from django.contrib.auth.models import User
from cashonly.core.models import Account
from cashonly.core.services import AccountManager


class UsernameCardnumberPinBackend(object):
    def authenticate(self, username=None, card_number=None, pin=None):
        if username is not None and card_number is not None:
            raise ValueError('username and card_number are mutually exclusive')
        if username is None and card_number is None:
            raise ValueError('either username and card_number is required')

        try:
            if username is not None:
                user = User.objects.get(username=username)
                account = user.account
            elif card_number is not None:
                account = Account.objects.get(card_number=card_number)
        except User.DoesNotExist:
            return None
        except Account.DoesNotExist:
            return None

        accmgr = AccountManager(account)
        if accmgr.check_pin(pin):
            return account.user
        return None

    def get_user(self, user_id):
        try:
            return User.objects.get(pk=user_id)
        except User.DoesNotExist:
            return None