# Copyright 2011 OpenStack Foundation
# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
#
#    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.

"""RequestContext: context for requests that persist through all of nova."""

import copy

from keystoneclient import auth
from keystoneclient import service_catalog
from oslo_context import context
from oslo_log import log as logging
from oslo_utils import timeutils
import six

from nova import exception
from nova.i18n import _, _LW
from nova import policy


LOG = logging.getLogger(__name__)


class _ContextAuthPlugin(auth.BaseAuthPlugin):
    """A keystoneclient auth plugin that uses the values from the Context.

    Ideally we would use the plugin provided by auth_token middleware however
    this plugin isn't serialized yet so we construct one from the serialized
    auth data.
    """

    def __init__(self, auth_token, sc):
        super(_ContextAuthPlugin, self).__init__()

        self.auth_token = auth_token
        sc = {'serviceCatalog': sc}
        self.service_catalog = service_catalog.ServiceCatalogV2(sc)

    def get_token(self, *args, **kwargs):
        return self.auth_token

    def get_endpoint(self, session, service_type=None, interface=None,
                     region_name=None, service_name=None, **kwargs):
        return self.service_catalog.url_for(service_type=service_type,
                                            service_name=service_name,
                                            endpoint_type=interface,
                                            region_name=region_name)


class RequestContext(context.RequestContext):
    """Security context and request information.

    Represents the user taking a given action within the system.

    """

    def __init__(self, user_id=None, project_id=None,
                 is_admin=None, read_deleted="no",
                 roles=None, remote_address=None, timestamp=None,
                 request_id=None, auth_token=None, overwrite=True,
                 quota_class=None, user_name=None, project_name=None,
                 service_catalog=None, instance_lock_checked=False,
                 user_auth_plugin=None, **kwargs):
        """:param read_deleted: 'no' indicates deleted records are hidden,
                'yes' indicates deleted records are visible,
                'only' indicates that *only* deleted records are visible.

           :param overwrite: Set to False to ensure that the greenthread local
                copy of the index is not overwritten.

           :param user_auth_plugin: The auth plugin for the current request's
                authentication data.

           :param kwargs: Extra arguments that might be present, but we ignore
                because they possibly came in from older rpc messages.
        """
        user = kwargs.pop('user', None)
        tenant = kwargs.pop('tenant', None)
        super(RequestContext, self).__init__(
            auth_token=auth_token,
            user=user_id or user,
            tenant=project_id or tenant,
            domain=kwargs.pop('domain', None),
            user_domain=kwargs.pop('user_domain', None),
            project_domain=kwargs.pop('project_domain', None),
            is_admin=is_admin,
            read_only=kwargs.pop('read_only', False),
            show_deleted=kwargs.pop('show_deleted', False),
            request_id=request_id,
            resource_uuid=kwargs.pop('resource_uuid', None),
            overwrite=overwrite)
        # oslo_context's RequestContext.to_dict() generates this field, we can
        # safely ignore this as we don't use it.
        kwargs.pop('user_identity', None)
        if kwargs:
            LOG.warning(_LW('Arguments dropped when creating context: %s') %
                        str(kwargs))

        # FIXME(dims): user_id and project_id duplicate information that is
        # already present in the oslo_context's RequestContext. We need to
        # get rid of them.
        self.user_id = user_id
        self.project_id = project_id
        self.roles = roles or []
        self.read_deleted = read_deleted
        self.remote_address = remote_address
        if not timestamp:
            timestamp = timeutils.utcnow()
        if isinstance(timestamp, six.string_types):
            timestamp = timeutils.parse_strtime(timestamp)
        self.timestamp = timestamp

        if service_catalog:
            # Only include required parts of service_catalog
            self.service_catalog = [s for s in service_catalog
                if s.get('type') in ('volume', 'volumev2', 'key-manager')]
        else:
            # if list is empty or none
            self.service_catalog = []

        self.instance_lock_checked = instance_lock_checked

        # NOTE(markmc): this attribute is currently only used by the
        # rs_limits turnstile pre-processor.
        # See https://lists.launchpad.net/openstack/msg12200.html
        self.quota_class = quota_class
        self.user_name = user_name
        self.project_name = project_name
        self.is_admin = is_admin
        self.user_auth_plugin = user_auth_plugin
        if self.is_admin is None:
            self.is_admin = policy.check_is_admin(self)

    def get_auth_plugin(self):
        if self.user_auth_plugin:
            return self.user_auth_plugin
        else:
            return _ContextAuthPlugin(self.auth_token, self.service_catalog)

    def _get_read_deleted(self):
        return self._read_deleted

    def _set_read_deleted(self, read_deleted):
        if read_deleted not in ('no', 'yes', 'only'):
            raise ValueError(_("read_deleted can only be one of 'no', "
                               "'yes' or 'only', not %r") % read_deleted)
        self._read_deleted = read_deleted

    def _del_read_deleted(self):
        del self._read_deleted

    read_deleted = property(_get_read_deleted, _set_read_deleted,
                            _del_read_deleted)

    def to_dict(self):
        values = super(RequestContext, self).to_dict()
        # FIXME(dims): defensive hasattr() checks need to be
        # removed once we figure out why we are seeing stack
        # traces
        values.update({
            'user_id': getattr(self, 'user_id', None),
            'project_id': getattr(self, 'project_id', None),
            'is_admin': getattr(self, 'is_admin', None),
            'read_deleted': getattr(self, 'read_deleted', 'no'),
            'roles': getattr(self, 'roles', None),
            'remote_address': getattr(self, 'remote_address', None),
            'timestamp': timeutils.strtime(self.timestamp) if hasattr(
                self, 'timestamp') else None,
            'request_id': getattr(self, 'request_id', None),
            'quota_class': getattr(self, 'quota_class', None),
            'user_name': getattr(self, 'user_name', None),
            'service_catalog': getattr(self, 'service_catalog', None),
            'project_name': getattr(self, 'project_name', None),
            'instance_lock_checked': getattr(self, 'instance_lock_checked',
                                             False)
        })
        return values

    @classmethod
    def from_dict(cls, values):
        return cls(**values)

    def elevated(self, read_deleted=None):
        """Return a version of this context with admin flag set."""
        context = copy.deepcopy(self)
        context.is_admin = True

        if 'admin' not in context.roles:
            context.roles.append('admin')

        if read_deleted is not None:
            context.read_deleted = read_deleted

        return context

    def __str__(self):
        return "<Context %s>" % self.to_dict()


def get_admin_context(read_deleted="no"):
    return RequestContext(user_id=None,
                          project_id=None,
                          is_admin=True,
                          read_deleted=read_deleted,
                          overwrite=False)


def is_user_context(context):
    """Indicates if the request context is a normal user."""
    if not context:
        return False
    if context.is_admin:
        return False
    if not context.user_id or not context.project_id:
        return False
    return True


def require_admin_context(ctxt):
    """Raise exception.AdminRequired() if context is not an admin context."""
    if not ctxt.is_admin:
        raise exception.AdminRequired()


def require_context(ctxt):
    """Raise exception.Forbidden() if context is not a user or an
    admin context.
    """
    if not ctxt.is_admin and not is_user_context(ctxt):
        raise exception.Forbidden()


def authorize_project_context(context, project_id):
    """Ensures a request has permission to access the given project."""
    if is_user_context(context):
        if not context.project_id:
            raise exception.Forbidden()
        elif context.project_id != project_id:
            raise exception.Forbidden()


def authorize_user_context(context, user_id):
    """Ensures a request has permission to access the given user."""
    if is_user_context(context):
        if not context.user_id:
            raise exception.Forbidden()
        elif context.user_id != user_id:
            raise exception.Forbidden()


def authorize_quota_class_context(context, class_name):
    """Ensures a request has permission to access the given quota class."""
    if is_user_context(context):
        if not context.quota_class:
            raise exception.Forbidden()
        elif context.quota_class != class_name:
            raise exception.Forbidden()
