MSC2946: Spaces Summary (round 2) (#2232)

* Initial cut at fixing up MSC2946 to work with latest spec

* bugfix: send response back correctly

* Initial working version of MSC2946

* msc2946: handle suggested_only; remove custom database

As the MSC doesn't require reverse lookups, we can just pull
the room state and inspect via the roomserver database. To
handle this, expand QueryCurrentState to support wildcards.

Use all this and handle `?suggested_only`.

* Sort child rooms

* msc2946: Make TestClientSpacesSummary pass

* msc2946: allow invited rooms to be spidered

* msc2946: support basic federation requests

* fix up go mod

roomserver/storage/shared/storage.go

@@ -979,6 +979,62 @@ func (d *Database) GetStateEvent(ctx context.Context, roomID, evType, stateKey s
 	return nil, nil
 }
 
+// Same as GetStateEvent but returns all matching state events with this event type. Returns no error
+// if there are no events with this event type.
+func (d *Database) GetStateEventsWithEventType(ctx context.Context, roomID, evType string) ([]*gomatrixserverlib.HeaderedEvent, error) {
+	roomInfo, err := d.RoomInfo(ctx, roomID)
+	if err != nil {
+		return nil, err
+	}
+	if roomInfo == nil {
+		return nil, fmt.Errorf("room %s doesn't exist", roomID)
+	}
+	// e.g invited rooms
+	if roomInfo.IsStub {
+		return nil, nil
+	}
+	eventTypeNID, err := d.EventTypesTable.SelectEventTypeNID(ctx, nil, evType)
+	if err == sql.ErrNoRows {
+		// No rooms have an event of this type, otherwise we'd have an event type NID
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	entries, err := d.loadStateAtSnapshot(ctx, roomInfo.StateSnapshotNID)
+	if err != nil {
+		return nil, err
+	}
+	var eventNIDs []types.EventNID
+	for _, e := range entries {
+		if e.EventTypeNID == eventTypeNID {
+			eventNIDs = append(eventNIDs, e.EventNID)
+		}
+	}
+	eventIDs, _ := d.EventsTable.BulkSelectEventID(ctx, nil, eventNIDs)
+	if err != nil {
+		eventIDs = map[types.EventNID]string{}
+	}
+	// return the events requested
+	eventPairs, err := d.EventJSONTable.BulkSelectEventJSON(ctx, nil, eventNIDs)
+	if err != nil {
+		return nil, err
+	}
+	if len(eventPairs) == 0 {
+		return nil, nil
+	}
+	var result []*gomatrixserverlib.HeaderedEvent
+	for _, pair := range eventPairs {
+		ev, err := gomatrixserverlib.NewEventFromTrustedJSONWithEventID(eventIDs[pair.EventNID], pair.EventJSON, false, roomInfo.RoomVersion)
+		if err != nil {
+			return nil, err
+		}
+		result = append(result, ev.Headered(roomInfo.RoomVersion))
+	}
+
+	return result, nil
+}
+
 // GetRoomsByMembership returns a list of room IDs matching the provided membership and user ID (as state_key).
 func (d *Database) GetRoomsByMembership(ctx context.Context, userID, membership string) ([]string, error) {
 	var membershipState tables.MembershipState