#
# 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.

from keystoneclient import exceptions as keystone_exceptions
from keystoneclient import session
from webob import exc

from heat.common import config
from heat.common import context


class KeystonePasswordAuthProtocol(object):
    """Middleware uses username and password to authenticate against Keystone.

    Alternative authentication middleware that uses username and password
    to authenticate against Keystone instead of validating existing auth token.
    The benefit being that you no longer require admin/service token to
    authenticate users.
    """

    def __init__(self, app, conf):
        self.app = app
        self.conf = conf
        self.session = session.Session.construct(self._ssl_options())

    def __call__(self, env, start_response):
        """Authenticate incoming request."""
        username = env.get('HTTP_X_AUTH_USER')
        password = env.get('HTTP_X_AUTH_KEY')
        # Determine tenant id from path.
        tenant = env.get('PATH_INFO').split('/')[1]
        auth_url = env.get('HTTP_X_AUTH_URL')
        user_domain_id = env.get('HTTP_X_USER_DOMAIN_ID')
        if not tenant:
            return self._reject_request(env, start_response, auth_url)
        try:
            ctx = context.RequestContext(username=username, password=password,
                                         tenant_id=tenant, auth_url=auth_url,
                                         user_domain_id=user_domain_id,
                                         is_admin=False)
            auth_ref = ctx.auth_plugin.get_access(self.session)
        except (keystone_exceptions.Unauthorized,
                keystone_exceptions.Forbidden,
                keystone_exceptions.NotFound,
                keystone_exceptions.AuthorizationFailure):
            return self._reject_request(env, start_response, auth_url)
        env.update(self._build_user_headers(auth_ref))

        return self.app(env, start_response)

    def _reject_request(self, env, start_response, auth_url):
        """Redirect client to auth server."""
        headers = [('WWW-Authenticate', "Keystone uri='%s'" % auth_url)]
        resp = exc.HTTPUnauthorized('Authentication required', headers)
        return resp(env, start_response)

    def _build_user_headers(self, token_info):
        """Build headers that represent authenticated user from auth token."""

        if token_info.get('version') == 'v3':
            keystone_token_info = {'token': token_info}
            tenant_id = token_info['project']['id']
            tenant_name = token_info['project']['name']
            user_id = token_info['user']['id']
            user_name = token_info['user']['name']
            roles = ','.join(
                [role['name'] for role in token_info['roles']])
            service_catalog = None
            auth_token = token_info['auth_token']
        else:
            keystone_token_info = token_info
            tenant_id = token_info['token']['tenant']['id']
            tenant_name = token_info['token']['tenant']['name']
            user_id = token_info['user']['id']
            user_name = token_info['user']['name']
            roles = ','.join(
                [role['name'] for role in token_info['user']['roles']])
            service_catalog = token_info['serviceCatalog']
            auth_token = token_info['token']['id']

        headers = {
            'keystone.token_info': keystone_token_info,
            'HTTP_X_IDENTITY_STATUS': 'Confirmed',
            'HTTP_X_PROJECT_ID': tenant_id,
            'HTTP_X_PROJECT_NAME': tenant_name,
            'HTTP_X_USER_ID': user_id,
            'HTTP_X_USER_NAME': user_name,
            'HTTP_X_ROLES': roles,
            'HTTP_X_SERVICE_CATALOG': service_catalog,
            'HTTP_X_AUTH_TOKEN': auth_token,
        }

        return headers

    def _ssl_options(self):
        opts = {'cacert': config.get_client_option('keystone', 'ca_file'),
                'insecure': config.get_client_option('keystone', 'insecure'),
                'cert': config.get_client_option('keystone', 'cert_file'),
                'key': config.get_client_option('keystone', 'key_file')}
        return opts


def filter_factory(global_conf, **local_conf):
    """Returns a WSGI filter app for use with paste.deploy."""
    conf = global_conf.copy()
    conf.update(local_conf)

    def auth_filter(app):
        return KeystonePasswordAuthProtocol(app, conf)
    return auth_filter
