from typing import TYPE_CHECKING, Any


if TYPE_CHECKING:
    from .terms import ExecutorTerm


class ExecContext:
    """
    Base context class that carries the instantiation state.

    This is passed to all CommandTerms upon execution.
    """

    def __init__(self, *, alias: str, args: list[str], content: str, initial_globals: dict[str, Any] = {}, **kwargs):
        self.alias = alias
        self.args = args
        self.content = content

        # Stack of scopes
        # Initialising globals this way to avoid modifying default arg
        globals = {} | initial_globals
        self.scopes: list[dict[str, Any]] = [globals]

        # Stack of terms that are *currently* executing with this context.
        self.termstack: list['ExecutorTerm'] = []

    def enter_scope(self, *args, **kwargs):
        new_scope = dict(*args, **kwargs)
        self.scopes.append(new_scope)

    def leave_scope(self):
        if len(self.scopes) > 1:
            self.scopes.pop()
        else:
            raise ValueError("Cannot leave global scope")

    @property
    def scope(self):
        # TODO: Move this to a more efficient ExecScope mapping type at some point
        fullscope = {}
        for scope in self.scopes:
            fullscope |= scope
        return fullscope

    @property
    def this_scope(self):
        return self.scopes[-1]