# Copyright (C) 2009-2017 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/>.

"""Handle subscriptions."""

from mailman.config import config
from mailman.database.transaction import flush
from mailman.interfaces.listmanager import ListDeletingEvent
from mailman.interfaces.pending import IPendings
from mailman.interfaces.subscriptions import (
    ISubscriptionManager, ISubscriptionService)
from mailman.interfaces.workflows import IWorkflowStateManager
from mailman.workflows.common import (PendableSubscription,
                                      PendableUnsubscription)
from public import public
from zope.component import getUtility
from zope.interface import implementer


@public
@implementer(ISubscriptionManager)
class SubscriptionManager:
    def __init__(self, mlist):
        self._mlist = mlist

    def register(self, subscriber=None, **kwargs):
        """See `ISubscriptionManager`."""
        workflow = self._mlist.subscription_policy(self._mlist, subscriber,
                                                   **kwargs)
        list(workflow)
        return workflow.token, workflow.token_owner, workflow.member

    def unregister(self, subscriber=None, **kwargs):
        workflow = self._mlist.unsubscription_policy(self._mlist, subscriber,
                                                     **kwargs)
        list(workflow)
        return workflow.token, workflow.token_owner, workflow.member

    def confirm(self, token):
        if token is None:
            raise LookupError
        pendable = getUtility(IPendings).confirm(token, expunge=False)
        if pendable is None:
            raise LookupError
        workflow_type = pendable.get('type')
        if workflow_type in {PendableSubscription.PEND_TYPE,
                             PendableUnsubscription.PEND_TYPE}:
            workflow = (self._mlist.subscription_policy  # pragma: nocover
                        if workflow_type == PendableSubscription.PEND_TYPE
                        else self._mlist.unsubscription_policy)(self._mlist)
        else:
            workflow = config.workflows[workflow_type](self._mlist)
        workflow.token = token
        workflow.restore()
        # In order to just run the whole workflow, all we need to do
        # is iterate over the workflow object. On calling the __next__
        # over the workflow iterator it automatically executes the steps
        # that needs to be done.
        list(workflow)
        return workflow.token, workflow.token_owner, workflow.member

    def discard(self, token):
        with flush():
            getUtility(IPendings).confirm(token)
            getUtility(IWorkflowStateManager).discard(token)


@public
def handle_ListDeletingEvent(event):
    """Delete a mailing list's members when the list is being deleted."""

    if not isinstance(event, ListDeletingEvent):
        return
    # Find all the members still associated with the mailing list.
    members = getUtility(ISubscriptionService).find_members(
            list_id=event.mailing_list.list_id)
    for member in members:
        member.unsubscribe()