[Hummingbird Pro] Fix compatibility issue with wpDiscuz and Gravatar

hummingbird-wpdiscuz-compat.php

<?php
/**
 * Plugin Name: [Hummingbird Pro] Fix compatibility issue with wpDiscuz and Gravatar
 * Description: Prevents Hummingbird from caching (guest) Gravatars generated by wpDiscuz infinitely, consuming disk space
 * Author: Anderson Salas @ WPMUDEV
 * Task: SLS-5966
 * Author URI: https://premium.wpmudev.org
 * License: GPLv2 or later
 */

add_action( 'plugins_loaded', function() {

    if ( ! defined( 'WPHB_VERSION' ) ) {
        return; // Hummingbird is not installed/enabled.
    }

    if ( ! defined( 'WPDISCUZ_DIR_PATH' ) ) {
        return; // wpDiscuz is not installed/enabled.
    }
    
    $gravatar = \Hummingbird\WP_Hummingbird::get_instance()->core->modules['gravatar'] ?? null;

    if ( null === $gravatar ) {
        return; // Gravatar module not loaded.
    }

    $enabled = $gravatar->get_options()['enabled'] ?? null;

    if ( true !== $enabled ) {
        return; // Gravatar module not enabled.
    }

    $removed = remove_filter( 'get_avatar_data', [ $gravatar, 'get_avatar_data' ], 10, 2 );

    add_filter( 'get_avatar_data', function( $args, $id_or_email ) use ( $gravatar ) {
        if ( '@example.com' === substr( $id_or_email, -12 ) && 25 === strlen( $id_or_email ) ) {
            return $args; // Do not cache if it's a dummy email from wpDiscuz ([UUID]@example.com)
        }
        return call_user_func_array( [ $gravatar, 'get_avatar_data' ], [ $args, $id_or_email ] );
    }, 10, 2 );

});