import parsePhoneNumberFromString, { type CountryCode, type PhoneNumberType } from 'libphonenumber-js/mobile/es6'

/** Result shape kept stable for consumers (same fields as previous `phone` package integration). */
export interface PhoneValidationResult {
  isValid: boolean
  phoneNumber: string | null
  countryIso2: string | null
  countryIso3: string | null
  countryCode: string | null
}

const INVALID_RESULT: PhoneValidationResult = {
  isValid: false,
  phoneNumber: null,
  countryIso2: null,
  countryIso3: null,
  countryCode: null,
}

const MOBILE_NUMBER_TYPES = new Set<PhoneNumberType>(['MOBILE', 'FIXED_LINE_OR_MOBILE'])

function isMobileNumberType(type: PhoneNumberType | undefined): boolean {
  return type !== undefined && MOBILE_NUMBER_TYPES.has(type)
}

function buildCandidates(value: string): string[] {
  const trimmed = value.trim()
  const digits = value.replace(/\D/g, '')
  const candidates = [trimmed]

  if (digits && digits !== trimmed) {
    candidates.push(digits)
  }
  if (digits.startsWith('0') && digits.length > 1) {
    candidates.push(digits.slice(1))
  }

  return [...new Set(candidates)]
}

function toValidationResult(parsed: NonNullable<ReturnType<typeof parsePhoneNumberFromString>>): PhoneValidationResult {
  return {
    isValid: true,
    phoneNumber: parsed.format('E.164'),
    countryIso2: parsed.country ?? null,
    countryIso3: null,
    countryCode: parsed.countryCallingCode ? `+${parsed.countryCallingCode}` : null,
  }
}

function runPhoneValidation(value: string, countryIso2: string): PhoneValidationResult {
  const country = countryIso2 as CountryCode

  for (const candidate of buildCandidates(value)) {
    const parsed = parsePhoneNumberFromString(candidate, country)
    if (!parsed?.isValid()) {
      continue
    }
    if (isMobileNumberType(parsed.getType())) {
      return toValidationResult(parsed)
    }
  }

  return INVALID_RESULT
}

export function validatePhoneNumber(nationalNumber: string, countryIso2: string): PhoneValidationResult {
  const trimmed = nationalNumber.trim()
  if (!trimmed) {
    return INVALID_RESULT
  }

  return runPhoneValidation(trimmed, countryIso2)
}

/** `null` when empty, otherwise whether the number is valid for the selected country. */
export function getPhoneValidationState(nationalNumber: string, countryIso2: string): boolean | null {
  if (!nationalNumber.trim()) {
    return null
  }
  return validatePhoneNumber(nationalNumber, countryIso2).isValid
}