waitable_presence.py

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