import 'dart:async';

import 'package:flutter/material.dart';

import 'dji_service.dart';
import 'login_page.dart';
import 'pb_service.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await pb.init();
  runApp(const DjiSampleApp());
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'DJI MSDK Sample',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: const Color(0xFF1565C0)),
        useMaterial3: true,
      ),
      home: const AuthGate(),
    );
  }
}

/// Shows the login screen until the user is authenticated with PocketBase.
class AuthGate extends StatefulWidget {
  const AuthGate({super.key});

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

class _AuthGateState extends State<AuthGate> {
  StreamSubscription<BackendStatus>? _sub;

  @override
  void initState() {
    super.initState();
    _sub = pb.status.listen((_) {
      if (mounted) setState(() {});
    });
  }

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

  @override
  Widget build(BuildContext context) {
    if (pb.isAuthed) {
      return const HomePage();
    }
    return LoginPage(onSignedIn: () => setState(() {}));
  }
}

enum RegistrationState { idle, registering, success, failed }

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

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final DjiService _dji = DjiService();
  StreamSubscription<Map<String, dynamic>>? _sub;
  StreamSubscription<BackendStatus>? _backendSub;
  BackendStatus _backend = BackendStatus.online;

  String _sdkVersion = '…';
  RegistrationState _registration = RegistrationState.idle;
  String? _registrationError;

  bool _connected = false;
  String? _model;

  int? _satellites;
  bool? _isFlying;
  String? _flightMode;
  double? _altitude;
  double? _latitude;
  double? _longitude;
  int? _batteryPercent;

  @override
  void initState() {
    super.initState();
    _backend = pb.currentStatus;
    // Route server interactions through PocketBase.
    pb.onCommand = _handleServerCommand;
    pb.stateProvider = _currentState;
    _backendSub = pb.status.listen((BackendStatus s) {
      if (mounted) setState(() => _backend = s);
    });
    _init();
  }

  Future<void> _init() async {
    _sub = _dji.events().listen(_onEvent, onError: (Object e) {
      _snack('Event channel error: $e');
    });
    try {
      final String version = await _dji.getSdkVersion();
      if (mounted) setState(() => _sdkVersion = version);
    } catch (_) {
      if (mounted) setState(() => _sdkVersion = 'unavailable');
    }
  }

  void _onEvent(Map<String, dynamic> event) {
    if (!mounted) return;
    // Persist every event to PocketBase (telemetry is throttled inside).
    pb.onEvent(event);
    switch (event['type'] as String?) {
      case 'registration':
        setState(() {
          switch (event['state'] as String?) {
            case 'registering':
              _registration = RegistrationState.registering;
              _registrationError = null;
              break;
            case 'success':
              _registration = RegistrationState.success;
              break;
            case 'failed':
              _registration = RegistrationState.failed;
              _registrationError = event['error'] as String?;
              break;
          }
        });
        break;
      case 'connection':
        setState(() {
          _connected = event['connected'] as bool? ?? false;
          _model = event['model'] as String?;
          if (!_connected) _clearTelemetry();
        });
        break;
      case 'telemetry':
        setState(() {
          _satellites = event['satelliteCount'] as int?;
          _isFlying = event['isFlying'] as bool?;
          _flightMode = event['flightMode'] as String?;
          _altitude = (event['altitude'] as num?)?.toDouble();
          _latitude = (event['latitude'] as num?)?.toDouble();
          _longitude = (event['longitude'] as num?)?.toDouble();
        });
        break;
      case 'battery':
        setState(() => _batteryPercent = event['percent'] as int?);
        break;
    }
  }

  void _clearTelemetry() {
    _satellites = null;
    _isFlying = null;
    _flightMode = null;
    _altitude = null;
    _latitude = null;
    _longitude = null;
    _batteryPercent = null;
  }

  /// Current app state shared with PocketBase for the device presence record.
  Map<String, dynamic> _currentState() => <String, dynamic>{
        'connected': _connected,
        'model': _model ?? '',
        'registration': _registrationWire(),
      };

  String _registrationWire() {
    switch (_registration) {
      case RegistrationState.success:
        return 'success';
      case RegistrationState.registering:
        return 'registering';
      case RegistrationState.failed:
        return 'failed';
      case RegistrationState.idle:
        return 'not registered';
    }
  }

  Future<void> _register() async {
    try {
      await _dji.registerApp();
    } catch (e) {
      _snack('registerApp failed: $e');
    }
  }

  Future<void> _connect() async {
    try {
      final bool started = await _dji.startConnection();
      _snack(started ? 'Scanning for product…' : 'Could not start connection');
    } catch (e) {
      _snack('startConnection failed: $e');
    }
  }

  void _handleServerCommand(String command, Map<String, dynamic> payload) {
    switch (command) {
      case 'registerApp':
        _register();
        break;
      case 'startConnection':
        _connect();
        break;
      case 'stopConnection':
        _dji.stopConnection();
        break;
      default:
        _snack('Unknown server command: $command');
        return;
    }
    _snack('Server command: $command');
  }

  Future<void> _logout() async {
    await pb.signOut();
    if (mounted) {
      Navigator.of(context).pushAndRemoveUntil(
        MaterialPageRoute<void>(
          builder: (_) => const AuthGate(),
        ),
        (Route<dynamic> route) => false,
      );
    }
  }

  void _snack(String msg) {
    if (!mounted) return;
    ScaffoldMessenger.of(context)
      ..clearSnackBars()
      ..showSnackBar(SnackBar(content: Text(msg)));
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('DJI MSDK Sample'),
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        actions: <Widget>[
          IconButton(
            tooltip: 'Log out',
            onPressed: _logout,
            icon: const Icon(Icons.logout),
          ),
        ],
      ),
      body: ListView(
        padding: const EdgeInsets.all(16),
        children: <Widget>[
          _backendCard(),
          const SizedBox(height: 12),
          _registrationCard(),
          const SizedBox(height: 12),
          _connectionCard(),
          const SizedBox(height: 12),
          _telemetryCard(),
        ],
      ),
    );
  }

  Widget _backendCard() {
    final (Color color, String label) = switch (_backend) {
      BackendStatus.online => (Colors.green, 'Streaming to PocketBase'),
      BackendStatus.signingIn => (Colors.orange, 'Connecting…'),
      BackendStatus.error => (Colors.red, 'Backend error'),
      BackendStatus.signedOut => (Colors.grey, 'Signed out'),
    };
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Row(
          children: <Widget>[
            Icon(Icons.cloud_done, color: color),
            const SizedBox(width: 10),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: <Widget>[
                  Text(label, style: Theme.of(context).textTheme.titleMedium),
                  const SizedBox(height: 2),
                  Text('${pb.userEmail} · device "${pb.deviceId}"',
                      style: const TextStyle(color: Colors.black54, fontSize: 12)),
                ],
              ),
            ),
            TextButton.icon(
              onPressed: _logout,
              icon: const Icon(Icons.logout),
              label: const Text('Log out'),
            ),
          ],
        ),
      ),
    );
  }

  Widget _registrationCard() {
    final (Color color, IconData icon, String label) = switch (_registration) {
      RegistrationState.idle => (Colors.grey, Icons.help_outline, 'Not registered'),
      RegistrationState.registering => (Colors.orange, Icons.sync, 'Registering…'),
      RegistrationState.success => (Colors.green, Icons.verified, 'Registered'),
      RegistrationState.failed => (Colors.red, Icons.error_outline, 'Registration failed'),
    };

    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Row(
              children: <Widget>[
                Icon(icon, color: color),
                const SizedBox(width: 8),
                Text(label, style: Theme.of(context).textTheme.titleMedium),
              ],
            ),
            const SizedBox(height: 4),
            Text('SDK version: $_sdkVersion'),
            if (_registrationError != null) ...<Widget>[
              const SizedBox(height: 4),
              Text(_registrationError!, style: const TextStyle(color: Colors.red)),
            ],
            const SizedBox(height: 12),
            FilledButton.icon(
              onPressed: _registration == RegistrationState.registering ? null : _register,
              icon: const Icon(Icons.app_registration),
              label: const Text('Register app'),
            ),
          ],
        ),
      ),
    );
  }

  Widget _connectionCard() {
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Row(
              children: <Widget>[
                Icon(_connected ? Icons.link : Icons.link_off,
                    color: _connected ? Colors.green : Colors.grey),
                const SizedBox(width: 8),
                Text(_connected ? 'Product connected' : 'No product',
                    style: Theme.of(context).textTheme.titleMedium),
              ],
            ),
            const SizedBox(height: 4),
            Text('Model: ${_model ?? '—'}'),
            const SizedBox(height: 12),
            OutlinedButton.icon(
              onPressed: _registration == RegistrationState.success ? _connect : null,
              icon: const Icon(Icons.usb),
              label: const Text('Connect to product'),
            ),
          ],
        ),
      ),
    );
  }

  Widget _telemetryCard() {
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Text('Telemetry', style: Theme.of(context).textTheme.titleMedium),
            const Divider(),
            _row('Battery', _batteryPercent == null ? '—' : '$_batteryPercent%'),
            _row('GPS satellites', _satellites?.toString() ?? '—'),
            _row('Flight mode', _flightMode ?? '—'),
            _row('Flying', _isFlying == null ? '—' : (_isFlying! ? 'yes' : 'no')),
            _row('Altitude', _altitude == null ? '—' : '${_altitude!.toStringAsFixed(1)} m'),
            _row('Latitude', _latitude?.toStringAsFixed(6) ?? '—'),
            _row('Longitude', _longitude?.toStringAsFixed(6) ?? '—'),
          ],
        ),
      ),
    );
  }

  Widget _row(String label, String value) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 4),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: <Widget>[
          Text(label, style: const TextStyle(color: Colors.black54)),
          Text(value, style: const TextStyle(fontWeight: FontWeight.w600)),
        ],
      ),
    );
  }
}