/**
 * Resolve login user_id → canonical user_id for UMS / Temporal Recall / MeInput queries.
 *
 * Env MEMIND_CANONICAL_USER_MAP:
 *   from=to,from2=to2
 *
 * Default: tang19821002 → 唐 (wx_ul610et8)
 */
const DEFAULT_MAP = new Map([
  [
    'd0678bbc-2a50-4e08-8bf0-6b6c9301e2d6',
    'a70ff537-8908-486e-9b6c-042e07cc25db',
  ],
]);

let cachedMap = null;

function parseCanonicalUserMap(raw) {
  const map = new Map(DEFAULT_MAP);
  const text = String(raw ?? '').trim();
  if (!text) return map;
  for (const part of text.split(',')) {
    const pair = part.trim();
    if (!pair) continue;
    const eq = pair.indexOf('=');
    if (eq <= 0) continue;
    const from = pair.slice(0, eq).trim();
    const to = pair.slice(eq + 1).trim();
    if (from && to) map.set(from, to);
  }
  return map;
}

function canonicalMap() {
  if (!cachedMap) {
    cachedMap = parseCanonicalUserMap(process.env.MEMIND_CANONICAL_USER_MAP);
  }
  return cachedMap;
}

/** @param {string | null | undefined} userId */
export function resolveCanonicalUserId(userId) {
  const id = String(userId ?? '').trim();
  if (!id) return id;
  return canonicalMap().get(id) ?? id;
}

export function resetCanonicalUserMapCache() {
  cachedMap = null;
}