#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You 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 time
from oauthlib.oauth2 import LegacyApplicationClient
from requests_oauthlib import OAuth2Session
import requests
from airavata_custos import settings


class KeycloakBackend(object):

    def authenticate_user(self, user_credentials):
        """
        Method to authenticate a gateway user with keycloak
        :param user_credentials: object of UserCredentials class
        :return: Token object, UserInfo object
        """
        try:
            token, user_info = self._get_token_and_user_info_password_flow(user_credentials)
            return token, user_info
        except Exception as e:
            return None

    def authenticate_account(self, account_credentials):
        """

        :param account_credentials: object of AccountCredentials class
        :return: Token object, UserInfo object
        """
        try:
            token, user_info = self._get_token_and_user_info_redirect_flow(account_credentials)
            return token, user_info
        except Exception as e:
            return None

    def authenticate_using_refresh_token(self, client_credentials, refresh_token):
        """

        :param client_credentials: object of ClientCredentials class
        :param refresh_token: openid connect refresh token
        :return: Token object
        """
        try:
            token = self._get_token_from_refresh_token(client_credentials, refresh_token)
            return token
        except Exception as e:
            return None

    @classmethod
    def _get_token_and_user_info_password_flow(cls, client_credentials):

        oauth2_session = OAuth2Session(client=LegacyApplicationClient(client_id=client_credentials.client_id))
        token = oauth2_session.fetch_token(token_url=settings.KEYCLOAK_TOKEN_URL,
                                           username=client_credentials.username,
                                           password=client_credentials.password,
                                           client_id=client_credentials.client_id,
                                           client_secret=client_credentials.client_secret,
                                           verify=settings.VERIFY_SSL)
        user_info = oauth2_session.get(settings.KEYCLOAK_USERINFO_URL).json()
        return cls._process_token(token), cls._process_userinfo(user_info)

    @classmethod
    def _get_token_and_user_info_redirect_flow(cls, client_credentials):
        oauth2_session = OAuth2Session(client_credentials.client_id,
                                       scope='openid',
                                       redirect_uri=client_credentials.redirect_uri,
                                       state=client_credentials.state)
        token = oauth2_session.fetch_token(settings.KEYCLOAK_TOKEN_URL,
                                           client_secret=client_credentials.client_secret,
                                           authorization_response=client_credentials.authorization_code_url,
                                           verify=settings.VERIFY_SSL)
        user_info = oauth2_session.get(settings.KEYCLOAK_USERINFO_URL).json()
        return cls._process_token(token), cls._process_userinfo(user_info)

    @classmethod
    def _get_token_from_refresh_token(cls, client_credentials, refresh_token):

        oauth2_session = OAuth2Session(client_credentials.client_id, scope='openid')
        auth = requests.auth.HTTPBasicAuth(client_credentials.client_id, client_credentials.client_secret)
        token = oauth2_session.refresh_token(token_url=settings.KEYCLOAK_TOKEN_URL,
                                             refresh_token=refresh_token,
                                             auth=auth,
                                             verify=settings.VERIFY_SSL)
        return cls._process_token(token)

    @classmethod
    def _process_token(cls, token):

        now = time.time()
        access_token = token['access_token']
        access_token_expires_at = now + token['expires_in']
        refresh_token = token['refresh_token']
        refresh_token_expires_at = now + token['refresh_expires_in']
        return Token(access_token, access_token_expires_at, refresh_token, refresh_token_expires_at)

    @classmethod
    def _process_userinfo(cls, userinfo):

        username = userinfo['preferred_username']
        email = userinfo['email']
        first_name = userinfo['given_name']
        last_name = userinfo['family_name']
        return UserInfo(username, email, first_name, last_name)


class Token(object):

    def __init__(self, access_token, access_token_expires_at, refresh_token, refresh_token_expires_at):
        self.access_token = access_token
        self.access_token_expires_at = access_token_expires_at
        self.refresh_token = refresh_token
        self.refresh_token_expires_at = refresh_token_expires_at


class UserInfo(object):

    def __init__(self, username, email, first_name, last_name):
        self.username = username
        self.email = email
        self.first_name = first_name
        self.last_name = last_name