from __future__ import annotations

import importlib.util
import os
import sys
from pathlib import Path
from types import ModuleType
from typing import Any

ENV_NAME = "PAPER_DB_CONFIG"

COMMON_ROOT = Path(__file__).resolve().parent
if str(COMMON_ROOT) not in sys.path:
    sys.path.insert(0, str(COMMON_ROOT))


def resolve_config_path(value: str | Path | None = None) -> Path:
    raw = value or os.environ.get(ENV_NAME)
    path = Path(raw).expanduser() if raw else Path.cwd() / "config.py"
    path = path.resolve()
    if not path.is_file():
        raise FileNotFoundError(f"config.pyがありません: {path}")
    return path


def load_module(path: Path) -> ModuleType:
    spec = importlib.util.spec_from_file_location(
        "paper_db_project_config", path
    )
    if spec is None or spec.loader is None:
        raise ImportError(f"config.pyを読み込めません: {path}")
    module = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(module)
    return module


def load_config(value: str | Path | None = None) -> tuple[Path, Any]:
    path = resolve_config_path(value)
    module = load_module(path)
    if not hasattr(module, "CONFIG"):
        raise AttributeError(f"CONFIGがありません: {path}")
    config = module.CONFIG
    if Path(config.path.project_root).resolve() != path.parent:
        raise ValueError(
            "project_rootはconfig.pyのディレクトリにしてください"
        )
    return path, config