Show "unplayed" dot on incoming audio messages

ts/messages/MessageReadStatus.ts

@@ -0,0 +1,26 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+/**
+ * `ReadStatus` represents your local read/viewed status of a single incoming message.
+ * Messages go from Unread to Read to Viewed; they never go "backwards".
+ *
+ * Note that a conversation can be marked unread, which is not at the message level.
+ *
+ * Be careful when changing these values, as they are persisted. Notably, we previously
+ * had a field called "unread", which is why Unread corresponds to 1 and Read to 0.
+ */
+export enum ReadStatus {
+  Unread = 1,
+  Read = 0,
+  Viewed = 2,
+}
+
+const STATUS_NUMBERS: Record<ReadStatus, number> = {
+  [ReadStatus.Unread]: 0,
+  [ReadStatus.Read]: 1,
+  [ReadStatus.Viewed]: 2,
+};
+
+export const maxReadStatus = (a: ReadStatus, b: ReadStatus): ReadStatus =>
+  STATUS_NUMBERS[a] > STATUS_NUMBERS[b] ? a : b;