def command_on_path(command: str) -> bool:
    """Return True if command is available in PATH, else False."""
    return bool(shutil.which(command))

def get_battery_stats() -> BatteryInfo:
    """Retrieve raw statistics from battery.

    Failure of `tlp_get_stats()` may be non-fatal, so we just return
    the message for display and let the user decide what to do.

    Returns:
        BatteryInfo: discharge status, and battery statistics or
        an error message.
    """
    try:
        raw_stats = tlp_get_stats()
        return parse_tlp_stats(raw_stats)
    except TlpCommandError as exc:
        return {'discharging': False, 'info': f"Error: {exc}"}

def on_ac_power() -> bool:
    """Return True if on AC power, else False.

    Raises:
        RuntimeError: If AC power cannot be determined.
   """
    base = Path("/sys/class/power_supply")
    if base.is_dir():
        for child in base.iterdir():
            type_file = child / "type"
            try:
                # Check for AC adaptor.
                if type_file.is_file() and type_file.read_text().strip() == "Mains":
                    # Then check if it online.
                    online_file = child / "online"
                    if online_file.is_file():
                        return online_file.read_text().strip() == "1"
            except OSError:
                pass
    # Unsupported system
    raise RuntimeError("Power supply information not available.")

def parse_args(argv: list[str]) -> Config:
    """Parse command-line arguments and return configuration.

    Args:
        argv: List of command-line arguments.

    Returns:
        tuple: (theme_dict, standard_font, small_font, scale_factor).
    """
    parser = argparse.ArgumentParser(
        description="A simple GUI to enable `tlp fullcharge`.",
        # Automatically add defaults to help text.
        formatter_class=argparse.ArgumentDefaultsHelpFormatter)

    parser.add_argument('-v', '--version',
                        action='version',
                        version=f"Battery Boost {version('tlp-battery-boost')}")

    parser.add_argument(
        '-f', '--font-size',
        type=int,
        choices=range(1, 6),
        default=3,
        metavar="{1-5}",
        help="Font size [1-5] (1=smallest, 5=largest)")

    parser.add_argument(
        '-t', '--theme',
        choices=['light', 'dark'],
        default='light' if DEFAULT_THEME == THEME[ThemeName.LIGHT] else 'dark',
        help="Color theme")

    parsed_args = parser.parse_args(argv)
    standard_font, small_font, scale_factor = FONT_SIZES[parsed_args.font_size]
    return THEME[ThemeName(parsed_args.theme)], standard_font, small_font, scale_factor