bbPress Topic and Reply Author Change / Override

So this tutorial is basically creating a custom "user" selection meta field under a metabox named "Topic/Reply Author Override" that will be place on the Topic/Reply edit screen.

Anything in this tutorial will work in a theme's functions.php file.

/**
* bbPress Topic and Reply Author Override
* https://www.proy.info/bbpress-topic-and-reply-author-change-override/
**/
class bbPress_Topic_and_Reply_Author_Override {
    /**
     * Constructor.
     */
    private $match_slugs = array();
    public function __construct() {
        if ( is_admin() ) {
            add_action( 'load-post.php',     array( $this, 'init_metabox' ) );
            add_action( 'load-post-new.php', array( $this, 'init_metabox' ) );
            $this->match_slugs = array('topic', 'reply');
        }
    }
    /**
     * Meta box initialization.
     */
    public function init_metabox() {
        add_action( 'add_meta_boxes', array( $this, 'add_metabox'  )        );
        add_action( 'save_post',      array( $this, 'save_metabox' ), 10, 2 );
    }
    /**
     * Adds the meta box.
     */
    public function add_metabox() {
        add_meta_box(
            'bbp_author_metabox',
            __( 'Topic Author Override', 'textdomain' ),
            array( $this, 'render_metabox' ),
            'topic', 'side', 'high'
        );
        add_meta_box(
            'bbp_author_metabox',
            __( 'Reply Author Override', 'textdomain' ),
            array( $this, 'render_metabox' ),
            'reply', 'side', 'high'
        );
    }
    /**
     * Renders the meta box.
     */
    public function render_metabox( $post ) {
        // Add nonce for security and authentication.
        wp_nonce_field( 'custom_nonce_action', 'custom_nonce' );
        $post_author_override = $post->post_author;
        if (is_admin() && $this->is_edit_page('new')){
            $post_author_override = wp_get_current_user()->ID;
        }
        $users = get_users();
        $user_select = '<select id="bbp_author_override_metabox" name="post_author_override" class="">';
        if($post_author_override ==0){
            $_bbp_anonymous_name = get_post_meta($post->ID, '_bbp_anonymous_name', true);
            $user_select .= 'Anonymous/Guest'.($_bbp_anonymous_name?' ('.$_bbp_anonymous_name.')':'').'';
        }
        //Leave the admin in the list
        foreach($users as $user) {
            //print_r($user);
            $selected = ($post_author_override == $user->ID)?'selected="selected"':'';
            $user_select .= '<option value="'.$user->ID.'"'.$selected.'>'.$user->display_name.' ('.$user->user_login.')</option>';
        }
        $user_select .='</select>';
        echo $user_select;
    }
    /**
     * Handles saving the meta box.
     *
     * @param int     $post_id Post ID.
     * @param WP_Post $post    Post object.
     * @return null
     */
    public function save_metabox( $post_id, $post ) {
        // Add nonce for security and authentication.
        $nonce_name   = isset( $_POST['custom_nonce'] ) ? $_POST['custom_nonce'] : '';
        $nonce_action = 'custom_nonce_action';
        // Check if nonce is set.
        if ( ! isset( $nonce_name ) ) {
            return;
        }
        // Check if nonce is valid.
        if ( ! wp_verify_nonce( $nonce_name, $nonce_action ) ) {
            return;
        }
        // Check if user has permissions to save data.
        if ( ! current_user_can( 'edit_post', $post_id ) ) {
            return;
        }
        // Check if not an autosave.
        if ( wp_is_post_autosave( $post_id ) ) {
            return;
        }
        // Check if not a revision.
        if ( wp_is_post_revision( $post_id ) ) {
            return;
        }
        // Check to match the slug
        if(!in_array($post->post_type, $this->match_slugs)){
            return;
        }
        if ( ! wp_is_post_revision( $post_id ) ){

            // unhook this function so it doesn't loop infinitely
            //remove_action('save_post','change_pos_auth');

            if ( isset($_POST['post_author_override']) ) {
                //$args = array('ID'=>$post_id,'post_author'=>$_POST['post_author_override']);
                //wp_update_post( $args );
                // re-hook this function
                //add_action('save_post','change_pos_auth');
                global $wpdb;
	        $wpdb->query($wpdb->prepare("UPDATE `".$wpdb->prefix . "posts` SET `post_author` = '".$_POST['post_author_override']."' WHERE `ID` = ".$post_id));
            }
        }
        
    }
    /**
    * is_edit_page
    * function to check if the current page is a post edit page
    */
    public function is_edit_page($new_edit = null){
        global $pagenow;
        //make sure we are on the backend
        if (!is_admin()) return false;
        if($new_edit == "edit")
            return in_array( $pagenow, array( 'post.php',  ) );
        elseif($new_edit == "new") //check for new post page
            return in_array( $pagenow, array( 'post-new.php' ) );
        else //check for either new or edit
            return in_array( $pagenow, array( 'post.php', 'post-new.php' ) );
    }
}
new bbPress_Topic_and_Reply_Author_Override();