'''
Python version: 3.7
https://www.mybluelinux.com/python-how-to-refresh-an-jwt-access-token-using-decorators/
https://stackoverflow.com/questions/37094419/python-requests-retry-request-after-re-authentication
'''

import requests
import time, os


class myAPI():
    host = None
    key = None
    secret = None
    access_token = None
    access_token_expiration = None

    def __init__(self, host):
        # the function that is executed when
        # an instance of the class is created
        self.host = host
        # self.key = key
        # self.secret = secret

        try:
            self._session = requests.Session()  # Session for tokens
            self.access_token = self.getAccessToken()
            if self.access_token is None:
                raise Exception("Request for access token failed.")

            self.session = requests.Session()  # Authenticated session
            self.session.auth = self.auth
            self.session.hooks['response'].append(self.reauth)
        except Exception as e:
            print(e)
        else:
            self.access_token_expiration = time.time() + 3600

    def reauth(self, res, *args, **kwargs):
        """Hook to re-authenticate whenever authentication expires."""
        if res.status_code == requests.codes.unauthorized:
            if res.request.headers.get('REATTEMPT'):
                res.raise_for_status()
            self.refresh_auth()
            req = res.request
            req.headers['REATTEMPT'] = 1
            req = self.session.auth(req)
            res = self.session.send(req)
            return res

    def refresh_auth(self):
        """Use the refresh token to get a new access token."""
        res = self._session.post(self.abs_url("api/token/refresh/"), data={"refresh": self.refresh})
        if res.status_code == 200:
            self.access_token = res.json()['access_token']
        else:
            # Token expired -> re-authenticate
            self.reauth()

    def authenticate(self):
        # the function that is
        # used to request the JWT
        try:
            # build the JWT and store
            # in the variable `token_body`
            refresh_token =  os.environ.get("REFRESH_TOKEN")

            # request an access token
            request = requests.post(self.host,
                                    headers={
                                        'Authorization': 'Basic ' + refresh_token,
                                        'cache-control': 'no-cache',
                                        'Content-Type': 'application/x-www-form-urlencoded',
                                        'accept': 'application/json'
                                    },
                                    data='grant_type=client_credentials&scope=gschliefgraben')

            # optional: raise exception for status code
            request.raise_for_status()
        except Exception as e:
            print(e)
            return None
        else:
            # assuming the response's structure is
            # {"access_token": ""}
            data = request.json()
            return data['access_token']