app.js

const express = require('express');
const cors = require('cors');
const path = require('path');
const pool = require('./db');
const http = require('http');
const { WebSocketServer } = require('ws');
require('dotenv').config();


const app = express();
const server = http.createServer(app);
const wss = new WebSocketServer({ server });

const port = process.env.BACKEND_PORT || 3000;

app.use(cors({
    origin: "*",
    methods: ["GET", "POST", "DELETE"],
    allowedHeaders: ["Content-Type"]
}));
app.use(express.json());

// Used for testing local HTML files. Likely remove before publishing.
app.use(express.static(path.join(__dirname)));
//app.use(express.static(path.join(__dirname, "testSites")));

/*
broadcasts message for websocket.
*/
function broadcast(data){
    const message = JSON.stringify(data);
    wss.clients.forEach(client => {
        if(client.readyState === client.OPEN){
            client.send(message);
        }
    });
}
wss.on('connection', (ws) => {
    console.log("WebSocket client connection.");
    ws.on('close', () => console.log('WebSocket client disconnected.'))
});

/*
Base test routes.
*/
app.get('/', (req, res) => {
    res.send("Hello world! My first NodeJS Express app.")
});
app.get('/status', (req, res) => {
    const output = {
        message: "testing",
        ok: true
    };
    
    res.json(output);
});

/*
Gets all comments for the specified page_url.
*/
app.get('/comments', async (req, res) => {
    try{
        const { page_url } = req.query;

        const result = await pool.query(
            `SELECT * FROM comments WHERE page_url = $1`,
            [page_url]
        );

        res.json(result.rows);
    } catch (err) {
        console.error("GET /comments:", err);
        res.status(500).send("Server error");
    }
});

/*
Saves comment box info to database.
*/
app.post('/comments', async (req, res) => {
    try{
        const { 
            page_url,
            dom_path,
            selected_text,
            comment_text,
            pos_x,
            pos_y,
            author_id
        } = req.body;

        const result = await pool.query(
            `INSERT INTO comments
            (page_url, dom_path, selected_text, comment_text, pos_x, pos_y, author_id)
            VALUES ($1,$2,$3,$4,$5,$6,$7)
            RETURNING *`,
            [page_url, dom_path, selected_text, comment_text, pos_x, pos_y, author_id]
        );

        const row = result.rows[0];
        broadcast({ type: 'comment_created', comment: row});

        res.json(row);
    } catch (err) {
        console.error("POST /comments:", err);
        res.status(500).send("Server error");
    }
});

/*
Updates comment box info in database.
*/
app.post("/comments/:id", async (req, res) => {
    try{
        const {
            comment_text,
            pos_x,
            pos_y
        } = req.body;

        const result = await pool.query(
            `UPDATE comments
            SET comment_text=$2, pos_x=$3, pos_y=$4
            WHERE id=$1
            RETURNING *`,
            [req.params.id, comment_text, pos_x, pos_y]
        );

        const row = result.rows[0];
        broadcast({ type: 'comment_updated', comment: row});

        res.json(row);
    } catch (err) {
        console.error("POST /comments/:id", err);
        res.status(500).send("Server error");
    }
});

/*
Deletes comment box from database. 
*/
app.delete("/comments/:id", async (req, res) => {
    try{
        const result = await pool.query(
            `DELETE FROM comments WHERE id=$1
            RETURNING *`,
            [req.params.id]
        )
        if (result.rowCount === 0){
            return res.status(404).send("Not found");
        }
        
        const row = result.rows[0];
        broadcast({ type: "comment_deleted", comment: row });

        res.send("Deleted");
    } catch (err){
        console.error("DELETE /comments/:id", err);
        res.status(500).send("Server error");
    }
});

/*
Initializes 'comments' table in database if does not already exist.
*/
async function initDB() {
    await pool.query(`
        CREATE TABLE IF NOT exists comments (
            id INTEGER PRIMARY KEY GENERATED ALWAYS AS IDENTITY,
            page_url TEXT NOT NULL,
            dom_path TEXT,
            selected_text TEXT,
            comment_text TEXT NOT NULL,
            pos_x INTEGER,
            pos_y INTEGER,
            author_id TEXT,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
        ) 
    `);
}

initDB()
    .then(() => {
        // Starts the server
        server.listen(port, () => console.log(`Server is running on port ${port}`));
    })
    .catch(err => {
        console.error("Failed to connect to database:", err.message);
        process.exit(1);
    });