import logger

from nacl.signing import VerifyKey
import nacl.exceptions

from getbykey import get_identity_by_key


def process_trust_signature(signature: bytes):
    if len(signature) != 128:
        logger.warn(
            f'Signature size is invalid for a signed identity')
    signer = signature[:32]
    signed = signature[32:65]
    signature = signature[65:]

    # If bad signature, it raises nacl.exceptions.BadSignatureError
    VerifyKey.verify(signer, signed, signature)

    else:
        # if good signature
        try:
            signer_identity = get_identity_by_key(signer)
            signed_identity = get_identity_by_key(signed)
        except KeyError:
            # if signer or signed identity are not in the identity set
            # this means they have not been announced yet
            pass
        else:
            # noop if already signed
            signer_identity.trusted.add(signed_identity)