import { resolveCanonicalUserId } from './canonical-user.mjs';
import { getActiveSnapshot } from './snapshot.mjs';

/**
 * Session bootstrap payload for /auth/me (RFC: 5～10KB snapshot at session start).
 *
 * @param {import('mysql2/promise').Pool | null | undefined} pool
 * @param {string} userId
 * @param {string} [projection]
 */
export async function loadSessionUserModelSnapshot(pool, userId, projection = 'default') {
  if (!pool?.query || !userId) return null;
  const canonicalUserId = resolveCanonicalUserId(userId);
  const snap = await getActiveSnapshot(pool, canonicalUserId, projection);
  if (!snap) return null;
  return {
    snapshot_id: snap.snapshot_id,
    user_id: snap.user_id,
    projection: snap.projection,
    profile_version: snap.profile_version,
    fast_revision: snap.fast_revision,
    content_hash: snap.content_hash,
    byte_size: snap.byte_size,
    stale_after_sec: snap.stale_after_sec,
    loaded_at_hint: 'session_start',
    core: snap.core,
    meta: snap.meta,
    ...(canonicalUserId !== userId ? { canonical_user_id: canonicalUserId } : {}),
  };
}