import json
import os
from dataclasses import asdict, dataclass
from pathlib import Path


def _tafa_dir() -> Path:
    p = Path.home() / ".tafa"
    p.mkdir(parents=True, exist_ok=True)
    return p


def config_path() -> Path:
    return _tafa_dir() / "config.json"


@dataclass
class AppConfig:
    sources: list[str]
    date_start: str
    date_end: str
    destination: str


def load_config() -> AppConfig | None:
    path = config_path()
    if not path.exists():
        return None
    try:
        data = json.loads(path.read_text())
        return AppConfig(
            sources=data["sources"],
            date_start=data["date_start"],
            date_end=data["date_end"],
            destination=data["destination"],
        )
    except (KeyError, json.JSONDecodeError, TypeError):
        return None


def save_config(cfg: AppConfig) -> None:
    path = config_path()
    tmp = path.with_suffix(".tmp")
    tmp.write_text(json.dumps(asdict(cfg), indent=2))
    os.replace(tmp, path)