from bu4.evaluation.av.envtype import envtype
from bu4.linking.states.linkingstate import LinkingState
from bu4.parsing.codes import CODE_MAKE, CODE_NULL
from bu4.evaluation.constructs.elambda import ELambda
from bu4.linking.states.afterlinking import AfterLinking
from bu4.linking.targets.allambda import ALLambda
from bu4.parsing.constructs.linked import Linked, Parsed
from bu4.linking.states.linkingfinished import LinkingFinished
from bu4.linking.states.linkingparsed import LinkingParsed
from bu4.evaluation.constructs.evaluable import Evaluable

__all__ = ('PLambda',)


class LLambda(Linked):
    value: Linked

    def __init__(self, promise: set[bytes], name: bytes, value: Parsed):
        assert name not in promise, f'overloaded: {name}'
        self.promise = promise
        self.name = name
        self._value = value

    def link(self) -> LinkingState:
        return AfterLinking(LinkingParsed(self.promise | {self.name}, self._value), ALLambda(self._given_value))

    def _given_value(self, value: Linked) -> LinkingState:
        self.value = value
        self.future = self.value.future - {self.name}
        return LinkingFinished(self)

    def evaluable(self, env: envtype) -> Evaluable:
        return ELambda(
            {name: container for name, container in env.items() if name in self.future},
            self.name,
            self.value
        )

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

    def unlink(self) -> Parsed:
        return PLambda(self.name, self._value)


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

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

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