bp_friends_filter_folder_scope( array $retval = array(), array $filter = array() )

function bp_friends_filter_folder_scope( $retval = array(), $filter = array() ) {

	// Determine the user_id.
	if ( ! empty( $filter['user_id'] ) ) {
		$user_id = (int) $filter['user_id'];
	} else {
		$user_id = bp_displayed_user_id()
			? bp_displayed_user_id()
			: bp_loggedin_user_id();
	}

	$folder_id = 0;
	$folders   = array();
	if ( ! empty( $filter['folder_id'] ) ) {
		$folder_id = (int) $filter['folder_id'];
	}

	// Determine friends of user.
	$friends = friends_get_friend_user_ids( $user_id );
	if ( empty( $friends ) ) {
		$friends = array( 0 );
	}

	if ( $user_id !== bp_loggedin_user_id() ) {
		array_push( $friends, bp_loggedin_user_id() );
	}

	if ( ! empty( $filter['search_terms'] ) ) {
		if ( ! empty( $folder_id ) ) {
			$folder_ids           = array();
			$user_root_folder_ids = bp_document_get_folder_children( (int) $folder_id );
			if ( $user_root_folder_ids ) {
				foreach ( $user_root_folder_ids as $single_folder ) {
					$single_folder_ids = bp_document_get_folder_children( (int) $single_folder );
					if ( $single_folder_ids ) {
						array_merge( $folder_ids, $single_folder_ids );
					}
					array_push( $folder_ids, $single_folder );
				}
			}
			$folder_ids[] = $folder_id;
			$folders      = array(
				'column'  => 'parent',
				'compare' => 'IN',
				'value'   => $folder_ids,
			);
		}
	} else {
		$folders = array(
			'column' => 'parent',
			'value'  => 0,
		);
	}

	if ( ! bp_is_profile_document_support_enabled() ) {
		$friends = array( 0 );
	}

	$args = array(
		'relation' => 'AND',
		array(
			'column'  => 'user_id',
			'compare' => 'IN',
			'value'   => (array) $friends,
		),
		array(
			'column'  => 'privacy',
			'compare' => '=',
			'value'   => 'friends',
		),
		$folders,
	);

	return $args;
}