from typing import TypeVar

from rainbowadn.hashing.hashmentionable import HashMentionable
from rainbowadn.hashing.hashpoint import HashPoint
from rainbowadn.hashing.nullability.notnull import NotNull
from rainbowadn.hashing.nullability.null import Null

__all__ = ('HashResolver',)

RHashMentioned = TypeVar('RHashMentioned')


class HashResolver:
    def _resolve(self, point: bytes) -> bytes:
        raise NotImplementedError

    def resolve(self, hashpoint: HashPoint[RHashMentioned]) -> RHashMentioned:
        assert isinstance(hashpoint, HashPoint)
        if isinstance(hashpoint.value, NotNull):
            return hashpoint.value.value
        elif isinstance(hashpoint.value, Null):
            resolved: bytes = self._resolve(bytes(hashpoint))
            assert isinstance(resolved, bytes)
            mentioned: RHashMentioned = hashpoint.factory.from_bytes(resolved[HashPoint.HASH_LENGTH:])
            assert isinstance(mentioned, HashMentionable)
            assert mentioned.__topology_hash__() == resolved[:HashPoint.HASH_LENGTH]
            return mentioned
        else:
            raise TypeError