import copy
from typing import Final

from jsonpath_ng import parse

from localstack.services.stepfunctions.asl.component.eval_component import EvalComponent
from localstack.services.stepfunctions.asl.eval.environment import Environment


class ResultPath(EvalComponent):
    DEFAULT_PATH: Final[str] = "$"

    result_path_src: Final[str | None]

    def __init__(self, result_path_src: str | None):
        self.result_path_src = result_path_src

    def _eval_body(self, env: Environment) -> None:
        state_input = env.states.get_input()

        # Discard task output if there is one, and set the output to be the state's input.
        if self.result_path_src is None:
            env.stack.clear()
            env.stack.append(state_input)
            return

        # Transform the output with the input.
        current_output = env.stack.pop()
        result_expr = parse(self.result_path_src)
        state_output = result_expr.update_or_create(state_input, copy.deepcopy(current_output))
        env.stack.append(state_output)
