"""Per-connection session log on disk (already redacted lines only)."""

from __future__ import annotations

import datetime as dt
import re
from pathlib import Path

from .logline import LogLine

SESSIONS_DIR = Path.home() / "KotaTechnicianTool" / "sessions"


class SessionLog:
    def __init__(self, root: Path = SESSIONS_DIR):
        self.root = root
        self.path: Path | None = None
        self._fh = None

    def start(self, device_hint: str) -> Path:
        self.stop()
        self.root.mkdir(parents=True, exist_ok=True)
        stamp = dt.datetime.now().strftime("%Y%m%d_%H%M%S")
        safe = re.sub(r"[^A-Za-z0-9]+", "", device_hint)[:20] or "board"
        self.path = self.root / f"session_{stamp}_{safe}.log"
        self._fh = self.path.open("a", encoding="utf-8", newline="\n")
        return self.path

    def write(self, line: LogLine) -> None:
        if self._fh is None:
            return
        ts = dt.datetime.fromtimestamp(line.host_time).strftime("%H:%M:%S.%f")[:-3]
        self._fh.write(f"[{ts}] {line.text}\n")
        self._fh.flush()

    def stop(self) -> None:
        if self._fh is not None:
            self._fh.close()
            self._fh = None