"""采购工具的本地运行目录策略。"""

from __future__ import annotations

from dataclasses import dataclass
import os
from pathlib import Path


@dataclass(frozen=True)
class RuntimePaths:
    """仅包含应用生成物的本地目录。

    日志和证据产物不落在源码树中，避免把含有现场信息的运行数据误提交到 Git。
    """

    root: Path
    logs: Path
    artifacts: Path

    @classmethod
    def from_root(cls, root: Path) -> "RuntimePaths":
        resolved_root = root.expanduser()
        return cls(
            root=resolved_root,
            logs=resolved_root / "logs",
            artifacts=resolved_root / "artifacts",
        )

    @classmethod
    def default(cls) -> "RuntimePaths":
        local_app_data = os.environ.get("LOCALAPPDATA")
        if local_app_data:
            return cls.from_root(Path(local_app_data) / "cmbuyer")

        return cls.from_root(Path.home() / ".local" / "share" / "cmbuyer")

    def ensure_exists(self) -> None:
        """创建运行目录；调用方负责向用户呈现无法创建目录的错误。"""

        self.logs.mkdir(parents=True, exist_ok=True)
        self.artifacts.mkdir(parents=True, exist_ok=True)