// Suggest helpers (pure, no network, no DB) — shared dedup policy:
// the same occurrence is only ever returned once (first provider wins).

/** Normalize a suggestion string for dedup comparisons. */
export function normSuggestKey(s) {
  return String(s ?? '').trim().toLowerCase().replace(/\s+/g, ' ');
}

/**
 * Deduplicate suggestion groups across providers: the same occurrence
 * (case/whitespace-insensitive) is kept only once, in the first provider
 * group (registry order). Within a group, order is preserved (first wins).
 * @param {Record<string, string[]>} groups
 * @param {string[]} order provider ids in priority order
 * @returns {Record<string, string[]>} same keys, deduped lists
 */
export function dedupeSuggestGroups(groups, order = ['yt', 'dm', 'tw', 'pt', 'od', 'ru']) {
  const src = groups && typeof groups === 'object' ? groups : {};
  const seen = new Set();
  const out = {};
  const pushList = (pid) => {
    const list = Array.isArray(src[pid]) ? src[pid] : [];
    const clean = [];
    for (const raw of list) {
      const t = String(raw ?? '').trim();
      if (!t) continue;
      const k = normSuggestKey(t);
      if (seen.has(k)) continue;
      seen.add(k);
      clean.push(t);
    }
    out[pid] = clean;
  };
  for (const pid of order) {
    if (Object.prototype.hasOwnProperty.call(src, pid)) pushList(pid);
  }
  for (const pid of Object.keys(src)) {
    if (!order.includes(pid)) pushList(pid);
  }
  return out;
}