/** Normalize Iranian/local input to E.164 (e.g. +989121111111). */
export function toE164CellNumber(input: string): string {
  const digits = input.replace(/\D/g, '')

  if (!digits) {
    return ''
  }

  if (digits.startsWith('98')) {
    return `+${digits}`
  }

  if (digits.startsWith('0')) {
    return `+98${digits.slice(1)}`
  }

  if (digits.length === 10 && digits.startsWith('9')) {
    return `+98${digits}`
  }

  return `+${digits}`
}

/** Display E.164 Iranian numbers as local format (e.g. 0912...). */
export function formatCellForDisplay(cellNumber: string): string {
  if (cellNumber.startsWith('+98')) {
    return `0${cellNumber.slice(3)}`
  }
  return cellNumber
}