from bu4.codes import CODE_NAME, CODE_NULL
from bu4.parsing.linked import Linked, LinkingState, Parsed
from bu4.linking.linkingfinished import LinkingFinished
from bu4.evaluation.aftervalue import envtype, Evaluable


__all__ = ('LName', 'PName',)


class LName(Linked):
    def __init__(self, promise: set[bytes], name: bytes):
        assert name in promise, f'undefined: {name}'
        self.name = name
        self.future = {name}

    def link(self) -> LinkingState:
        return LinkingFinished(self)

    def evaluable(self, env: envtype) -> Evaluable:
        return env[self.name]

    def __str__(self):
        return f'[{self.name.decode()}]'

    def unlink(self) -> Parsed:
        return PName(self.name)


class PName(Parsed):
    def __init__(self, name: bytes):
        self.name = name

    def link(self, promise: set[bytes]) -> Linked:
        return LName(promise, self.name)

    def __bytes__(self):
        return bytes([CODE_NAME, *self.name, CODE_NULL])