"""
core/app_settings.py

Platform-aware persistence for application settings.

Stored independently of profiles so they survive profile switches and
reflect per-computer preferences (theme, font, paths, etc.).

Locations:
  Windows : %APPDATA%/labUI/settings.json
  macOS   : ~/Library/Application Support/labUI/settings.json
  Linux   : $XDG_CONFIG_HOME/labUI/settings.json  (default ~/.config/labUI/)
"""

import json
import os
import sys
from pathlib import Path


def _settings_path() -> Path:
    if sys.platform == "win32":
        base = Path(os.environ.get("APPDATA", Path.home()))
    elif sys.platform == "darwin":
        base = Path.home() / "Library" / "Application Support"
    else:
        base = Path(os.environ.get("XDG_CONFIG_HOME", Path.home() / ".config"))
    return base / "labUI" / "settings.json"


SETTINGS_PATH = _settings_path()


def load_settings(defaults: dict) -> dict:
    """Return defaults merged with any saved settings. Never raises."""
    cfg = dict(defaults)
    try:
        if SETTINGS_PATH.exists():
            with open(SETTINGS_PATH) as f:
                cfg.update(json.load(f))
    except Exception:
        pass
    return cfg


def save_settings(cfg: dict) -> None:
    """Persist cfg to disk. Never raises."""
    try:
        SETTINGS_PATH.parent.mkdir(parents=True, exist_ok=True)
        with open(SETTINGS_PATH, "w") as f:
            json.dump(cfg, f, indent=2)
    except Exception:
        pass