spaghiajoeojo / express-beans

export declare type ResultOk<T> = {

  ok: true,

  value: T,

};

export declare type ResultError<E = Error> = {

  ok: false,

  error: E,

};

export declare type Result<T, E = Error> = ResultOk<T> | ResultError<E>;

export declare type ResultAsync<T> = Promise<Result<T>>;

export const isOk = <T>(result: Result<T>): result is ResultOk<T> => result.ok;

export const isError = <T>(result: Result<T>): result is ResultError => !result.ok;

const commuteError = (thrown: any) => {

  if (thrown instanceof Error) {

    return thrown;

  }

  return new Error(String(thrown));

};

export const wrap = <T>(fn: () => T | Promise<T>): Result<T> | Promise<Result<T>> => {

  try {

    const result = fn();

    if (result instanceof Promise) {

      return result

        .then((value) => ({ ok: true as const, value }))

        .catch((error) => ({ ok: false as const, error: commuteError(error) }));

    }

    return {

      ok: true as const,

      value: result,

    };

  } catch (error) {

    return {

      ok: false as const,

      error: commuteError(error),

    };

  }

};

export const unwrap = <T>(result: Result<T>): T => {

  if (isOk(result)) {

    return result.value;

  }

  throw result.error;

};

export const unwrapAsync = async <T>(resultAsync: ResultAsync<T>): Promise<T> => {

  const result = await resultAsync;

  if (isOk(result)) {

    return result.value;

  }

  throw result.error;

};

export const wrapValue = <T>(value: T): Result<T> => ({ ok: true as const, value });

export const wrapError = <E = Error>(error: E): ResultError<E> => ({ ok: false as const, error });