export const CARD_BRANDS = [
  "visa",
  "mastercard",
  "unionpay",
  "amex",
  "diners",
  "discover",
  "jcb",
] as const

export type CardBrand = (typeof CARD_BRANDS)[number]

export const CARD_BRAND_LABELS: Record<CardBrand, string> = {
  visa: "Visa",
  mastercard: "Mastercard",
  unionpay: "UnionPay",
  amex: "American Express",
  diners: "Diners Club",
  discover: "Discover",
  jcb: "JCB",
}

export const CARD_BRAND_LOGOS: Record<CardBrand, string> = {
  visa: "/payment-logos/visa.svg",
  mastercard: "/payment-logos/mastercard.svg",
  unionpay: "/payment-logos/unionpay.svg",
  amex: "/payment-logos/amex.svg",
  diners: "/payment-logos/diners.svg",
  discover: "/payment-logos/discover.svg",
  jcb: "/payment-logos/jcb.svg",
}

const CARD_BRAND_ALIASES: Record<string, CardBrand> = {
  visa: "visa",
  mastercard: "mastercard",
  unionpay: "unionpay",
  amex: "amex",
  americanexpress: "amex",
  diners: "diners",
  dinersclub: "diners",
  discover: "discover",
  jcb: "jcb",
}

export function normalizeCardBrand(
  input: string | null | undefined
): CardBrand | null {
  if (typeof input !== "string") {
    return null
  }

  const key = input
    .trim()
    .toLowerCase()
    .replace(/[\s_-]+/g, "")
  return CARD_BRAND_ALIASES[key] ?? null
}

export function getCardBrandLogoUrl(
  input: string | null | undefined
): string | null {
  const brand = normalizeCardBrand(input)
  return brand ? CARD_BRAND_LOGOS[brand] : null
}

type CardNumberResult = {
  card: { type?: string } | null
  isPotentiallyValid: boolean
}

type CardValidatorApi = {
  number?: (value: string) => CardNumberResult
}

type CardValidatorModule = CardValidatorApi & {
  default?: CardValidatorApi
}

export async function detectCardBrand(
  cardNumber: string
): Promise<CardBrand | null> {
  const digits = cardNumber.replace(/\D/g, "")
  if (!digits) {
    return null
  }

  try {
    const loadedValidator =
      (await import("card-validator")) as unknown as CardValidatorModule
    const validator = loadedValidator.default ?? loadedValidator

    if (typeof validator.number !== "function") {
      return null
    }

    const result = validator.number(digits)
    if (!result.card || !result.isPotentiallyValid) {
      return null
    }

    return result.card.type ? normalizeCardBrand(result.card.type) : null
  } catch {
    return null
  }
}