core/homeassistant/components/sensor/significant_change.py

"""Helper to test significant sensor state changes."""
from __future__ import annotations

from typing import Any

from homeassistant.const import (
    ATTR_DEVICE_CLASS,
    ATTR_UNIT_OF_MEASUREMENT,
    TEMP_FAHRENHEIT,
)
from homeassistant.core import HomeAssistant, callback
from homeassistant.helpers.significant_change import (
    check_absolute_change,
    check_percentage_change,
)

from . import SensorDeviceClass


def _absolute_and_relative_change(
    old_state: int | float | None,
    new_state: int | float | None,
    absolute_change: int | float,
    percentage_change: int | float,
) -> bool:
    return check_absolute_change(
        old_state, new_state, absolute_change
    ) and check_percentage_change(old_state, new_state, percentage_change)


@callback
def async_check_significant_change(
    hass: HomeAssistant,
    old_state: str,
    old_attrs: dict,
    new_state: str,
    new_attrs: dict,
    **kwargs: Any,
) -> bool | None:
    """Test if state significantly changed."""
    if (device_class := new_attrs.get(ATTR_DEVICE_CLASS)) is None:
        return None

    absolute_change: float | None = None
    percentage_change: float | None = None
    if device_class == SensorDeviceClass.TEMPERATURE:
        if new_attrs.get(ATTR_UNIT_OF_MEASUREMENT) == TEMP_FAHRENHEIT:
            absolute_change = 1.0
        else:
            absolute_change = 0.5

    if device_class in (SensorDeviceClass.BATTERY, SensorDeviceClass.HUMIDITY):
        absolute_change = 1.0

    if device_class in (
        SensorDeviceClass.AQI,
        SensorDeviceClass.CO,
        SensorDeviceClass.CO2,
        SensorDeviceClass.PM25,
        SensorDeviceClass.PM10,
        SensorDeviceClass.VOLATILE_ORGANIC_COMPOUNDS,
    ):
        absolute_change = 1.0
        percentage_change = 2.0

    try:
        # New state is invalid, don't report it
        new_state_f = float(new_state)
    except ValueError:
        return False

    try:
        # Old state was invalid, we should report again
        old_state_f = float(old_state)
    except ValueError:
        return True

    if absolute_change is not None and percentage_change is not None:
        return _absolute_and_relative_change(
            old_state_f, new_state_f, absolute_change, percentage_change
        )
    if absolute_change is not None:
        return check_absolute_change(old_state_f, new_state_f, absolute_change)

    return None