/// Bottom navigation: products, scan, and shop log.
library;

import 'package:flutter/material.dart';

import 'products_screen.dart';
import 'scan_screen.dart';
import 'services/app_settings.dart';
import 'services/product_repository.dart';
import 'shop_log_screen.dart';

class HomeShell extends StatefulWidget {
  const HomeShell({super.key, required this.repository});

  final ProductRepository repository;

  @override
  State<HomeShell> createState() => _HomeShellState();
}

class _HomeShellState extends State<HomeShell> {
  static const _scanIndex = 1;
  static const _shopLogIndex = 2;

  int _index = _scanIndex;
  int _revision = 0;
  AppSettings? _settings;
  int _seenGeneration = 0;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    final settings = SettingsScope.maybeOf(context);
    if (settings != _settings) {
      _settings?.removeListener(_onSettings);
      _settings = settings;
      _seenGeneration = settings?.catalogGeneration ?? 0;
      _settings?.addListener(_onSettings);
    }
  }

  @override
  void dispose() {
    _settings?.removeListener(_onSettings);
    super.dispose();
  }

  void _onSettings() {
    final generation = _settings?.catalogGeneration ?? 0;
    if (generation == _seenGeneration) return;
    _seenGeneration = generation;
    if (mounted) setState(() => _revision++);
  }

  void _onTripSaved() {
    setState(() {
      _index = _shopLogIndex;
      _revision++;
    });
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Shopping trip saved.')),
      );
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: switch (_index) {
        0 => ProductsScreen(
            key: ValueKey('products-$_revision'),
            repository: widget.repository,
          ),
        1 => ScanScreen(
            repository: widget.repository,
            onTripSaved: _onTripSaved,
          ),
        _ => ShopLogScreen(
            key: ValueKey('shops-$_revision'),
            repository: widget.repository,
          ),
      },
      bottomNavigationBar: NavigationBar(
        selectedIndex: _index,
        onDestinationSelected: (index) => setState(() => _index = index),
        destinations: const [
          NavigationDestination(
            icon: Icon(Icons.inventory_2_outlined),
            selectedIcon: Icon(Icons.inventory_2),
            label: 'Products',
          ),
          NavigationDestination(
            icon: Icon(Icons.photo_camera_outlined),
            selectedIcon: Icon(Icons.photo_camera),
            label: 'Scan',
          ),
          NavigationDestination(
            icon: Icon(Icons.receipt_long_outlined),
            selectedIcon: Icon(Icons.receipt_long),
            label: 'Shop log',
          ),
        ],
      ),
    );
  }
}