MERN-template/client/components/pages/login.jsx

import React, { useContext, useRef } from 'react';
import { Redirect } from 'react-router-dom';

import { TokenContext } from '../utilities/token-provider';

const validateEmail = require('../../../common/utilities/validate-email');

const LogIn = props => {
	//context
	const authTokens = useContext(TokenContext);

	//misplaced?
	if (authTokens.accessToken) {
		return <Redirect to='/' />;
	}

	//refs
	const emailRef = useRef();
	const passwordRef = useRef();

	return (
		<div className='page'>
			<h1 className='centered'>Login</h1>
			<form className='constricted' onSubmit={
				async evt => {
					//on submit
					evt.preventDefault();
					const [err, newTokens] = await handleSubmit(emailRef.current.value, passwordRef.current.value);
					if (err) {
						alert(err);
					}

					//save auth tokens and redirect
					if (newTokens) {
						authTokens.setAccessToken(newTokens.accessToken);
						authTokens.setRefreshToken(newTokens.refreshToken);

						props.history.push('/');
					}
				}
			}>
				<div>
					<label htmlFor="email">Email:</label>
					<input type="email" name="email" ref={emailRef} />
				</div>

				<div>
					<label htmlFor="password">Password:</label>
					<input type="password" name="password" ref={passwordRef} />
				</div>

				<button type='submit'>Login</button>
			</form>
		</div>
	);
};

//DOCS: returns two values: err and authTokens
const handleSubmit = async (email, password) => {
	email = email.trim();

	const err = handleValidation(email, password);

	if (err) {
		return [err, false];
	}

	//send to the auth server
	const result = await fetch(`${process.env.AUTH_URI}/auth/login`, {
		method: 'POST',
		headers: {
			'Content-Type': 'application/json',
			'Access-Control-Allow-Origin': '*'
		},
		body: JSON.stringify({
			email,
			password,
		})
	});

	//handle errors
	if (!result.ok) {
		const err = `${result.status}: ${await result.text()}`;
		console.error(err);
		return [err, false];
	}

	//return the new auth tokens
	const newTokens = await result.json();
	return [null, newTokens];
};

//returns an error message, or null on success
const handleValidation = (email, password) => {
	if (!validateEmail(email)) {
		return 'invalid email';
	}

	if (password.length < 8) {
		return 'invalid password (Must be at least 8 characters long)';
	}

	return null;
};


export default LogIn;