signup.php

<?php
// Database connection details
$host = 'localhost';
$db = 'coursehub'; // Replace with your database name
$user = 'root'; // Replace with your database username
$pass = ''; // Replace with your database password

// Create a connection
$conn = new mysqli($host, $user, $pass, $db);

// Check connection
if ($conn->connect_error) {
    die('Connection failed: ' . $conn->connect_error);
}

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    // Retrieve and sanitize form inputs
    $username = htmlspecialchars(trim($_POST['username']));
    $email = htmlspecialchars(trim($_POST['email']));
    $password = htmlspecialchars(trim($_POST['password']));
    $confirm_password = htmlspecialchars(trim($_POST['confirm_password']));

    // Validate form inputs
    if (empty($username) || empty($email) || empty($password) || empty($confirm_password)) {
        die('All fields are required.');
    }

    if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        die('Invalid email address.');
    }

    if ($password !== $confirm_password) {
        die('Passwords do not match.');
    }

    // Hash the password for security
    $hashed_password = password_hash($password, PASSWORD_DEFAULT);

    // Check if the username or email already exists
    $stmt = $conn->prepare('SELECT * FROM users WHERE username = ? OR email = ?');
    $stmt->bind_param('ss', $username, $email);
    $stmt->execute();
    $result = $stmt->get_result();

    if ($result->num_rows > 0) {
        die('Username or email is already taken.');
    }

    $stmt->close();

    // Insert the new user into the database
    $stmt = $conn->prepare('INSERT INTO users (username, email, password) VALUES (?, ?, ?)');
    $stmt->bind_param('sss', $username, $email, $hashed_password);

    if ($stmt->execute()) {
        header('Location: login.html');
        exit();
    } else {
        echo 'Error: ' . $stmt->error;
    }

    $stmt->close();
}

$conn->close();
?>