import { ValidationError } from './errors.js';

export function parsePagination(req, { defaultLimit = 50, max = 200 } = {}) {
  const q = req.query || {};
  const limit  = q.limit  === undefined ? defaultLimit : Number(q.limit);
  const offset = q.offset === undefined ? 0            : Number(q.offset);
  if (!Number.isFinite(limit) || limit < 1 || limit > max) {
    throw new ValidationError(`limit must be 1..${max}`, { limit: q.limit });
  }
  if (!Number.isFinite(offset) || offset < 0) {
    throw new ValidationError('offset must be >= 0', { offset: q.offset });
  }
  return { limit, offset };
}