Refactor calendar event update flow

src/govoplan_calendar/backend/service.py

@@ -2918,7 +2918,13 @@ def create_event(session: Session, *, tenant_id: str, user_id: str | None, paylo
     return event
 
 
-def update_event(session: Session, *, tenant_id: str, user_id: str | None, event_id: str, payload: CalendarEventUpdateRequest) -> CalendarEvent:
+def _event_update_calendar_ids(
+    session: Session,
+    *,
+    tenant_id: str,
+    event_id: str,
+    payload: CalendarEventUpdateRequest,
+) -> tuple[str, str]:
     event_locator = (
         session.query(CalendarEvent.calendar_id)
         .filter(
@@ -2934,6 +2940,16 @@ def update_event(session: Session, *, tenant_id: str, user_id: str | None, event
     target_calendar_id = payload.calendar_id or original_calendar_id
     if payload.calendar_id is not None:
         get_calendar(session, tenant_id=tenant_id, calendar_id=target_calendar_id)
+    return original_calendar_id, target_calendar_id
+
+
+def _lock_event_update_sources(
+    session: Session,
+    *,
+    tenant_id: str,
+    original_calendar_id: str,
+    target_calendar_id: str,
+) -> tuple[CalendarSyncSource | None, CalendarSyncSource | None]:
     original_source = active_sync_source_for_calendar(
         session,
         tenant_id=tenant_id,
@@ -2953,16 +2969,35 @@ def update_event(session: Session, *, tenant_id: str, user_id: str | None, event
         original_source = locked_sources[original_source.id]
     if target_source is not None:
         target_source = locked_sources[target_source.id]
-    event = get_event(session, tenant_id=tenant_id, event_id=event_id)
+    return original_source, target_source
-    previous = calendar_event_change_payload(event, prefix="previous_")
+
-    original_caldav = event.source_kind == "caldav" and bool(event.source_href)
+
+def _assert_event_update_sync_fields(
+    payload: CalendarEventUpdateRequest,
+    *,
+    original_source: CalendarSyncSource | None,
+    target_source: CalendarSyncSource | None,
+) -> None:
     supplied_sync_fields = {"source_kind", "source_href", "etag"} & payload.model_fields_set
     if (original_source is not None or target_source is not None) and supplied_sync_fields:
         raise CalendarError(
             "source_kind, source_href, and etag are sync-owned fields on synchronized calendars"
         )
-    if payload.calendar_id is not None:
+
+
+def _move_event_for_update(
+    session: Session,
+    *,
+    event: CalendarEvent,
+    payload: CalendarEventUpdateRequest,
+    original_source: CalendarSyncSource | None,
+    target_source: CalendarSyncSource | None,
+) -> None:
+    if payload.calendar_id is None:
+        assert_sync_mutation_allowed(original_source)
+        return
     assert_sync_mutation_allowed(target_source)
+    original_caldav = event.source_kind == "caldav" and bool(event.source_href)
     if payload.calendar_id != event.calendar_id and original_source and original_caldav:
         assert_sync_mutation_allowed(original_source)
         from govoplan_calendar.backend.outbox import enqueue_caldav_delete
@@ -2972,8 +3007,14 @@ def update_event(session: Session, *, tenant_id: str, user_id: str | None, event
         event.source_href = None
         event.etag = None
     event.calendar_id = payload.calendar_id
-    else:
+
-        assert_sync_mutation_allowed(original_source)
+
+def _apply_event_update_values(
+    event: CalendarEvent,
+    *,
+    user_id: str | None,
+    payload: CalendarEventUpdateRequest,
+) -> None:
     scalar_fields = (
         "sequence",
         "summary",
@@ -3002,7 +3043,13 @@ def update_event(session: Session, *, tenant_id: str, user_id: str | None, event
     for attr in scalar_fields:
         value = getattr(payload, attr)
         if value is not None:
-            setattr(event, attr, value.upper() if attr in {"status", "transparency", "classification"} and isinstance(value, str) else value)
+            value = (
+                value.upper()
+                if attr in {"status", "transparency", "classification"}
+                and isinstance(value, str)
+                else value
+            )
+            setattr(event, attr, value)
     if payload.start_at is not None:
         event.start_at = normalize_datetime(payload.start_at)
     if "end_at" in payload.model_fields_set:
@@ -3012,6 +3059,36 @@ def update_event(session: Session, *, tenant_id: str, user_id: str | None, event
     event.updated_by_user_id = user_id
     if payload.sequence is None:
         event.sequence += 1
+
+
+def update_event(session: Session, *, tenant_id: str, user_id: str | None, event_id: str, payload: CalendarEventUpdateRequest) -> CalendarEvent:
+    original_calendar_id, target_calendar_id = _event_update_calendar_ids(
+        session,
+        tenant_id=tenant_id,
+        event_id=event_id,
+        payload=payload,
+    )
+    original_source, target_source = _lock_event_update_sources(
+        session,
+        tenant_id=tenant_id,
+        original_calendar_id=original_calendar_id,
+        target_calendar_id=target_calendar_id,
+    )
+    event = get_event(session, tenant_id=tenant_id, event_id=event_id)
+    previous = calendar_event_change_payload(event, prefix="previous_")
+    _assert_event_update_sync_fields(
+        payload,
+        original_source=original_source,
+        target_source=target_source,
+    )
+    _move_event_for_update(
+        session,
+        event=event,
+        payload=payload,
+        original_source=original_source,
+        target_source=target_source,
+    )
+    _apply_event_update_values(event, user_id=user_id, payload=payload)
     validate_event_time(event)
     event.raw_ics = None
     session.flush()