"""Read controller settings using the bundled upstream VESC Tool decoder."""
import math

FIELDS = frozenset({"l_current_max", "l_current_min", "l_current_max_scale", "l_current_min_scale",
    "l_in_current_max", "l_in_current_min", "l_min_erpm", "l_max_erpm", "l_max_duty",
    "l_watt_max", "l_watt_min", "si_motor_poles", "si_gear_ratio", "si_wheel_diameter"})


def read_limits(link):
    configuration = link.configuration()
    result = {}
    for parameter in configuration["motor"]["parameters"]:
        name, value = parameter["name"], parameter.get("value")
        if name in FIELDS and type(value) in (int, float) and math.isfinite(value):
            result[name] = value
    if set(result) != FIELDS:
        raise ValueError("Native configuration is missing limit fields")
    return result