core/homeassistant/helpers/event.py

"""Helpers for listening to events."""
from datetime import datetime, timedelta
import functools as ft
import logging
from typing import Any, Awaitable, Callable, Dict, Iterable, Optional, Union

import attr

from homeassistant.const import (
    ATTR_NOW,
    EVENT_CORE_CONFIG_UPDATE,
    EVENT_STATE_CHANGED,
    EVENT_TIME_CHANGED,
    MATCH_ALL,
    SUN_EVENT_SUNRISE,
    SUN_EVENT_SUNSET,
)
from homeassistant.core import CALLBACK_TYPE, Event, HomeAssistant, State, callback
from homeassistant.helpers.sun import get_astral_event_next
from homeassistant.helpers.template import Template
from homeassistant.loader import bind_hass
from homeassistant.util import dt as dt_util
from homeassistant.util.async_ import run_callback_threadsafe

TRACK_STATE_CHANGE_CALLBACKS = "track_state_change_callbacks"
TRACK_STATE_CHANGE_LISTENER = "track_state_change_listener"

_LOGGER = logging.getLogger(__name__)

# PyLint does not like the use of threaded_listener_factory
# pylint: disable=invalid-name


def threaded_listener_factory(async_factory: Callable[..., Any]) -> CALLBACK_TYPE:
    """Convert an async event helper to a threaded one."""

    @ft.wraps(async_factory)
    def factory(*args: Any, **kwargs: Any) -> CALLBACK_TYPE:
        """Call async event helper safely."""
        hass = args[0]

        if not isinstance(hass, HomeAssistant):
            raise TypeError("First parameter needs to be a hass instance")

        async_remove = run_callback_threadsafe(
            hass.loop, ft.partial(async_factory, *args, **kwargs)
        ).result()

        def remove() -> None:
            """Threadsafe removal."""
            run_callback_threadsafe(hass.loop, async_remove).result()

        return remove

    return factory


@callback
@bind_hass
def async_track_state_change(
    hass: HomeAssistant,
    entity_ids: Union[str, Iterable[str]],
    action: Callable[[str, State, State], None],
    from_state: Union[None, str, Iterable[str]] = None,
    to_state: Union[None, str, Iterable[str]] = None,
) -> CALLBACK_TYPE:
    """Track specific state changes.

    entity_ids, from_state and to_state can be string or list.
    Use list to match multiple.

    Returns a function that can be called to remove the listener.

    Must be run within the event loop.
    """
    match_from_state = process_state_match(from_state)
    match_to_state = process_state_match(to_state)

    # Ensure it is a lowercase list with entity ids we want to match on
    if entity_ids == MATCH_ALL:
        pass
    elif isinstance(entity_ids, str):
        entity_ids = (entity_ids.lower(),)
    else:
        entity_ids = tuple(entity_id.lower() for entity_id in entity_ids)

    @callback
    def state_change_listener(event: Event) -> None:
        """Handle specific state changes."""
        old_state = event.data.get("old_state")
        if old_state is not None:
            old_state = old_state.state

        new_state = event.data.get("new_state")
        if new_state is not None:
            new_state = new_state.state

        if match_from_state(old_state) and match_to_state(new_state):
            hass.async_run_job(
                action,
                event.data.get("entity_id"),
                event.data.get("old_state"),
                event.data.get("new_state"),
            )

    if entity_ids != MATCH_ALL:
        # If we have a list of entity ids we use
        # async_track_state_change_event to route
        # by entity_id to avoid iterating though state change
        # events and creating a jobs where the most
        # common outcome is to return right away because
        # the entity_id does not match since usually
        # only one or two listeners want that specific
        # entity_id.
        return async_track_state_change_event(hass, entity_ids, state_change_listener)

    return hass.bus.async_listen(EVENT_STATE_CHANGED, state_change_listener)


track_state_change = threaded_listener_factory(async_track_state_change)


@bind_hass
def async_track_state_change_event(
    hass: HomeAssistant, entity_ids: Iterable[str], action: Callable[[Event], None]
) -> Callable[[], None]:
    """Track specific state change events indexed by entity_id.

    Unlike async_track_state_change, async_track_state_change_event
    passes the full event to the callback.

    In order to avoid having to iterate a long list
    of EVENT_STATE_CHANGED and fire and create a job
    for each one, we keep a dict of entity ids that
    care about the state change events so we can
    do a fast dict lookup to route events.
    """

    entity_callbacks = hass.data.setdefault(TRACK_STATE_CHANGE_CALLBACKS, {})

    if TRACK_STATE_CHANGE_LISTENER not in hass.data:

        @callback
        def _async_state_change_dispatcher(event: Event) -> None:
            """Dispatch state changes by entity_id."""
            entity_id = event.data.get("entity_id")

            if entity_id not in entity_callbacks:
                return

            for action in entity_callbacks[entity_id]:
                try:
                    hass.async_run_job(action, event)
                except Exception:  # pylint: disable=broad-except
                    _LOGGER.exception(
                        "Error while processing state changed for %s", entity_id
                    )

        hass.data[TRACK_STATE_CHANGE_LISTENER] = hass.bus.async_listen(
            EVENT_STATE_CHANGED, _async_state_change_dispatcher
        )

    entity_ids = [entity_id.lower() for entity_id in entity_ids]

    for entity_id in entity_ids:
        if entity_id not in entity_callbacks:
            entity_callbacks[entity_id] = []

        entity_callbacks[entity_id].append(action)

    @callback
    def remove_listener() -> None:
        """Remove state change listener."""
        _async_remove_state_change_listeners(hass, entity_ids, action)

    return remove_listener


@callback
def _async_remove_state_change_listeners(
    hass: HomeAssistant, entity_ids: Iterable[str], action: Callable[[Event], None]
) -> None:
    """Remove a listener."""
    entity_callbacks = hass.data[TRACK_STATE_CHANGE_CALLBACKS]

    for entity_id in entity_ids:
        entity_callbacks[entity_id].remove(action)
        if len(entity_callbacks[entity_id]) == 0:
            del entity_callbacks[entity_id]

    if not entity_callbacks:
        hass.data[TRACK_STATE_CHANGE_LISTENER]()
        del hass.data[TRACK_STATE_CHANGE_LISTENER]


@callback
@bind_hass
def async_track_template(
    hass: HomeAssistant,
    template: Template,
    action: Callable[[str, State, State], None],
    variables: Optional[Dict[str, Any]] = None,
) -> CALLBACK_TYPE:
    """Add a listener that track state changes with template condition."""
    from . import condition  # pylint: disable=import-outside-toplevel

    # Local variable to keep track of if the action has already been triggered
    already_triggered = False

    @callback
    def template_condition_listener(entity_id: str, from_s: State, to_s: State) -> None:
        """Check if condition is correct and run action."""
        nonlocal already_triggered
        template_result = condition.async_template(hass, template, variables)

        # Check to see if template returns true
        if template_result and not already_triggered:
            already_triggered = True
            hass.async_run_job(action, entity_id, from_s, to_s)
        elif not template_result:
            already_triggered = False

    return async_track_state_change(
        hass, template.extract_entities(variables), template_condition_listener
    )


track_template = threaded_listener_factory(async_track_template)


@callback
@bind_hass
def async_track_same_state(
    hass: HomeAssistant,
    period: timedelta,
    action: Callable[..., None],
    async_check_same_func: Callable[[str, State, State], bool],
    entity_ids: Union[str, Iterable[str]] = MATCH_ALL,
) -> CALLBACK_TYPE:
    """Track the state of entities for a period and run an action.

    If async_check_func is None it use the state of orig_value.
    Without entity_ids we track all state changes.
    """
    async_remove_state_for_cancel: Optional[CALLBACK_TYPE] = None
    async_remove_state_for_listener: Optional[CALLBACK_TYPE] = None

    @callback
    def clear_listener() -> None:
        """Clear all unsub listener."""
        nonlocal async_remove_state_for_cancel, async_remove_state_for_listener

        if async_remove_state_for_listener is not None:
            async_remove_state_for_listener()
            async_remove_state_for_listener = None
        if async_remove_state_for_cancel is not None:
            async_remove_state_for_cancel()
            async_remove_state_for_cancel = None

    @callback
    def state_for_listener(now: Any) -> None:
        """Fire on state changes after a delay and calls action."""
        nonlocal async_remove_state_for_listener
        async_remove_state_for_listener = None
        clear_listener()
        hass.async_run_job(action)

    @callback
    def state_for_cancel_listener(
        entity: str, from_state: State, to_state: State
    ) -> None:
        """Fire on changes and cancel for listener if changed."""
        if not async_check_same_func(entity, from_state, to_state):
            clear_listener()

    async_remove_state_for_listener = async_track_point_in_utc_time(
        hass, state_for_listener, dt_util.utcnow() + period
    )

    async_remove_state_for_cancel = async_track_state_change(
        hass, entity_ids, state_for_cancel_listener
    )

    return clear_listener


track_same_state = threaded_listener_factory(async_track_same_state)


@callback
@bind_hass
def async_track_point_in_time(
    hass: HomeAssistant, action: Callable[..., None], point_in_time: datetime
) -> CALLBACK_TYPE:
    """Add a listener that fires once after a specific point in time."""
    utc_point_in_time = dt_util.as_utc(point_in_time)

    @callback
    def utc_converter(utc_now: datetime) -> None:
        """Convert passed in UTC now to local now."""
        hass.async_run_job(action, dt_util.as_local(utc_now))

    return async_track_point_in_utc_time(hass, utc_converter, utc_point_in_time)


track_point_in_time = threaded_listener_factory(async_track_point_in_time)


@callback
@bind_hass
def async_track_point_in_utc_time(
    hass: HomeAssistant, action: Callable[..., Any], point_in_time: datetime
) -> CALLBACK_TYPE:
    """Add a listener that fires once after a specific point in UTC time."""
    # Ensure point_in_time is UTC
    point_in_time = dt_util.as_utc(point_in_time)

    @callback
    def point_in_time_listener(event: Event) -> None:
        """Listen for matching time_changed events."""
        now = event.data[ATTR_NOW]

        if now < point_in_time or hasattr(point_in_time_listener, "run"):
            return

        # Set variable so that we will never run twice.
        # Because the event bus might have to wait till a thread comes
        # available to execute this listener it might occur that the
        # listener gets lined up twice to be executed. This will make
        # sure the second time it does nothing.
        setattr(point_in_time_listener, "run", True)
        async_unsub()

        hass.async_run_job(action, now)

    async_unsub = hass.bus.async_listen(EVENT_TIME_CHANGED, point_in_time_listener)

    return async_unsub


track_point_in_utc_time = threaded_listener_factory(async_track_point_in_utc_time)


@callback
@bind_hass
def async_call_later(
    hass: HomeAssistant, delay: float, action: Callable[..., None]
) -> CALLBACK_TYPE:
    """Add a listener that is called in <delay>."""
    return async_track_point_in_utc_time(
        hass, action, dt_util.utcnow() + timedelta(seconds=delay)
    )


call_later = threaded_listener_factory(async_call_later)


@callback
@bind_hass
def async_track_time_interval(
    hass: HomeAssistant,
    action: Callable[..., Union[None, Awaitable]],
    interval: timedelta,
) -> CALLBACK_TYPE:
    """Add a listener that fires repetitively at every timedelta interval."""
    remove = None

    def next_interval() -> datetime:
        """Return the next interval."""
        return dt_util.utcnow() + interval

    @callback
    def interval_listener(now: datetime) -> None:
        """Handle elapsed intervals."""
        nonlocal remove
        remove = async_track_point_in_utc_time(hass, interval_listener, next_interval())
        hass.async_run_job(action, now)

    remove = async_track_point_in_utc_time(hass, interval_listener, next_interval())

    def remove_listener() -> None:
        """Remove interval listener."""
        remove()

    return remove_listener


track_time_interval = threaded_listener_factory(async_track_time_interval)


@attr.s
class SunListener:
    """Helper class to help listen to sun events."""

    hass = attr.ib(type=HomeAssistant)
    action: Callable[..., None] = attr.ib()
    event: str = attr.ib()
    offset: Optional[timedelta] = attr.ib()
    _unsub_sun: Optional[CALLBACK_TYPE] = attr.ib(default=None)
    _unsub_config: Optional[CALLBACK_TYPE] = attr.ib(default=None)

    @callback
    def async_attach(self) -> None:
        """Attach a sun listener."""
        assert self._unsub_config is None

        self._unsub_config = self.hass.bus.async_listen(
            EVENT_CORE_CONFIG_UPDATE, self._handle_config_event
        )

        self._listen_next_sun_event()

    @callback
    def async_detach(self) -> None:
        """Detach the sun listener."""
        assert self._unsub_sun is not None
        assert self._unsub_config is not None

        self._unsub_sun()
        self._unsub_sun = None
        self._unsub_config()
        self._unsub_config = None

    @callback
    def _listen_next_sun_event(self) -> None:
        """Set up the sun event listener."""
        assert self._unsub_sun is None

        self._unsub_sun = async_track_point_in_utc_time(
            self.hass,
            self._handle_sun_event,
            get_astral_event_next(self.hass, self.event, offset=self.offset),
        )

    @callback
    def _handle_sun_event(self, _now: Any) -> None:
        """Handle solar event."""
        self._unsub_sun = None
        self._listen_next_sun_event()
        self.hass.async_run_job(self.action)

    @callback
    def _handle_config_event(self, _event: Any) -> None:
        """Handle core config update."""
        assert self._unsub_sun is not None
        self._unsub_sun()
        self._unsub_sun = None
        self._listen_next_sun_event()


@callback
@bind_hass
def async_track_sunrise(
    hass: HomeAssistant, action: Callable[..., None], offset: Optional[timedelta] = None
) -> CALLBACK_TYPE:
    """Add a listener that will fire a specified offset from sunrise daily."""
    listener = SunListener(hass, action, SUN_EVENT_SUNRISE, offset)
    listener.async_attach()
    return listener.async_detach


track_sunrise = threaded_listener_factory(async_track_sunrise)


@callback
@bind_hass
def async_track_sunset(
    hass: HomeAssistant, action: Callable[..., None], offset: Optional[timedelta] = None
) -> CALLBACK_TYPE:
    """Add a listener that will fire a specified offset from sunset daily."""
    listener = SunListener(hass, action, SUN_EVENT_SUNSET, offset)
    listener.async_attach()
    return listener.async_detach


track_sunset = threaded_listener_factory(async_track_sunset)


@callback
@bind_hass
def async_track_utc_time_change(
    hass: HomeAssistant,
    action: Callable[..., None],
    hour: Optional[Any] = None,
    minute: Optional[Any] = None,
    second: Optional[Any] = None,
    local: bool = False,
) -> CALLBACK_TYPE:
    """Add a listener that will fire if time matches a pattern."""
    # We do not have to wrap the function with time pattern matching logic
    # if no pattern given
    if all(val is None for val in (hour, minute, second)):

        @callback
        def time_change_listener(event: Event) -> None:
            """Fire every time event that comes in."""
            hass.async_run_job(action, event.data[ATTR_NOW])

        return hass.bus.async_listen(EVENT_TIME_CHANGED, time_change_listener)

    matching_seconds = dt_util.parse_time_expression(second, 0, 59)
    matching_minutes = dt_util.parse_time_expression(minute, 0, 59)
    matching_hours = dt_util.parse_time_expression(hour, 0, 23)

    next_time = None

    def calculate_next(now: datetime) -> None:
        """Calculate and set the next time the trigger should fire."""
        nonlocal next_time

        localized_now = dt_util.as_local(now) if local else now
        next_time = dt_util.find_next_time_expression_time(
            localized_now, matching_seconds, matching_minutes, matching_hours
        )

    # Make sure rolling back the clock doesn't prevent the timer from
    # triggering.
    last_now: Optional[datetime] = None

    @callback
    def pattern_time_change_listener(event: Event) -> None:
        """Listen for matching time_changed events."""
        nonlocal next_time, last_now

        now = event.data[ATTR_NOW]

        if last_now is None or now < last_now:
            # Time rolled back or next time not yet calculated
            calculate_next(now)

        last_now = now

        if next_time <= now:
            hass.async_run_job(action, dt_util.as_local(now) if local else now)
            calculate_next(now + timedelta(seconds=1))

    # We can't use async_track_point_in_utc_time here because it would
    # break in the case that the system time abruptly jumps backwards.
    # Our custom last_now logic takes care of resolving that scenario.
    return hass.bus.async_listen(EVENT_TIME_CHANGED, pattern_time_change_listener)


track_utc_time_change = threaded_listener_factory(async_track_utc_time_change)


@callback
@bind_hass
def async_track_time_change(
    hass: HomeAssistant,
    action: Callable[..., None],
    hour: Optional[Any] = None,
    minute: Optional[Any] = None,
    second: Optional[Any] = None,
) -> CALLBACK_TYPE:
    """Add a listener that will fire if UTC time matches a pattern."""
    return async_track_utc_time_change(hass, action, hour, minute, second, local=True)


track_time_change = threaded_listener_factory(async_track_time_change)


def process_state_match(
    parameter: Union[None, str, Iterable[str]]
) -> Callable[[str], bool]:
    """Convert parameter to function that matches input against parameter."""
    if parameter is None or parameter == MATCH_ALL:
        return lambda _: True

    if isinstance(parameter, str) or not hasattr(parameter, "__iter__"):
        return lambda state: state == parameter

    parameter_tuple = tuple(parameter)
    return lambda state: state in parameter_tuple