2 files changed, 68 insertions, 0 deletions

diff --git a/matrix/history.go b/matrix/history.go
index 7275c15..af81ed2 100644
--- a/matrix/history.go
+++ b/matrix/history.go
@@ -21,6 +21,7 @@ import (
 	"compress/gzip"
 	"encoding/binary"
 	"encoding/gob"
+	"errors"
 
 	sync "github.com/sasha-s/go-deadlock"
 	bolt "go.etcd.io/bbolt"
@@ -107,6 +108,37 @@ func (hm *HistoryManager) Get(room *rooms.Room, eventID string) (event *mautrix.
 	return
 }
 
+var EventNotFoundError = errors.New("event not found")
+
+func (hm *HistoryManager) Update(room *rooms.Room, eventID string, update func(event *mautrix.Event) error) error {
+	return hm.db.Update(func (tx *bolt.Tx) error {
+		rid := []byte(room.ID)
+		eventIDs := tx.Bucket(bucketRoomEventIDs).Bucket(rid)
+		if eventIDs == nil {
+			return nil
+		}
+		streamIndex := eventIDs.Get([]byte(eventID))
+		if streamIndex == nil {
+			return nil
+		}
+		stream := tx.Bucket(bucketRoomStreams).Bucket(rid)
+		eventData := stream.Get(streamIndex)
+		if eventData == nil {
+			return EventNotFoundError
+		}
+
+		if event, err := unmarshalEvent(eventData); err != nil {
+			return err
+		} else if err = update(event); err != nil {
+			return err
+		} else if eventData, err = marshalEvent(event); err != nil {
+			return err
+		} else {
+			return stream.Put(streamIndex, eventData)
+		}
+	})
+}
+
 func (hm *HistoryManager) Append(room *rooms.Room, events []*mautrix.Event) error {
 	return hm.store(room, events, true)
 }
diff --git a/matrix/matrix.go b/matrix/matrix.go
index 05736ce..9178ca0 100644
--- a/matrix/matrix.go
+++ b/matrix/matrix.go
@@ -209,6 +209,7 @@ func (c *Container) OnLogin() {
 	// Just pass encrypted events as messages, they'll show up with an encryption unsupported message.
 	c.syncer.OnEventType(mautrix.EventEncrypted, c.HandleMessage)
 	c.syncer.OnEventType(mautrix.EventSticker, c.HandleMessage)
+	c.syncer.OnEventType(mautrix.EventRedaction, c.HandleRedaction)
 	c.syncer.OnEventType(mautrix.StateAliases, c.HandleMessage)
 	c.syncer.OnEventType(mautrix.StateCanonicalAlias, c.HandleMessage)
 	c.syncer.OnEventType(mautrix.StateTopic, c.HandleMessage)
@@ -307,6 +308,41 @@ func (c *Container) SendPreferencesToMatrix() {
 	}
 }
 
+func (c *Container) HandleRedaction(source EventSource, evt *mautrix.Event) {
+	room := c.GetOrCreateRoom(evt.RoomID)
+	var redactedEvt *mautrix.Event
+	err := c.history.Update(room, evt.Redacts, func(redacted *mautrix.Event) error {
+		redacted.Unsigned.RedactedBy = evt.ID
+		redacted.Unsigned.RedactedBecause = evt
+		redactedEvt = redacted
+		return nil
+	})
+	if err != nil {
+		debug.Print("Failed to mark", evt.Redacts, "as redacted:", err)
+	}
+
+	if !room.Loaded() {
+		return
+	}
+
+	mainView := c.ui.MainView()
+
+	roomView := mainView.GetRoom(evt.RoomID)
+	if roomView == nil {
+		debug.Printf("Failed to handle event %v: No room view found.", evt)
+		return
+	}
+
+	// TODO make this less hacky?
+	message := roomView.ParseEvent(redactedEvt)
+	if message != nil {
+		roomView.AddMessage(message)
+		if c.syncer.FirstSyncDone {
+			c.ui.Render()
+		}
+	}
+}
+
 // HandleMessage is the event handler for the m.room.message timeline event.
 func (c *Container) HandleMessage(source EventSource, evt *mautrix.Event) {
 	room := c.GetOrCreateRoom(evt.RoomID)