Form Submission with Validation and Email Delivery through SMTP

form.html

<section class="contactForm">
    <form method="post" action="process">
        <div class="row">
            <div class="col-6">
                <input type="text" name="demo-name" id="demo-name" value="" placeholder="Name">
            </div>
            <div class="col-6">
                <input type="email" name="demo-email" id="demo-email" value="" placeholder="Email">
            </div>
            <div class="col-12">
                <div class="textarea-wrapper">
                    <textarea name="demo-message" id="demo-message" placeholder="Message" rows="1"></textarea>
                </div>
            </div>
            <div class="col-12">
                <ul class="actions">
                    <li><input type="submit" value="Ok" class="primary js-submit-form"></li>
                    <li><input type="reset" value="Reset" class="primary js-reset-form"></li>
                    <li><span class="process_response"></span></li>
                </ul>
            </div>
        </div>
    </form>
</section>

Mailer.php

<?php

namespace App;

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;

class Mailer
{
    private $client;
    private $name;
    private $email;
    private $subject;
    private $content;
    private $loginUser = 'loginUser@myDomain.com';
    private $loginPassword = 'myPassword';
    private $SMTPServer = 'myMailServer.com';
    private $sentTo = 'info@myDomain.com';

    public function __construct($name, $email, $subject, $content)
    {
        $this->client = new PHPMailer();
        $this->name = $name;
        $this->email = $email;
        $this->subject = $subject;
        $this->content = $content;
    }

    public function setup()
    {
        //Tell PHPMailer to use SMTP
        $this->client->isSMTP();

        //Enable SMTP debugging
        //SMTP::DEBUG_OFF = off (for production use)
        //SMTP::DEBUG_CLIENT = client messages
        //SMTP::DEBUG_SERVER = client and server messages
        $this->client->SMTPDebug = env('APP_DEBUG') ? SMTP::DEBUG_SERVER : SMTP::DEBUG_OFF;

        //Set the hostname of the mail server
        $this->client->Host = $this->SMTPServer;

        //Set the SMTP port number:
        // - 465 for SMTP with implicit TLS, a.k.a. RFC8314 SMTPS or
        // - 587 for SMTP+STARTTLS
        $this->client->Port = 587;

        //Set the encryption mechanism to use:
        // - SMTPS (implicit TLS on port 465) or
        // - STARTTLS (explicit TLS on port 587)
        $this->client->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;

        //Whether to use SMTP authentication
        $this->client->SMTPAuth = true;

        //Username to use for SMTP authentication - use full email address for gmail
        $this->client->Username = $this->loginUser;

        //Password to use for SMTP authentication
        $this->client->Password = $this->loginPassword;

        //Set who the message is to be sent from
        //Note that with gmail you can only use your account address (same as `Username`)
        //or predefined aliases that you have configured within your account.
        //Do not use user-submitted addresses in here
        $this->client->setFrom($this->email, 'Sent from myDomain.com');

        //Set an alternative reply-to address
        //This is a good place to put user-submitted addresses
        $this->client->addReplyTo($this->email, $this->name);

        //Set who the message is to be sent to
        $this->client->addAddress($this->sentTo, 'myDomain.com');

        //Set the subject line
        $this->client->Subject = $this->subject;

        $this->client->Body = <<<EOT
        Email: {$this->email}
        <br>Name: {$this->name}
        <br>Message: {$this->content}
        EOT;

        //Replace the plain text body with one created manually
        $this->client->AltBody = $this->content;
    }

    public function send()
    {
        if (!$this->client->send()) {
            // echo 'Mailer Error: ' . $this->client->ErrorInfo;
            return false;
        }
        return true;
    }
}

process.php

<?php

namespace App;

class Process
{
    public function contactezNous()
    {
        $params['demo-name'] = $this->protectHtml($this->request['demo-name']);
        $params['demo-email'] = $this->protectHtml($this->request['demo-email']);
        $params['demo-message'] = $this->protectHtml($this->request['demo-message']);

        $params['subject'] = 'Contactez Nous Request';
        $params['description'] = <<<DESCRIPTION
            {$params['demo-message']}
            DESCRIPTION;

        // if given data is not empty
        if (
            empty($params["demo-name"]) ||
            empty($params["demo-email"]) ||
            empty($params["demo-message"])
        ) {
            $response = new Response('error', null, "Invalid input request");
            return false;
        }

        // validate fields length
        if (
            strlen($params['demo-name']) > 50 ||
            strlen($params['demo-email']) > 200
        ) {
            $response = new Response('error', null, "Invalid input request.");
            return false;
        }

        // validate demo-email
        if (filter_var($params['demo-email'], FILTER_VALIDATE_EMAIL) === false) {
            $response = new Response('error', null, "Invalid email address.");
            return false;
        }

        return $this->process($params);
    }

    public function process($params)
    {
        $name = $params['demo-name'];
        $email = $params["demo-email"];
        $subject = $params["subject"];
        $content = $params["description"];

        // send email
        $mailer = new Mailer($name, $email, $subject, $content);
        $mailer->setup();
        if (!$mailer->send()) {
            $response = new Response('error', null, "Message could not be delivered.");
            return false;
        }

        // if message was sent successfully
        $response = new Response('success', null, "Thank you for your message.");
        return false;

    }

    public function protectHtml($var)
    {
        if(empty($var)){
            return '';
        }

        return htmlspecialchars(trim($var), ENT_QUOTES, "UTF-8");
    }
}

validation.js

<script>
    $( document ).ready(function() {
      $(document).on('click', '.contactForm .js-reset-form', function(e){
        $('.js-submit-form').prop('disabled', false);
      });
      $(document).on('click', '.contactForm .js-submit-form', function(e){
        e.preventDefault();
        $('.js-submit-form').prop('disabled', true);
        var frm = $('.contactForm form');
        if(isValidForm(frm, $('.process_response_msg'))){
          $.ajax({
            type: 'post',
            url: 'contact-form-process',
            data: frm.serialize(),
            dataType: 'json',
            success: function (response) {
              $('.process_response_msg').html(response.message);
              if(response.status === 'error'){
                $('.js-submit-form').prop('disabled', false);
              }
            },
            error: function (response) {
              $('.process_response_msg').html(response.message);
            },
          });
        } else {
          $('.js-submit-form').prop('disabled', false);
        }
      });
      function isValidForm(frm, msgDiv){
        var name = frm.find('input[name="demo-name"]').val(),
          email = frm.find('input[name="demo-email"]').val(),
          message = frm.find('textarea[name="demo-message"]').val();
        if(name.length === 0 || email.length === 0 || message.length === 0){
          msgDiv.html("all fields are mandatory");
          return false;
        }
        if(!(/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/).test(email)){
          msgDiv.html("enter valid email");
          return false;
        }
        if(!(/^[a-zA-Z]{1,}$/).test(name)){
          msgDiv.html("enter a single word name");
          return false;
        }
        return true;
      }
    });
  </script>