core/homeassistant/helpers/event.py

165 lines
5.4 KiB
Python

"""
Helpers for listening to events
"""
import functools as ft
from ..util import dt as dt_util
from ..const import (
ATTR_NOW, EVENT_STATE_CHANGED, EVENT_TIME_CHANGED, MATCH_ALL)
def track_state_change(hass, entity_ids, action, from_state=None,
to_state=None):
"""
Track specific state changes.
entity_ids, from_state and to_state can be string or list.
Use list to match multiple.
Returns the listener that listens on the bus for EVENT_STATE_CHANGED.
Pass the return value into hass.bus.remove_listener to remove it.
"""
from_state = _process_match_param(from_state)
to_state = _process_match_param(to_state)
# Ensure it is a lowercase list with entity ids we want to match on
if isinstance(entity_ids, str):
entity_ids = (entity_ids.lower(),)
else:
entity_ids = tuple(entity_id.lower() for entity_id in entity_ids)
@ft.wraps(action)
def state_change_listener(event):
""" The listener that listens for specific state changes. """
if event.data['entity_id'] not in entity_ids:
return
if 'old_state' in event.data:
old_state = event.data['old_state'].state
else:
old_state = None
if _matcher(old_state, from_state) and \
_matcher(event.data['new_state'].state, to_state):
action(event.data['entity_id'],
event.data.get('old_state'),
event.data['new_state'])
hass.bus.listen(EVENT_STATE_CHANGED, state_change_listener)
return state_change_listener
def track_point_in_time(hass, action, point_in_time):
"""
Adds a listener that fires once after a spefic point in time.
"""
utc_point_in_time = dt_util.as_utc(point_in_time)
@ft.wraps(action)
def utc_converter(utc_now):
""" Converts passed in UTC now to local now. """
action(dt_util.as_local(utc_now))
return track_point_in_utc_time(hass, utc_converter, utc_point_in_time)
def track_point_in_utc_time(hass, action, point_in_time):
"""
Adds 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)
@ft.wraps(action)
def point_in_time_listener(event):
""" Listens for matching time_changed events. """
now = event.data[ATTR_NOW]
if now >= point_in_time and \
not hasattr(point_in_time_listener, 'run'):
# 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.
point_in_time_listener.run = True
hass.bus.remove_listener(EVENT_TIME_CHANGED,
point_in_time_listener)
action(now)
hass.bus.listen(EVENT_TIME_CHANGED, point_in_time_listener)
return point_in_time_listener
# pylint: disable=too-many-arguments
def track_utc_time_change(hass, action, year=None, month=None, day=None,
hour=None, minute=None, second=None, local=False):
""" Adds 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 (year, month, day, hour, minute, second)):
@ft.wraps(action)
def time_change_listener(event):
""" Fires every time event that comes in. """
action(event.data[ATTR_NOW])
hass.bus.listen(EVENT_TIME_CHANGED, time_change_listener)
return time_change_listener
pmp = _process_match_param
year, month, day = pmp(year), pmp(month), pmp(day)
hour, minute, second = pmp(hour), pmp(minute), pmp(second)
@ft.wraps(action)
def pattern_time_change_listener(event):
""" Listens for matching time_changed events. """
now = event.data[ATTR_NOW]
if local:
now = dt_util.as_local(now)
mat = _matcher
# pylint: disable=too-many-boolean-expressions
if mat(now.year, year) and \
mat(now.month, month) and \
mat(now.day, day) and \
mat(now.hour, hour) and \
mat(now.minute, minute) and \
mat(now.second, second):
action(now)
hass.bus.listen(EVENT_TIME_CHANGED, pattern_time_change_listener)
return pattern_time_change_listener
# pylint: disable=too-many-arguments
def track_time_change(hass, action, year=None, month=None, day=None,
hour=None, minute=None, second=None):
""" Adds a listener that will fire if UTC time matches a pattern. """
track_utc_time_change(hass, action, year, month, day, hour, minute, second,
local=True)
def _process_match_param(parameter):
""" Wraps parameter in a tuple if it is not one and returns it. """
if parameter is None or parameter == MATCH_ALL:
return MATCH_ALL
elif isinstance(parameter, str) or not hasattr(parameter, '__iter__'):
return (parameter,)
else:
return tuple(parameter)
def _matcher(subject, pattern):
""" Returns True if subject matches the pattern.
Pattern is either a tuple of allowed subjects or a `MATCH_ALL`.
"""
return MATCH_ALL == pattern or subject in pattern