import parsePhoneNumberFromString, { getCountryCallingCode, type CountryCode } from 'libphonenumber-js/mobile/es6'
import { getPhoneMaskForCountry } from './phoneMask'

const nationalDigitsForMask = (parsed: NonNullable<ReturnType<typeof parsePhoneNumberFromString>>): string =>
  parsed.formatNational().replace(/\D/g, '')

const tryParseForCountry = (candidate: string, country: CountryCode): ReturnType<typeof parsePhoneNumberFromString> => {
  const parsed = parsePhoneNumberFromString(candidate, country) ?? parsePhoneNumberFromString(candidate)
  if (!parsed?.isValid() || parsed.country !== country) {
    return undefined
  }
  return parsed
}

/** Whether the value likely contains a country calling code or international formatting. */
export const shouldNormalizePhoneInput = (value: string, countryIso2: string): boolean => {
  const trimmed = value.trim()
  if (!trimmed) {
    return false
  }
  if (trimmed.includes('+') || trimmed.startsWith('00')) {
    return true
  }

  const digits = trimmed.replace(/\D/g, '')
  const mask = getPhoneMaskForCountry(countryIso2)
  if (!mask) {
    return false
  }

  const maxDigits = (mask.match(/0/g) ?? []).length
  if (digits.length > maxDigits) {
    return true
  }

  try {
    const callingCode = getCountryCallingCode(countryIso2 as CountryCode)
    if (digits.startsWith(callingCode) && digits.length > maxDigits - 1) {
      return true
    }
  } catch {
    return false
  }

  return false
}

/**
 * Converts international/autocomplete values to national digits for the IMask field.
 * IMask reapplies spacing from the country mask.
 */
export const normalizeNationalPhoneInput = (value: string, countryIso2: string): string => {
  const trimmed = value.trim()
  if (!trimmed) {
    return ''
  }

  const country = countryIso2.trim().toUpperCase() as CountryCode
  const digits = trimmed.replace(/\D/g, '')

  const candidates = new Set<string>([trimmed])
  if (digits) {
    candidates.add(digits)
    candidates.add(`+${digits}`)
  }

  for (const candidate of candidates) {
    const parsed = tryParseForCountry(candidate, country)
    if (parsed) {
      return nationalDigitsForMask(parsed)
    }
  }

  try {
    const callingCode = getCountryCallingCode(country)
    if (digits.startsWith(callingCode) && digits.length > callingCode.length) {
      const withoutCode = digits.slice(callingCode.length)
      const parsed = tryParseForCountry(withoutCode, country) ?? tryParseForCountry(`0${withoutCode}`, country)
      if (parsed) {
        return nationalDigitsForMask(parsed)
      }
    }
  } catch {
    return trimmed
  }

  return trimmed
}