import { getExampleNumber, type CountryCode } from 'libphonenumber-js/mobile/es6'
import examples from 'libphonenumber-js/mobile/examples'

const maskCache = new Map<string, string>()

/** IMask pattern with space grouping derived from libphonenumber mobile example numbers. */
export const getPhoneMaskForCountry = (countryIso2: string): string | undefined => {
  const country = countryIso2.trim().toUpperCase() as CountryCode
  const cached = maskCache.get(country)
  if (cached) {
    return cached
  }

  const example = getExampleNumber(country, examples)
  if (!example) {
    return undefined
  }

  const groups = example
    .formatNational()
    .split(/\D+/)
    .filter(Boolean)
    .map((part) => part.length)

  const mask = groups.map((size) => '0'.repeat(size)).join(' ')
  maskCache.set(country, mask)
  return mask
}