Add function to generate filename from manifest.

We were doing this in two separate places; better to only do it in one!

Author: jamesremuscat

src/replay.js

@@ -1,4 +1,5 @@
 import { BlobReader, TextWriter, ZipReader } from '@zip.js/zip.js';
+import dayjs from './dates.js';
 import { diff, patch } from './diffs.js';
 
 export const REPLAY_FRAME_REGEX = /^([0-9]{5,11})(i?).json$/;
@@ -197,3 +198,8 @@ export const loadReplayFromFile = async(file) => {
   await replay._init();
   return replay;
 };
+
+export const filenameFromManifest = (manifest, extension = 'zip') => {
+  const startTime = dayjs(manifest.startTime * 1000);
+  return `${startTime.format('YYYY-MM-DD HH-mm')} ${manifest.name} - ${manifest.description}.${extension}`.replaceAll(/[\\/]/g, '_');
+};

src/tests/replay.test.js

@@ -1,4 +1,4 @@
-import { createIframe } from '../replay.js';
+import { createIframe, filenameFromManifest } from '../replay.js';
 
 describe('Replay module', () => {
   describe('creation of iframes', () => {
@@ -32,4 +32,17 @@ describe('Replay module', () => {
       expect(iframe.messages[0]).toEqual([12345, 'foo', 'bar']);
     });
   });
+
+  describe('#filenameFromManifest', () => {
+    it('suggests a filename', () => {
+      const manifest = {
+        startTime: new Date('2025-01-31 12:34:56 +00:00').getTime() / 1000,
+        name: 'Service Name',
+        description: 'Description with invalid/unwanted characters'
+      };
+
+      const filename = filenameFromManifest(manifest, 'ext');
+      expect(filename).toEqual('2025-01-31 12-34 Service Name - Description with invalid_unwanted characters.ext');
+    });
+  });
 });