import { Request, Response, NextFunction } from 'express';
import { ErrorDTO } from '../schemas/miscSchema';
import * as jwt from '../tools/jwt';

/**
 * Checks if user is singed in.
 * Returns 401 when user is unauthorized.
 * 
 * To check if user is an admin, chain requireUser and requireAdmin together.
 * So: use requireUser first, and after that requireAdmin to enforce
 * admin privilege requirement.
 *
 * @param      {Request}                  req     The request
 * @param      {Response}                 res     The resource
 * @param      {(Function|NextFunction)}  next    The next
 * @return     {any}                      Next function on success, unauthorized error otherwise
 */
const requireUser = (req: Request, res: Response, next: NextFunction) => {
	const user: jwt.JwtStatus = res.locals.user;
	let error: ErrorDTO | null = null;

	// No user? Something errored partway. Display an error.
	if (!user)
		error = {
			status: 'error',
			error: 'Unauthorized, please sign in',
			code: 'unauthorized_generic'
		};
	// Check if token is expired first.
	// This is because a token can be valid 
	// (if signature matches) while being expired.
	else if (user.expired)
		error = {
			status: 'error',
			error: 'Token expired, please sign in again',
			code: 'expired_token'
		};
	// Previous checks failed?
	// As a last resort, check if the token is valid.
	else if (!user.valid)
		error = {
			status: 'error',
			error: 'Invalid token, please sign in',
			code: 'invalid_token'
		};

	if (error !== null)
		return res.status(401)
				  .send(error);

	return next();
};

export default requireUser;