Implement local redaction (#1182)

* Create redaction events and apply checks (but do not send them)

* Send redactions to the roomserver

* Linting

* Slightly better wording

currentstateserver/api/wrapper.go

@@ -7,6 +7,24 @@ import (
 	"github.com/matrix-org/util"
 )
 
+// GetEvent returns the current state event in the room or nil.
+func GetEvent(ctx context.Context, stateAPI CurrentStateInternalAPI, roomID string, tuple gomatrixserverlib.StateKeyTuple) *gomatrixserverlib.HeaderedEvent {
+	var res QueryCurrentStateResponse
+	err := stateAPI.QueryCurrentState(ctx, &QueryCurrentStateRequest{
+		RoomID:      roomID,
+		StateTuples: []gomatrixserverlib.StateKeyTuple{tuple},
+	}, &res)
+	if err != nil {
+		util.GetLogger(ctx).WithError(err).Error("Failed to QueryCurrentState")
+		return nil
+	}
+	ev, ok := res.StateEvents[tuple]
+	if ok {
+		return ev
+	}
+	return nil
+}
+
 // PopulatePublicRooms extracts PublicRoom information for all the provided room IDs. The IDs are not checked to see if they are visible in the
 // published room directory.
 // due to lots of switches