bbp_buddypress_add_notification( int $reply_id, int $topic_id, int $forum_id, array $anonymous_data = false, int $author_id, bool $is_edit = false, int $reply_to )

function bbp_buddypress_add_notification( $reply_id = 0, $topic_id = 0, $forum_id = 0, $anonymous_data = false, $author_id = 0, $is_edit = false, $reply_to = 0 ) {

	// Bail if somehow this is hooked to an edit action
	if ( !empty( $is_edit ) ) {
		return;
	}

	// Get autohr information
	$topic_author_id   = bbp_get_topic_author_id( $topic_id );
	$secondary_item_id = $author_id;

	// Hierarchical replies
	if ( !empty( $reply_to ) ) {
		$reply_to_item_id = bbp_get_topic_author_id( $reply_to );
	}

	// Get some reply information
	$args = array(
		'user_id'          => $topic_author_id,
		'item_id'          => $topic_id,
		'component_name'   => bbp_get_component_name(),
		'component_action' => 'bbp_new_reply',
		'date_notified'    => get_post( $reply_id )->post_date,
	);

 	// Notify the topic author if not the current reply author
 	if ( $author_id !== $topic_author_id ) {
		$args['secondary_item_id'] = $secondary_item_id ;

		bp_notifications_add_notification( $args );
 	}
 
 	// Notify the immediate reply author if not the current reply author
 	if ( !empty( $reply_to ) && ( $author_id !== $reply_to_item_id ) ) {
		$args['secondary_item_id'] = $reply_to_item_id ;

		bp_notifications_add_notification( $args );
 	}
}