"""Persist whether the audio beat detector should be running (survives process restarts)."""

from __future__ import annotations

import json
import os
from typing import Any, Dict, Optional


def _db_path() -> str:
    base = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
    return os.path.join(base, "db", "audio_run.json")


def coerce_audio_device(device: Any) -> Optional[Any]:
    """Match ``/api/audio/start`` body coercion (None = host default input)."""
    if device in ("", None):
        return None
    try:
        return int(device)
    except (TypeError, ValueError):
        return device


def read_audio_run_state() -> Dict[str, Any]:
    path = _db_path()
    try:
        with open(path, "r", encoding="utf-8") as f:
            raw = json.load(f)
    except (OSError, json.JSONDecodeError, TypeError):
        return {"enabled": False, "device": None}
    if not isinstance(raw, dict):
        return {"enabled": False, "device": None}
    enabled = bool(raw.get("enabled"))
    dev = raw.get("device", None)
    return {"enabled": enabled, "device": dev}


def write_audio_run_state(*, enabled: bool, device: Any = None) -> None:
    """Write run intent. When ``enabled`` is false, keep ``device`` from the previous file for next start."""
    path = _db_path()
    prev = read_audio_run_state()
    if enabled:
        data = {"enabled": True, "device": device}
    else:
        data = {"enabled": False, "device": prev.get("device")}
    try:
        os.makedirs(os.path.dirname(path), exist_ok=True)
        with open(path, "w", encoding="utf-8") as f:
            json.dump(data, f, indent=2)
    except OSError as e:
        print(f"[audio_run_persist] save failed: {e!r}")