from __future__ import unicode_literals

import binascii

from pymacaroons2 import Caveat
from pymacaroons2.utils import (
    convert_to_bytes,
    convert_to_string,
    sign_first_party_caveat,
)

from .base_first_party import (
    BaseFirstPartyCaveatDelegate,
    BaseFirstPartyCaveatVerifierDelegate,
)


class FirstPartyCaveatDelegate(BaseFirstPartyCaveatDelegate):

    def __init__(self, *args, **kwargs):
        super(FirstPartyCaveatDelegate, self).__init__(*args, **kwargs)

    def add_first_party_caveat(self, macaroon, predicate, **kwargs):
        predicate = convert_to_bytes(predicate)
        # Check it's valid utf-8 for first party caveats.
        # Will raise a unicode error if not.
        predicate.decode("utf-8")
        caveat = Caveat(caveat_id=predicate, version=macaroon.version)
        macaroon.caveats.append(caveat)
        encode_key = binascii.unhexlify(macaroon.signature_bytes)
        macaroon.signature = sign_first_party_caveat(encode_key, predicate)
        return macaroon


class FirstPartyCaveatVerifierDelegate(BaseFirstPartyCaveatVerifierDelegate):

    def __init__(self, *args, **kwargs):
        super(FirstPartyCaveatVerifierDelegate, self).__init__(*args, **kwargs)

    def verify_first_party_caveat(self, verifier, caveat, signature):
        predicate = convert_to_string(caveat.caveat_id)
        caveat_met = sum(callback(predicate) for callback in verifier.callbacks)
        return caveat_met

    def update_signature(self, signature, caveat):
        return binascii.unhexlify(
            sign_first_party_caveat(signature, caveat.caveat_id_bytes)
        )
