"""Minimal stdlib logging helper (kept dependency-free from the javis package).

Logs go to stderr and to a rotating file under ``<config dir>/logs/slave.log``
so tablet/Pi problems can be diagnosed after the fact.
"""
from __future__ import annotations

import logging
import sys
from logging.handlers import RotatingFileHandler

_configured = False
_FMT = logging.Formatter(
    "%(asctime)s | %(levelname)-7s | %(name)s - %(message)s", datefmt="%H:%M:%S",
)


def _configure_once() -> None:
    global _configured
    if _configured:
        return
    root = logging.getLogger("javis_slave")
    root.setLevel(logging.INFO)
    root.propagate = False

    handler = logging.StreamHandler(sys.stderr)
    handler.setFormatter(_FMT)
    root.addHandler(handler)

    try:
        from .config import config_dir
        log_dir = config_dir() / "logs"
        log_dir.mkdir(parents=True, exist_ok=True)
        fh = RotatingFileHandler(log_dir / "slave.log", maxBytes=2_000_000,
                                 backupCount=3, encoding="utf-8")
        fh.setFormatter(logging.Formatter(
            "%(asctime)s | %(levelname)-7s | %(name)s - %(message)s"))
        root.addHandler(fh)
    except Exception as exc:  # noqa: BLE001  (read-only FS etc. — stderr still works)
        root.warning(f"file logging disabled: {exc}")
    _configured = True


def get_logger(name: str) -> logging.Logger:
    _configure_once()
    return logging.getLogger(f"javis_slave.{name}")