waitable_presence.py

   1 #!/usr/bin/env python3
   2
   3 # © Copyright 2021-2022, Scott Gasch
   4
   5 """A PresenceDetector that is waitable.  This is not part of
   6 base_presence.py because I do not want to bring these dependencies
   7 into that lower-level module (especially state_tracker).
   8 """
   9
  10 import datetime
  11 import logging
  12 from typing import Optional, Tuple
  13
  14 from overrides import overrides
  15
  16 import base_presence
  17 import site_config
  18 import state_tracker
  19 from type.locations import Location
  20
  21 logger = logging.getLogger(__name__)
  22
  23
  24 class WaitablePresenceDetectorWithMemory(state_tracker.WaitableAutomaticStateTracker):
  25     """
  26     This is a waitable class that keeps a PresenceDetector internally
  27     and periodically polls it to detect changes in presence in a
  28     particular location.  Example suggested usage pattern::
  29
  30         detector = waitable_presence.WaitablePresenceDetectorWithMemory(60.0)
  31         while True:
  32             changed = detector.wait(timeout=60 * 5)  # or, None for "forever"
  33             (someone_is_home, since) = detector.is_someone_home()
  34             if changed:
  35                 detector.reset()
  36             logger.debug(
  37                 f'someone_is_home={someone_is_home}, since={since}, changed={changed}'
  38             )
  39     """
  40
  41     def __init__(
  42         self,
  43         override_update_interval_sec: float = 60.0,
  44         override_location: Location = site_config.get_location(),
  45         injected_presence_detector: Optional[base_presence.PresenceDetection] = None,
  46     ) -> None:
  47         self.last_someone_is_home: Optional[bool] = None
  48         self.someone_is_home: Optional[bool] = None
  49         self.everyone_gone_since: Optional[datetime.datetime] = None
  50         self.someone_home_since: Optional[datetime.datetime] = None
  51         self.location = override_location
  52         if injected_presence_detector is not None:
  53             self.detector: base_presence.PresenceDetection = injected_presence_detector
  54         else:
  55             self.detector = base_presence.PresenceDetection()
  56         super().__init__(
  57             {
  58                 'poll_presence': override_update_interval_sec,
  59                 'check_detector': override_update_interval_sec * 5,
  60             }
  61         )
  62
  63     @overrides
  64     def update(
  65         self,
  66         update_id: str,
  67         now: datetime.datetime,
  68         last_invocation: Optional[datetime.datetime],
  69     ) -> None:
  70         if update_id == 'poll_presence':
  71             self.poll_presence(now)
  72         elif update_id == 'check_detector':
  73             self.check_detector()
  74         else:
  75             raise Exception(f'Unknown update type {update_id} in {__file__}')
  76
  77     def poll_presence(self, now: datetime.datetime) -> None:
  78         logger.debug('Checking presence in %s now...', self.location)
  79         self.detector.update()
  80         if self.detector.is_anyone_in_location_now(self.location):
  81             self.someone_is_home = True
  82             self.someone_home_since = now
  83         else:
  84             self.someone_is_home = False
  85             self.everyone_gone_since = now
  86         if self.someone_is_home != self.last_someone_is_home:
  87             self.something_changed()
  88             self.last_someone_is_home = self.someone_is_home
  89
  90     def check_detector(self) -> None:
  91         if len(self.detector.dark_locations) > 0:
  92             logger.debug('PresenceDetector is incomplete; trying to reinitialize...')
  93             self.detector = base_presence.PresenceDetection()
  94
  95     def is_someone_home(self) -> Optional[Tuple[bool, datetime.datetime]]:
  96         """Returns a tuple of a bool that indicates whether someone is home
  97         and a datetime that indicates how long either someone has been
  98         home or no one has been home.
  99
 100         """
 101         if self.someone_is_home is None:
 102             return None  # checked too soon, wait a bit.
 103         if self.someone_is_home:
 104             assert self.someone_home_since is not None
 105             return (True, self.someone_home_since)
 106         else:
 107             assert self.everyone_gone_since is not None
 108             return (False, self.everyone_gone_since)