oauth.py

import json

from rauth import OAuth1Service, OAuth2Service
from flask import current_app, url_for, request, redirect, session
from services.secrets import FB_ID, FB_SECRET


class OAuthSignIn(object):
    providers = None

    def __init__(self, provider_name):
        self.provider_name = provider_name

    def authorize(self):
        pass

    def callback(self):
        pass

    def get_callback_url(self):
        return url_for('oauth_callback',
            provider=self.provider_name,
            _external=True,
            _scheme="https"
        )

    @classmethod
    def get_provider(self, provider_name):
        if self.providers is None:
            self.providers = {}
            for provider_class in self.__subclasses__():
                provider = provider_class()
                self.providers[provider.provider_name] = provider
        return self.providers[provider_name]


class FacebookSignIn(OAuthSignIn):
    def __init__(self):
        super(FacebookSignIn, self).__init__('facebook')
        self.consumer_id = FB_ID
        self.consumer_secret = FB_SECRET
        self.service = OAuth2Service(
            name='facebook',
            client_id=self.consumer_id,
            client_secret=self.consumer_secret,
            authorize_url='https://graph.facebook.com/oauth/authorize',
            access_token_url='https://graph.facebook.com/oauth/access_token',
            base_url='https://graph.facebook.com/'
        )

    def authorize(self):
        return redirect(self.service.get_authorize_url(
            scope='user_posts',
            response_type='code',
            redirect_uri=self.get_callback_url())
        )

    def callback(self):
        def decode_json(payload):
            return json.loads(payload.decode('utf-8'))

        if 'code' not in request.args:
            return None, None, None
        oauth_session = self.service.get_auth_session(
            params={
                'code': request.args['code'],
                'grant_type': 'authorization_code',
                'redirect_uri': self.get_callback_url()
            },
            decoder=decode_json
        )

        me = oauth_session.get('me?fields=id').json()
        return (
            me['id'],
            oauth_session.access_token
        )