PHP Class that wraps creating custom "My Account" endpoints inside WooCommerce

class.endpoint.php

<?php
defined( 'ABSPATH' ) or exit;

class CUSTOM_WC_My_Account_Endpoint {
	/**
	 * Properties
	 *
	 * @prop string $endpoint URI slug of endpoint
	 * @prop string $title Text to display on menu
	 * @prop callback $callback Display/Draw function to call
	 * @prop callback $menu_items Override the new menu attribute method
	 */
	public $endpoint;
	public $title;
	public $callback;
	public $menu_items;

	/**
	 * Constructor
	 *
	 * @param string $endpoint URI slug of endpoint
	 * @param string $title Text to display on menu
	 * @param callback $callback Optional.  Display/Draw function to call
	 * @param callback $menu_items Optional.  Override new_menu_items method
	 */
	public function __construct( $endpoint, $title, $callback = null, $menu_items = null ) {

        // Grab the parameters for the life of this object
	    $this->endpoint   = $endpoint;
	    $this->title      = $title;
	    $this->callback   = $callback;
	    $this->menu_items = $menu_items;

		// Insert a new endpoint into WordPress.
		add_action( 'init', array( $this, 'add_endpoints' ) );
		add_filter( 'query_vars', array( $this, 'add_query_vars' ), 0 );

		// Change the My Accout page title.
		add_filter( 'the_title', array( $this, 'endpoint_title' ) );

		// Insert new tab/page into the My Account page.
		add_filter( 'woocommerce_account_menu_items', array( $this, 'new_menu_items' ) );
		add_action( 'woocommerce_account_' . $this->endpoint .  '_endpoint', array( $this, 'endpoint_content' ) );
	}

	/**
	 * Register new endpoint to use inside My Account page.
	 *
	 * @see https://developer.wordpress.org/reference/functions/add_rewrite_endpoint/
	 */
	public function add_endpoints() {
		add_rewrite_endpoint( $this->endpoint, EP_ROOT | EP_PAGES );
	}

	/**
	 * Add new query var.
	 *
	 * @param array $vars
	 * @return array
	 */
	public function add_query_vars( $vars ) {
		$vars[] = $this->endpoint;

		return $vars;
	}

	/**
	 * Set endpoint title.
	 *
	 * @param string $title
	 * @return string
	 */
	public function endpoint_title( $title ) {
		global $wp_query;

		$is_endpoint = isset( $wp_query->query_vars[ $this->endpoint ] );

		if ( $is_endpoint && ! is_admin() && is_main_query() && in_the_loop() && is_account_page() ) {
			// New page title.
			$title = __( $this->title, 'woocommerce' );

			remove_filter( 'the_title', array( $this, 'endpoint_title' ) );
		}

		return $title;
	}

	/**
	 * Insert the new endpoint into the My Account menu.
	 *
	 * If this function isn't overridden during construction, it will
	 * (by default) place the new menu item at the bottom of the My Account
	 * menu, just above 'Customer Logout'.
	 *
	 * @param array $items
	 * @return array
	 */
	public function new_menu_items( $items ) {
	    if ( $this->menu_items ) {
	        return call_user_func( $this->menu_items, $items );
        } else {
            // Remove the logout menu item.
            $logout = $items['customer-logout'];
            unset( $items['customer-logout'] );

            // Insert your custom endpoint.
            $items[ $this->endpoint ] = __( $this->title, 'woocommerce' );

            // Insert back the logout item.
            $items['customer-logout'] = $logout;

		    return $items;
        }
	}

	/**
	 * Endpoint HTML content.
	 */
	public function endpoint_content() {
	    if ( $this->callback ) {
	        call_user_func( $this->callback );
	    } else {
    		echo '<p>You need to override this with your own callback!</p>';
        }
	}

	/**
	 * Plugin install action.
	 * Flush rewrite rules to make our custom endpoint available.
	 */
	public static function install() {
		flush_rewrite_rules();
	}
}

This is a refactoring of the forked script making the class self-contained (no hardcoded values), allowing you to use this class multiple times to create more than one My Account endpoint easily.

Usage:

require_once 'class.endpoint.php'

function CUSTOM_my_endpoint_draw() {
    // create and display the content of your endpoint
    $html = "<p>Your content here</p>";

    // ...

    echo $html;  // Note:  This function should 'echo' the final output
}

function CUSTOM_my_endpoint_menu( $items ) {
    // Re-arrange the My Account menu items

    // ...

    return $items;  // Note:  This function returns the array of menu items
}

$my_new_endpoint = new CUSTOM_WC_My_Account_Endpoint(
    'my-endpoint',  # https://.../my-account/my-endpoint/...
    'My Endpoint',  # Text displayed in My Account menu
    'CUSTOM_my_endpoint_draw',  # name of drawing function
    'CUSTOM_my_endpoint_menu'  # name of menu function
);

// Register the plugin (can't be done from inside the class)
register_activation_hook( __FILE__, array( $my_new_endpoint, 'install' ) );