# Copyright (C) 2007-2008 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
# USA.

"""The default built-in starting chain."""

__all__ = ['BuiltInChain']
__metaclass__ = type


import logging

from zope.interface import implements

from mailman.chains.base import Link
from mailman.configuration import config
from mailman.i18n import _
from mailman.interfaces import IChain, LinkAction


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



class BuiltInChain:
    """Default built-in chain."""

    implements(IChain)

    name = 'built-in'
    description = _('The built-in moderation chain.')

    _link_descriptions = (
        ('approved', LinkAction.jump, 'accept'),
        ('emergency', LinkAction.jump, 'hold'),
        ('loop', LinkAction.jump, 'discard'),
        # Do all of the following before deciding whether to hold the message
        # for moderation.
        ('administrivia', LinkAction.defer, None),
        ('implicit-dest', LinkAction.defer, None),
        ('max-recipients', LinkAction.defer, None),
        ('max-size', LinkAction.defer, None),
        ('news-moderation', LinkAction.defer, None),
        ('no-subject', LinkAction.defer, None),
        ('suspicious-header', LinkAction.defer, None),
        # Now if any of the above hit, jump to the hold chain.
        ('any', LinkAction.jump, 'hold'),
        # Take a detour through the self header matching chain, which we'll
        # create later.
        ('truth', LinkAction.detour, 'header-match'),
        # Finally, the builtin chain selfs to acceptance.
        ('truth', LinkAction.jump, 'accept'),
        )

    def __init__(self):
        self._cached_links = None

    def get_links(self, mlist, msg, msgdata):
        """See `IChain`."""
        if self._cached_links is None:
            self._cached_links = links = []
            for rule_name, action, chain_name in self._link_descriptions:
                # Get the named rule.
                rule = config.rules[rule_name]
                # Get the chain, if one is defined.
                if chain_name is None:
                    chain = None
                else:
                    chain = config.chains[chain_name]
                links.append(Link(rule, action, chain))
        return iter(self._cached_links)