/**
 * Lets any layer fail a request with an HTTP status, which the error middleware
 * turns into the response.
 *
 * @module
 */

import { APIErrorCode } from "../../shared/api.ts";

/** Passed to an {@link APIException}; any other status is a type error. */
export type APIStatus = 400 | 401 | 403 | 404 | 409 | 429 | 500 | 502;

const CODES: Record<APIStatus, APIErrorCode> = {
  400: APIErrorCode.BAD_REQUEST,
  401: APIErrorCode.UNAUTHORIZED,
  403: APIErrorCode.FORBIDDEN,
  404: APIErrorCode.NOT_FOUND,
  409: APIErrorCode.CONFLICT,
  429: APIErrorCode.RATE_LIMITED,
  500: APIErrorCode.SERVER_ERROR,
  502: APIErrorCode.BAD_GATEWAY,
};

/**
 * Thrown by a route, a service or a remote fetch to answer the request with an
 * error. The error middleware sends it as an `APIFailure`, message included,
 * so the message must be fit for the user. Use 401 for a caller who isn't
 * signed in, 403 for one who is but may not, and 404 rather than 403 when the
 * caller mustn't learn that the thing exists.
 */
export class APIException extends Error {
  readonly code: APIErrorCode;
  readonly status: APIStatus;

  constructor(status: APIStatus, message: string) {
    super(message);
    this.status = status;
    this.code = CODES[status];
  }
}