Ajax連絡フォームを作成するためのWordPressプラグインを構築する

<?php
/*
Plugin Name: Ajax Contact Form
Plugin URI:  (Your Plugin URI)
Description: A simple contact form using AJAX.
Author: Abbas Suterwala
Version: 1.0
Author URI: (Your Author URI)
*/
?>

define('ACFSURL', WP_PLUGIN_URL."/".dirname( plugin_basename( __FILE__ ) ) );
define('ACFPATH', WP_PLUGIN_DIR."/".dirname( plugin_basename( __FILE__ ) ) );

function ajaxcontact_enqueuescripts() {
    wp_enqueue_script('ajaxcontact', ACFSURL.'/js/ajaxcontact.js', array('jquery'));
    wp_localize_script( 'ajaxcontact', 'ajaxcontactajax', array( 'ajaxurl' => admin_url( 'admin-ajax.php' ) ) );
}
add_action('wp_enqueue_scripts', 'ajaxcontact_enqueuescripts');

function ajaxcontact_show_contact() {
?>
<div>
    <div style="background-color://m.sbmmt.com/link/93ac0c50dd620dc7b88e5fe05c70e15bE6E6FA ;color:blue;"></div>
    <input type="text" id="ajaxcontactname" placeholder="Name"><br>
    <input type="email" id="ajaxcontactemail" placeholder="Email"><br>
    <input type="text" id="ajaxcontactsubject" placeholder="Subject"><br>
    <textarea id="ajaxcontactcontents" placeholder="Message"></textarea><br>
    <a href="//m.sbmmt.com/link/93ac0c50dd620dc7b88e5fe05c70e15b" onclick="ajaxformsendmail(this.form);" style="cursor: pointer">Send Mail</a>
</div>
<?php
}

function ajaxcontact_send_mail() {
    $results = '';
    $error = 0;
    $name = isset($_POST['acfname']) ? sanitize_text_field($_POST['acfname']) : '';
    $email = isset($_POST['acfemail']) ? sanitize_email($_POST['acfemail']) : '';
    $subject = isset($_POST['acfsubject']) ? sanitize_text_field($_POST['acfsubject']) : '';
    $contents = isset($_POST['acfcontents']) ? wp_kses_post($_POST['acfcontents']) : '';
    $admin_email = get_option('admin_email');

    if (!is_email($email)) {
        $results = $email." :email address is not valid.";
        $error = 1;
    } elseif (empty($name)) {
        $results = "Name is invalid.";
        $error = 1;
    } elseif (empty($subject)) {
        $results = "Subject is invalid.";
        $error = 1;
    } elseif (empty($contents)) {
        $results = "Content is invalid.";
        $error = 1;
    }

    if ($error == 0) {
        $headers = 'From: ' . $email . "\r\n";
        if (wp_mail($admin_email, $subject, $contents, $headers)) {
            $results = "*Thanks for your mail.";
        } else {
            $results = "*The mail could not be sent.";
        }
    }
    die($results);
}