Get Last-Seen + Online Status

curl https://api.bio.re/api/v1/presence/00000000-0000-4000-8000-000000000001/last-seen \
  -H "Authorization: Bearer $ACCESS_TOKEN"

type PresenceSnapshot = {
  userId: string;
  lastSeen: string | null; // ISO-8601 or null
  isOnline: boolean;
};

async function getPresence(
  accessToken: string,
  userId: string,
): Promise<PresenceSnapshot> {
  const res = await fetch(
    `https://api.bio.re/api/v1/presence/${userId}/last-seen`,
    { headers: { Authorization: `Bearer ${accessToken}` } },
  );
  const json = await res.json();
  if (!res.ok || !json.success) {
    throw Object.assign(new Error(json?.error?.message ?? 'Presence fetch failed'), {
      code: json?.error?.code,
    });
  }
  return json.data;
}

import { useQuery } from '@tanstack/react-query';

export const presenceKeys = {
  forUser: (userId: string) => ['presence', userId] as const,
};

// Poll every 60s — matches the presence:{userId} Redis TTL.
// Sockets that disconnect cleanly write lastSeen immediately;
// sockets that drop will age out within 60s, so polling at this
// cadence keeps the UI within one tick of reality.
export function usePresence(userId: string, enabled = true) {
  return useQuery({
    queryKey: presenceKeys.forUser(userId),
    queryFn: async () => {
      const res = await fetch(`/api/v1/presence/${userId}/last-seen`);
      const json = await res.json();
      if (!res.ok || !json.success) {
        throw Object.assign(new Error(json?.error?.message ?? 'Presence fetch failed'), {
          code: json?.error?.code,
        });
      }
      return json.data as PresenceSnapshot;
    },
    enabled,
    refetchInterval: 60_000,
    // Stale = the moment we get the response. We want fresh on remount.
    staleTime: 0,
  });
}

function formatPresence(snap: PresenceSnapshot, now = Date.now()): string {
  if (snap.isOnline) return 'Online';
  if (!snap.lastSeen) return 'Last seen a while ago'; // ambiguous null — never / TTL / read fail
  const diffMs = now - new Date(snap.lastSeen).getTime();
  const min = Math.floor(diffMs / 60_000);
  if (min < 1) return 'Just now';
  if (min < 60) return `Last seen ${min}m ago`;
  const hr = Math.floor(min / 60);
  if (hr < 24) return `Last seen ${hr}h ago`;
  const day = Math.floor(hr / 24);
  return `Last seen ${day}d ago`;
}