API Firebase Express

index.js

'use strict';

const functions = require('firebase-functions');
const admin = require('firebase-admin');

const cors = require('cors')

console.log(process.env.NODE_ENV);

if (process.env.NODE_ENV === "production") {
    admin.initializeApp();
}
else {
    var serviceAccount = require("../../serviceaccount.json"); //ask this file to the project owner
    var firebaseApp = admin.initializeApp({
        credential: admin.credential.cert(serviceAccount),
        databaseURL: "https://PROJECTNAME.firebaseio.com/"
    });
}

// export GCLOUD_PROJECT=paradigma-dev-firebase

var db = admin.database();
const express = require('express');
const app = express();

const authenticate = async (req, res, next) => {
    if (!req.headers.authorization || !req.headers.authorization.startsWith('Bearer ')) {
        res.status(403).send('Unauthorized');
        return;
    }
    const idToken = req.headers.authorization.split('Bearer ')[1];
    try {
        const decodedIdToken = await admin.auth().verifyIdToken(idToken);
        // console.log(decodedIdToken);
        req.user = decodedIdToken;
        next();
        return;
    } catch (e) {
        res.status(403).send('Unauthorized');
        return;
    }
};

// domain restriction
// var whitelist = ["https://SITE.COM"];
// var corsOptions = { origin: (origin, callback) => (whitelist.indexOf(origin) !== -1 || !origin) ? callback(null, true) : callback(new Error('Not allowed by CORS')) }

// open for all domains
var corsOptions = { origin: false }

app.use(cors(corsOptions));
app.use(authenticate);

// var user = {
//     name: 'Thiago Souza',
//     picture: 'https://lh4.googleusercontent.com/-VdKZ1Kor6ek/AAAAAAAAAAI/XXXAAAXXX98/JZfhKFQ8hfI/photo.jpg',
//     premium: true,
//     iss: 'https://securetoken.google.com/PROJECT',
//     aud: 'PROJECT',
//     auth_time: 1558646048,
//     user_id: 'UID',
//     sub: 'UID',
//     iat: 1558646048,
//     exp: 1558649648,
//     email: 'EMAIL',
//     email_verified: true,
//     firebase: {
//         identities: { 'google.com': [Array], email: [Array] },
//         sign_in_provider: 'google.com'
//     },
//     uid: 'UID'
// }


// GET /api/post/{postId}
// Get details about a message
app.get('/post/:postId', async (req, res) => {

    console.log("logged user", req.user);

    const { postId } = req.params;
    const locale = req.query.locale || "pt-BR";

    try {
        var post = await firebaseGetData(`/flamelink/environments/production/content/posts/${locale}/${postId}`);
        if (!post) res.set('Cache-Control', 'private, max-age=300').status(404).json({ errorCode: 404, errorMessage: `post '${postId}' not found` });
    } catch (error) {
        console.log('Error getting post details', postId, error.message);
        return res.sendStatus(500);
    }

    return res.status(200).json(post);
});



app.get('/charts/', async (req, res) => {

    console.log("logged user", req.user);

    // const { postId } = req.params;
    const locale = req.query.locale || "pt-BR";

    try {
        var charts = await firebaseGetDataArray(`/flamelink/environments/production/content/charts/${locale}`);
        if (!charts) res.set('Cache-Control', 'private, max-age=300').status(404).json({ errorCode: 404, errorMessage: `charts not found` });
        return res.status(200).json(chartsResult);
    } catch (error) {
        console.log('Error getting post details', error.message);
        return res.sendStatus(500);
    }
});


// Expose the API as a function
exports.api = functions.https.onRequest(app);

async function firebaseGetData(path) {
    console.log("getData", path);
    try {
        let dataRef = await db.ref(path).limitToLast(50).once("value");
        console.log("dataRef.val()", dataRef.val());
        return (!dataRef.exists()) ? null : dataRef.val();
    } catch (error) {
        console.info(error)
        return null;
    }
}

async function firebaseGetDataArray(path) {
    console.log("getData", path);
    try {
        let dataRef = await db.ref(path).once("value");
        var data = [];
        dataRef.forEach(item => data.push(item.val()))
        return data;
    } catch (error) {
        console.info(error)
        return null;
    }

}

package.json

{
  "name": "functions",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "cors": "^2.8.5",
    "express": "^4.17.0",
    "firebase-admin": "^8.0.0",
    "firebase-functions": "^2.3.1"
  }
}