send_otp.php

<?php
session_start();

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;

require 'PHPmailer/src/Exception.php';
require 'PHPmailer/src/PHPMailer.php';
require 'PHPmailer/src/SMTP.php';

// Validate and sanitize email input
if ($_SERVER["REQUEST_METHOD"] === "POST" && isset($_POST['email'])) {
    $email = filter_var($_POST['email'], FILTER_SANITIZE_EMAIL);

    // Check if email is valid
    if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
        $conn = require __DIR__ . "/db_connection.php";

        // Check if email already exists in database
        $stmt = $conn->prepare("SELECT * FROM users WHERE email = ?");
        $stmt->bind_param("s", $email);
        $stmt->execute();
        $result = $stmt->get_result();
        $stmt->close();

        if ($result->num_rows === 0) { // Email does not exist, proceed with sending OTP
            // Generate random OTP
            $otp = rand(100000, 999999);
            $_SESSION['otp'] = $otp;
            $_SESSION['email'] = $email;

            // Send OTP via email using PHPMailer
            try {
                $mail = new PHPMailer(true);
                
                //Server settings
                $mail->SMTPDebug = 0;                                        // Enable verbose debug output
                $mail->isSMTP();                                             // Set mailer to use SMTP
                $mail->Host       = 'smtp.gmail.com';                        // Specify main and backup SMTP servers
                $mail->SMTPAuth   = true;                                    // Enable SMTP authentication
                $mail->Username   = 'chanjiajun321@gmail.com';               // SMTP username
                $mail->Password   = 'ivdg inba cphd pmlp';                   // SMTP password
                $mail->SMTPSecure = 'tls';                                   // Enable TLS encryption, `ssl` also accepted
                $mail->Port       = 587;                                     // TCP port to connect to

                // Recipients
                $mail->setFrom('chanjiajun321@gmail.com', 'IKUN MUSIC');
                $mail->addAddress($email);

                // Content
                $mail->isHTML(true);
                $mail->Subject = 'Your OTP for IKUN MUSIC';
                $mail->Body =   'Dear Mr/Ms,
                                <br>
                                <br>
                                Your OTP Code is: <b>'. $otp. '</b>
                                <br>
                                <br>
                                Thank you for choosing Ikun Music. 
                                <br>
                                <br>
                                This OTP is valid for a limited time only. Please enter it on our website to complete your registration.
                                <br>
                                <br>
                                <img src= "cid:ikunmusicgif">
                                <br>
                                <br>
                                Cheers,
                                <br>
                                <br>
                                The Ikun Music Team';

                $mail->AddEmbeddedImage('assets/gif/jinitaimei.gif', 'ikunmusicgif', 'ikunmusicgif.gif');             

                $mail->send();
                echo json_encode(['status' => 'success', 'message' => 'OTP sent successfully to ' . $email]);

            } catch (Exception $e) {
                echo json_encode(['status' => 'error', 'message' => 'OTP could not be sent. Mailer Error: ' . $mail->ErrorInfo]);
            }
        } else {
            echo json_encode(['status' => 'error', 'message' => 'Email already exists']);
        }
    } else {
        echo json_encode(['status' => 'error', 'message' => 'Invalid email']);
    }
} else {
    echo json_encode(['status' => 'error', 'message' => 'Invalid request']);
}
?>