#  Copyright (c) PARRRATE T&V 2021. All rights reserved.

from typing import Mapping, Iterator

from bu4.evaluation.av.envtype import envtype
from bu4.evaluation.constructs.evaluable import Evaluable
from bu4.evaluation.targets.avnamedcontainer import AVNamedContainer

__all__ = ('LambdaEnv',)


class LambdaEnv(Mapping[bytes, Evaluable]):
    def __getitem__(self, k: bytes) -> Evaluable:
        if k == self.name:
            return self.container
        else:
            return self.env[k]

    def __len__(self) -> int:
        return len(self.env) + 1

    def __iter__(self) -> Iterator[Evaluable]:
        yield self.name
        yield from self.env

    def __init__(self, env: envtype, name: bytes, evaluable: Evaluable, *, memoize):
        self.env = env
        self.name = name
        self.container = AVNamedContainer(evaluable, name).after_value if memoize else evaluable

    @staticmethod
    def strfy(self):
        return ''.join(f'\x7b{evaluable}|{name.decode()}\x7d' for name, evaluable in self.items())

    def __str__(self):
        return self.strfy(self)