app.js

const express = require('express');
const jwt = require('jsonwebtoken');
const bodyParser = require('body-parser');
const cors = require('cors');

// Create an instance of Express
const app = express();

// port of server
const port = 3000;

// Use body-parser middleware to parse request bodies
app.use(bodyParser.json());

// for access control alow origin
app.use(cors());

// importing database and jwt functions
const { db } = require('./utility/database')
const { authenticateToken, secretKey } = require('./utility/tokenManager')

app.post('/login', (req, res) => {

    // Login route - generates and returns a token
    // [POST] http://localhost:3000/login
    // in body add username and password as JSON

    const { username, password } = req.body;

    // checks the validity of the user credential
    const sql = 'SELECT * FROM users WHERE username = ? AND password = ?';

    db.query(sql, [username, password], (err, results) => {

        if (err) {
            return res.status(500).json({ message: 'Database error.', error: err });
        }

        if (results.length === 0) {
            return res.status(401).json({ message: 'Invalid credentials.' });
        }

        // generate jwt token
        const user = { username: username, role: 'admin' };
        const token = jwt.sign(user, secretKey, { expiresIn: '1h' });
        res.json({ token: token });

    });
});

app.post('/signup', (req, res) => {

    // Signup route - registers a new user
    // [POST] http://localhost:3000/signup
    // in body add username and password as JSON

    const { username, password } = req.body;

    if (username.length === 0 || password.length === 0) {
        return res.status(400).json({ message: 'Invalid username or password' });
    }

    // Check if the username already exists in the database
    const checkUserSql = 'SELECT * FROM users WHERE username = ?';
    db.query(checkUserSql, [username], (err, results) => {
        if (err) {
            return res.status(500).json({ message: 'Database error.', error: err });
        }

        if (results.length > 0) {
            return res.status(400).json({ message: 'Username already exists.' });
        }

        // SQL query to insert a new user into the database
        const insertUserSql = 'INSERT INTO users (username, password) VALUES (?, ?)';
        db.query(insertUserSql, [username, password], (err, result) => {
            if (err) {
                return res.status(500).json({ message: 'Database error.', error: err });
            }

            const user = { username: username, role: 'admin' };

            const token = jwt.sign(user, secretKey, { expiresIn: '1h' });

            res.json({ message: "Account Created Successfully", token: token });
        });
    });
});


// unneccesary api route ~ for checking purposes no token needed ~ public
app.get('/users', (req, res) => {

    // SQL query to fetch all usernames from the database table
    // [GET] http://localhost:3000/users
    // Empty body

    const sql = 'SELECT username FROM users';
    db.query(sql, (err, results) => {
        if (err) {
            return res.status(500).json({ message: 'Database error.' });
        }

        res.json(results);
    });
});

app.post('/newList', authenticateToken, (req, res) => {
    const { id, name, username } = req.body;

    // SQL query to insert a new user into the database
    const sql = 'INSERT INTO notes VALUES (?, ?, ?)';
    db.query(sql, [id, name, username], (err, result) => {
        if (err) {
            return res.status(500).json({ message: 'Database error.', msg: err });
        }

        const successMsg = { message: "added list", listName: name };
        res.status(201).json(successMsg);
    });
});

app.post('/newListElement', authenticateToken, (req, res) => {
    const { id, nid, name, complete } = req.body;

    // SQL query to insert a new list title into the database
    const sql = 'INSERT INTO tasks VALUES (?, ?, ?, ?)';
    db.query(sql, [id, nid, name, complete], (err, result) => {
        if (err) {
            return res.status(500).json({ message: 'Database error.', msg: err });
        }

        const successMsg = { message: "added list item", listItemName: name };
        res.status(201).json(successMsg);
    });
});

app.post('/updateTaskElement', authenticateToken, (req, res) => {
    const { id, nid, name, complete } = req.body;

    // SQL query to update a task into the database
    const sql = 'UPDATE tasks SET name = ?, complete = ? WHERE id = ?';
    db.query(sql, [name, complete, id], (err, result) => {
        if (err) {
            return res.status(500).json({ message: 'Database error.', msg: err });
        }

        const successMsg = { message: "updated list item" + result, listItemName: name };
        res.status(201).json(successMsg);
    });
});

app.post('/deleteCompletedFromList', authenticateToken, (req, res) => {
    const { nid } = req.body;

    // SQL query to delete completed task elements from the database
    const sql = 'DELETE FROM tasks WHERE nid = ? AND complete = 1';
    db.query(sql, [nid], (err, result) => {
        if (err) {
            return res.status(500).json({ message: 'Database error.', msg: err });
        }

        const successMsg = { message: "deleted completed list item" + result, listId: nid };
        res.status(201).json(successMsg);
    });
});

app.post('/deleteList', authenticateToken, (req, res) => {
    const { id } = req.body;

    // SQL query to delete a list and its tasks 
    const sql = 'DELETE FROM tasks WHERE nid = ?;';
    const sql2 = 'DELETE FROM notes WHERE id = ?;';
    db.query(sql, [id], (err, result) => {
        if (err) {
            return res.status(500).json({ message: 'Database error.', msg: err });
        }
        db.query(sql2, [id], (err, result) => {
            if (err) {
                return res.status(500).json({ message: 'Database error.', msg: err });
            }
        })
        const successMsg = { message: "deleted the list" + result, listId: id };
        res.status(201).json(successMsg);
    });
});

// unneccesary api route ~ for checking purposes no token needed ~ public
app.get('/users/:id', (req, res) => {
    const id = parseInt(req.params.id);

    // SQL query to fetch a username with the specified ID
    const sql = 'SELECT username FROM users WHERE id = ?';
    db.query(sql, [id], (err, results) => {
        if (err) {
            return res.status(500).json({ message: 'Database error.' });
        }

        if (results.length === 0) {
            return res.status(404).json({ message: 'User not found.' });
        }

        res.json(results[0]);
    });
});

app.get('/lists/:id', authenticateToken, (req, res) => {
    const id = req.params.id;

    // first select all lists of the user
    const sql = 'SELECT * FROM notes WHERE username = ?';
    db.query(sql, [id], (err, results) => {
        if (err) {
            return res.status(500).json({ message: 'Database error.', id: id });
        }
        var notesArray = JSON.parse(JSON.stringify(results));

        // Create an array to hold all the promises
        const promiseArray = [];

        notesArray.forEach((element) => {
            // then get all the task of the specified list
            let sql2 = 'SELECT id, name, complete FROM tasks WHERE nid = ?';

            // Create a promise for each query
            const promise = new Promise((resolve, reject) => {
                db.query(sql2, [element.id], (err, results) => {
                    if (err) {
                        reject(err);
                    } else {
                        const tmp = JSON.parse(JSON.stringify(results));
                        element.tasks = tmp;
                        resolve();
                    }
                });
            });

            promiseArray.push(promise);
        });

        // Wait for all the promises to resolve
        Promise.all(promiseArray)
            .then(() => {
                res.json(notesArray);
            })
            .catch((error) => {
                return res.status(500).json({ message: 'Database error.', error: error });
            });
    });
});

// Start the server
app.listen(port, () => {
    console.log(`Server started on port ${port}`);
});