"""Persist a handful of user choices to ~/HVideoTool/settings.json.

Slimmed down for the image-inspector tool: it remembers the detector, the model
path, the overlay threshold, and the last opened folder.
"""

from __future__ import annotations

import json
from pathlib import Path

from .config import AppConfig

_PATH = Path.home() / "HVideoTool" / "settings.json"


def _read() -> dict:
    try:
        return json.loads(_PATH.read_text(encoding="utf-8"))
    except (OSError, ValueError):
        return {}


def _write(data: dict) -> None:
    _PATH.parent.mkdir(parents=True, exist_ok=True)
    _PATH.write_text(json.dumps(data, ensure_ascii=False, indent=2), encoding="utf-8")


def apply(config: AppConfig) -> None:
    """Overlay persisted settings onto ``config`` (mutates it in place)."""
    data = _read()
    if data.get("detector"):
        config.detector = data["detector"]
    if "model_path" in data:
        config.model_path = data["model_path"]
    if "threshold" in data:
        config.default_threshold = float(data["threshold"])


def save(config: AppConfig) -> None:
    """Persist the configurable settings, preserving other keys (e.g. last_dir)."""
    data = _read()
    data.update(
        detector=config.detector,
        model_path=config.model_path,
        threshold=config.default_threshold,
    )
    _write(data)


def last_dir() -> str | None:
    return _read().get("last_dir")


def set_last_dir(path: str) -> None:
    data = _read()
    data["last_dir"] = path
    _write(data)