_3layer_good.js

//////////////////////////////////////////////////////////////////////
// surface: handling http requests for login
// "app" is an express application
// "authenticationService" is a service that knows how to authenticate users

app.use(loggingMiddleware);
app.use(handleUnknownErrorsMiddleware);
app.post('/api/login', reqLogin);

function loggingMiddleware(req, res, next) {
    res.on('finish', () => {
        console.log(`INFO: Method ${req.method} called at URL ${req.originalUrl} - Status: ${res.statusCode}`);
    });
    next();
}

function handleUnknownErrorsMiddleware(err, req, res, next){
    console.error(`ERROR: An error occurred on method ${req.method} at URL ${req.originalUrl} - Error: ${err.message}`);
    res.status(500).send('Server error occurred');
}

async function reqLogin(req, res){
    const { login, password } = req.body;
    if (!login || !password) {
        return res.status(400).json({ error: 'Login and password are required' });
    }
    const result = await authenticationService.authenticate(login, password);
    if (result.success) {
        res.status(200).json({ message: 'Authentication successful', token: result.token });
    } else {
        res.status(401).json({ error: 'Authentication failed' });
    }
}





//////////////////////////////////////////////////////////////////////
// authenticationService

const {userDao, filters} = require('./adapters/databaseAdapter');
const {userByToken} = require('./adapters/cacheAdapter')
const {isEqual} = filters
const {hash, randomToken} = require('some-crypto-thing')

async function authenticate(login, password) {
    const user = await userDao.findWhere([isEqual("login", login), isEqual("password", hash(password))]);
    if (user) {
        const token = randomToken()
        await userByToken.set(token, user)
        return { success: true, token: token }; // Exemplo de token
    } else {
        return { success: false };
    }
}

async function getUserByToken(token) {
    // exercise. think about it.
}

module.exports = {
    authenticate,
    getUserByToken
};



//////////////////////////////////////////////////////////////////////
// databaseAdapter.
// in this case, persisting things to firebase

const admin = require('firebase-admin');
const db = admin.firestore();

class BaseDao {
    constructor(collectionName) {
        this.collection = db.collection(collectionName);
    }

    async findWhere(conditions) {
        let query = this.collection;
        for (const condition of conditions) {
            query = query.where(condition.field, condition.operator, condition.value);
        }
        const snapshot = await query.get();
        if (snapshot.empty) {
            return null;
        }
        let results = [];
        snapshot.forEach(doc => results.push({ id: doc.id, ...doc.data() }));
        return results.length === 1 ? results[0] : results;
    }
}

const filters = {
    isEqual(field, value){
        return {field, operator: '==', value}
    }
}

module.exports = {
    userDao: new BaseDao("users"),
    filters: filters
};