bbp_update_reply_forum_id( int $reply_id, int $forum_id )

function bbp_update_reply_forum_id( $reply_id = 0, $forum_id = 0 ) {

	// Validation
	$reply_id = bbp_get_reply_id( $reply_id );
	$forum_id = bbp_get_forum_id( $forum_id );

	// If no forum_id was passed, walk up ancestors and look for forum type
	if ( empty( $forum_id ) ) {

		// Get ancestors
		$ancestors = (array) get_post_ancestors( $reply_id );

		// Loop through ancestors
		if ( !empty( $ancestors ) ) {
			foreach ( $ancestors as $ancestor ) {

				// Get first parent that is a forum
				if ( get_post_field( 'post_type', $ancestor ) === bbp_get_forum_post_type() ) {
					$forum_id = $ancestor;

					// Found a forum, so exit the loop and continue
					continue;
				}
			}
		}
	}

	// Update the forum ID
	bbp_update_forum_id( $reply_id, $forum_id );

	return apply_filters( 'bbp_update_reply_forum_id', (int) $forum_id, $reply_id );
}