seconds since epoch
    \d+.                                          # pid
    (?P<listname>[^@]+)                           # list's internal_name()
    @                                             # localpart@dom.ain
    (?P<hostname>[^>]+)                           # list's host_name
    >                                             # trailer
    """, re.VERBOSE)



class NewsRunner(Runner):
    def _dispose(self, mlist, msg, msgdata):
        # Make sure we have the most up-to-date state
        mlist.Load()
        if not msgdata.get('prepped'):
            prepare_message(mlist, msg, msgdata)
        try:
            # Flatten the message object, sticking it in a StringIO object
            fp = StringIO(msg.as_string())
            conn = None
            try:
                try:
                    nntp_host, nntp_port = Utils.nntpsplit(mlist.nntp_host)
                    conn = nntplib.NNTP(nntp_host, nntp_port,
                                        readermode=True,
                                        user=config.nntp.username,
                                        password=config.nntp.password)
                    conn.post(fp)
                except nntplib.error_temp, e:
                    log.error('(NNTPDirect) NNTP error for list "%s": %s',
                              mlist.internal_name(), e)
                except socket.error, e:
                    log.error('(NNTPDirect) socket error for list "%s": %s',
                              mlist.internal_name(), e)
            finally:
                if conn:
                    conn.quit()
        except Exception, e:
            # Some other exception occurred, which we definitely did not
            # expect, so set this message up for requeuing.
            self._log(e)
            return True
        return False



def prepare_message(mlist, msg, msgdata):
    # If the newsgroup is moderated, we need to add this header for the Usenet
    # software to accept the posting, and not forward it on to the n.g.'s
    # moderation address.  The posting would not have gotten here if it hadn't
    # already been approved.  1 == open list, mod n.g., 2 == moderated
    if mlist.news_moderation in (NewsModeration.open_moderated,
                                 NewsModeration.moderated):
        del msg['approved']
        msg['Approved'] = mlist.posting_address
    # Should we restore the original, non-prefixed subject for gatewayed
    # messages? TK: We use stripped_subject (prefix stripped) which was
    # crafted in CookHeaders.py to ensure prefix was stripped from the subject
    # came from mailing list user.
    stripped_subject = msgdata.get('stripped_subject') \
                       or msgdata.get('origsubj')
    if not mlist.news_prefix_subject_too and stripped_subject is not None:
        del msg['subject']
        msg['subject'] = stripped_subject
    # Add the appropriate Newsgroups: header
    ngheader = msg['newsgroups']
    if ngheader is not None:
        # See if the Newsgroups: header already contains our linked_newsgroup.
        # If so, don't add it again.  If not, append our linked_newsgroup to
        # the end of the header list
        ngroups = [s.strip() for s in ngheader.split(',')]
        if mlist.linked_newsgroup not in ngroups:
            ngroups.append(mlist.linked_newsgroup)
            # Subtitute our new header for the old one.
            del msg['newsgroups']
            msg['Newsgroups'] = COMMASPACE.join(ngroups)
    else:
        # Newsgroups: isn't in the message
        msg['Newsgroups'] = mlist.linked_newsgroup
    # Note: We need to be sure two messages aren't ever sent to the same list
    # in the same process, since message ids need to be unique.  Further, if
    # messages are crossposted to two Usenet-gated mailing lists, they each
    # need to have unique message ids or the nntpd will only accept one of
    # them.  The solution here is to substitute any existing message-id that
    # isn't ours with one of ours, so we need to parse it to be sure we're not
    # looping.
    #
    # Our Message-ID format is <mailman.secs.pid.listname@hostname>
    msgid = msg['message-id']
    hackmsgid = True
    if msgid:
        mo = mcre.search(msgid)
        if mo:
            lname, hname = mo.group('listname', 'hostname')
            if lname == mlist.internal_name() and hname == mlist.host_name:
                hackmsgid = False
    if hackmsgid:
        del msg['message-id']
        msg['Message-ID'] = email.utils.make_msgid()
    # Lines: is useful
    if msg['Lines'] is None:
        # BAW: is there a better way?
        count = len(list(email.Iterators.body_line_iterator(msg)))
        msg['Lines'] = str(count)
    # Massage the message headers by remove some and rewriting others.  This
    # woon't completely sanitize the message, but it will eliminate the bulk
    # of the rejections based on message headers.  The NNTP server may still
    # reject the message because of other problems.
    for header in config.nntp.remove_headers.split():
        del msg[header]
    for rewrite_pairs in config.nntp.rewrite_duplicate_headers.splitlines():
        if len(rewrite_pairs.strip()) == 0:
            continue
        header, rewrite = rewrite_pairs.split()
        values = msg.get_all(header, [])
        if len(values) < 2:
            # We only care about duplicates
            continue
        del msg[header]
        # But keep the first one...
        msg[header] = values[0]
        for v in values[1:]:
            msg[rewrite] = v
    # Mark this message as prepared in case it has to be requeued
    msgdata['prepped'] = True