Custom Wordpress registration

<?php

// register a new user
function feralf_add_new_member() {
    if (isset( $_POST["feralf_user_login"] ) && wp_verify_nonce($_POST['feralf_register_nonce'], 'feralf-register-nonce')) {

        global $feralf_settings;

        $user_login     = $_POST["feralf_user_login"];
        $user_email     = $_POST["feralf_user_email"];
        $user_first     = $_POST["feralf_user_first"];
        $user_last      = $_POST["feralf_user_last"];
        $user_pass      = $_POST["feralf_user_pass"];
        $pass_confirm   = $_POST["feralf_user_pass_confirm"];
        $user_phone     = $_POST["feralf_user_phone"];
        $user_street        = $_POST["feralf_user_street"];
        $user_city      = $_POST["feralf_user_city"];
        $user_postalcode        = $_POST["feralf_user_postalcode"];
        $user_country       = $_POST["feralf_user_country"];
        $user_region        = $_POST["feralf_user_region"];

        // this is required for username checks
        require_once(ABSPATH . WPINC . '/registration.php');

        if(username_exists($user_login)) {
            // Username already registered
            feralf_errors()->add('username_unavailable', __('Username already taken', 'feralf'), 'register');
        }
        if(!validate_username($user_login)) {
            // invalid username
            feralf_errors()->add('username_invalid', __('Invalid username', 'feralf'), 'register');
        }
        if($user_login == '') {
            // empty username
            feralf_errors()->add('username_empty', __('Enter a username', 'feralf'), 'register');
        }
        if(!is_email($user_email)) {
            //invalid email
            feralf_errors()->add('email_invalid', __('Invalid email', 'feralf'), 'register');
        }
        if(email_exists($user_email)) {
            //Email address already registered
            feralf_errors()->add('email_used', __('Email already used', 'feralf'), 'register');
        }
        if($user_pass == '') {
            // passwords do not match
            feralf_errors()->add('password_empty', __('Enter a password', 'feralf'), 'register');
        }
        if($user_pass != $pass_confirm) {
            // passwords do not match
            feralf_errors()->add('password_mismatch', __('Passwords don\'t match', 'feralf'), 'register');
        }

        $errors = feralf_errors()->get_error_messages();

        // only create the user in if there are no errors
        if(empty($errors)) {

            $new_user_id = wp_insert_user(array(
                    'user_login'        => $user_login,
                    'user_pass'         => $user_pass,
                    'user_email'        => $user_email,
                    'first_name'        => $user_first,
                    'last_name'         => $user_last,
                    'user_registered'   => date('Y-m-d H:i:s'),
                    'user_phone'        =>  $user_phone,
                    'user_street'       =>  $user_street,
                    'user_city'         =>  $user_city,
                    'user_postalcode'   =>  $user_postalcode,
                    'user_country'      =>  $user_country,
                    'user_region'       =>  $user_region,
                    'role'              => 'subscriber'
                )
            );
            if($new_user_id) {
                // send an email to the admin alerting them of the registration
                wp_new_user_notification($new_user_id);

                // log the new user in
                wp_setcookie($user_login, $user_pass, true);
                wp_set_current_user($new_user_id, $user_login);
                do_action('wp_login', $user_login);

                // send the newly created user to the home page after logging them in
                wp_redirect(get_permalink($feralf_settings['redirect'])); exit;
            }

        }

    }
}
add_action('init', 'feralf_add_new_member');

// logs a member in after submitting a form
function feralf_login_member() {

    if(isset($_POST['feralf_user_login']) && wp_verify_nonce($_POST['feralf_login_nonce'], 'feralf-login-nonce')) {

        // this returns the user ID and other info from the user name
        $user = get_userdatabylogin($_POST['feralf_user_login']);

        if(!$user) {
            // if the user name doesn't exist
            feralf_errors()->add('empty_username', __('Invalid username', 'feralf'), 'login');
        }

        if(!isset($_POST['feralf_user_pass']) || $_POST['feralf_user_pass'] == '') {
            // if no password was entered
            feralf_errors()->add('empty_password', __('Enter a password', 'feralf'), 'login');
        }

        // check the user's login with their password
        if(!wp_check_password($_POST['feralf_user_pass'], $user->user_pass, $user->ID)) {
            // if the password is incorrect for the specified user
            feralf_errors()->add('empty_password', __('Incorrect password', 'feralf'), 'login');
        }

        // retrieve all error messages
        $errors = feralf_errors()->get_error_messages();

        // only log the user in if there are no errors
        if(empty($errors)) {

            wp_setcookie($_POST['feralf_user_login'], $_POST['feralf_user_pass'], true);
            wp_set_current_user($user->ID, $_POST['feralf_user_login']);
            do_action('wp_login', $_POST['feralf_user_login']);

            wp_redirect($_POST['refalf_redirect']); exit;
        }
    }
}
add_action('init', 'feralf_login_member');

function feralf_change_password() {
    // reset a users password
    if(isset($_POST['feralf_action']) && $_POST['feralf_action'] == 'change-password') {

        global $user_ID;

        if(!is_user_logged_in())
            return;

        if(wp_verify_nonce($_POST['feralf_password_nonce'], 'rcp-password-nonce')) {

            if($_POST['feralf_user_pass'] == '' || $_POST['feralf_user_pass_confirm'] == '') {
                // password(s) field empty
                feralf_errors()->add('password_empty', __('Enter a password', 'feralf'), 'password');
            }
            if($_POST['feralf_user_pass'] != $_POST['feralf_user_pass_confirm']) {
                // passwords do not match
                feralf_errors()->add('password_mismatch', __('Passwords don\'t match', 'feralf'), 'password');
            }

            // retrieve all error messages, if any
            $errors = feralf_errors()->get_error_messages();

            if(empty($errors)) {
                // change the password here
                $user_data = array(
                    'ID' => $user_ID,
                    'user_pass' => $_POST['feralf_user_pass']
                );
                wp_update_user($user_data);
                // send password change email here (if WP doesn't)
                wp_redirect(add_query_arg('password-updated', 'true', $_POST['feralf_redirect']));
                exit;
            }
        }
    }
}
add_action('init', 'feralf_change_password');

// used for tracking error messages
function feralf_errors(){
    static $wp_error; // Will hold global variable safely
    return isset($wp_error) ? $wp_error : ($wp_error = new WP_Error(null, null, null));
}

// displays error messages from form submissions
function feralf_show_error_messages($data = '') {
    if($codes = feralf_errors()->get_error_codes()) {
        echo '<div class="feralf_errors">';
            // Loop error codes and display errors
           foreach($codes as $code){
                if(feralf_errors()->get_error_data($code) == $data) {
                    $message = feralf_errors()->get_error_message($code);
                    echo '<p class="feralf_error"><span>' . $message . '</span></p>';
                }
            }
        echo '</div>';
    }
}