from __future__ import annotations

import importlib
from dataclasses import dataclass
from typing import Type

from app.jobs.base import BaseJob


@dataclass(frozen=True)
class HandlerRef:
    module: str
    cls_name: str


def parse_handler_path(handler_path: str) -> HandlerRef:
    """
    支持两种格式：
    - "pkg.mod:ClassName"（推荐）
    - "pkg.mod.ClassName"
    """
    if ":" in handler_path:
        module, cls_name = handler_path.split(":", 1)
        return HandlerRef(module=module, cls_name=cls_name)
    if "." not in handler_path:
        raise ValueError(f"Invalid handler_path: {handler_path}")
    module, cls_name = handler_path.rsplit(".", 1)
    return HandlerRef(module=module, cls_name=cls_name)


def load_job_class(handler_path: str) -> Type[BaseJob]:
    ref = parse_handler_path(handler_path)
    mod = importlib.import_module(ref.module)
    cls = getattr(mod, ref.cls_name, None)
    if cls is None:
        raise ImportError(f"Class not found: {ref.module}.{ref.cls_name}")
    if not isinstance(cls, type) or not issubclass(cls, BaseJob):
        raise TypeError(f"Handler is not a BaseJob subclass: {handler_path}")
    return cls


def instantiate(handler_path: str) -> BaseJob:
    cls = load_job_class(handler_path)
    return cls()