from typing import Callable, Optional
import numpy as np
from .Signature import Signature

class IKeyPair:
    def __init__(self, private_key: bytes, public_key: bytes):
        self.private_key = private_key
        self.public_key = public_key

    def sign(self, msg: bytes, custom_sign_function: Optional[Callable[[bytes, bytes, bytes], bytes]] = None) -> Signature:
        if custom_sign_function is not None:
            signature_bytes = custom_sign_function(msg, self.private_key, self.public_key)
        else:
            signature_bytes = self.default_sign_function(msg, self.private_key, self.public_key)
        return self.create_signature(signature_bytes)

    def default_sign_function(self, message: bytes, private_key: bytes, public_key: bytes) -> bytes:
        # Implement the default signing logic here
        pass

    def create_signature(self, signature_bytes: bytes) -> Signature:
        # Create and return a Signature object from the signature bytes
        pass
