1 files changed, 101 insertions, 0 deletions
diff --git a/waitable_presence.py b/waitable_presence.py
new file mode 100644
index 0000000..9e0a9d0
--- /dev/null
+++ b/waitable_presence.py
@@ -0,0 +1,101 @@
+#!/usr/bin/env python3
+
+"""A PresenceDetector that is waitable.  This is not part of
+base_presence.py because I do not want to bring these dependencies
+into that lower-level module (especially state_tracker).
+
+"""
+
+import datetime
+import logging
+from typing import Optional, Tuple
+
+from overrides import overrides
+
+import base_presence
+from type.locations import Location
+import site_config
+import state_tracker
+
+logger = logging.getLogger(__name__)
+
+
+class WaitablePresenceDetectorWithMemory(state_tracker.WaitableAutomaticStateTracker):
+    """
+    This is a waitable class that keeps a PresenceDetector internally
+    and periodically polls it to detect changes in presence in a
+    particular location.  Example suggested usage pattern:
+
+        detector = waitable_presence.WaitablePresenceDetectorWithMemory(60.0)
+        while True:
+            changed = detector.wait(timeout=60 * 5)  # or, None for "forever"
+            (someone_is_home, since) = detector.is_someone_home()
+            if changed:
+                detector.reset()
+            logger.debug(
+                f'someone_is_home={someone_is_home}, since={since}, changed={changed}'
+            )
+    """
+
+    def __init__(
+            self,
+            override_update_interval_sec: float = 60.0,
+            override_location: Location = site_config.get_location(),
+    ) -> None:
+        self.last_someone_is_home: Optional[bool] = None
+        self.someone_is_home: Optional[bool] = None
+        self.everyone_gone_since: Optional[datetime.datetime] = None
+        self.someone_home_since: Optional[datetime.datetime] = None
+        self.location = override_location
+        self.detector: base_presence.PresenceDetection = base_presence.PresenceDetection()
+        super().__init__(
+            {
+                'poll_presence': override_update_interval_sec,
+                'check_detector': override_update_interval_sec * 5,
+            }
+        )
+
+    @overrides
+    def update(
+        self,
+        update_id: str,
+        now: datetime.datetime,
+        last_invocation: Optional[datetime.datetime],
+    ) -> None:
+        if update_id == 'poll_presence':
+            self.poll_presence(now)
+        elif update_id == 'check_detector':
+            self.check_detector()
+        else:
+            raise Exception(f'Unknown update type {update_id} in {__file__}')
+
+    def poll_presence(self, now: datetime.datetime) -> None:
+        logger.debug(f'Checking presence in {self.location} now...')
+        self.detector.update()
+        if self.detector.is_anyone_in_location_now(self.location):
+            self.someone_is_home = True
+            self.someone_home_since = now
+        else:
+            self.someone_is_home = False
+            self.everyone_gone_since = now
+        if self.someone_is_home != self.last_someone_is_home:
+            self.something_changed()
+            self.last_someone_is_home = self.someone_is_home
+
+    def check_detector(self) -> None:
+        if len(self.detector.dark_locations) > 0:
+            logger.debug('PresenceDetector is incomplete; trying to reinitialize...')
+            self.detector = base_presence.PresenceDetection()
+
+    def is_someone_home(self) -> Tuple[bool, datetime.datetime]:
+        """Returns a tuple of a bool that indicates whether someone is home
+        and a datetime that indicates how long either someone has been
+        home or no one has been home.
+
+        """
+        if self.someone_is_home is None:
+            raise Exception("Too Soon!")
+        if self.someone_is_home:
+            return (True, self.someone_home_since)
+        else:
+            return (False, self.everyone_gone_since)