// from https://github.com/vercel/next.js/blob/canary/packages/next/src/client/components/http-access-fallback/http-access-fallback.ts

export const HTTPAccessErrorStatus = {
  NOT_FOUND: 404,
  FORBIDDEN: 403,
  UNAUTHORIZED: 401,
};

const ALLOWED_CODES = new Set(Object.values(HTTPAccessErrorStatus));

export const HTTP_ERROR_FALLBACK_ERROR_CODE = 'NEXT_HTTP_ERROR_FALLBACK';

export type HTTPAccessFallbackError = Error & {
  digest: `${typeof HTTP_ERROR_FALLBACK_ERROR_CODE};${string}`;
};

/**
 * Checks an error to determine if it's an error generated by
 * the HTTP navigation APIs `notFound()`, `forbidden()` or `unauthorized()`.
 *
 * @param error the error that may reference a HTTP access error
 * @returns true if the error is a HTTP access error
 */
export function isHTTPAccessFallbackError(error: unknown): error is HTTPAccessFallbackError {
  if (typeof error !== 'object' || error === null || !('digest' in error) || typeof error.digest !== 'string') {
    return false;
  }
  const [prefix, httpStatus] = error.digest.split(';');

  return prefix === HTTP_ERROR_FALLBACK_ERROR_CODE && ALLOWED_CODES.has(Number(httpStatus));
}

export function getAccessFallbackHTTPStatus(error: HTTPAccessFallbackError | NotFoundError): number {
  if (isNotFoundError(error)) {
    return 404;
  }
  const httpStatus = error.digest.split(';')[1];
  return Number(httpStatus);
}

export function getAccessFallbackErrorTypeByStatus(
  status: number,
): 'not-found' | 'forbidden' | 'unauthorized' | undefined {
  switch (status) {
    case 401:
      return 'unauthorized';
    case 403:
      return 'forbidden';
    case 404:
      return 'not-found';
    default:
      return;
  }
}

// Legacy notFound()

const NOT_FOUND_ERROR_CODE = 'NEXT_NOT_FOUND';

type NotFoundError = Error & { digest: typeof NOT_FOUND_ERROR_CODE };

/**
 * Checks an error to determine if it's an error generated by the `notFound()`
 * helper.
 *
 * @param error the error that may reference a not found error
 * @returns true if the error is a not found error
 */
export function isNotFoundError(error: unknown): error is NotFoundError {
  if (typeof error !== 'object' || error === null || !('digest' in error)) {
    return false;
  }

  return error.digest === NOT_FOUND_ERROR_CODE;
}