From 86c0e9e66936d3c18aca88fa4c9aab53acfd8d3d Mon Sep 17 00:00:00 2001
From: Bruno Windels <274386+bwindels@users.noreply.github.com>
Date: Fri, 22 Jul 2022 17:46:53 +0200
Subject: [PATCH] logic for whether a key should be shared by membership and h.
 visibility

---
 src/matrix/e2ee/common.js | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/matrix/e2ee/common.js b/src/matrix/e2ee/common.js
index 2b9d46b9..cc3bfff5 100644
--- a/src/matrix/e2ee/common.js
+++ b/src/matrix/e2ee/common.js
@@ -69,3 +69,28 @@ export function createRoomEncryptionEvent() {
         }
     }
 }
+
+
+// Use enum when converting to TS
+export const HistoryVisibility = Object.freeze({
+    Joined: "joined",
+    Invited: "invited",
+    WorldReadable: "world_readable",
+    Shared: "shared",
+});
+
+export function shouldShareKey(membership, historyVisibility) {
+    switch (historyVisibility) {
+        case HistoryVisibility.WorldReadable:
+            return true;
+        case HistoryVisibility.Shared:
+            // was part of room at some time
+            return membership !== undefined;
+        case HistoryVisibility.Joined:
+            return membership === "join";
+        case HistoryVisibility.Invited:
+            return membership === "invite" || membership === "join";
+        default:
+            return false;
+    }
+}