class BaseHandler(tornado.web.RequestHandler):
    def get_current_user(self):
        user_json = self.get_secure_cookie("authdemo_user")
        if not user_json: return None
        return tornado.escape.json_decode(user_json)

class GoogleOAuth2LoginHandler(tornado.web.RequestHandler,
                               tornado.auth.GoogleOAuth2Mixin):
    @tornado.gen.coroutine
    def get(self):
        if self.get_argument('code', False):
            user = yield self.get_authenticated_user(
                redirect_uri='GOOGLE_CALLBACK',
                code=self.get_argument('code'))
            # Save the user with e.g. set_secure_cookie
            print user
            # get user info
            http=tornado.httpclient.AsyncHTTPClient()
            auth_string = "%s %s" % (user['token_type'], user['access_token'])
            response = yield http.fetch('https://www.googleapis.com/userinfo/v2/me',
                headers={"Authorization": auth_string})
            user = json.loads(response.body)
            email = user['email']
            if email.endswith('@YOURDOMAIN.COM'):
                user_json = json.dumps(dict(email=email))
                self.set_secure_cookie("authdemo_user", user_json)
            self.redirect('/')

        else:
            yield self.authorize_redirect(
                redirect_uri='GOOGLE_CALLBACK',
                client_id=self.settings['google_oauth']['key'],
                scope=['profile', 'email'],
                response_type='code',
                extra_params={'approval_prompt': 'auto'})
                
class Application(tornado.web.Application):
    def __init__(self):
        handlers = [
            (r"/", MainHandler),
            (r"/auth/google", GoogleOAuth2LoginHandler),
        ]
        settings = dict(
            debug=True,
            template_path=os.path.join(os.path.dirname(__file__), "templates"),
            static_path=os.path.join(os.path.dirname(__file__), "static"),
            cookie_secret='modify_this',
            autoescape=None,
            login_url = r'/auth/google',
            google_oauth = {'key': 'GOOGKE_KEY',
                            'secret': 'GOOGKE_SECRET'}
        )
        tornado.web.Application.__init__(self, handlers, **settings)