Add cleanup job for downloaded ids

internal/torrent/refresh.go

@@ -142,6 +142,20 @@ func (t *TorrentManager) refreshTorrents() []string {
 		})
 	})
 
+	t.workerPool.Submit(func() {
+		// update DownloadedIDs field of torrents
+		allTorrents.IterCb(func(accessKey string, torrent *Torrent) {
+			deletedIDs := torrent.DownloadedIDs.Difference(freshIDs)
+			if deletedIDs.Cardinality() > 0 {
+				deletedIDs.Each(func(id string) bool {
+					torrent.DownloadedIDs.Remove(id)
+					return false
+				})
+				t.writeTorrentToFile(torrent)
+			}
+		})
+	})
+
 	return updatedPaths.ToSlice()
 }