# 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.

import uuid

from oslo.utils import timeutils
import six

from keystone import assignment
from keystone.common import controller
from keystone.common import dependency
from keystone.common import validation
from keystone import exception
from keystone.i18n import _
from keystone.models import token_model
from keystone.openstack.common import log
from keystone.trust import schema


LOG = log.getLogger(__name__)


def _trustor_trustee_only(trust, user_id):
    if (user_id != trust.get('trustee_user_id') and
            user_id != trust.get('trustor_user_id')):
                raise exception.Forbidden()


def _admin_trustor_only(context, trust, user_id):
    if user_id != trust.get('trustor_user_id') and not context['is_admin']:
        raise exception.Forbidden()


@dependency.requires('assignment_api', 'identity_api', 'token_provider_api',
                     'trust_api')
class TrustV3(controller.V3Controller):
    collection_name = "trusts"
    member_name = "trust"

    @classmethod
    def base_url(cls, context, path=None):
        """Construct a path and pass it to V3Controller.base_url method."""

        # NOTE(stevemar): Overriding path to /OS-TRUST/trusts so that
        # V3Controller.base_url handles setting the self link correctly.
        path = '/OS-TRUST/' + cls.collection_name
        return super(TrustV3, cls).base_url(context, path=path)

    def _get_user_id(self, context):
        if 'token_id' in context:
            token_id = context['token_id']
            token_data = self.token_provider_api.validate_token(token_id)
            token_ref = token_model.KeystoneToken(token_id=token_id,
                                                  token_data=token_data)
            return token_ref.user_id
        return None

    def get_trust(self, context, trust_id):
        user_id = self._get_user_id(context)
        trust = self.trust_api.get_trust(trust_id)
        if not trust:
            raise exception.TrustNotFound(trust_id=trust_id)
        _trustor_trustee_only(trust, user_id)
        self._fill_in_roles(context, trust,
                            self.assignment_api.list_roles())
        return TrustV3.wrap_member(context, trust)

    def _fill_in_roles(self, context, trust, all_roles):
        if trust.get('expires_at') is not None:
            trust['expires_at'] = (timeutils.isotime
                                   (trust['expires_at'],
                                    subsecond=True))

        if 'roles' not in trust:
            trust['roles'] = []
        trust_full_roles = []
        for trust_role in trust['roles']:
            if isinstance(trust_role, six.string_types):
                trust_role = {'id': trust_role}
            matching_roles = [x for x in all_roles
                              if x['id'] == trust_role['id']]
            if matching_roles:
                full_role = assignment.controllers.RoleV3.wrap_member(
                    context, matching_roles[0])['role']
                trust_full_roles.append(full_role)
        trust['roles'] = trust_full_roles
        trust['roles_links'] = {
            'self': (self.base_url(context) + "/%s/roles" % trust['id']),
            'next': None,
            'previous': None}

    def _clean_role_list(self, context, trust, all_roles):
        trust_roles = []
        all_role_names = dict((r['name'], r) for r in all_roles)
        for role in trust.get('roles', []):
            if 'id' in role:
                trust_roles.append({'id': role['id']})
            elif 'name' in role:
                rolename = role['name']
                if rolename in all_role_names:
                    trust_roles.append({'id':
                                        all_role_names[rolename]['id']})
                else:
                    raise exception.RoleNotFound("role %s is not defined" %
                                                 rolename)
            else:
                raise exception.ValidationError(attribute='id or name',
                                                target='roles')
        return trust_roles

    @controller.protected()
    @validation.validated(schema.trust_create, 'trust')
    def create_trust(self, context, trust=None):
        """Create a new trust.

        The user creating the trust must be the trustor.

        """
        # Explicitly prevent a trust token from creating a new trust.
        auth_context = context.get('environment',
                                   {}).get('KEYSTONE_AUTH_CONTEXT', {})
        if auth_context.get('is_delegated_auth'):
            raise exception.Forbidden(
                _('Cannot create a trust'
                  ' with a token issued via delegation.'))

        if not trust:
            raise exception.ValidationError(attribute='trust',
                                            target='request')
        if trust.get('project_id'):
            self._require_role(trust)
        self._require_user_is_trustor(context, trust)
        self._require_trustee_exists(trust['trustee_user_id'])
        all_roles = self.assignment_api.list_roles()
        clean_roles = self._clean_role_list(context, trust, all_roles)
        self._require_trustor_has_role_in_project(trust, clean_roles)
        trust['expires_at'] = self._parse_expiration_date(
            trust.get('expires_at'))
        trust_id = uuid.uuid4().hex
        new_trust = self.trust_api.create_trust(trust_id, trust, clean_roles)
        self._fill_in_roles(context, new_trust, all_roles)
        return TrustV3.wrap_member(context, new_trust)

    def _require_trustee_exists(self, trustee_user_id):
        self.identity_api.get_user(trustee_user_id)

    def _require_user_is_trustor(self, context, trust):
        user_id = self._get_user_id(context)
        if user_id != trust.get('trustor_user_id'):
            raise exception.Forbidden(
                _("The authenticated user should match the trustor."))

    def _require_role(self, trust):
        if not trust.get('roles'):
            raise exception.Forbidden(
                _('At least one role should be specified.'))

    def _get_user_role(self, trust):
        if not self._attribute_is_empty(trust, 'project_id'):
            return self.assignment_api.get_roles_for_user_and_project(
                trust['trustor_user_id'], trust['project_id'])
        else:
            return []

    def _require_trustor_has_role_in_project(self, trust, clean_roles):
        user_roles = self._get_user_role(trust)
        for trust_role in clean_roles:
            matching_roles = [x for x in user_roles
                              if x == trust_role['id']]
            if not matching_roles:
                raise exception.RoleNotFound(role_id=trust_role['id'])

    def _parse_expiration_date(self, expiration_date):
        if expiration_date is None:
            return None
        if not expiration_date.endswith('Z'):
            expiration_date += 'Z'
        try:
            return timeutils.parse_isotime(expiration_date)
        except ValueError:
            raise exception.ValidationTimeStampError()

    @controller.protected()
    def list_trusts(self, context):
        query = context['query_string']
        trusts = []
        if not query:
            self.assert_admin(context)
            trusts += self.trust_api.list_trusts()
        if 'trustor_user_id' in query:
            user_id = query['trustor_user_id']
            calling_user_id = self._get_user_id(context)
            if user_id != calling_user_id:
                raise exception.Forbidden()
            trusts += (self.trust_api.
                       list_trusts_for_trustor(user_id))
        if 'trustee_user_id' in query:
            user_id = query['trustee_user_id']
            calling_user_id = self._get_user_id(context)
            if user_id != calling_user_id:
                raise exception.Forbidden()
            trusts += self.trust_api.list_trusts_for_trustee(user_id)
        for trust in trusts:
            # get_trust returns roles, list_trusts does not
            # It seems in some circumstances, roles does not
            # exist in the query response, so check first
            if 'roles' in trust:
                del trust['roles']
            if trust.get('expires_at') is not None:
                trust['expires_at'] = (timeutils.isotime
                                       (trust['expires_at'],
                                        subsecond=True))
        return TrustV3.wrap_collection(context, trusts)

    @controller.protected()
    def delete_trust(self, context, trust_id):
        trust = self.trust_api.get_trust(trust_id)
        if not trust:
            raise exception.TrustNotFound(trust_id=trust_id)

        user_id = self._get_user_id(context)
        _admin_trustor_only(context, trust, user_id)
        self.trust_api.delete_trust(trust_id)

    @controller.protected()
    def list_roles_for_trust(self, context, trust_id):
        trust = self.get_trust(context, trust_id)['trust']
        if not trust:
            raise exception.TrustNotFound(trust_id=trust_id)
        user_id = self._get_user_id(context)
        _trustor_trustee_only(trust, user_id)
        return {'roles': trust['roles'],
                'links': trust['roles_links']}

    @controller.protected()
    def check_role_for_trust(self, context, trust_id, role_id):
        """Checks if a role has been assigned to a trust."""
        trust = self.trust_api.get_trust(trust_id)
        if not trust:
            raise exception.TrustNotFound(trust_id=trust_id)
        user_id = self._get_user_id(context)
        _trustor_trustee_only(trust, user_id)
        if not any(role['id'] == role_id for role in trust['roles']):
            raise exception.RoleNotFound(role_id=role_id)

    @controller.protected()
    def get_role_for_trust(self, context, trust_id, role_id):
        """Get a role that has been assigned to a trust."""
        self.check_role_for_trust(context, trust_id, role_id)
        role = self.assignment_api.get_role(role_id)
        return assignment.controllers.RoleV3.wrap_member(context, role)
