👔 filter calendars when searching for alternatives

Filter out calendars which are:
- not administrated by the current user
- not set as an alternative to the calendar of the declined event

src/clear_bookings.py

@@ -375,7 +375,7 @@ def clear(target_calendars: list, is_test: bool=False) -> dict:
                 other_bookings = find_other_bookings(event, calendar)
 
                 # Find free alternative rooms for the time slot of the declined event
-                alternatives = find_alternatives(event, principal)
+                alternatives = find_alternatives(event, principal, target_calendars)
 
                 # Create a set for all events as an overview
                 event.is_declined = True
@@ -622,15 +622,23 @@ def find_other_bookings(event: DavEvent, calendar: caldav.Calendar) -> list[DavE
             and e.extended_uid != event.extended_uid
             and not e.missing_required_fields]
 
-def find_alternatives(event: DavEvent, principal: Principal) -> list[Calendar]:
+def find_alternatives(event: DavEvent, principal: Principal,
+                      target_calendars: list) -> list[Calendar]:
     """
     Find alternative rooms for the time slot of the declined event.
     :param event: The event to find alternatives for.
     :param principal: The principal to search for alternative rooms.
+    :param target_calendars: Calendars administrated by the current user
     :return: List of alternative calendars that are available for the time slot.
     """
     # Get all calendars of the principal
     calendars = principal.calendars()
+    alternative_calendars = {
+        calendar.name: [c.name for c in calendar.alternatives.all()]
+        for calendar in target_calendars
+    }
+    print("Alternative calendars for event calendar: "
+          f"{', '.join([a for a in alternative_calendars[event.obj.parent.id]])}")
 
     alternatives = []
     for calendar in calendars:
@@ -638,6 +646,16 @@ def find_alternatives(event: DavEvent, principal: Principal) -> list[Calendar]:
         if calendar.id == event.obj.parent.id:
             continue
 
+        # Skip if the calendar is not administrated by the current user
+        if calendar.id not in alternative_calendars.keys():
+            continue
+
+        # Skip if the calendar is not an alternative to the calendar of the
+        # declined event
+        if calendar.id not in alternative_calendars[event.obj.parent.id]:
+            continue
+
+
         # Search for events in the alternative calendar that overlap with the
         # declined event
         events_fetched = calendar.search(
@@ -659,6 +677,8 @@ def find_alternatives(event: DavEvent, principal: Principal) -> list[Calendar]:
         if not blocked:
             alternatives.append(calendar)
 
+    print("Available alternative calendars for event: "
+          f"{', '.join([a.id for a in alternatives])}")
     return alternatives