Raid_Manager/app/lib/breadcrumb_page.dart

import 'package:flutter/material.dart';
import 'package:flutter_breadcrumb/flutter_breadcrumb.dart';
import 'package:provider/provider.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 _BreadCrumbNode _rootPage = _BreadCrumbNode(rootName, defaultRoute);
  late Widget _currentpage = _rootPage.widget;

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

  void switchPage(String name) {
    final pageNode = _findPage(name, _rootPage);
    if (pageNode != null) {
      _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 _last(_BreadCrumbNode node) {
    if (node.next != null) {
      return _last(node.next!);
    } else {
      return node;
    }
  }

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

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

  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);
}

class BreadCrumbPage extends StatefulWidget {
  const BreadCrumbPage(
      {Key? key, required this.mainPage, required this.rootName})
      : super(key: key);

  final Widget mainPage;
  final String rootName;

  @override
  State<BreadCrumbPage> createState() => _BreadCrumbPageState();
}

class _BreadCrumbPageState extends State<BreadCrumbPage> {
  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider<BreadCrumbController>(
      create: (BuildContext context) =>
          BreadCrumbController(widget.mainPage, widget.rootName),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Padding(
            padding: const EdgeInsets.only(left: 12, top: 8, bottom: 8),
            child: Consumer<BreadCrumbController>(
              builder: (_, controller, __) => BreadCrumb(
                items: controller
                    .getNames()
                    .map((e) => BreadCrumbItem(
                          padding: const EdgeInsets.all(2),
                          content: Text(e,
                              style: Theme.of(context).textTheme.labelMedium),
                          onTap: () {
                            controller.switchPage(e);
                          },
                        ))
                    .toList(growable: false),
                divider: Icon(
                  Icons.chevron_right,
                  color: Theme.of(context).textTheme.labelMedium?.color,
                ),
              ),
            ),
          ),
          Divider(color: Colors.white.withOpacity(0.3), height: 1),
          Consumer<BreadCrumbController>(
            builder: (_, value, __) => value.getCurrentPage(),
          )
          // currentPage
        ],
      ),
    );
  }
}