const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test');
const db = mongoose.connection;

db.once('err', () => {
    console.log(err);
});

db.once('open', () => {
    console.log('DB connected');
});

const UserSchema = mongoose.Schema({
    user_id: String,
    password: String
});

const User = mongoose.model('user', UserSchema);
const app = require('express')();
const session = require('express-session');
const MongoStore = require('connect-mongo')(session);
const bodyParser = require('body-parser');
const url = require('url');

app.set('view engine', 'ejs');
app.set('views', 'views');
app.use(bodyParser.urlencoded({ extended: false }));
app.use(session({
    secret: 'keyboard cat',
    resave: false,
    saveUninitialized: true,
    store: new MongoStore({
        url: "mongodb://localhost/test",
        collection: "sessions"
    })
}));


app.get('/', (req, res) => {
    if(req.session.logined) {
        res.render('logout', { id: req.session.user_id });
    } else {
        res.render('login');
    }
});

app.get('/register', (req, res) => {
    res.render('register');
});

app.post('/register', (req, res) => {
    let uid = req.body.user_id;
    let upwd = req.body.password;
    duplicate(req, res, uid, upwd);
});

app.post('/', (req, res) => {
    let uid = req.body.user_id;
    let upwd = req.body.password;
    duplicate(req, res, uid, upwd);
});

app.post('/logout', (req, res) => {
    req.session.destroy();
    res.redirect('/');
});

app.listen(3000, () => {
    console.log('listening 3000port');
});

function duplicate(req, res, uid, upwd) {
    let parseUrl = url.parse(req.url);
    let resource = parseUrl.pathname;
    if(resource == '/register') {
        User.findOne({ "user_id": uid }, (err, user) => {
            if(err) return res.json(err);

            if(user) {
                console.log('user id duplicate');
                res.send(`
                    <a href="/">Back</a>
                    <h1>User id duplicate</h1>
                `);
            } else {
                User.create({ "user_id": uid, "password": upwd }, (err) => {
                    if(err) return res.json(err);
                    console.log('Success');
                    res.redirect('/');
                })
            }
        })
    } else {
        User.findOne({ "user_id": uid }, (err, user) => {
            if(err) return res.json(err);

            if(user) {
                User.findOne({ "password": upwd })
                    .exec((err, user) => {
                    if(err) return res.json(err);

                    if(!user) {
                        console.log('different password');
                        res.send(`
                        <a href="/">Back</a>
                        <h1>Cannot find user</h1>
                    `);
                    } else {
                        console.log('Welcome');
                        req.session.user_id = uid;
                        req.session.logined = true;
                        res.redirect('/');
                    }
                })
            } else {
                console.log('Cannot find user');
                res.send(`
                    <a href="/">Back</a>
                    <h1>Cannot find user</h1>
                `);
            }
        })
    }
}