# Copyright 2012 OpenStack Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

"""Main entry point into the Token persistence service."""

import abc
import copy

from oslo.utils import timeutils
import six

from keystone.common import cache
from keystone.common import dependency
from keystone.common import manager
from keystone import config
from keystone import exception
from keystone.openstack.common import log
from keystone.openstack.common import versionutils


CONF = config.CONF
LOG = log.getLogger(__name__)
SHOULD_CACHE = cache.should_cache_fn('token')

# NOTE(blk-u): The config options are not available at import time.
EXPIRATION_TIME = lambda: CONF.token.cache_time
REVOCATION_CACHE_EXPIRATION_TIME = lambda: CONF.token.revocation_cache_time


@dependency.requires('assignment_api', 'identity_api', 'token_provider_api',
                     'trust_api')
class PersistenceManager(manager.Manager):
    """Default pivot point for the Token backend.

    See :mod:`keystone.common.manager.Manager` for more details on how this
    dynamically calls the backend.

    """

    def __init__(self):
        super(PersistenceManager, self).__init__(CONF.token.driver)

    @versionutils.deprecated(as_of=versionutils.deprecated.JUNO,
                             in_favor_of='token_provider_api.unique_id',
                             remove_in=+1,
                             what='token_api.unique_id')
    def unique_id(self, token_id):
        return self.token_provider_api.unique_id(token_id)

    def _assert_valid(self, token_id, token_ref):
        """Raise TokenNotFound if the token is expired."""
        current_time = timeutils.normalize_time(timeutils.utcnow())
        expires = token_ref.get('expires')
        if not expires or current_time > timeutils.normalize_time(expires):
            raise exception.TokenNotFound(token_id=token_id)

    def get_token(self, token_id):
        if not token_id:
            # NOTE(morganfainberg): There are cases when the
            # context['token_id'] will in-fact be None. This also saves
            # a round-trip to the backend if we don't have a token_id.
            raise exception.TokenNotFound(token_id='')
        unique_id = self.token_provider_api.unique_id(token_id)
        token_ref = self._get_token(unique_id)
        # NOTE(morganfainberg): Lift expired checking to the manager, there is
        # no reason to make the drivers implement this check. With caching,
        # self._get_token could return an expired token. Make sure we behave
        # as expected and raise TokenNotFound on those instances.
        self._assert_valid(token_id, token_ref)
        return token_ref

    @cache.on_arguments(should_cache_fn=SHOULD_CACHE,
                        expiration_time=EXPIRATION_TIME)
    def _get_token(self, token_id):
        # Only ever use the "unique" id in the cache key.
        return self.driver.get_token(token_id)

    def create_token(self, token_id, data):
        unique_id = self.token_provider_api.unique_id(token_id)
        data_copy = copy.deepcopy(data)
        data_copy['id'] = unique_id
        ret = self.driver.create_token(unique_id, data_copy)
        if SHOULD_CACHE(ret):
            # NOTE(morganfainberg): when doing a cache set, you must pass the
            # same arguments through, the same as invalidate (this includes
            # "self"). First argument is always the value to be cached
            self._get_token.set(ret, self, unique_id)
        return ret

    def delete_token(self, token_id):
        if not CONF.token.revoke_by_id:
            return
        unique_id = self.token_provider_api.unique_id(token_id)
        self.driver.delete_token(unique_id)
        self._invalidate_individual_token_cache(unique_id)
        self.invalidate_revocation_list()

    def delete_tokens(self, user_id, tenant_id=None, trust_id=None,
                      consumer_id=None):
        if not CONF.token.revoke_by_id:
            return
        token_list = self.driver._list_tokens(user_id, tenant_id, trust_id,
                                              consumer_id)
        self.driver.delete_tokens(user_id, tenant_id, trust_id, consumer_id)
        for token_id in token_list:
            unique_id = self.token_provider_api.unique_id(token_id)
            self._invalidate_individual_token_cache(unique_id)
        self.invalidate_revocation_list()

    @cache.on_arguments(should_cache_fn=SHOULD_CACHE,
                        expiration_time=REVOCATION_CACHE_EXPIRATION_TIME)
    def list_revoked_tokens(self):
        return self.driver.list_revoked_tokens()

    def invalidate_revocation_list(self):
        # NOTE(morganfainberg): Note that ``self`` needs to be passed to
        # invalidate() because of the way the invalidation method works on
        # determining cache-keys.
        self.list_revoked_tokens.invalidate(self)

    def delete_tokens_for_domain(self, domain_id):
        """Delete all tokens for a given domain.

        It will delete all the project-scoped tokens for the projects
        that are owned by the given domain, as well as any tokens issued
        to users that are owned by this domain.

        However, deletion of domain_scoped tokens will still need to be
        implemented as stated in TODO below.
        """
        if not CONF.token.revoke_by_id:
            return
        projects = self.assignment_api.list_projects()
        for project in projects:
            if project['domain_id'] == domain_id:
                for user_id in self.assignment_api.list_user_ids_for_project(
                        project['id']):
                    self.delete_tokens_for_user(user_id, project['id'])
        # TODO(morganfainberg): implement deletion of domain_scoped tokens.

        users = self.identity_api.list_users(domain_id)
        user_ids = (user['id'] for user in users)
        self.delete_tokens_for_users(user_ids)

    def delete_tokens_for_user(self, user_id, project_id=None):
        """Delete all tokens for a given user or user-project combination.

        This method adds in the extra logic for handling trust-scoped token
        revocations in a single call instead of needing to explicitly handle
        trusts in the caller's logic.
        """
        if not CONF.token.revoke_by_id:
            return
        self.delete_tokens(user_id, tenant_id=project_id)
        for trust in self.trust_api.list_trusts_for_trustee(user_id):
            # Ensure we revoke tokens associated to the trust / project
            # user_id combination.
            self.delete_tokens(user_id, trust_id=trust['id'],
                               tenant_id=project_id)
        for trust in self.trust_api.list_trusts_for_trustor(user_id):
            # Ensure we revoke tokens associated to the trust / project /
            # user_id combination where the user_id is the trustor.

            # NOTE(morganfainberg): This revocation is a bit coarse, but it
            # covers a number of cases such as disabling of the trustor user,
            # deletion of the trustor user (for any number of reasons). It
            # might make sense to refine this and be more surgical on the
            # deletions (e.g. don't revoke tokens for the trusts when the
            # trustor changes password). For now, to maintain previous
            # functionality, this will continue to be a bit overzealous on
            # revocations.
            self.delete_tokens(trust['trustee_user_id'], trust_id=trust['id'],
                               tenant_id=project_id)

    def delete_tokens_for_users(self, user_ids, project_id=None):
        """Delete all tokens for a list of user_ids.

        :param user_ids: list of user identifiers
        :param project_id: optional project identifier
        """
        if not CONF.token.revoke_by_id:
            return
        for user_id in user_ids:
            self.delete_tokens_for_user(user_id, project_id=project_id)

    def _invalidate_individual_token_cache(self, token_id):
        # NOTE(morganfainberg): invalidate takes the exact same arguments as
        # the normal method, this means we need to pass "self" in (which gets
        # stripped off).

        # FIXME(morganfainberg): Does this cache actually need to be
        # invalidated? We maintain a cached revocation list, which should be
        # consulted before accepting a token as valid.  For now we will
        # do the explicit individual token invalidation.
        self._get_token.invalidate(self, token_id)
        self.token_provider_api.invalidate_individual_token_cache(token_id)


# NOTE(morganfainberg): @dependency.optional() is required here to ensure the
# class-level optional dependency control attribute is populated as empty
# this is because of the override of .__getattr__ and ensures that if the
# optional dependency injector changes attributes, this class doesn't break.
@dependency.optional()
@dependency.requires('token_provider_api')
@dependency.provider('token_api')
class Manager(object):
    """The token_api provider.

    This class is a proxy class to the token_provider_api's persistence
    manager.
    """
    def __init__(self):
        # NOTE(morganfainberg): __init__ is required for dependency processing.
        super(Manager, self).__init__()

    def __getattr__(self, item):
        """Forward calls to the `token_provider_api` persistence manager."""
        # TODO(morganfainberg): Once the `token_api` is deprecated, apply a
        # @versionutils.deprecated decorator to each item forwarded.
        f = getattr(self.token_provider_api.persistence, item)
        setattr(self, item, f)
        return f


@six.add_metaclass(abc.ABCMeta)
class Driver(object):
    """Interface description for a Token driver."""

    @abc.abstractmethod
    def get_token(self, token_id):
        """Get a token by id.

        :param token_id: identity of the token
        :type token_id: string
        :returns: token_ref
        :raises: keystone.exception.TokenNotFound

        """
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def create_token(self, token_id, data):
        """Create a token by id and data.

        :param token_id: identity of the token
        :type token_id: string
        :param data: dictionary with additional reference information

        ::

            {
                expires=''
                id=token_id,
                user=user_ref,
                tenant=tenant_ref,
                metadata=metadata_ref
            }

        :type data: dict
        :returns: token_ref or None.

        """
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def delete_token(self, token_id):
        """Deletes a token by id.

        :param token_id: identity of the token
        :type token_id: string
        :returns: None.
        :raises: keystone.exception.TokenNotFound

        """
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def delete_tokens(self, user_id, tenant_id=None, trust_id=None,
                      consumer_id=None):
        """Deletes tokens by user.

        If the tenant_id is not None, only delete the tokens by user id under
        the specified tenant.

        If the trust_id is not None, it will be used to query tokens and the
        user_id will be ignored.

        If the consumer_id is not None, only delete the tokens by consumer id
        that match the specified consumer id.

        :param user_id: identity of user
        :type user_id: string
        :param tenant_id: identity of the tenant
        :type tenant_id: string
        :param trust_id: identity of the trust
        :type trust_id: string
        :param consumer_id: identity of the consumer
        :type consumer_id: string
        :returns: None.
        :raises: keystone.exception.TokenNotFound

        """
        if not CONF.token.revoke_by_id:
            return
        token_list = self._list_tokens(user_id,
                                       tenant_id=tenant_id,
                                       trust_id=trust_id,
                                       consumer_id=consumer_id)

        for token in token_list:
            try:
                self.delete_token(token)
            except exception.NotFound:
                pass

    @abc.abstractmethod
    def _list_tokens(self, user_id, tenant_id=None, trust_id=None,
                     consumer_id=None):
        """Returns a list of current token_id's for a user

        This is effectively a private method only used by the ``delete_tokens``
        method and should not be called by anything outside of the
        ``token_api`` manager or the token driver itself.

        :param user_id: identity of the user
        :type user_id: string
        :param tenant_id: identity of the tenant
        :type tenant_id: string
        :param trust_id: identity of the trust
        :type trust_id: string
        :param consumer_id: identity of the consumer
        :type consumer_id: string
        :returns: list of token_id's

        """
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def list_revoked_tokens(self):
        """Returns a list of all revoked tokens

        :returns: list of token_id's

        """
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def flush_expired_tokens(self):
        """Archive or delete tokens that have expired.
        """
        raise exception.NotImplemented()  # pragma: no cover