"""Numeric derivative of data coming from a source sensor over time."""
from __future__ import annotations
from datetime import datetime, timedelta
from decimal import Decimal, DecimalException
import logging
from typing import TYPE_CHECKING
import voluptuous as vol
from homeassistant.components.sensor import PLATFORM_SCHEMA, RestoreSensor, SensorEntity
from homeassistant.config_entries import ConfigEntry
from homeassistant.const import (
ATTR_UNIT_OF_MEASUREMENT,
CONF_NAME,
CONF_SOURCE,
STATE_UNAVAILABLE,
STATE_UNKNOWN,
UnitOfTime,
)
from homeassistant.core import Event, HomeAssistant, State, callback
from homeassistant.helpers import config_validation as cv, entity_registry as er
from homeassistant.helpers.entity_platform import AddEntitiesCallback
from homeassistant.helpers.event import async_track_state_change_event
from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
from .const import (
CONF_ROUND_DIGITS,
CONF_TIME_WINDOW,
CONF_UNIT,
CONF_UNIT_PREFIX,
CONF_UNIT_TIME,
)
_LOGGER = logging.getLogger(__name__)
ATTR_SOURCE_ID = "source"
# SI Metric prefixes
UNIT_PREFIXES = {
None: 1,
"n": 1e-9,
"ยต": 1e-6,
"m": 1e-3,
"k": 1e3,
"M": 1e6,
"G": 1e9,
"T": 1e12,
}
# SI Time prefixes
UNIT_TIME = {
UnitOfTime.SECONDS: 1,
UnitOfTime.MINUTES: 60,
UnitOfTime.HOURS: 60 * 60,
UnitOfTime.DAYS: 24 * 60 * 60,
}
ICON = "mdi:chart-line"
DEFAULT_ROUND = 3
DEFAULT_TIME_WINDOW = 0
PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
{
vol.Optional(CONF_NAME): cv.string,
vol.Required(CONF_SOURCE): cv.entity_id,
vol.Optional(CONF_ROUND_DIGITS, default=DEFAULT_ROUND): vol.Coerce(int),
vol.Optional(CONF_UNIT_PREFIX, default=None): vol.In(UNIT_PREFIXES),
vol.Optional(CONF_UNIT_TIME, default=UnitOfTime.HOURS): vol.In(UNIT_TIME),
vol.Optional(CONF_UNIT): cv.string,
vol.Optional(CONF_TIME_WINDOW, default=DEFAULT_TIME_WINDOW): cv.time_period,
}
)
async def async_setup_entry(
hass: HomeAssistant,
config_entry: ConfigEntry,
async_add_entities: AddEntitiesCallback,
) -> None:
"""Initialize Derivative config entry."""
registry = er.async_get(hass)
# Validate + resolve entity registry id to entity_id
source_entity_id = er.async_validate_entity_id(
registry, config_entry.options[CONF_SOURCE]
)
unit_prefix = config_entry.options[CONF_UNIT_PREFIX]
if unit_prefix == "none":
unit_prefix = None
derivative_sensor = DerivativeSensor(
name=config_entry.title,
round_digits=int(config_entry.options[CONF_ROUND_DIGITS]),
source_entity=source_entity_id,
time_window=cv.time_period_dict(config_entry.options[CONF_TIME_WINDOW]),
unique_id=config_entry.entry_id,
unit_of_measurement=None,
unit_prefix=unit_prefix,
unit_time=config_entry.options[CONF_UNIT_TIME],
)
async_add_entities([derivative_sensor])
async def async_setup_platform(
hass: HomeAssistant,
config: ConfigType,
async_add_entities: AddEntitiesCallback,
discovery_info: DiscoveryInfoType | None = None,
) -> None:
"""Set up the derivative sensor."""
derivative = DerivativeSensor(
name=config.get(CONF_NAME),
round_digits=config[CONF_ROUND_DIGITS],
source_entity=config[CONF_SOURCE],
time_window=config[CONF_TIME_WINDOW],
unit_of_measurement=config.get(CONF_UNIT),
unit_prefix=config[CONF_UNIT_PREFIX],
unit_time=config[CONF_UNIT_TIME],
unique_id=None,
)
async_add_entities([derivative])
class DerivativeSensor(RestoreSensor, SensorEntity):
"""Representation of an derivative sensor."""
_attr_icon = ICON
_attr_should_poll = False
def __init__(
self,
*,
name: str | None,
round_digits: int,
source_entity: str,
time_window: timedelta,
unit_of_measurement: str | None,
unit_prefix: str | None,
unit_time: UnitOfTime,
unique_id: str | None,
) -> None:
"""Initialize the derivative sensor."""
self._attr_unique_id = unique_id
self._sensor_source_id = source_entity
self._round_digits = round_digits
self._state: float | int | Decimal = 0
# List of tuples with (timestamp_start, timestamp_end, derivative)
self._state_list: list[tuple[datetime, datetime, Decimal]] = []
self._attr_name = name if name is not None else f"{source_entity} derivative"
self._attr_extra_state_attributes = {ATTR_SOURCE_ID: source_entity}
if unit_of_measurement is None:
final_unit_prefix = "" if unit_prefix is None else unit_prefix
self._unit_template = f"{final_unit_prefix}{{}}/{unit_time}"
# we postpone the definition of unit_of_measurement to later
self._attr_native_unit_of_measurement = None
else:
self._attr_native_unit_of_measurement = unit_of_measurement
self._unit_prefix = UNIT_PREFIXES[unit_prefix]
self._unit_time = UNIT_TIME[unit_time]
self._time_window = time_window.total_seconds()
async def async_added_to_hass(self) -> None:
"""Handle entity which will be added."""
await super().async_added_to_hass()
restored_data = await self.async_get_last_sensor_data()
if restored_data:
self._attr_native_unit_of_measurement = (
restored_data.native_unit_of_measurement
)
try:
self._state = Decimal(restored_data.native_value) # type: ignore[arg-type]
except SyntaxError as err:
_LOGGER.warning("Could not restore last state: %s", err)
@callback
def calc_derivative(event: Event) -> None:
"""Handle the sensor state changes."""
old_state: State | None
new_state: State | None
if (
(old_state := event.data.get("old_state")) is None
or old_state.state in (STATE_UNKNOWN, STATE_UNAVAILABLE)
or (new_state := event.data.get("new_state")) is None
or new_state.state in (STATE_UNKNOWN, STATE_UNAVAILABLE)
):
return
if self.native_unit_of_measurement is None:
unit = new_state.attributes.get(ATTR_UNIT_OF_MEASUREMENT)
self._attr_native_unit_of_measurement = self._unit_template.format(
"" if unit is None else unit
)
# filter out all derivatives older than `time_window` from our window list
self._state_list = [
(time_start, time_end, state)
for time_start, time_end, state in self._state_list
if (new_state.last_updated - time_end).total_seconds()
< self._time_window
]
try:
elapsed_time = (
new_state.last_updated - old_state.last_updated
).total_seconds()
delta_value = Decimal(new_state.state) - Decimal(old_state.state)
new_derivative = (
delta_value
/ Decimal(elapsed_time)
/ Decimal(self._unit_prefix)
* Decimal(self._unit_time)
)
except ValueError as err:
_LOGGER.warning("While calculating derivative: %s", err)
except DecimalException as err:
_LOGGER.warning(
"Invalid state (%s > %s): %s", old_state.state, new_state.state, err
)
except AssertionError as err:
_LOGGER.error("Could not calculate derivative: %s", err)
# add latest derivative to the window list
self._state_list.append(
(old_state.last_updated, new_state.last_updated, new_derivative)
)
def calculate_weight(
start: datetime, end: datetime, now: datetime
) -> float:
window_start = now - timedelta(seconds=self._time_window)
if start < window_start:
weight = (end - window_start).total_seconds() / self._time_window
else:
weight = (end - start).total_seconds() / self._time_window
return weight
# If outside of time window just report derivative (is the same as modeling it in the window),
# otherwise take the weighted average with the previous derivatives
if elapsed_time > self._time_window:
derivative = new_derivative
else:
derivative = Decimal(0)
for start, end, value in self._state_list:
weight = calculate_weight(start, end, new_state.last_updated)
derivative = derivative + (value * Decimal(weight))
self._state = derivative
self.async_write_ha_state()
self.async_on_remove(
async_track_state_change_event(
self.hass, self._sensor_source_id, calc_derivative
)
)
@property
def native_value(self) -> float | int | Decimal:
"""Return the state of the sensor."""
value = round(self._state, self._round_digits)
if TYPE_CHECKING:
assert isinstance(value, (float, int, Decimal))
return value