# Copyright 2017 Huawei Technologies Co.,LTD.
# 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.

import re

from keystonemiddleware import auth_token
from oslo_log import log

from cyborg.common import exception
from cyborg.common.i18n import _
from cyborg.common import utils


LOG = log.getLogger(__name__)


class AuthTokenMiddleware(auth_token.AuthProtocol):
    """A wrapper on Keystone auth_token middleware.

    Does not perform verification of authentication tokens
    for public routes in the API.

    """
    def __init__(self, app, conf, public_api_routes=None):
        public_api_routes = public_api_routes or []
        self.app = app
        route_pattern_tpl = r'%s(\.json)?$'

        try:
            self.public_api_routes = [re.compile(route_pattern_tpl % route_tpl)
                                      for route_tpl in public_api_routes]
        except re.error as e:
            msg = _('Cannot compile public API routes: %s') % e

            LOG.error(msg)
            raise exception.ConfigInvalid(error_msg=msg)

        super(AuthTokenMiddleware, self).__init__(app, conf)

    def __call__(self, env, start_response):
        path = utils.safe_rstrip(env.get('PATH_INFO'), '/')

        # The information whether the API call is being performed against the
        # public API is required for some other components. Saving it to the
        # WSGI environment is reasonable thereby.
        env['is_public_api'] = any(map(lambda pattern: re.match(pattern, path),
                                       self.public_api_routes))

        if env['is_public_api']:
            return self.app(env, start_response)

        return super(AuthTokenMiddleware, self).__call__(env, start_response)

    @classmethod
    def factory(cls, global_config, **local_conf):
        public_routes = local_conf.get('acl_public_routes', '')
        public_api_routes = [path.strip() for path in public_routes.split(',')]

        def _factory(app):
            return cls(app, global_config, public_api_routes=public_api_routes)

        return _factory
