from __future__ import absolute_import, unicode_literals

from ..parameters import parse_token_response, prepare_token_request
from oauthlib.common import generate_token
from .base import Client, AUTH_HEADER

class BackendApplicationClient(Client):
    def __init__(self, client_id,
                 default_token_placement=AUTH_HEADER,
                 token_type='Bearer',
                 access_token=None,
                 refresh_token=None,
                 mac_key=None,
                 mac_algorithm=None,
                 token=None,
                 scope=None,
                 state=None,
                 redirect_url=None,
                 state_generator=generate_token,
                 **kwargs):
        # forward parameters to super class
        super(BackendApplicationClient, self).__init__(client_id,
                 default_token_placement,
                 token_type,
                 access_token,
                 refresh_token,
                 mac_key,
                 mac_algorithm,
                 token,
                 scope,
                 state,
                 redirect_url,
                 state_generator,
                 **kwargs)
        # store kwargs (client_id and scope are already stored by super class method)
        # better still would be to add this piece of code directly in the `Client` superclass
        self.kwargs = kwargs

    def prepare_request_body(self, body='', scope=None, **kwargs):
        if scope is None:
            # no new scope provided, use the class scope
            scope = self.scope
        if not kwargs:
            # empty kwargs, use class kwargs
            kwargs = self.kwargs
        if self.client_id and 'client_id' not in kwargs:
            # kwargs does not contains client_id but the class has one, add it
            kwargs['client_id'] = self.client_id
        return prepare_token_request('client_credentials', body=body,
                                     scope=scope, **kwargs)