import 'dart:async';
import 'dart:io';

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

import 'package:pocketbase/pocketbase.dart';
import 'package:provider/provider.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:window_manager/window_manager.dart';

import 'package:shoppinglist/services/api.dart';
import 'package:shoppinglist/models/models.dart';
import 'package:shoppinglist/providers/theme.dart';

late final PocketBase pb;
late final ApiService apiService;

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  if (Platform.isAndroid || Platform.isIOS) {
    await SystemChrome.setPreferredOrientations([DeviceOrientation.portraitUp]);
  }

  if (Platform.isWindows || Platform.isLinux || Platform.isMacOS) {
    await windowManager.ensureInitialized();
    const WindowOptions windowOptions = WindowOptions(
      size: Size(400, 720),
      minimumSize: Size(380, 600),
      center: true,
      title: 'Einkaufsliste',
    );
    windowManager.waitUntilReadyToShow(windowOptions, () async {
      await windowManager.show();
      await windowManager.focus();
    });
  }

  final SharedPreferences prefs = await SharedPreferences.getInstance();

  final AsyncAuthStore store = AsyncAuthStore(
    save: (String data) async => prefs.setString('pb_auth', data),
    initial: prefs.getString('pb_auth'),
  );

  pb = PocketBase('https://pb.flumm.io', authStore: store);
  apiService = ApiService(pb);

  runApp(
    ChangeNotifierProvider(
      create: (_) => ThemeProvider(prefs),
      child: const MyApp(),
    ),
  );
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return Consumer<ThemeProvider>(
      builder: (context, themeProvider, child) {
        return MaterialApp(
          title: 'Einkaufsliste',
          debugShowCheckedModeBanner: false,
          theme: ThemeData(
            colorScheme: ColorScheme.fromSeed(
              seedColor: Colors.deepPurple,
              brightness: Brightness.light,
            ),
            useMaterial3: true,
          ),
          darkTheme: ThemeData(
            colorScheme: ColorScheme.fromSeed(
              seedColor: Colors.deepPurple,
              brightness: Brightness.dark,
            ),
            useMaterial3: true,
          ),
          themeMode: themeProvider.themeMode,
          home: const AuthGate(),
        );
      },
    );
  }
}

class AuthGate extends StatefulWidget {
  const AuthGate({super.key});

  @override
  State<AuthGate> createState() => _AuthGateState();
}

class _AuthGateState extends State<AuthGate> {
  StreamSubscription? _authSub;
  bool _loggedIn = false;

  @override
  void initState() {
    super.initState();
    _loggedIn = pb.authStore.isValid;
    _authSub = pb.authStore.onChange.listen((_) {
      setState(() {
        _loggedIn = pb.authStore.isValid;
      });
    });
  }

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

  @override
  Widget build(BuildContext context) {
    if (!_loggedIn) {
      return const LoginPage();
    } else {
      return const ListsPage();
    }
  }
}

class LoginPage extends StatefulWidget {
  const LoginPage({super.key});

  @override
  State<LoginPage> createState() => _LoginPageState();
}

class _LoginPageState extends State<LoginPage> {
  final TextEditingController _emailCtl = TextEditingController();
  final TextEditingController _pwCtl = TextEditingController();
  bool _isRegister = false;
  bool _loading = false;
  String? _error;

  Future<void> _submit() async {
    setState(() {
      _loading = true;
      _error = null;
    });
    try {
      final String email = _emailCtl.text.trim();
      final String password = _pwCtl.text.trim();
      if (_isRegister) {
        await apiService.register(email, password);
      } else {
        await apiService.login(email, password);
      }
    } catch (e) {
      setState(() => _error = e.toString());
    } finally {
      if (mounted) {
        setState(() => _loading = false);
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(_isRegister ? 'Registrierung' : 'Login')),
      body: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            TextField(
              controller: _emailCtl,
              decoration: const InputDecoration(labelText: 'Email'),
              keyboardType: TextInputType.emailAddress,
            ),
            const SizedBox(height: 8),
            TextField(
              controller: _pwCtl,
              decoration: const InputDecoration(labelText: 'Passwort'),
              obscureText: true,
            ),
            const SizedBox(height: 20),
            if (_error != null) ...[
              Text(
                _error!,
                style: TextStyle(color: Theme.of(context).colorScheme.error),
              ),
              const SizedBox(height: 12),
            ],
            ElevatedButton(
              onPressed: _loading ? null : _submit,
              child: _loading
                  ? const CircularProgressIndicator()
                  : Text(_isRegister ? 'Registrieren' : 'Einloggen'),
            ),
            TextButton(
              onPressed: _loading
                  ? null
                  : () => setState(() => _isRegister = !_isRegister),
              child: Text(
                _isRegister ? 'Ich habe schon ein Konto' : 'Neu registrieren',
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class ListsPage extends StatefulWidget {
  const ListsPage({super.key});

  @override
  State<ListsPage> createState() => _ListsPageState();
}

class _ListsPageState extends State<ListsPage> {
  late Future<List<Liste>> _listsFuture;

  @override
  void initState() {
    super.initState();
    _loadLists();
  }

  void _loadLists() {
    setState(() => _listsFuture = apiService.getLists());
  }

  Future<void> _createList() async {
    final TextEditingController titleCtl = TextEditingController();
    final bool? ok = await showDialog<bool>(
      context: context,
      builder: (c) => AlertDialog(
        title: const Text('Neue Liste'),
        content: TextField(
          controller: titleCtl,
          decoration: const InputDecoration(labelText: 'Titel'),
          autofocus: true,
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(c, false),
            child: const Text('Abbrechen'),
          ),
          TextButton(
            onPressed: () => Navigator.pop(c, true),
            child: const Text('Erstellen'),
          ),
        ],
      ),
    );
    if (ok != true || titleCtl.text.trim().isEmpty) return;

    try {
      await apiService.createList(titleCtl.text.trim());
      _loadLists();
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(
          context,
        ).showSnackBar(SnackBar(content: Text('Fehler: $e')));
      }
    }
  }

  void _openList(Liste list) {
    Navigator.push(
      context,
      MaterialPageRoute(builder: (_) => ListDetailPage(list: list)),
    ).then((_) => _loadLists());
  }

  @override
  Widget build(BuildContext context) {
    final ThemeProvider themeProvider = Provider.of<ThemeProvider>(
      context,
      listen: false,
    );

    return Scaffold(
      appBar: AppBar(
        title: const Text('Deine Listen'),
        actions: [
          PopupMenuButton<ThemeMode>(
            onSelected: (mode) => themeProvider.setThemeMode(mode),
            itemBuilder: (context) => [
              const PopupMenuItem(value: ThemeMode.light, child: Text('Hell')),
              const PopupMenuItem(value: ThemeMode.dark, child: Text('Dunkel')),
              const PopupMenuItem(
                value: ThemeMode.system,
                child: Text('System'),
              ),
            ],
            icon: const Icon(Icons.brightness_6_outlined),
          ),
          IconButton(
            tooltip: 'Ausloggen',
            icon: const Icon(Icons.logout),
            onPressed: () {
              apiService.logout();
            },
          ),
        ],
      ),
      body: FutureBuilder<List<Liste>>(
        future: _listsFuture,
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return const Center(child: CircularProgressIndicator());
          }
          if (snapshot.hasError) {
            return Center(child: Text('Fehler: ${snapshot.error}'));
          }
          final lists = snapshot.data ?? [];
          if (lists.isEmpty) {
            return const Center(child: Text('Keine Listen gefunden.'));
          }
          return ListView.builder(
            itemCount: lists.length,
            itemBuilder: (c, i) {
              final l = lists[i];
              return ListTile(title: Text(l.title), onTap: () => _openList(l));
            },
          );
        },
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _createList,
        child: const Icon(Icons.add),
      ),
    );
  }
}

class ListDetailPage extends StatefulWidget {
  final Liste list;
  const ListDetailPage({super.key, required this.list});

  @override
  State<ListDetailPage> createState() => _ListDetailPageState();
}

class _ListDetailPageState extends State<ListDetailPage> {
  late Future<List<Item>> _itemsFuture;

  @override
  void initState() {
    super.initState();
    _loadItems();
  }

  void _loadItems() {
    setState(() => _itemsFuture = apiService.getItems(widget.list.id));
  }

  Future<void> _addItem() async {
    final TextEditingController ctl = TextEditingController();
    final bool? ok = await showDialog<bool>(
      context: context,
      builder: (c) => AlertDialog(
        title: const Text('Eintrag hinzufügen'),
        content: TextField(
          controller: ctl,
          decoration: const InputDecoration(labelText: 'Name'),
          autofocus: true,
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(c, false),
            child: const Text('Abbrechen'),
          ),
          TextButton(
            onPressed: () => Navigator.pop(c, true),
            child: const Text('Hinzufügen'),
          ),
        ],
      ),
    );
    if (ok != true || ctl.text.trim().isEmpty) return;

    try {
      final List<Item> items = await _itemsFuture;
      final int maxPos = items.fold<int>(
        -1,
        (max, item) => item.position > max ? item.position : max,
      );
      await apiService.createItem(widget.list.id, ctl.text.trim(), maxPos + 1);
      _loadItems();
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(
          context,
        ).showSnackBar(SnackBar(content: Text('Fehler: $e')));
      }
    }
  }

  Future<void> _toggleItem(Item item) async {
    try {
      setState(() => item.checked = !item.checked);
      await apiService.updateItem(item.id, checked: item.checked);
    } catch (e) {
      setState(() => item.checked = !item.checked);
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Fehler beim Aktualisieren: $e')),
        );
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(widget.list.title)),
      body: FutureBuilder<List<Item>>(
        future: _itemsFuture,
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return const Center(child: CircularProgressIndicator());
          }
          if (snapshot.hasError) {
            return Center(child: Text('Fehler: ${snapshot.error}'));
          }
          final items = snapshot.data ?? [];
          return ListView.builder(
            itemCount: items.length,
            itemBuilder: (c, i) {
              final it = items[i];
              return CheckboxListTile(
                title: Text(it.name),
                value: it.checked,
                onChanged: (_) => _toggleItem(it),
              );
            },
          );
        },
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _addItem,
        child: const Icon(Icons.add),
      ),
    );
  }
}