Use correct timestamp for receipts of edited messages

ts/util/getMessageSentTimestamp.ts

@@ -0,0 +1,42 @@
+// Copyright 2023 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import type { MessageAttributesType } from '../model-types.d';
+import type { LoggerType } from '../types/Logging';
+import { assertDev } from './assert';
+
+export type GetMessageSentTimestampOptionsType = Readonly<{
+  includeEdits?: boolean;
+  log: LoggerType;
+}>;
+
+export function getMessageSentTimestamp(
+  {
+    editMessageTimestamp,
+    sent_at: sentAt,
+    timestamp,
+  }: Pick<
+    MessageAttributesType,
+    'editMessageTimestamp' | 'sent_at' | 'timestamp'
+  >,
+  { includeEdits = true, log }: GetMessageSentTimestampOptionsType
+): number {
+  if (includeEdits && editMessageTimestamp) {
+    return editMessageTimestamp;
+  }
+
+  if (sentAt) {
+    return sentAt;
+  }
+
+  if (timestamp) {
+    log.error('message lacked sent_at. Falling back to timestamp');
+    return timestamp;
+  }
+
+  assertDev(
+    false,
+    'message lacked sent_at and timestamp. Falling back to current time'
+  );
+  return Date.now();
+}