const kilogramsToPounds = 2.2046226218

export function physicalWeightKg(value: unknown): number | null {
  if (value == null || value === '') return null
  const number = Number(value)
  return Number.isFinite(number) && number > 0 ? number : null
}

export function physicalWeightLb(value: unknown): number | null {
  const weight = physicalWeightKg(value)
  return weight === null ? null : weight * kilogramsToPounds
}

export function totalPhysicalWeightLb(items: readonly ({ grossWeightKg?: number | null } | undefined)[]): number | null {
  let total = 0
  for (const item of items) {
    const weight = physicalWeightLb(item?.grossWeightKg)
    if (weight === null) return null
    total += weight
  }
  return total
}