import { computed, type Ref } from 'vue'

/** Strip separators; keep digits and letters (suffix may contain letters). */
export function normalizePidSearchValue(value: string): string {
  return value.replace(/[^0-9a-zA-Z]/g, '')
}

/**
 * Check if a string looks like a personnummer (Swedish personal identity number)
 * @param value - String value to check
 * @returns Boolean indicating if the value looks like a personnummer
 */
export function isPidString(value: string): boolean {
  const normalized = normalizePidSearchValue(value)
  const digitsOnly = value.replace(/\D/g, '')

  if (normalized.length < 6 && digitsOnly.length < 6) {
    return false
  }

  const firstSix = digitsOnly.substring(0, 6)
  if (firstSix.length >= 6) {
    const year = parseInt(firstSix.substring(0, 4))
    const month = parseInt(firstSix.substring(4, 6))

    if (year >= 1900 && year <= 2099 && month >= 1 && month <= 12) {
      return true
    }
  }

  if (/^\d{8}/.test(normalized) && normalized.length >= 8) {
    return true
  }

  if (digitsOnly.length >= 8) {
    return true
  }

  return false
}

/** Format as yyyymmdd-nnnn; last four may be alphanumeric (e.g. coordination numbers). */
export function formatPidWithDash(value: string): string {
  if (!isPidString(value)) {
    return value.replace(/-$/, '')
  }

  const normalized = normalizePidSearchValue(value)

  if (normalized.length <= 8) {
    return normalized.slice(0, 8)
  }

  const datePart = normalized.slice(0, 8)
  if (!/^\d{8}$/.test(datePart)) {
    const digits = value.replace(/\D/g, '')
    if (digits.length > 8) {
      return `${digits.slice(0, 8)}-${digits.slice(8)}`
    }
    return digits
  }

  return `${datePart}-${normalized.slice(8, 12)}`
}

export const PID_MASK = '00000000-XXXX'

export const PID_MASK_OPTIONS = {
  lazy: true,
  definitions: {
    X: /[0-9A-Za-z]/,
  },
} as const

/**
 * Composable for detecting if a string looks like a personnummer (Swedish personal identity number)
 * @param value - Reactive string value to check (Ref<string>)
 * @returns Computed boolean indicating if the value looks like a personnummer
 */
export function useIsPid(value: Ref<string>) {
  const isPid = computed(() => isPidString(value.value))

  return {
    isPid,
  }
}