Holiday update calendar once per day (#116421)

homeassistant/components/holiday/calendar.py

@@ -2,16 +2,17 @@
 
 from __future__ import annotations
 
-from datetime import datetime
+from datetime import datetime, timedelta
 
 from holidays import HolidayBase, country_holidays
 
 from homeassistant.components.calendar import CalendarEntity, CalendarEvent
 from homeassistant.config_entries import ConfigEntry
 from homeassistant.const import CONF_COUNTRY
-from homeassistant.core import HomeAssistant
+from homeassistant.core import CALLBACK_TYPE, HomeAssistant, callback
 from homeassistant.helpers.device_registry import DeviceEntryType, DeviceInfo
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
+from homeassistant.helpers.event import async_track_point_in_utc_time
 from homeassistant.util import dt as dt_util
 
 from .const import CONF_PROVINCE, DOMAIN
@@ -77,6 +78,9 @@ class HolidayCalendarEntity(CalendarEntity):
 
     _attr_has_entity_name = True
     _attr_name = None
+    _attr_event: CalendarEvent | None = None
+    _attr_should_poll = False
+    unsub: CALLBACK_TYPE | None = None
 
     def __init__(
         self,
@@ -100,14 +104,36 @@ class HolidayCalendarEntity(CalendarEntity):
         )
         self._obj_holidays = obj_holidays
 
-    @property
-    def event(self) -> CalendarEvent | None:
+    def get_next_interval(self, now: datetime) -> datetime:
+        """Compute next time an update should occur."""
+        tomorrow = dt_util.as_local(now) + timedelta(days=1)
+        return dt_util.start_of_local_day(tomorrow)
+
+    def _update_state_and_setup_listener(self) -> None:
+        """Update state and setup listener for next interval."""
+        now = dt_util.utcnow()
+        self._attr_event = self.update_event(now)
+        self.unsub = async_track_point_in_utc_time(
+            self.hass, self.point_in_time_listener, self.get_next_interval(now)
+        )
+
+    @callback
+    def point_in_time_listener(self, time_date: datetime) -> None:
+        """Get the latest data and update state."""
+        self._update_state_and_setup_listener()
+        self.async_write_ha_state()
+
+    async def async_added_to_hass(self) -> None:
+        """Set up first update."""
+        self._update_state_and_setup_listener()
+
+    def update_event(self, now: datetime) -> CalendarEvent | None:
         """Return the next upcoming event."""
         next_holiday = None
         for holiday_date, holiday_name in sorted(
             self._obj_holidays.items(), key=lambda x: x[0]
         ):
-            if holiday_date >= dt_util.now().date():
+            if holiday_date >= now.date():
                 next_holiday = (holiday_date, holiday_name)
                 break
 
@@ -121,6 +147,11 @@ class HolidayCalendarEntity(CalendarEntity):
             location=self._location,
         )
 
+    @property
+    def event(self) -> CalendarEvent | None:
+        """Return the next upcoming event."""
+        return self._attr_event
+
     async def async_get_events(
         self, hass: HomeAssistant, start_date: datetime, end_date: datetime
     ) -> list[CalendarEvent]: