# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2012 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.

"""
Starting point for routing EC2 requests.

"""

import urlparse

from eventlet.green import httplib
import webob.dec
import webob.exc

from nova import flags
from nova import utils
from nova import wsgi


FLAGS = flags.FLAGS
flags.DEFINE_string('keystone_ec2_url',
                    'http://localhost:5000/v2.0/ec2tokens',
                    'URL to get token from ec2 request.')


class EC2Token(wsgi.Middleware):
    """Authenticate an EC2 request with keystone and convert to token."""

    @webob.dec.wsgify(RequestClass=wsgi.Request)
    def __call__(self, req):
        # Read request signature and access id.
        try:
            signature = req.params['Signature']
            access = req.params['AWSAccessKeyId']
        except KeyError:
            raise webob.exc.HTTPBadRequest()

        # Make a copy of args for authentication and signature verification.
        auth_params = dict(req.params)
        # Not part of authentication args
        auth_params.pop('Signature')

        # Authenticate the request.
        creds = {
            'ec2Credentials': {
                'access': access,
                'signature': signature,
                'host': req.host,
                'verb': req.method,
                'path': req.path,
                'params': auth_params,
            }
        }
        creds_json = utils.dumps(creds)
        headers = {'Content-Type': 'application/json'}

        # Disable 'has no x member' pylint error
        # for httplib and urlparse
        # pylint: disable-msg=E1101
        o = urlparse.urlparse(FLAGS.keystone_ec2_url)
        if o.scheme == 'http':
            conn = httplib.HTTPConnection(o.netloc)
        else:
            conn = httplib.HTTPSConnection(o.netloc)
        conn.request('POST', o.path, body=creds_json, headers=headers)
        response = conn.getresponse().read()
        conn.close()

        # NOTE(vish): We could save a call to keystone by
        #             having keystone return token, tenant,
        #             user, and roles from this call.

        result = utils.loads(response)
        try:
            token_id = result['access']['token']['id']
        except (AttributeError, KeyError):
            raise webob.exc.HTTPBadRequest()

        # Authenticated!
        req.headers['X-Auth-Token'] = token_id
        return self.application
