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

from bu4.linking.states.afterlinking import AfterLinking
from bu4.linking.targets.alchain import ALChain
from bu4.linking.states.linkingfinished import LinkingFinished
from bu4.linking.states.linkingparsed import LinkingParsed
from bu4.linking.states.linkingstate import LinkingState
from bu4.parsing.constructs.linked import Linked

__all__ = ('prepare',)


def _afterlinking_iteration(state: AfterLinking) -> LinkingState:
    if isinstance(state.state, LinkingFinished):
        state = state.target.given(state.state.linked)
    elif isinstance(state.state, AfterLinking):
        state.state, state.target = state.state.state, ALChain(state.state.target, state.target)
    elif isinstance(state.state, LinkingParsed):
        state.state = state.state.parsed.link(state.state.promise).link()
    else:
        raise TypeError
    return state


def prepare(linked: Linked) -> Linked:
    state = linked.link()
    while True:
        if isinstance(state, LinkingFinished):
            return state.linked
        elif isinstance(state, AfterLinking):
            state = _afterlinking_iteration(state)
        else:
            raise TypeError