news_navigation_bar.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import '../../../authentication/service/auth_provider.dart';
import '../../../generated/l10n.dart';
import '../../../widgets/scaffold.dart';
import '../../settings/view/source_page.dart';
import 'news_feed_favorite_page.dart';
import 'news_feed_page.dart';
import 'news_feed_personal_page.dart';

class NewsNavigationBar extends StatefulWidget {
  const NewsNavigationBar({this.tabIndex = 0});

  static const String routeName = '/news_feed';
  final int tabIndex;

  @override
  _NewsNavigationBarState createState() => _NewsNavigationBarState();
}

class _NewsNavigationBarState extends State<NewsNavigationBar>
    with TickerProviderStateMixin {
  int currentTab = 0;
  List<Widget> tabs;
  TabController tabController;
  final PageStorageBucket bucket = PageStorageBucket();

  @override
  void initState() {
    super.initState();
    tabController = TabController(vsync: this, length: 3);
    tabController.addListener(() {
      if (!tabController.indexIsChanging) {
        setState(() {
          currentTab = tabController.index;
        });
      }
    });
    tabs = [
      const NewsFeedPage(key: PageStorageKey('NewsFeed')),
      const NewsFeedFavoritePage(key: PageStorageKey('NeqSnawsFeedFavorite')),
      const NewsFeedPersonalPage(key: PageStorageKey('NewsFeedPersonal')),
    ];

    // Show "Select sources" page if user has no preference set
    final authProvider = Provider.of<AuthProvider>(context, listen: false);
    if (!authProvider.isAnonymous) {
      authProvider.currentUser.then((final user) {
        if (user?.sources?.isEmpty ?? true) {
          Navigator.of(context).push(MaterialPageRoute<SourcePage>(
              builder: (final context) => SourcePage()));
        }
      });
    }
  }

  @override
  void dispose() {
    tabController.dispose();
    super.dispose();
  }

  @override
  Widget build(final BuildContext context) {
    return DefaultTabController(
      length: tabs.length,
      initialIndex: widget.tabIndex,
      child: AppScaffold(
        title: const Text('News feed'),
        body: PageStorage(
          child: TabBarView(controller: tabController, children: tabs),
          bucket: bucket,
        ),
        appBarBottom: newsNavigationBar(context),
      ),
    );
  }

  Widget newsNavigationBar(final BuildContext context) => TabBar(
        controller: tabController,
        tabs: [
          const Tab(text: 'News'),
          const Tab(text: 'Favorites'),
          const Tab(text: 'Personal'),
        ],
        labelColor: Colors.white,
        unselectedLabelColor: Theme.of(context).unselectedWidgetColor,
        indicatorColor: Colors.white,
      );
}