# Copyright 2017 AT&T Intellectual Property.  All other 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 requests
import logging

from keystoneauth1 import session
from keystoneauth1.identity import v3


class DrydockSession(object):
    """
    A session to the Drydock API maintaining credentials and API options

    :param string host: The Drydock server hostname or IP
    :param int port: (optional) The service port appended if specified
    :param string token: Auth token
    :param string marker: (optional) external context marker
    """

    def __init__(self, host, port=None, scheme='http', token=None,
                 marker=None):
        self.__session = requests.Session()
        self.__session.headers.update({
            'X-Auth-Token': token,
            'X-Context-Marker': marker
        })
        self.host = host
        self.scheme = scheme

        if port:
            self.port = port
            self.base_url = "%s://%s:%s/api/" % (self.scheme, self.host,
                                                 self.port)
        else:
            # assume default port for scheme
            self.base_url = "%s://%s/api/" % (self.scheme, self.host)

        self.token = token
        self.marker = marker

        self.logger = logging.getLogger(__name__)

    def get(self, endpoint, query=None):
        """
        Send a GET request to Drydock.

        :param string endpoint: The URL string following the hostname and API prefix
        :param dict query: A dict of k, v pairs to add to the query string
        :return: A requests.Response object
        """
        resp = self.__session.get(
            self.base_url + endpoint, params=query, timeout=10)

        return resp

    def post(self, endpoint, query=None, body=None, data=None):
        """
        Send a POST request to Drydock. If both body and data are specified,
        body will will be used.

        :param string endpoint: The URL string following the hostname and API prefix
        :param dict query: A dict of k, v parameters to add to the query string
        :param string body: A string to use as the request body. Will be treated as raw
        :param data: Something json.dumps(s) can serialize. Result will be used as the request body
        :return: A requests.Response object
        """

        self.logger.debug("Sending POST with drydock_client session")
        if body is not None:
            self.logger.debug("Sending POST with explicit body: \n%s" % body)
            resp = self.__session.post(
                self.base_url + endpoint, params=query, data=body, timeout=10)
        else:
            self.logger.debug("Sending POST with JSON body: \n%s" % str(data))
            resp = self.__session.post(
                self.base_url + endpoint, params=query, json=data, timeout=10)

        return resp


class KeystoneClient(object):
    @staticmethod
    def get_endpoint(endpoint, ks_sess=None, auth_info=None):
        """
        Wraps calls to keystone for lookup of an endpoint by service type
        :param endpoint: The endpoint to look up
        :param ks_sess: A keystone session to use for accessing endpoint catalogue
        :param auth_info: Authentication info to use for building a token if a ``ks_sess`` is not specified
        :returns: The url string of the endpoint
        :rtype: str
        """
        if ks_sess is None:
            ks_sess = KeystoneClient.get_ks_session(**auth_info)

        return ks_sess.get_endpoint(
            interface='internal', service_type=endpoint)

    @staticmethod
    def get_token(ks_sess=None, auth_info=None):
        """
        Returns the simple token string for a token acquired from keystone

        :param ks_sess: an existing Keystone session to retrieve a token from
        :param auth_info: dictionary of information required to generate a keystone token
        """
        if ks_sess is None:
            ks_sess = KeystoneClient.get_ks_session(**auth_info)
        return ks_sess.get_auth_headers().get('X-Auth-Token')

    @staticmethod
    def get_ks_session(**kwargs):
        # Establishes a keystone session
        if 'token' in kwargs:
            auth = v3.TokenMethod(token=kwargs.get('token'))
        else:
            auth = v3.Password(**kwargs)
        return session.Session(auth=auth)