auth.js

// ----------------------------------- AUTHENTICATE USER  -------------------------------------------
module.exports = function(app, db, session, bcrypt, logStream) {
    /*
     * Authenticate a MONGODB ATLAS user  - Authentifier un utilisateur sur Mongodb ATLAS
     * @params JSON OBJECT - EXAMPLE : {"email":"urEmail","password":"urPassword"}
     * @return JSON OBJECT - dbUser
     * @error  Status 403
     */

    app.post("/getAuth", function(req, res) {
        // AN ANONYMOUS USER ALREADY HAS A BACK END SESSION ID, WE LOOK AT IT - Un utilisateur anonyme possède déjà un id de session , gràce au module node session
        console.log("reqsessionId ; " + req.sessionID);

        // step 1. Getting front end DATA (email and password) - On récupère log in et mot de passe du front end
        var frontEndUser = req.body;

        // step 2. FINDING EMAIL IN DATABASE - ON cherche l'email dans la db
        db.collection("users").findOne({ email: frontEndUser.email }, function(findErr, dbUser) {

            if (findErr) res.status(403).send({ errorCode: "403" });

            if (!dbUser) {
                console.log("USER is not present in the DATABASE");
                res.status(403).send({ errorCode: "403" });
            } else {
                // step 3. COMPARING PASSWORDS ( front end vs db ) - ON compare le password entré et celui de la database
                if (bcrypt.compareSync(frontEndUser.password, dbUser.password)) { // Passwords match

                    // step 4. BUILDING THE BACKEND USER SESSION - AJOUT DES DATAS DU USER A LA SESSION ET LE FAIT QUIL EST LOGGE
                    req.session.loggedIn = true;
                    req.session.user = dbUser;

                    // step 5. SENDING USER DATA TO FRONT END ENVOI DU USER AU FRONT END
                    res.send(dbUser);

                    // step 6. USER CONNEXION IS WRITTEN IN LOGS
                    var d = new Date(Date.now());
                    logStream.write('USER : ' + req.session.user.email + ' CONNECTED AT : ' + d.toString() + '\r\n');
                    // logStream.end('\r\n');

                } else {

                    // step 7 : Passwords don't match  Erreur de mot de passe
                    console.log("Passwords don't match");
                    res.status(403).send({ errorCode: "403" });
                }
            }
        });
    });

    /*
     * Loggin out an APP user  - Delogge un utilisateur
     * @params NONE
     * @return 200
     * @error NONE
     */

    app.post("/logout", function(req, res) {
        req.session.loggedIn = false;
        req.session = null;
        console.log("NOT LOGGED ANY MORE");
        res.sendStatus(200);
    });

    // -----------------------------------FIN AUTH USER-------------------------------------------
};