"""Location helpers for Home Assistant."""

from homeassistant.const import ATTR_LATITUDE, ATTR_LONGITUDE
from homeassistant.core import State
from homeassistant.util import location as loc_util


def has_location(state):
    """Test if state contains a valid location."""
    return (isinstance(state, State) and
            isinstance(state.attributes.get(ATTR_LATITUDE), float) and
            isinstance(state.attributes.get(ATTR_LONGITUDE), float))


def closest(latitude, longitude, states):
    """Return closest state to point."""
    with_location = [state for state in states if has_location(state)]

    if not with_location:
        return None

    return min(
        with_location,
        key=lambda state: loc_util.distance(
            latitude, longitude, state.attributes.get(ATTR_LATITUDE),
            state.attributes.get(ATTR_LONGITUDE))
    )