# Copyright (C) 2007-2010 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/>.

"""The terminal 'hold' chain."""

from __future__ import absolute_import, unicode_literals

__metaclass__ = type
__all__ = [
    'HoldChain',
    'HoldNotification',
    ]


import logging

from email.mime.message import MIMEMessage
from email.mime.text import MIMEText
from email.utils import formatdate, make_msgid
from zope.component import getUtility
from zope.event import notify
from zope.interface import implements

from mailman.Utils import maketext, oneline, wrap
from mailman.app.moderator import hold_message
from mailman.app.replybot import can_acknowledge
from mailman.chains.base import ChainNotification, TerminalChainBase
from mailman.config import config
from mailman.core.i18n import _
from mailman.email.message import UserNotification
from mailman.interfaces.autorespond import IAutoResponseSet, Response
from mailman.interfaces.languages import ILanguageManager
from mailman.interfaces.pending import IPendable, IPendings
from mailman.interfaces.usermanager import IUserManager


log = logging.getLogger('mailman.vette')
SEMISPACE = '; '



class HeldMessagePendable(dict):
    implements(IPendable)
    PEND_KEY = 'held message'


class HoldNotification(ChainNotification):
    """A notification event signaling that a message is being held."""



def autorespond_to_sender(mlist, sender, lang=None):
    """Should Mailman automatically respond to this sender?

    :param mlist: The mailing list.
    :type mlist: `IMailingList`.
    :param sender: The sender's email address.
    :type sender: string
    :param lang: Optional language.
    :type lang: `ILanguage` or None
    :return: True if an automatic response should be sent, otherwise False.
        If an automatic response is not sent, a message is sent indicating
        that, er no more will be sent today.
    :rtype: bool
    """
    if lang is None:
        lang = mlist.preferred_language
    max_autoresponses_per_day = int(config.mta.max_autoresponses_per_day)
    if max_autoresponses_per_day == 0:
        # Unlimited.
        return True
    # Get an IAddress from an email address.
    user_manager = getUtility(IUserManager)
    address = user_manager.get_address(sender)
    if address is None:
        address = user_manager.create_address(sender)
    response_set = IAutoResponseSet(mlist)
    todays_count = response_set.todays_count(address, Response.hold)
    if todays_count < max_autoresponses_per_day:
        # This person has not reached their automatic response limit, so it's
        # okay to send a response.
        response_set.response_sent(address, Response.hold)
        return True
    elif todays_count == max_autoresponses_per_day:
        # The last one we sent was the last one we should send today.  Instead
        # of sending an automatic response, send them the "no more today"
        # message.
        log.info('hold autoresponse limit hit: %s', sender)
        response_set.response_sent(address, Response.hold)
        # Send this notification message instead.
        text = Utils.maketext(
            'nomoretoday.txt',
            {'sender' : sender,
             'listname': mlist.fqdn_listname,
             'num' : count,
             'owneremail': mlist.owner_address,
             },
            lang=lang)
        with _.using(lang.code):
            msg = Message.UserNotification(
                sender, mlist.owner_address,
                _('Last autoresponse notification for today'),
                text, lang=lang)
        msg.send(mlist)
        return False
    else:
        # We've sent them everything we're going to send them today.
        log.info('Automatic response limit discard: %s', sender)
        return False



class HoldChain(TerminalChainBase):
    """Hold a message."""

    name = 'hold'
    description = _('Hold a message and stop processing.')

    def _process(self, mlist, msg, msgdata):
        """See `TerminalChainBase`."""
        # Start by decorating the message with a header that contains a list
        # of all the rules that matched.  These metadata could be None or an
        # empty list.
        rule_hits = msgdata.get('rule_hits')
        if rule_hits:
            msg['X-Mailman-Rule-Hits'] = SEMISPACE.join(rule_hits)
        rule_misses = msgdata.get('rule_misses')
        if rule_misses:
            msg['X-Mailman-Rule-Misses'] = SEMISPACE.join(rule_misses)
        # Hold the message by adding it to the list's request database.
        # XXX How to calculate the reason?
        request_id = hold_message(mlist, msg, msgdata, None)
        # Calculate a confirmation token to send to the author of the
        # message.
        pendable = HeldMessagePendable(type=HeldMessagePendable.PEND_KEY,
                                       id=request_id)
        token = getUtility(IPendings).add(pendable)
        # Get the language to send the response in.  If the sender is a
        # member, then send it in the member's language, otherwise send it in
        # the mailing list's preferred language.
        member = mlist.members.get_member(msg.sender)
        language = (member.preferred_language
                    if member else mlist.preferred_language)
        # A substitution dictionary for the email templates.
        charset = mlist.preferred_language.charset
        original_subject = msg.get('subject')
        if original_subject is None:
            original_subject = _('(no subject)')
        else:
            original_subject = oneline(original_subject, charset)
        substitutions = dict(
            listname    = mlist.fqdn_listname,
            subject     = original_subject,
            sender      = msg.sender,
            reason      = 'XXX', #reason,
            confirmurl  = '{0}/{1}'.format(mlist.script_url('confirm'), token),
            admindb_url = mlist.script_url('admindb'),
            )
        # At this point the message is held, but now we have to craft at least
        # two responses.  The first will go to the original author of the
        # message and it will contain the token allowing them to approve or
        # discard the message.  The second one will go to the moderators of
        # the mailing list, if the list is so configured.
        #
        # Start by possibly sending a response to the message author.  There
        # are several reasons why we might not go through with this.  If the
        # message was gated from NNTP, the author may not even know about this
        # list, so don't spam them.  If the author specifically requested that
        # acknowledgments not be sent, or if the message was bulk email, then
        # we do not send the response.  It's also possible that either the
        # mailing list, or the author (if they are a member) have been
        # configured to not send such responses.
        if (not msgdata.get('fromusenet') and
            can_acknowledge(msg) and
            mlist.respond_to_post_requests and
            autorespond_to_sender(mlist, msg.sender, language)):
            # We can respond to the sender with a message indicating their
            # posting was held.
            subject = _(
              'Your message to $mlist.fqdn_listname awaits moderator approval')
            send_language_code = msgdata.get('lang', language.code)
            text = maketext('postheld.txt', substitutions,
                            lang=send_language_code, mlist=mlist)
            adminaddr = mlist.bounces_address
            nmsg = UserNotification(
                msg.sender, adminaddr, subject, text,
                getUtility(ILanguageManager)[send_language_code])
            nmsg.send(mlist)
        # Now the message for the list moderators.  This one should appear to
        # come from <list>-owner since we really don't need to do bounce
        # processing on it.
        if mlist.admin_immed_notify:
            # Now let's temporarily set the language context to that which the
            # administrators are expecting.
            with _.using(mlist.preferred_language.code):
                language = mlist.preferred_language
                charset = language.charset
                # We need to regenerate or re-translate a few values in the
                # substitution dictionary.
                #d['reason'] = _(reason) # XXX reason
                substitutions['subject'] = original_subject
                # craft the admin notification message and deliver it
                subject = _(
                    '$mlist.fqdn_listname post from $msg.sender requires '
                    'approval')
                nmsg = UserNotification(mlist.owner_address,
                                        mlist.owner_address,
                                        subject, lang=language)
                nmsg.set_type('multipart/mixed')
                text = MIMEText(
                    maketext('postauth.txt', substitutions,
                             raw=True, mlist=mlist),
                    _charset=charset)
                dmsg = MIMEText(wrap(_("""\
If you reply to this message, keeping the Subject: header intact, Mailman will
discard the held message.  Do this if the message is spam.  If you reply to
this message and include an Approved: header with the list password in it, the
message will be approved for posting to the list.  The Approved: header can
also appear in the first line of the body of the reply.""")),
                                _charset=language.charset)
                dmsg['Subject'] = 'confirm ' + token
                dmsg['From'] = mlist.request_address
                dmsg['Date'] = formatdate(localtime=True)
                dmsg['Message-ID'] = make_msgid()
                nmsg.attach(text)
                nmsg.attach(MIMEMessage(msg))
                nmsg.attach(MIMEMessage(dmsg))
                nmsg.send(mlist, **dict(tomoderators=True))
        # Log the held message
        # XXX reason
        reason = 'n/a'
        log.info('HOLD: %s post from %s held, message-id=%s: %s',
                 mlist.fqdn_listname, msg.sender,
                 msg.get('message-id', 'n/a'), reason)
        notify(HoldNotification(mlist, msg, msgdata, self))