authentication.js

const admin = require('firebase-admin')

const getAuthToken = (req, res, next) => {
    if (
        req.headers.authorization &&
        req.headers.authorization.split(' ')[0] === 'Bearer'
    ) {
        req.authToken = req.headers.authorization.split(' ')[1];
    } else {
        req.authToken = null;
    }
    next();
};

module.exports = {
    checkIfAuthenticated: function (req, res, next) {
        getAuthToken(req, res, async () => {
            try {
                const { authToken } = req;
                const userInfo = await admin
                    .auth()
                    .verifyIdToken(authToken);
                req.authId = userInfo.uid;
                return next();
            } catch (e) {
                return res
                    .status(401)
                    .send({ error: 'You are not authorized to make this request' });
            }
        });
    }
}