const express = require("express");
const app = express();

app.get("/", (req, res) => {
  res.send("Welcome to Express Routing");
});

app.get("/user/:id", (req, res) => {
  res.send("User ID: " + req.params.id);
});

app.get("/search", (req, res) => {
  res.send("Searching for: " + req.query.keyword);
});

app.get("/student/:name/:course", (req, res) => {
  res.send("Student: " + req.params.name +
           ", Course: " + req.params.course);
});

app.listen(3000);
1(2)
const express = require("express");
const app = express();

app.use(express.urlencoded({ extended: true }));
let students = [];

app.get("/", (req, res) => {
  res.send(`
    <form method="POST" action="/add">
      ID: <input name="id"><br>
      Name: <input name="name"><br>
      <button>Add Student</button>
    </form>
    <a href="/students">View Students</a>
    <p>To delete, open /delete/101</p>
  `);
});

app.post("/add", (req, res) => {
  students.push(req.body);
  res.send("Student added successfully");
});

app.get("/students", (req, res) => {
  res.json(students);
});

app.get("/delete/:id", (req, res) => {
  students = students.filter(s => s.id != req.params.id);
  res.send("Student deleted successfully");
});

app.listen(3000);
1(3)
const express = require("express");
const app = express();

app.use((req, res, next) => {
  console.log("Middleware executed!");
  next();
});

app.get("/", (req, res) => {
  res.send("Welcome! Middleware has already run.");
});

app.listen(3000);
2(1)
const express = require("express");
const app = express();

app.set("view engine", "ejs");

app.get("/", (req, res) => {
  res.render("index", {
    title: "vignan",
    message: "Hello students from vignan college!"
  });
});

app.listen(3000);
2(1.1)
<html>
<head>
  <title><%= title %></title>
</head>
<body>
  <h1><%= message %></h1>
</body>
</html>
2(2)
const express = require("express");
const app = express();

app.use(express.urlencoded({ extended: true }));

app.get("/", (req, res) => {
  res.send(`
    <form action="/submit" method="POST">
      Name: <input name="name"><br>
      Email: <input name="email"><br>
      <button>Submit</button>
    </form>
  `);
});

app.post("/submit", (req, res) => {
  res.send("Received: Name = " + req.body.name +
           ", Email = " + req.body.email);
});

app.listen(3000);
3(1)
const express = require("express");
const session = require("express-session");
const app = express();

app.use(session({
  secret: "secretkey",
  resave: false,
  saveUninitialized: true
}));

app.get("/", (req, res) => {
  req.session.visits = (req.session.visits || 0) + 1;
  res.send("You visited this page " +
           req.session.visits + " times");
});

app.listen(3000);
3(2)
const express = require("express");
const session = require("express-session");
const app = express();

app.use(express.urlencoded({ extended: true }));
app.use(session({
  secret: "secret",
  resave: false,
  saveUninitialized: true
}));

app.get("/login", (req, res) => {
  res.send(`
    <form method="POST" action="/login">
      Username: <input name="username"><br>
      Password: <input name="password" type="password"><br>
      <button>Login</button>
    </form>
  `);
});

app.post("/login", (req, res) => {
  if (req.body.username == "admin" &&
      req.body.password == "1234") {
    req.session.user = "admin";
    res.send("Login successful! <a href='/dashboard'>Dashboard</a>");
  } else {
    res.send("Invalid login!");
  }
});

app.get("/dashboard", (req, res) => {
  if (req.session.user)
    res.send("Welcome, admin! <a href='/logout'>Logout</a>");
  else
    res.send("Please login first.");
});

app.get("/logout", (req, res) => {
  req.session.destroy(() => res.send("Logged out successfully."));
});

app.listen(3000);