# Copyright 2013 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 Credentials service."""

import abc

import six

from keystone.common import dependency
from keystone.common import driver_hints
from keystone.common import manager
from keystone import config
from keystone import exception
from keystone.openstack.common import log


CONF = config.CONF

LOG = log.getLogger(__name__)


@dependency.provider('credential_api')
class Manager(manager.Manager):
    """Default pivot point for the Credential backend.

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

    """

    def __init__(self):
        super(Manager, self).__init__(CONF.credential.driver)

    @manager.response_truncated
    def list_credentials(self, hints=None):
        return self.driver.list_credentials(hints or driver_hints.Hints())


@six.add_metaclass(abc.ABCMeta)
class Driver(object):
    # credential crud

    @abc.abstractmethod
    def create_credential(self, credential_id, credential):
        """Creates a new credential.

        :raises: keystone.exception.Conflict

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

    @abc.abstractmethod
    def list_credentials(self, hints):
        """List all credentials.

        :param hints: contains the list of filters yet to be satisfied.
                      Any filters satisfied here will be removed so that
                      the caller will know if any filters remain.

        :returns: a list of credential_refs or an empty list.

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

    @abc.abstractmethod
    def list_credentials_for_user(self, user_id):
        """List credentials for a user.

        :param user_id: ID of a user to filter credentials by.

        :returns: a list of credential_refs or an empty list.

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

    @abc.abstractmethod
    def get_credential(self, credential_id):
        """Get a credential by ID.

        :returns: credential_ref
        :raises: keystone.exception.CredentialNotFound

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

    @abc.abstractmethod
    def update_credential(self, credential_id, credential):
        """Updates an existing credential.

        :raises: keystone.exception.CredentialNotFound,
                 keystone.exception.Conflict

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

    @abc.abstractmethod
    def delete_credential(self, credential_id):
        """Deletes an existing credential.

        :raises: keystone.exception.CredentialNotFound

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

    @abc.abstractmethod
    def delete_credentials_for_project(self, project_id):
        """Deletes all credentials for a project."""
        self._delete_credentials(lambda cr: cr['project_id'] == project_id)

    @abc.abstractmethod
    def delete_credentials_for_user(self, user_id):
        """Deletes all credentials for a user."""
        self._delete_credentials(lambda cr: cr['user_id'] == user_id)

    def _delete_credentials(self, match_fn):
        """Do the actual credential deletion work (default implementation).

        :param match_fn: function that takes a credential dict as the
                         parameter and returns true or false if the
                         identifier matches the credential dict.
        """
        for cr in self.list_credentials():
            if match_fn(cr):
                try:
                    self.credential_api.delete_credential(cr['id'])
                except exception.CredentialNotFound:
                    LOG.debug('Deletion of credential is not required: %s',
                              cr['id'])
