# Copyright (C) 2015-2017 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/>.

"""Common support between subscription and unsubscription."""

import uuid

from datetime import timedelta
from enum import Enum
from mailman.interfaces.address import IAddress
from mailman.interfaces.pending import IPendable, IPendings
from mailman.interfaces.subscriptions import TokenOwner
from mailman.interfaces.user import IUser
from mailman.interfaces.usermanager import IUserManager
from mailman.interfaces.workflows import (ISubscriptionWorkflow,
                                          IUnsubscriptionWorkflow, IWorkflow)
from mailman.utilities.datetime import now
from mailman.workflows.base import Workflow
from zope.component import getUtility
from zope.interface import implementer
from zope.interface.exceptions import DoesNotImplement


class WhichSubscriber(Enum):
    address = 1
    user = 2


@implementer(IPendable)
class PendableSubscription(dict):
    PEND_TYPE = 'subscription'


@implementer(IPendable)
class PendableUnsubscription(dict):
    PEND_TYPE = 'unsubscription'


class SubscriptionWorkflowCommon(Workflow):
    """Common support between subscription and unsubscription."""

    def __init__(self, mlist, subscriber):
        super().__init__()
        self.mlist = mlist
        self.address = None
        self.user = None
        self.which = None
        self.member = None
        self._set_token(TokenOwner.no_one)
        # The subscriber must be either an IUser or IAddress.
        if IAddress.providedBy(subscriber):
            self.address = subscriber
            self.user = self.address.user
            self.which = WhichSubscriber.address
        elif IUser.providedBy(subscriber):
            self.address = subscriber.preferred_address
            self.user = subscriber
            self.which = WhichSubscriber.user
        self.subscriber = subscriber

    @property
    def user_key(self):
        # For save.
        return self.user.user_id.hex

    @user_key.setter
    def user_key(self, hex_key):
        # For restore.
        uid = uuid.UUID(hex_key)
        self.user = getUtility(IUserManager).get_user_by_id(uid)
        if self.user is None:
            self.user = self.address.user

    @property
    def address_key(self):
        # For save.
        return self.address.email

    @address_key.setter
    def address_key(self, email):
        # For restore.
        self.address = getUtility(IUserManager).get_address(email)
        assert self.address is not None

    @property
    def subscriber_key(self):
        return self.which.value

    @subscriber_key.setter
    def subscriber_key(self, key):
        self.which = WhichSubscriber(key)

    @property
    def token_owner_key(self):
        return self.token_owner.value

    @token_owner_key.setter
    def token_owner_key(self, value):
        self.token_owner = TokenOwner(value)

    def _set_token(self, token_owner):
        assert isinstance(token_owner, TokenOwner)
        pendings = getUtility(IPendings)
        # Clear out the previous pending token if there is one.
        if self.token is not None:
            pendings.confirm(self.token)
        # Create a new token to prevent replay attacks.  It seems like this
        # would produce the same token, but it won't because the pending adds a
        # bit of randomization.
        self.token_owner = token_owner
        if token_owner is TokenOwner.no_one:
            self.token = None
            return

        if ISubscriptionWorkflow.implementedBy(self.__class__):
            pendable_class = PendableSubscription
        elif IUnsubscriptionWorkflow.implementedBy(self.__class__):
            pendable_class = PendableUnsubscription
        else:
            raise DoesNotImplement(IWorkflow)

        pendable = pendable_class(
            list_id=self.mlist.list_id,
            email=self.address.email,
            display_name=self.address.display_name,
            when=now().replace(microsecond=0).isoformat(),
            token_owner=token_owner.name,
            )
        self.token = pendings.add(pendable, timedelta(days=3650))