function parseNullableNumber(value) {
  if (value === undefined || value === null || value === '') {
    return null;
  }

  const parsed = Number.parseFloat(value);
  return Number.isFinite(parsed) ? parsed : null;
}

function decorateOfficialVehicle(row) {
  return {
    ...row,
    source: 'official',
    confidence: 1,
    accuracy_m: parseNullableNumber(row.accuracy_meters),
    is_estimated: false
  };
}

function sortLiveVehicles(a, b) {
  if (a.source !== b.source) {
    return a.source === 'official' ? -1 : 1;
  }

  return new Date(b.last_seen_at).getTime() - new Date(a.last_seen_at).getTime();
}

module.exports = {
  decorateOfficialVehicle,
  parseNullableNumber,
  sortLiveVehicles
};