server.js

const express = require('express');
const session = require('express-session');
const mysql = require("mysql2/promise");
const bcrypt = require('bcryptjs');

const app = express();
const saltRounds = 10;

app.use(express.static(__dirname + '/src/assets'));
app.set('view engine', 'ejs');
app.set('views', __dirname + '/src/views');
app.use(express.json());
app.use(express.urlencoded({ extended: false }));

app.use(session({
    secret: process.env.SESSION_SECRET || 'a-strong-default-secret-for-development',
    resave: false,
    saveUninitialized: true,
    cookie: { secure: false }
}));

const pool = mysql.createPool({
    host: process.env.DB_HOST,
    user: process.env.DB_USER,
    password: process.env.DB_PASSWORD,
    database: process.env.DB_DATABASE,
    waitForConnections: true,
    connectionLimit: 10,
    queueLimit: 0
});

function requireLogin(req, res, next) {
    if (req.session && req.session.user) {
        return next();
    } else {
        return res.redirect('/');
    }
}

async function getProfileData(userEmail) {
    let sql = "SELECT * FROM people WHERE email=(?)";
    const [[userDATA]] = await pool.query(sql, [userEmail]);

    sql = "SELECT paper_id FROM coauthors WHERE coauthor=(?)";
    const [paperRows] = await pool.query(sql, [userEmail]);
    const paperIds = paperRows.map(p => p.paper_id);

    let papers = [];
    let coauthors = [];

    if (paperIds.length > 0) {
        sql = "SELECT project_id, title, description, project_lead, citations, YEAR(year) as year FROM projects WHERE project_id IN (?)";
        [papers] = await pool.query(sql, [paperIds]);

        sql = "SELECT * FROM coauthors WHERE paper_id IN (?)";
        [coauthors] = await pool.query(sql, [paperIds]);
    }

    return { userDATA, papers, coauthors };
}

app.get("/", (req, res) => res.sendFile(__dirname + "/src/views/homepage.html"));
app.get("/homepage.html", (req, res) => res.sendFile(__dirname + "/src/views/homepage.html"));
app.get("/feedback.html", (req, res) => res.sendFile(__dirname + "/src/views/feedback.html"));
app.get("/signup.html", (req, res) => res.sendFile(__dirname + "/src/views/signup.html"));
app.get("/registration.html", (req, res) => res.sendFile(__dirname + "/src/views/registration.html"));

app.get("/conferences.ejs", async (req, res) => {
    try {
        const sql = "SELECT id, date, platform, title FROM conferences ORDER BY date DESC";
        const [conferences] = await pool.query(sql);
        res.render("conferences", { conferences });
    } catch (err) {
        console.error("Error fetching conferences:", err);
        res.status(500).send("Error loading conference data.");
    }
});

app.get("/projects.ejs", async (req, res) => {
    try {
        const sql = "SELECT project_id, title, description, project_lead, citations, domain, YEAR(year) as year FROM projects";
        const [projects] = await pool.query(sql);
        res.render("projects", { projects });
    } catch (err) {
        console.error("Error fetching projects:", err);
        res.status(500).send("Error loading project data.");
    }
});

app.get("/people.ejs", async (req, res) => {
    try {
        const sql = "SELECT * FROM people";
        const [users] = await pool.query(sql);
        res.render('people', { users });
    } catch (err) {
        console.error("Error fetching people:", err);
        res.status(500).send("Error loading people data.");
    }
});

app.post("/login", async (req, res) => {
    const { roles: role, username, password } = req.body;
    try {
        const sql = "SELECT * FROM login WHERE username=(?)";
        const [[login_info]] = await pool.query(sql, [username]);

        if (!login_info) {
            return res.status(401).send("Incorrect Credentials");
        }

        const role_in_db = login_info.type;
        const hashedPassword = login_info.password;

        const match = await bcrypt.compare(password, hashedPassword);

        if (role_in_db === role && match) {
            req.session.user = username;
            req.session.role = role_in_db;
            req.session.loginTime = new Date().toLocaleString();

            const roleRedirects = {
                admin: "/admin.ejs",
                faculty: "/profileFaculty",
                mtech: "/profileMTECH",
                btech: "/profileBTECH",
                phd: "/profilePHD"
            };
            res.redirect(roleRedirects[role] || '/');
        } else {
            res.status(401).send("Incorrect Credentials");
        }
    } catch (err) {
        console.error("Login Error:", err);
        res.status(500).send("An error occurred during login.");
    }
});

app.post("/signup", async (req, res) => {
    const { name, email, department, domain, password, type } = req.body;
    const con = await pool.getConnection();

    try {
        await con.beginTransaction();

        const hashedPassword = await bcrypt.hash(password, saltRounds);

        const sql1 = "INSERT INTO people(name,email,department,type,domain) values(?,?,?,?,?)";
        await con.query(sql1, [name, email, department, type, domain]);

        const sql2 = "INSERT INTO login(username,password,type) values(?,?,?)";
        await con.query(sql2, [email, hashedPassword, type]);

        await con.commit();
        res.redirect("/");

    } catch (err) {
        await con.rollback();
        console.error("Signup Error:", err);
        res.status(500).send("Error creating user. The email might already be registered.");
    } finally {
        if (con) con.release();
    }
});

app.get("/profileFaculty", requireLogin, async (req, res) => {
    try {
        const data = await getProfileData(req.session.user);
        res.render('profileFaculty', data);
    } catch (err) {
        console.error(err);
        res.status(500).send("Error loading profile.");
    }
});

app.get("/profilePHD", requireLogin, async (req, res) => {
    try {
        const data = await getProfileData(req.session.user);
        res.render('profilePHD', data);
    } catch (err) {
        console.error(err);
        res.status(500).send("Error loading profile.");
    }
});

app.get("/profileBTECH", requireLogin, async (req, res) => {
    try {
        const data = await getProfileData(req.session.user);
        res.render('profileBTECH', data);
    } catch (err) {
        console.error(err);
        res.status(500).send("Error loading profile.");
    }
});

app.get("/profileMTECH", requireLogin, async (req, res) => {
    try {
        const data = await getProfileData(req.session.user);
        res.render('profileMTECH', data);
    } catch (err) {
        console.error(err);
        res.status(500).send("Error loading profile.");
    }
});

app.get("/admin.ejs", requireLogin, async (req, res) => {
    if (req.session.role !== 'admin') {
        return res.status(403).send("Access Forbidden");
    }

    try {
        const [
            [[user]],
            [all_feedback],
            [[{ people_count }]],
            [[{ projects_count }]],
            [[{ conference_count }]]
        ] = await Promise.all([
            pool.query("SELECT * FROM people WHERE email=(?)", [req.session.user]),
            pool.query("SELECT * FROM feedback ORDER BY id DESC"),
            pool.query("SELECT count(*) as people_count FROM people"),
            pool.query("SELECT count(*) as projects_count FROM projects"),
            pool.query("SELECT count(*) as conference_count FROM conferences")
        ]);

        const counts = { people: people_count, projects: projects_count, conference: conference_count };
        res.render('admin', { userDATA: user, all_feedback, counts });
    } catch (err) {
        console.error("Admin dashboard error:", err);
        res.status(500).send("Error loading admin dashboard.");
    }
});

app.post("/feedback", async (req, res) => {
    const { name, email, feedback } = req.body;
    try {
        const sql = "INSERT INTO feedback(name, email, feedback) VALUES(?,?,?)";
        await pool.query(sql, [name, email, feedback]);
        res.redirect("/");
    } catch (err) {
        console.error("Feedback submission error:", err);
        res.status(500).send("Failed to submit feedback.");
    }
});

app.get('/logout', (req, res) => {
  req.session.destroy(err => {
    if (err) {
      return res.redirect('/admin.ejs'); // Or some error page
    }
    res.clearCookie('connect.sid'); // The default session cookie name
    res.redirect('/');
  });
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
    console.log(`Server started on port ${PORT}`);
});