verify_email.php

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Email Verification</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
</head>
<body>
    <div class="container mt-5">
        <div class="row justify-content-center">
            <div class="col-md-6">
                <div class="card">
                    <div class="card-header">
                        <h3 class="text-center">Email Verification</h3>
                    </div>
                    <div class="card-body">
                        <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="POST">
                            <div class="form-group">
                                <label for="email">Enter your email address:</label>
                                <input type="email" id="email" name="email" class="form-control" required>
                            </div>
                            <button type="submit" class="btn btn-primary btn-block">Verify Email</button>
                        </form>
                    </div>
                </div>
            </div>
        </div>
    </div>
</body>
</html>

<?php
session_start();
require_once 'config.php';

// Check if the form is submitted
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    // Validate email input
    if (isset($_POST['email'])) {
        $email = $_POST['email'];
        
        // Check if the email exists in the users table
        $stmt = $conn->prepare("SELECT id FROM users WHERE email = ?");
        if ($stmt) {
            $stmt->bind_param("s", $email);
            $stmt->execute();
            $stmt->store_result();
            
            if ($stmt->num_rows > 0) {
                $_SESSION['email_verified'] = true;
                header("Location: start_test.php?course_id=" . $_SESSION['course_id']);
                exit();
            } else {
                echo '<div class="alert alert-danger mt-3">Email not found. Please try again.</div>';
            }
            
            $stmt->close();
        } else {
            echo '<div class="alert alert-danger mt-3">Database error: ' . $conn->error . '</div>';
        }
    }
}
?>