/* ── localStorage cache ── */
const CACHE_PREFIX = 'nma_v1_';
const CACHE_TTL = 60 * 60 * 1000; // 1 hour

function saveCache(key, prs) {
  try {
    const slim = prs.map(pr => ({
      number: pr.number, title: pr.title, html_url: pr.html_url,
      merged_at: getMerged(pr),
    }));
    localStorage.setItem(CACHE_PREFIX + key, JSON.stringify({ ts: Date.now(), prs: slim }));
  } catch (e) { /* quota exceeded or unavailable */ }
}

function loadCache(key) {
  try {
    const raw = localStorage.getItem(CACHE_PREFIX + key);
    if (!raw) return null;
    const parsed = JSON.parse(raw);
    if (Date.now() - parsed.ts > CACHE_TTL) return null;
    return parsed;
  } catch { return null; }
}

function getCacheTs(key) {
  try {
    const raw = localStorage.getItem(CACHE_PREFIX + key);
    if (!raw) return null;
    return JSON.parse(raw).ts;
  } catch { return null; }
}

function clearAllCaches() {
  try {
    for (const k of Object.keys(localStorage)) {
      if (k.startsWith(CACHE_PREFIX)) localStorage.removeItem(k);
    }
  } catch {}
}

function fmtRelative(ts) {
  if (!ts) return '';
  const sec = Math.round((Date.now() - ts) / 1000);
  if (sec < 60) return 'just now';
  const min = Math.floor(sec / 60);
  if (min < 60) return `${min}m ago`;
  const hr = Math.floor(min / 60);
  return `${hr}h ${min % 60}m ago`;
}