"""极简注册表：按名字注册 / 构建模型、数据集等组件。"""

from __future__ import annotations

from collections.abc import Callable, Iterator
from typing import Any, TypeVar

T = TypeVar("T")


class Registry:
    def __init__(self, name: str) -> None:
        self.name = name
        self._entries: dict[str, Callable[..., Any]] = {}

    def register(self, name: str | None = None) -> Callable[[T], T]:
        """装饰器；`name` 缺省时使用被装饰对象的 __name__。"""

        def wrapper(obj: T) -> T:
            key = name or getattr(obj, "__name__", None)
            if key is None:
                raise ValueError(f"无法推断注册名: {obj!r}")
            if key in self._entries:
                raise KeyError(f"{self.name} 中已存在同名条目: {key}")
            self._entries[key] = obj  # type: ignore[assignment]
            return obj

        return wrapper

    def get(self, name: str) -> Callable[..., Any]:
        if name not in self._entries:
            raise KeyError(f"{self.name} 中找不到 '{name}'，可用: {sorted(self._entries)}")
        return self._entries[name]

    def build(self, cfg: dict, **kwargs: Any) -> Any:
        """按 `{"name": ..., 其余作为构造参数}` 构建对象。"""
        cfg = dict(cfg)
        name = cfg.pop("name", None)
        if name is None:
            raise KeyError(f"构建 {self.name} 需要 'name' 字段: {cfg}")
        return self.get(name)(**{**cfg, **kwargs})

    def __contains__(self, name: object) -> bool:
        return name in self._entries

    def __iter__(self) -> Iterator[str]:
        return iter(self._entries)

    def __len__(self) -> int:
        return len(self._entries)