From d50dae52082a09d9b640a8ab6935e7314fcd1e14 Mon Sep 17 00:00:00 2001
From: Germain <germains@element.io>
Date: Wed, 2 Mar 2022 09:02:14 +0000
Subject: [PATCH] Decrypt thread last reply on EventTile mount and update
 (#7930)

Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>
---
 src/components/views/rooms/EventTile.tsx | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/components/views/rooms/EventTile.tsx b/src/components/views/rooms/EventTile.tsx
index e5c7989518..62784f6d5c 100644
--- a/src/components/views/rooms/EventTile.tsx
+++ b/src/components/views/rooms/EventTile.tsx
@@ -514,6 +514,11 @@ export default class EventTile extends React.Component<IProps, IState> {
 
         const room = MatrixClientPeg.get().getRoom(this.props.mxEvent.getRoomId());
         room?.on(ThreadEvent.New, this.onNewThread);
+
+        if (this.state.threadLastReply?.isEncrypted()) {
+            this.state.threadLastReply.once(MatrixEventEvent.Decrypted, this.onEventDecryption);
+            MatrixClientPeg.get().decryptEventIfNeeded(this.state.threadLastReply);
+        }
     }
 
     private setupNotificationListener = (thread: Thread): void => {
@@ -596,6 +601,7 @@ export default class EventTile extends React.Component<IProps, IState> {
         if (this.threadState) {
             this.threadState.off(NotificationStateEvents.Update, this.onThreadStateUpdate);
         }
+        this.state.threadLastReply?.removeListener(MatrixEventEvent.Decrypted, this.onEventDecryption);
     }
 
     componentDidUpdate(prevProps: IProps, prevState: IState, snapshot) {
@@ -604,8 +610,20 @@ export default class EventTile extends React.Component<IProps, IState> {
             MatrixClientPeg.get().on(RoomEvent.Receipt, this.onRoomReceipt);
             this.isListeningForReceipts = true;
         }
+
+        if (this.state.threadLastReply !== prevState.threadLastReply) {
+            if (this.state.threadLastReply.isEncrypted()) {
+                this.state.threadLastReply.once(MatrixEventEvent.Decrypted, this.onEventDecryption);
+                MatrixClientPeg.get().decryptEventIfNeeded(this.state.threadLastReply);
+            }
+            prevState.threadLastReply?.removeListener(MatrixEventEvent.Decrypted, this.onEventDecryption);
+        }
     }
 
+    private onEventDecryption = () => {
+        this.forceUpdate();
+    };
+
     private onNewThread = (thread: Thread) => {
         if (thread.id === this.props.mxEvent.getId()) {
             this.updateThread(thread);