"""动作处理器公共接口，供后端校验时修改大屏 JSON 副本，不操作前端画布"""

from abc import ABC, abstractmethod
from typing import Generic, TypeVar

from app.schemas.actions.base import ActionModel
from app.schemas.screen import Screen, ScreenNode

ActionT = TypeVar("ActionT", bound=ActionModel)


class BaseActionHandler(ABC, Generic[ActionT]):
    @abstractmethod
    def apply(self, screen: Screen, action: ActionT) -> Screen:
        """检查动作能否执行，返回修改后的大屏副本，保留原始输入"""
        raise NotImplementedError

    def copy_target(self, screen: Screen, target_id: str) -> tuple[Screen, ScreenNode]:
        # 遍历节点
        for index, node in enumerate(screen.nodes):
            # 如果找到目标，复制完整大屏，并返回副本中同一位置的节点
            if node.id == target_id:
                result = screen.model_copy(deep=True)
                # 返回副本内的节点引用，让调用方的修改直接体现在 result 中
                return result, result.nodes[index]

        # 遍历后仍未找到目标时明确报错，不能把无效动作当作执行成功
        raise ValueError(f"目标组件不存在: {target_id}")