feat(web): add sortDmChannels utility with unread-first sorting

2026-04-02 17:48:24 +02:00
parent 03667947aa
commit 68fe04ef58
2 changed files with 119 additions and 0 deletions
@@ -0,0 +1,35 @@
+import type { DmChannel } from '@backspace/shared';
+
+/**
+ * Sort DM channels: unread first (by recency), then read (by recency).
+ * Does not mutate the input array.
+ *
+ * @param dmChannels - The DM channels to sort
+ * @param unreadChannels - Set of channel IDs that have unread messages
+ * @param currentChannelId - The currently active channel (excluded from unread group)
+ */
+export function sortDmChannels(
+  dmChannels: DmChannel[],
+  unreadChannels: Set<string>,
+  currentChannelId: string | null,
+): DmChannel[] {
+  const getTime = (dm: DmChannel) => dm.lastMessage?.createdAt ?? dm.createdAt;
+  const isUnread = (dm: DmChannel) => unreadChannels.has(dm.id) && dm.id !== currentChannelId;
+
+  const unread: DmChannel[] = [];
+  const read: DmChannel[] = [];
+
+  for (const dm of dmChannels) {
+    if (isUnread(dm)) {
+      unread.push(dm);
+    } else {
+      read.push(dm);
+    }
+  }
+
+  const byRecency = (a: DmChannel, b: DmChannel) => getTime(b) - getTime(a);
+  unread.sort(byRecency);
+  read.sort(byRecency);
+
+  return [...unread, ...read];
+}