[CoursePress] - User Signup with ajax. Changes the `course_signup` shortcode to register users with ajax

cp_ajax_usersignup.php

<?php
/**
* Plugin Name: [CoursePress] - User Signup with ajax
* Plugin URI: https://premium.wpmudev.org/
* Description: Changes the `course_signup` shortcode to register users with ajax
* Author: Panos Lyrakis @ WPMUDEV
* Author URI: https://premium.wpmudev.org/
* License: GPLv2 or later
*/

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

if ( ! class_exists( 'WPMUDEV_CP_UserSignup_Ajax' ) ) {
    
    class WPMUDEV_CP_UserSignup_Ajax {

        private static $_instance = null;

        public static function get_instance() {

            if( is_null( self::$_instance ) ){
                self::$_instance = new WPMUDEV_CP_UserSignup_Ajax();
            }
            return self::$_instance;
            
        }

        private function __construct() {

        	if ( ! class_exists( 'CoursePress_UserLogin' ) ) {
        		return;
        	}

        	add_action( 'coursepress_after_signup_form', array( $this, 'plant_inputs' ) );
        	add_action( 'wp_footer', array( $this, 'footer_scripts' ) );
        	add_action( 'wp_ajax__cp_ajax_signup', array( $this, 'cp_ajax_signup' ) );
			add_action( 'wp_ajax_nopriv__cp_ajax_signup', array( $this, 'cp_ajax_signup' )  );

        }


        public function cp_ajax_signup() {

        	check_ajax_referer( '_cp_ajax_signup', '_cp_ajax_signup' );
	
			$_POST['student-settings-submit'] = '1';
			wp_send_json( $this->process_registration_form() );
        }


        public function process_registration_form() {
        	if ( isset( $_POST['student-settings-submit'] ) && isset( $_POST['_wpnonce'] )
				&& wp_verify_nonce( $_POST['_wpnonce'], 'student_signup' ) ) {

				check_admin_referer( 'student_signup' );

				/**
				 * Trigger before validating registration form
				 **/
				do_action( 'coursepress_before_signup_validation' );

				$min_password_length = CoursePress_Helper_Utility::get_minimum_password_length();
				$username = $_POST['username'];
				$firstname = $_POST['first_name'];
				$lastname = $_POST['last_name'];
				$email = $_POST['email'];
				$passwd = $_POST['password'];
				$passwd2 = $_POST['password_confirmation'];
				$redirect_url = $_POST['redirect_url'];
				$found_errors = 0;
				$form_message = '';
				$form_message_class = '';

				if ( $username && $firstname && $lastname && $email && $passwd && $passwd2 ) {

					if ( username_exists( $username ) ) {
						$form_message = __( 'Username already exists. Please choose another one.', 'coursepress' );
						$found_errors++;
					} elseif ( ! validate_username( $username ) ) {
						$form_message = __( 'Invalid username!', 'coursepress' );
						$found_errors++;
					} elseif ( ! is_email( $email ) ) {
						$form_message = __( 'E-mail address is not valid.', 'coursepress' );
						$found_errors++;
					} elseif ( email_exists( $email ) ) {
						$form_message = __( 'Sorry, that email address is already used!', 'coursepress' );
						$found_errors++;
					} elseif ( $passwd != $passwd2 ) {
						$form_message = __( 'Passwords don\'t match', 'coursepress' );
						$found_errors++;
					} elseif ( ! CoursePress_Helper_Utility::is_password_strong() ) {
						if ( CoursePress_Helper_Utility::is_password_strength_meter_enabled() ) {
							$form_message = __( 'Your password is too weak.', 'coursepress' );
						} else {
							$form_message = sprintf( __( 'Your password must be at least %d characters long and have at least one letter and one number in it.', 'coursepress' ), $min_password_length );
						}
						$found_errors++;
					} elseif ( isset( $_POST['tos_agree'] ) && ! cp_is_true( $_POST['tos_agree'] ) ) {
						$form_message = __( 'You must agree to the Terms of Service in order to signup.', 'coursepress' );
						$found_errors++;
					}
				} else {
					$form_message = __( 'All fields are required.', 'coursepress' );
					$found_errors++;
				}

				if ( $found_errors > 0 ) {
					$form_message_class = 'red';

					return array(
								'success' 	=> false,
								'message' 	=> $form_message,
								'class'		=> $form_message_class
							);
				} else {
					// Register new user
					$student_data = array(
						'default_role' => get_option( 'default_role', 'subscriber' ),
						'user_login' => $username,
						'user_email' => $email,
						'first_name' => $firstname,
						'last_name' => $lastname,
						'user_pass' => $passwd,
						'password_txt' => $passwd,
					);

					$student_data = CoursePress_Helper_Utility::sanitize_recursive( $student_data );
					$student_id = wp_insert_user( $student_data );

					if ( ! empty( $student_id ) ) {
						// Send registration email
						CoursePress_Data_Student::send_registration( $student_id, $student_data );

						$creds = array(
							'user_login' => $username,
							'user_password' => $passwd,
							'remember' => true,
						);
						$user = wp_signon( $creds, false );

						if ( is_wp_error( $user ) ) {

							return array(
										'success' 	=> false,
										'message' 	=> $user->get_error_message(),
										'class'		=> 'red'
									);
						}

						if ( ! empty( $_POST['course_id'] ) ) {
							$url = get_permalink( (int) $_POST['course_id'] );
							//wp_safe_redirect( $url );
							return array( 
										'success' 		=> true,
										'redirect_url' 	=> $url 
									);
						} else {
							if ( ! empty( $redirect_url ) ) {
								$url = esc_url_raw( apply_filters( 'coursepress_redirect_after_signup_redirect_url', $redirect_url ) );
							} else {
								$url = esc_url_raw( apply_filters( 'coursepress_redirect_after_signup_url', CoursePress_Core::get_slug( 'student_dashboard', true ) ) );
							}

							return array( 
										'success' 		=> true,
										'redirect_url' 	=> $url 
									);
						}
						
					} else {

						return array(
									'success' 	=> false,
									'message' 	=> $user->get_error_message(),
									'class'		=> 'red'
								);
					}
				}
			}
			return array(
						'success' 	=> false,
						'message' 	=> 'Something went wrong'
					);
        }


        public function footer_scripts() {

        	global $post;

			if ( ! $post instanceof WP_Post || ! has_shortcode( $post->post_content, 'course_signup' ) ) {
				return;
			}
			
			?>
			<script type="text/javascript">
				(function($){
					$( document ).ready(function(){

						$( '#student-settings .submit-link input' ).on( 'click', function(e){
							e.preventDefault();

							var form = $( '#student-settings' ),
								data = form.serialize(),
								ajaxurl = '<?php echo admin_url( 'admin-ajax.php' ); ?>';		

							$.post( ajaxurl, data, function( response ) {

		                        if ( ! response.success ) {
		                        	let error_msg = response.message,
		                        		error_class = response.class,
		                        		el = $( '.coursepress-form-signup p[class^="form-info-"]' );

		                        	el.removeAttr('class').addClass( 'form-info-' + error_class ).html( error_msg );                        	
		                        }
		                        else {
		                        	if ( typeof response.redirect_url !== "undefined" ){
		                        		window.location = response.redirect_url;
		                        	}
		                        	else {
		                        		location.reload();	
		                        	}
		                        	
		                        }
		                    });

						});
					});
				})(jQuery);
			</script>
			<?php

        }


        public function plant_inputs() {
        	echo '<input type="hidden" name="action" value="_cp_ajax_signup">';
			wp_nonce_field( '_cp_ajax_signup', '_cp_ajax_signup' );
        }

    }

    if ( ! function_exists( 'wpmudev_cp_usersignup_ajax' ) ) {

        function wpmudev_cp_usersignup_ajax() {
            return WPMUDEV_CP_UserSignup_Ajax::get_instance();
        };

        add_action( 'plugins_loaded', 'wpmudev_cp_usersignup_ajax', 10 );
    }


}