From fa6a2f08ab2c49775b3c0e12ff0c77d5db92bd19 Mon Sep 17 00:00:00 2001
From: Allen Porter <allen@thebends.org>
Date: Sun, 4 May 2025 20:07:02 -0700
Subject: [PATCH] Update remote calendar to do all event handling in an
 executor (#144232)

---
 .../components/remote_calendar/calendar.py    | 43 ++++++++++++++-----
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/homeassistant/components/remote_calendar/calendar.py b/homeassistant/components/remote_calendar/calendar.py
index bd83a5f18cc..2f60918f010 100644
--- a/homeassistant/components/remote_calendar/calendar.py
+++ b/homeassistant/components/remote_calendar/calendar.py
@@ -29,7 +29,7 @@ async def async_setup_entry(
     """Set up the remote calendar platform."""
     coordinator = entry.runtime_data
     entity = RemoteCalendarEntity(coordinator, entry)
-    async_add_entities([entity])
+    async_add_entities([entity], True)
 
 
 class RemoteCalendarEntity(
@@ -48,25 +48,46 @@ class RemoteCalendarEntity(
         super().__init__(coordinator)
         self._attr_name = entry.data[CONF_CALENDAR_NAME]
         self._attr_unique_id = entry.entry_id
+        self._event: CalendarEvent | None = None
 
     @property
     def event(self) -> CalendarEvent | None:
         """Return the next upcoming event."""
-        now = dt_util.now()
-        events = self.coordinator.data.timeline_tz(now.tzinfo).active_after(now)
-        if event := next(events, None):
-            return _get_calendar_event(event)
-        return None
+        return self._event
 
     async def async_get_events(
         self, hass: HomeAssistant, start_date: datetime, end_date: datetime
     ) -> list[CalendarEvent]:
         """Get all events in a specific time frame."""
-        events = self.coordinator.data.timeline_tz(start_date.tzinfo).overlapping(
-            start_date,
-            end_date,
-        )
-        return [_get_calendar_event(event) for event in events]
+
+        def events_in_range() -> list[CalendarEvent]:
+            """Return all events in the given time range."""
+            events = self.coordinator.data.timeline_tz(start_date.tzinfo).overlapping(
+                start_date,
+                end_date,
+            )
+            return [_get_calendar_event(event) for event in events]
+
+        return await self.hass.async_add_executor_job(events_in_range)
+
+    async def async_update(self) -> None:
+        """Refresh the timeline.
+
+        This is called when the coordinator updates. Creating the timeline may
+        require walking through the entire calendar and handling recurring
+        events, so it is done as a separate task without blocking the event loop.
+        """
+        await super().async_update()
+
+        def next_timeline_event() -> CalendarEvent | None:
+            """Return the next active event."""
+            now = dt_util.now()
+            events = self.coordinator.data.timeline_tz(now.tzinfo).active_after(now)
+            if event := next(events, None):
+                return _get_calendar_event(event)
+            return None
+
+        self._event = await self.hass.async_add_executor_job(next_timeline_event)
 
 
 def _get_calendar_event(event: Event) -> CalendarEvent: