My Custom Form Wordpress March

<?php
/**
 * Contact form functionality
 * Used within the loop
 * @link https://developer.wordpress.org/reference/functions/wp_nonce_field/
 * @link https://codex.wordpress.org/Class_Reference/WP_Error
 * @link https://developer.wordpress.org/reference/functions/wp_is_mobile/
 * @link https://developer.wordpress.org/reference/functions/wp_kses_data/
 * @link https://developer.wordpress.org/reference/functions/wp_remote_retrieve_response_code/
 * @link https://developer.wordpress.org/reference/functions/wp_get_referer/
 */


defined( 'ABSPATH' ) or die( 'No script kiddies please!' );


// Validate Fields Contact Form
function gym_contact_validate_form(){
  if (isset($_POST['submit']) && isset($_POST['gymclub_nonce_field'])) {

     if (wp_verify_nonce( $_POST['gymclub_nonce_field'], 'custom_action_nonce')) {
         //user posted variables
        $to = get_option('gym_contact_admin_email');
        $name = isset ($_POST['message_name'])? esc_sql(sanitize_text_field($_POST['message_name'])):"";
        $email = isset($_POST['message_email'])? esc_sql(sanitize_text_field(sanitize_email($_POST['message_email']))):"";
        $phone = isset($_POST['message_phone'])? esc_sql(sanitize_text_field($_POST['message_phone'])):"";
        $message = isset($_POST['message_text'])? esc_sql(sanitize_text_field($_POST['message_text'])):"";


        // If any field is left empty, add the error message to the error array
        if ( empty($name) || empty($email) || empty($phone) || empty($message) ) {
            array_push( $this->form_errors, 'No field should be left empty' );
        }

        // if the name field isn't alphabetic, add the error message
        if ( strlen($name) < 4 ) {
            array_push( $this->form_errors, 'Name should be at least 4 characters' );
        }

        // Check if the email is valid
        if ( !is_email($email) ) {
            array_push( $this->form_errors, 'Email is not valid' );
        }


        $headers[] = 'From: '. $name . ' <' . $email . '>';
        $sent = wp_mail( $to, $subject, $message, $headers );

        if ($sent){

            $r = array(
                  'name'  => $name,
                  'email' => $email,
                  'to' => $to,
                  'subject' => $subject,
                  'message' => $message);
             wp_send_json_success($r);
           } else {
            $r = array('message' => 'Mail Error');
            wp_send_json_error($r);
           }

           $r = array('message' => 'Validate Error' );
           wp_send_json_error($r);

     }// end verify nonce

    } //end isset

}// end function

// WordPress Ajax
add_action( 'wp_ajax_gym_contact_create_entry', 'gym_contact_create_entry' );
add_action( 'wp_ajax_nopriv_my_contact', 'gym_contact_create_entry' );


// Ajax insert data contact entry
function gym_contact_create_entry($name, $email, $phone, $message ) {
  global $wpdb;
  $table_name = $wpdb->prefix . 'contact';

  $wpdb->insert(
        $table_name,
        array(
            'name' => $name,
            'email' => $email,
            'phone' => $phone,
            'message' => $message,
            'time' => current_time( 'mysql' )
        )
    );
}



 ?>


 <?php get_header(); ?>


<script src="https://www.google.com/recaptcha/api.js" async defer></script>

<article class="container">
    <?php if (have_posts()):
    while (have_posts()): the_post();  ?>
  <div class="row contact">
    <div class="col-md-6">
      <div class="form-area">
            <div class="text-center contact-h"><?php the_title();?></div>

            <form id="contact-form" action="<?php the_permalink(); ?>" method="post">
                  <div class="group form-group">
                      <input class="form-control" id="name" type="text" name="message_name" value="<?php if (isset($_POST['message_name'])) { echo esc_attr($_POST['message_name']);} ?>">
                      <span class="highlight"></span>
                      <span class="bar"></span>
                      <label for="name"><?php echo __('Name', 'gymclub'); ?></label>
                  </div><!-- end div group form-group -->
                  <div class="group form-group">
                      <input class="form-control"  id="email" type="email" name="message_email" value="<?php if (isset($_POST['message_email'])) { echo esc_attr($_POST['message_email']);} ?>">
                      <span class="highlight"></span>
                      <span class="bar"></span>
                      <label for="message_email"><?php echo __('Email', 'gymclub'); ?></label>
                  </div><!-- end div group form-group -->
                  <div class="group form-group">
                      <input class="form-control"  id="phone" type="tel" name="message_phone" value="<?php if (isset($_POST['message_phone'])) { echo esc_attr( $_POST['message_phone']); } ?>">
                      <span class="highlight"></span>
                      <span class="bar"></span>
                      <label for="message_phone"><?php echo __('Phone', 'gymclub'); ?></label>
                  </div><!-- end div group form-group -->
                  <div class="group form-group">
                      <div class="text-group">
                          <textarea class="form-control" id="message" type="text" name="message_text" rows="4"><?php if (isset($_POST['message_text'])) { echo esc_textarea($_POST['message_text']); } ?></textarea>
                          <label for="message_text" class="input-label"><?php echo __('Message', 'gymclub'); ?></label>
                          <i class="bar"></i>
                      </div><!-- end div text-group -->
                  </div><!-- end div group form-group -->
                  <p class="message_success" id="message_success">Hola desde el formulario</p>
                  <p class="message_error" id="message_error">Hola desde el formulario</p>
                  <div class="g-recaptcha" data-sitekey="6Ld61NkUAAAAAJJ60gH6Ku38xJwj8nzKWbYiaecs"></div>
                  <!--<input type="hidden" name="submitted" value="custom_action">-->
                  <?php wp_nonce_field( 'custom_action_nonce', 'gymclub_nonce_field' ); ?>
                  <button class="btn btn-primary" id="submit" type="submit" id="gymclub-submit" name="submit"><?php echo __('Send', 'gymclub'); ?></button>
            </form><!-- end form -->
      </div><!--end respond -->
   </div><!-- end div col-md-6 -->

    <div class="col-md-6" itemscope itemtype="http://schema.org/LocalBusiness">
        <h3><?php echo __('Dates', 'gymclub'); ?></h3>
        <span class="dates_contact" itemprop="name"><i class="fas fa-building"></i><?php echo esc_attr( get_option('gym_contact_name_company') ); ?></span>
        <div  itemprop="address" itemscope itemtype="http://schema.org/PostalAddress">
          <span class="dates_contact" itemprop="streetAddress"><i class="fas fa-map-marked-alt"></i><?php echo esc_attr( get_option('gym_contact_address_company') ); ?></span>
           <span class="dates_contact" itemprop="telephone"><i class="fas fa-phone"></i><?php echo esc_attr( get_option('gym_contact_phone_company') ); ?></span>
           <span class="dates_contact" itemprop="email"><i class="far fa-envelope"></i><?php echo esc_attr( get_option('gym_contact_admin_email') ); ?></span>
           <span class="dates_contact" itemprop="postalCode"><i class="fas fa-mail-bulk"></i><?php echo esc_attr( get_option('gym_contact_code_postal_company') ); ?></span>
        </div><!-- end div itemprop -->
     </div><!--end div col-md-6 div itemscope -->

 </div><!-- end div contact -->

  <?php endwhile;
  endif;?>

</article><!-- end section -->


<?php get_footer(); ?>