//npm init
//npm install nodemon, mysql2, express, cors


const express = require('express');
const mysql = require('mysql2/promise');
const cors = require('cors');

const app = express();

app.use(cors());
app.use(express.json());

const dbPool = mysql.createPool({
    host: 'localhost',     
    user: 'root',         
    password:  '',
    database: 'database_name', 
    port: 3306,         
});


app.get('/', (req, res) => {
  res.send('Backend running');
});



// -------------- CRUD --------------

// CREATE
app.post('/api/users', async (req, res) => {
    try {
        const { name, email } = req.body;

        if (!name || !email) {
            return res.status(400).json({ error: 'Error for the frontend (name or email missing)' });
        }

        const sql = "INSERT INTO users (name, email) VALUES (?, ?)";
        const [result] = await dbPool.query(sql, [name, email]);
        res.status(201).json({ message: "Response for the frontend", id: result.insertId });
    } catch (error) {
        console.error("Error for the backend ", error);
        res.status(500).json({ error: 'Error for the frontend' });
    }
});

// READ 
app.get('/api/users', async (req, res) => {
    try {
        const sql = "SELECT id, name, email FROM users";
        const [result] = await dbPool.query(sqlQuery);
        res.json(result);
    } catch (error) {
        console.error("Error for the backend ", error);
        res.status(500).json({ error: 'Error for the frontend' });
    }
});


// UPDATE
app.patch('/api/users/:id', async (req, res) => {
    try {
        const { id } = req.params;
        const { name, email } = req.body;

        if (!name || !email) {
             return res.status(400).json({ error: 'Error for the frontend (name or email missing)' });
        }

        const sql = "UPDATE users SET name = ?, email = ? WHERE id = ?";
        const [result] = await dbPool.query(sql, [name, email, id]);

         res.status(201).json({ message: "Response for the frontend", id: result.insertId });
    } catch (error) {
        console.error("Error for the backend ", error);
        res.status(500).json({ error: 'Error for the frontend' });
    }
});

// DELETE 
app.delete('/api/users/:id', async (req, res) => {
    try {
        const { id } = req.params;
        const sql = "DELETE FROM users WHERE id = ?";
        const [result] = await dbPool.query(sql, [id]);

       res.status(201).json({ message: "Response for the frontend", id: result.insertId });
    } catch (error) {
        console.error("Error for the backend ", error);
        res.status(500).json({ error: 'Error for the frontend' });
    }
});

const PORT = 3001;

app.listen(PORT, () => {
  console.log('Server is running on: http://localhost:'+PORT);
});