Financial-Times / n-error

import nError from './creator';

import { isFetchResponseError, isFetchNetworkError } from './checker';

import { CATEGORIES } from './constants';

// parse the response error based on content-type text/html, text/plain or application/json

// https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch

// https://msdn.microsoft.com/en-us/library/ms526971(v=exchg.10).aspx

export const parseFetchResponseError = async response => {

	if (response.ok) {

		return nError({

			category: CATEGORIES.FETCH_RESPONSE_OK,

			status: response.status,

			message: "it shouldn't be caught as exception, please check the code",

		});

	}

	const { status, headers } = response;

	const contentType = headers.get('content-type');

	const parseMethod =

		contentType && contentType.includes('application/json') ? 'json' : 'text';

	const message = await response[parseMethod](); // system Error would be thrown if it fails

	return nError({

		category: CATEGORIES.FETCH_RESPONSE_ERROR,

		status,

		message,

		contentType,

	});

};

export const parseFetchNetworkError = e =>

	nError({

		category: CATEGORIES.FETCH_NETWORK_ERROR,

		message: e.message,

		code: e.code,

	});

export const parseFetchError = async e => {

	if (isFetchResponseError(e)) {

		const parsedError = await parseFetchResponseError(e);

		return parsedError;

	}

	if (isFetchNetworkError(e)) {

		return parseFetchNetworkError(e);

	}

	return e; // uncaught exception

};