Raid_Manager/app/lib/breadcrumb_page/breadcrumb_controller.dart

import 'package:flutter/widgets.dart';

class _BreadCrumbNode {
  String name;
  Widget widget;
  _BreadCrumbNode? next;

  _BreadCrumbNode(this.name, this.widget);
}

class BreadCrumbController extends ChangeNotifier {
  final Widget defaultRoute;
  final String rootName;

  late final _BreadCrumbNode _rootPage =
      _BreadCrumbNode(rootName, defaultRoute);
  late Widget _currentpage = _rootPage.widget;

  void pushPage(Widget widget, String name) {
    _findPage(null, _rootPage).next = _BreadCrumbNode(name, widget);
    _currentpage = widget;
    notifyListeners();
  }

  void switchPage(String name) {
    final pageNode = _findPage(name, _rootPage);
    _currentpage = pageNode.widget;
    // hope for garbage collector to free the floating items (;
    pageNode.next = null;
    notifyListeners();
  }

  List<String> getNames() {
    return _genNameList(_rootPage);
  }

  Widget getCurrentPage() {
    return _currentpage;
  }

  _BreadCrumbNode _findPage(String? name, _BreadCrumbNode node) {
    if (node.name == name) {
      return node;
    }

    if (node.next != null) {
      return _findPage(name, node.next!);
    } else {
      return node;
    }
  }

  List<String> _genNameList(_BreadCrumbNode node) {
    if (node.next != null) {
      return _genNameList(node.next!)..insert(0, node.name);
    } else {
      return [node.name];
    }
  }

  BreadCrumbController(this.defaultRoute, this.rootName);
}