cb_prestige_qr/lib/app/navigation/main_shell.dart

import 'dart:async';
import 'dart:ui';

import 'package:cb_prestige_qr/core/presentation/widgets/global_loading_overlay.dart';
import 'package:cb_prestige_qr/core/widgets/center_nav_button.dart';
import 'package:cb_prestige_qr/core/widgets/nav_item.dart';
import 'package:cb_prestige_qr/features/analysis/presentation/views/analysis_view.dart';
import 'package:cb_prestige_qr/features/history/presentation/views/history_view.dart';
import 'package:cb_prestige_qr/features/home/presentation/views/home_view.dart';
import 'package:cb_prestige_qr/features/scan/presentation/views/scan_flow.dart';
import 'package:cb_prestige_qr/features/settings/presentation/views/settings_view.dart';
import 'package:flutter/material.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';

final navIndexProvider = NotifierProvider<NavIndexNotifier, int>(
  NavIndexNotifier.new,
);

class NavIndexNotifier extends Notifier<int> {
  @override
  int build() => 0;

  void setIndex(int index) {
    if (state == index) return;
    state = index;
  }
}

class MainShell extends ConsumerStatefulWidget {
  const MainShell({super.key});

  @override
  ConsumerState<MainShell> createState() => _MainShellState();
}

class _MainShellState extends ConsumerState<MainShell> {
  Timer? _timer;
  var _isLoading = false;

  void _startLoading([Duration duration = const Duration(seconds: 1)]) {
    _timer?.cancel();
    if (!_isLoading) {
      setState(() => _isLoading = true);
    }
    _timer = Timer(duration, () {
      if (!mounted) return;
      setState(() => _isLoading = false);
    });
  }

  @override
  void initState() {
    super.initState();
    final initialIndex = ref.read(navIndexProvider);
    if (initialIndex != 0) {
      _startLoading();
    }
  }

  @override
  void dispose() {
    _timer?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final selectedIndex = ref.watch(navIndexProvider);
    final theme = Theme.of(context);

    ref.listen<int>(navIndexProvider, (previous, next) {
      if (previous == null || previous == next || next == 0) return;
      _startLoading();
    });

    const pages = <Widget>[
      HomeView(),
      AnalysisView(),
      SizedBox(),
      HistoryView(),
      SettingsView(),
    ];

    return Stack(
      children: [
        Scaffold(
          extendBody: true,
          body: IndexedStack(index: selectedIndex, children: pages),
          bottomNavigationBar: Padding(
            padding: const EdgeInsets.symmetric(horizontal: 0),
            child: ClipRRect(
              borderRadius: BorderRadius.circular(16),
              child: BackdropFilter(
                filter: ImageFilter.blur(sigmaX: 20, sigmaY: 20),
                child: Container(
                  height: 70 + MediaQuery.of(context).padding.bottom,
                  decoration: BoxDecoration(
                    color: theme.scaffoldBackgroundColor,
                    borderRadius: BorderRadius.circular(16),
                    border: Border.all(color: Colors.white.withAlpha(31)),
                    boxShadow: [
                      BoxShadow(
                        color: Colors.black.withAlpha(31),
                        blurRadius: 25,
                        offset: const Offset(0, 10),
                      ),
                    ],
                  ),
                  child: Padding(
                    padding: EdgeInsets.only(
                      bottom: MediaQuery.of(context).padding.bottom,
                    ),
                    child: Row(
                      children: [
                        Expanded(
                          child: NavItem(
                            icon: Icons.home_rounded,
                            isActive: selectedIndex == 0,
                            onTap: () =>
                                ref.read(navIndexProvider.notifier).setIndex(0),
                          ),
                        ),
                        Expanded(
                          child: NavItem(
                            icon: Icons.analytics,
                            isActive: selectedIndex == 1,
                            onTap: () =>
                                ref.read(navIndexProvider.notifier).setIndex(1),
                          ),
                        ),
                        Expanded(
                          child: CenterNavButton(
                            isActive: false,
                            onTap: () {
                              Navigator.push(
                                context,
                                MaterialPageRoute(
                                  builder: (_) => const ScanFlow(),
                                ),
                              );
                            },
                          ),
                        ),
                        Expanded(
                          child: NavItem(
                            icon: Icons.history_rounded,
                            isActive: selectedIndex == 3,
                            onTap: () =>
                                ref.read(navIndexProvider.notifier).setIndex(3),
                          ),
                        ),
                        Expanded(
                          child: NavItem(
                            icon: Icons.person_rounded,
                            isActive: selectedIndex == 4,
                            onTap: () =>
                                ref.read(navIndexProvider.notifier).setIndex(4),
                          ),
                        ),
                      ],
                    ),
                  ),
                ),
              ),
            ),
          ),
        ),
        GlobalLoadingOverlay(isLoading: _isLoading),
      ],
    );
  }
}