# Copyright 2014 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.

"""oAuthlib request validator."""

import six

from keystone.common import dependency
from keystone.contrib.oauth1 import core as oauth1
from keystone import exception
from keystone.openstack.common import log


METHOD_NAME = 'oauth_validator'
LOG = log.getLogger(__name__)


@dependency.requires('oauth_api')
class OAuthValidator(oauth1.RequestValidator):

    # TODO(mhu) set as option probably?
    @property
    def enforce_ssl(self):
        return False

    @property
    def safe_characters(self):
        # oauth tokens are generated from a uuid hex value
        return set("abcdef0123456789")

    def _check_token(self, token):
        # generic token verification when they're obtained from a uuid hex
        return (set(token) <= self.safe_characters and
                len(token) == 32)

    def check_client_key(self, client_key):
        return self._check_token(client_key)

    def check_request_token(self, request_token):
        return self._check_token(request_token)

    def check_access_token(self, access_token):
        return self._check_token(access_token)

    def check_nonce(self, nonce):
        # Assuming length is not a concern
        return set(nonce) <= self.safe_characters

    def check_verifier(self, verifier):
        return (all(i in oauth1.VERIFIER_CHARS for i in verifier) and
                len(verifier) == 8)

    def get_client_secret(self, client_key, request):
        client = self.oauth_api.get_consumer_with_secret(client_key)
        return client['secret']

    def get_request_token_secret(self, client_key, token, request):
        token_ref = self.oauth_api.get_request_token(token)
        return token_ref['request_secret']

    def get_access_token_secret(self, client_key, token, request):
        access_token = self.oauth_api.get_access_token(token)
        return access_token['access_secret']

    def get_default_realms(self, client_key, request):
        # realms weren't implemented with the previous library
        return []

    def get_realms(self, token, request):
        return []

    def get_redirect_uri(self, token, request):
        # OOB (out of band) is supposed to be the default value to use
        return 'oob'

    def get_rsa_key(self, client_key, request):
        # HMAC signing is used, so return a dummy value
        return ''

    def invalidate_request_token(self, client_key, request_token, request):
        # this method is invoked when an access token is generated out of a
        # request token, to make sure that request token cannot be consumed
        # anymore. This is done in the backend, so we do nothing here.
        pass

    def validate_client_key(self, client_key, request):
        try:
            return self.oauth_api.get_consumer(client_key) is not None
        except exception.NotFound:
            return False

    def validate_request_token(self, client_key, token, request):
        try:
            return self.oauth_api.get_request_token(token) is not None
        except exception.NotFound:
            return False

    def validate_access_token(self, client_key, token, request):
        try:
            return self.oauth_api.get_access_token(token) is not None
        except exception.NotFound:
            return False

    def validate_timestamp_and_nonce(self,
                                     client_key,
                                     timestamp,
                                     nonce,
                                     request,
                                     request_token=None,
                                     access_token=None):
        return True

    def validate_redirect_uri(self, client_key, redirect_uri, request):
        # we expect OOB, we don't really care
        return True

    def validate_requested_realms(self, client_key, realms, request):
        # realms are not used
        return True

    def validate_realms(self,
                        client_key,
                        token,
                        request,
                        uri=None,
                        realms=None):
        return True

    def validate_verifier(self, client_key, token, verifier, request):
        try:
            req_token = self.oauth_api.get_request_token(token)
            return req_token['verifier'] == verifier
        except exception.NotFound:
            return False

    def verify_request_token(self, token, request):
        # there aren't strong expectations on the request token format
        return isinstance(token, six.string_types)

    def verify_realms(self, token, realms, request):
        return True

    # The following save_XXX methods are called to create tokens. I chose to
    # keep the original logic, but the comments below show how that could be
    # implemented. The real implementation logic is in the backend.
    def save_access_token(self, token, request):
        pass
#        token_duration = CONF.oauth1.request_token_duration
#        request_token_id = request.client_key
#        self.oauth_api.create_access_token(request_token_id,
#                                           token_duration,
#                                           token["oauth_token"],
#                                           token["oauth_token_secret"])

    def save_request_token(self, token, request):
        pass
#        project_id = request.headers.get('Requested-Project-Id')
#        token_duration = CONF.oauth1.request_token_duration
#        self.oauth_api.create_request_token(request.client_key,
#                                            project_id,
#                                            token_duration,
#                                            token["oauth_token"],
#                                            token["oauth_token_secret"])

    def save_verifier(self, token, verifier, request):
        # keep the old logic for this, as it is done in two steps and requires
        # information that the request validator has no access to
        pass
