// ------------------------------------------------------
// server.js

// .......................................................
// requires
var fs = require('fs');
var express = require('express');
var myBusinessLogic = require('../businessLogic/businessLogic.js');

// .......................................................
// security options

/*
1. Generate a self-signed certificate-key pair
openssl req -newkey rsa:2048 -new -nodes -x509 -days 3650 -keyout key.pem -out certificate.pem

2. Import them to a keystore (some programs use a keystore)
keytool -importcert -file certificate.pem -keystore my.keystore
*/

var securityOptions = {
    key: fs.readFileSync('key.pem'),
    cert: fs.readFileSync('certificate.pem'),
    requestCert: true
};

// .......................................................
// create the secure server (HTTPS)

var app = express();
var secureServer = require('https').createServer(securityOptions, app);

// ------------------------------------------------------
// helper functions for auth

// .............................................
// true if req == GET /login

function isGETLogin (req) {
    if (req.path != "/login") { return false; }
    if ( req.method != "GET" ) { return false; }
    return true;
} // ()

// .............................................
// your auth policy  here:
// true if req does have permissions
// (you may check here permissions and roles
//  allowed to access the REST action depending
//  on the URI being accessed)

function reqHasPermission (req) {
    // decode req.accessToken, extract
    // supposed fields there: userId:roleId:expiryTime
    // and check them

    // for the moment we do a very rigorous check
    if (req.headers.accessToken != "you-are-welcome") {
        return false;
    }
    return true;
} // ()

// ------------------------------------------------------
// install a function to transparently perform the auth check
// of incoming request, BEFORE they are actually invoked

app.use (function(req, res, next) {
    if (! isGETLogin (req) ) {
        if (! reqHasPermission (req) ){
            res.writeHead(401);  // unauthorized
            res.end();
            return; // don't call next()
        }
    } else {
        console.log (" * is a login request ");
    }
    next(); // continue processing the request
});

// ------------------------------------------------------
// copy everything in the req body to req.body

app.use (function(req, res, next) {
    var data='';
    req.setEncoding('utf8');
    req.on('data', function(chunk) {
       data += chunk;
    });
    req.on('end', function() {
        req.body = data;
        next();
    });
});

// ------------------------------------------------------
// REST requests
// ------------------------------------------------------

// .......................................................
// authenticating method
// GET /login?user=xxx&password=yyy

app.get('/login', function(req, res){
    var user = req.query.user;
    var password = req.query.password;

    // rigorous auth check of user-passwrod
    if (user != "foobar" || password != "1234") {
        res.writeHead(403);  // forbidden
    } else {
        // OK: create an access token with fields user, role and expiry time, hash it
        // and put it on a response header field
        res.setHeader ('accessToken', "you-are-welcome");
        res.writeHead(200);
    }
    res.end();
});

// .......................................................
// "regular" methods (just an example)
// newBook()
// PUT /book

app.put('/book', function (req,res){
    var bookData = JSON.parse (req.body);

    myBusinessLogic.newBook(bookData, function (err) {
        if (err) {
            res.writeHead(409);
            res.end();
            return;
        }
        // no error:
        res.writeHead(200);
        res.end();
    });
});

// .......................................................
// "main()"

secureServer.listen (8081);

echo "----   first: do login "
curl -v "https://localhost:8081/login?user=foobar&password=1234" --cacert certificate.pem

# now, in a real case, you should copy the accessToken received before, in the following request

echo "----  new book"
curl -X POST  -d '{"id": "12341324", "author": "Herman Melville", "title": "Moby-Dick"}' "https://localhost:8081/book" --cacert certificate.pem --header "accessToken: you-are-welcome"

-require/import modules & files into the system (comment out db & router until those files are filled in)
        const db = require('../db/conf');
        const router = require('./router/whateverRouter');
        const express = require('express');
        const bodyParser = require('body-parser');
    -define port & ip
        const port = 3000;
        const ip = 'localhost';
    -create an instance of express server
        -const app = express();
    -list out what the app will use
        .use(express.static('whatever frontend client folder'))
        .use(bodyParser.json())
        .use(bodyParser.urlencoded({extended: true}))
        .use('/api', router)
    -listen for server
        app.listen(port, ip, () => {
        console.log("server started");
        });
    -test to see if server can start up ($ npm start)