/**
 * Structured card/wallet decline information extracted from PayPal responses.
 *
 * A declined capture used to surface as a generic "Failed to capture PayPal
 * order" 500. This maps PayPal's processor response codes and issue names to
 * a buyer-friendly message plus a `retryable` flag, so storefronts can say
 * "insufficient funds — try another card" and decide whether to offer a retry.
 */

export type PayPalDeclineInfo = {
  /** Processor `response_code` (e.g. "5120") or PayPal issue name. */
  code: string
  /** Buyer-friendly message, safe to show in the storefront. */
  message: string
  /**
   * Whether another attempt could plausibly succeed (usually with a different
   * card or funding source). `false` marks hard declines — fraud, restricted
   * accounts — where inviting a retry only frustrates the buyer.
   */
  retryable: boolean
  avs_code?: string
  cvv_code?: string
}

const PROCESSOR_CODES: Record<string, { message: string; retryable: boolean }> =
  {
    "0500": {
      message:
        "The card was declined by the issuing bank. Please try a different card or contact your bank.",
      retryable: true,
    },
    "1330": {
      message: "The card account is not valid. Please use a different card.",
      retryable: true,
    },
    "5100": {
      message: "The card was declined. Please try a different payment method.",
      retryable: true,
    },
    "5110": {
      message:
        "The card's security code (CVV) did not match. Please check the code and try again.",
      retryable: true,
    },
    "5120": {
      message:
        "The card was declined due to insufficient funds. Please use a different payment method.",
      retryable: true,
    },
    "5400": {
      message: "The card has expired. Please use a different card.",
      retryable: true,
    },
    "5180": {
      message:
        "This card cannot be used for this purchase. Please use a different card.",
      retryable: true,
    },
    "9500": {
      message:
        "This transaction was declined. Please contact your bank or use a different payment method.",
      retryable: false,
    },
    "9520": {
      message:
        "This card has been reported lost or stolen and cannot be used. Please use a different card.",
      retryable: false,
    },
    "00N7": {
      message:
        "The card's security code (CVV) was incorrect. Please check the code and try again.",
      retryable: true,
    },
  }

const ISSUE_NAMES: Record<string, { message: string; retryable: boolean }> = {
  INSTRUMENT_DECLINED: {
    message:
      "Your payment method was declined. Please try a different card or payment method.",
    retryable: true,
  },
  TRANSACTION_REFUSED: {
    message:
      "The payment was refused. Please try again or use a different payment method.",
    retryable: true,
  },
  PAYER_CANNOT_PAY: {
    message:
      "This PayPal account cannot complete the payment. Please use a different payment method.",
    retryable: false,
  },
  PAYER_ACCOUNT_RESTRICTED: {
    message:
      "The PayPal account is restricted and cannot complete this payment.",
    retryable: false,
  },
  PAYER_ACCOUNT_LOCKED_OR_CLOSED: {
    message:
      "The PayPal account is locked or closed. Please use a different payment method.",
    retryable: false,
  },
  INSUFFICIENT_FUNDS: {
    message:
      "The payment was declined due to insufficient funds. Please use a different payment method.",
    retryable: true,
  },
  CARD_EXPIRED: {
    message: "The card has expired. Please use a different card.",
    retryable: true,
  },
  COMPLIANCE_VIOLATION: {
    message: "This transaction cannot be processed.",
    retryable: false,
  },
}

const GENERIC_DECLINE: { message: string; retryable: boolean } = {
  message:
    "The payment was declined. Please try again or use a different payment method.",
  retryable: true,
}

/**
 * Extract decline info from a PayPal response body — either a 4xx error body
 * (`{ name, details: [{ issue }] }`) or a 2xx capture/authorize payload whose
 * capture came back DECLINED/FAILED (carrying `processor_response`).
 * Returns null when the payload holds no recognizable decline.
 */
export function extractPayPalDecline(
  payload: unknown
): PayPalDeclineInfo | null {
  if (!payload || typeof payload !== "object") return null
  const body = payload as Record<string, any>

  // 4xx error body with issue details (e.g. 422 UNPROCESSABLE_ENTITY).
  const details = Array.isArray(body.details) ? body.details : []
  for (const detail of details) {
    const issue = String(detail?.issue || "").toUpperCase()
    if (issue && ISSUE_NAMES[issue]) {
      return { code: issue, ...ISSUE_NAMES[issue] }
    }
    if (issue === "INSTRUMENT_DECLINED" || issue.includes("DECLINED")) {
      return { code: issue, ...GENERIC_DECLINE }
    }
  }

  // 2xx payload with a non-completed capture carrying processor_response.
  const captures: Record<string, any>[] = []
  const direct = body.purchase_units?.[0]?.payments?.captures
  if (Array.isArray(direct)) captures.push(...direct)
  if (body.processor_response) captures.push(body)

  for (const capture of captures) {
    const status = String(capture?.status || "").toUpperCase()
    const processor = capture?.processor_response as
      | Record<string, any>
      | undefined
    if (!processor) continue
    if (status && status !== "DECLINED" && status !== "FAILED") continue

    const responseCode = String(processor.response_code || "").toUpperCase()
    const mapped = PROCESSOR_CODES[responseCode] ?? GENERIC_DECLINE
    return {
      code: responseCode || "DECLINED",
      ...mapped,
      avs_code: processor.avs_code ? String(processor.avs_code) : undefined,
      cvv_code: processor.cvv_code ? String(processor.cvv_code) : undefined,
    }
  }

  return null
}