import 'dart:async';

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

import 'dji_service.dart';
import 'flight_model.dart';
import 'login_page.dart';
import 'pb_auth.dart';
import 'theme.dart';
import 'ui/album_page.dart';
import 'ui/flight_control_page.dart';
import 'ui/go_fly_page.dart';
import 'uploader.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await SystemChrome.setPreferredOrientations(<DeviceOrientation>[DeviceOrientation.portraitUp]);
  await auth.init();
  runApp(const DjiSampleApp());
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'PilotVault',
      theme: PV.theme(),
      // The app is usable without signing in; login lives behind the user panel.
      home: const HomePage(),
    );
  }
}

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

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

class _HomePageState extends State<HomePage> {
  final DjiService _dji = DjiService();
  final FlightModel _model = FlightModel();
  StreamSubscription<Map<String, dynamic>>? _sub;
  StreamSubscription<AuthStatus>? _authSub;
  StreamSubscription<Position>? _phoneLocSub;

  // Streams telemetry to the API Server and receives commands back.
  late final ServerUploader _uploader;
  StreamSubscription<UploadStatus>? _uploadSub;
  final TextEditingController _serverHost =
      TextEditingController(text: '10.2.1.101:8080');

  @override
  void initState() {
    super.initState();
    _uploader = ServerUploader(
      onCommand: _handleServerCommand,
      snapshotProvider: _buildStateSnapshot,
    );
    _uploadSub = _uploader.status.listen((UploadStatus s) {
      _model.upload = s;
      _model.bump();
    });
    // Rebuild when the session changes so the user panel reflects sign-in/out.
    _authSub = auth.status.listen((_) {
      if (mounted) setState(() {});
    });
    _init();
    _startPhoneLocation();
  }

  /// Streams the phone's own GPS (coarse, low-frequency) and reports it to the
  /// server as a telemetry field — a location fallback for the Web App's auto
  /// bounding box when the drone has no fix. Best-effort: silently gives up if
  /// location services or permission are unavailable.
  Future<void> _startPhoneLocation() async {
    try {
      if (!await Geolocator.isLocationServiceEnabled()) return;
      LocationPermission perm = await Geolocator.checkPermission();
      if (perm == LocationPermission.denied) {
        perm = await Geolocator.requestPermission();
      }
      if (perm == LocationPermission.denied || perm == LocationPermission.deniedForever) {
        return;
      }
      _phoneLocSub = Geolocator.getPositionStream(
        locationSettings: const LocationSettings(
          accuracy: LocationAccuracy.low, // country-level is all the bbox needs
          distanceFilter: 1000, // metres — infrequent updates
        ),
      ).listen((Position pos) {
        _model.phoneLatitude = pos.latitude;
        _model.phoneLongitude = pos.longitude;
        _model.bump();
        // Report to the server (rides the existing telemetry channel; only the
        // phone fields are present, so it never disturbs drone telemetry).
        _uploader.onEvent(<String, dynamic>{
          'type': 'telemetry',
          'phoneLatitude': pos.latitude,
          'phoneLongitude': pos.longitude,
        });
      });
    } catch (_) {
      // Location plugin/permission unavailable — non-fatal.
    }
  }

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

  void _onEvent(Map<String, dynamic> event) {
    if (!mounted) return;
    // Forward every event to the API server (throttled internally).
    _uploader.onEvent(event);
    switch (event['type'] as String?) {
      case 'registration':
        switch (event['state'] as String?) {
          case 'registering':
            _model.registration = RegistrationState.registering;
            _model.registrationError = null;
            break;
          case 'success':
            _model.registration = RegistrationState.success;
            break;
          case 'failed':
            _model.registration = RegistrationState.failed;
            _model.registrationError = event['error'] as String?;
            break;
        }
        _model.bump();
        break;
      case 'connection':
        _model.connected = event['connected'] as bool? ?? false;
        _model.model = event['model'] as String?;
        if (!_model.connected) _clearTelemetry();
        _model.bump();
        break;
      case 'telemetry':
        // Ignore stray telemetry that arrives after a disconnect — otherwise it
        // repopulates values _clearTelemetry() just wiped, leaving stale readings.
        if (!_model.connected) break;
        _model.satellites = event['satelliteCount'] as int?;
        _model.isFlying = event['isFlying'] as bool?;
        _model.flightMode = event['flightMode'] as String?;
        _model.altitude = (event['altitude'] as num?)?.toDouble();
        _model.latitude = (event['latitude'] as num?)?.toDouble();
        _model.longitude = (event['longitude'] as num?)?.toDouble();
        _model.bump();
        break;
      case 'battery':
        // Same guard: a battery packet trailing a disconnect must not revive the
        // last percentage (the reported "disconnected but still 42%" bug).
        if (!_model.connected) break;
        _model.batteryPercent = event['percent'] as int?;
        _model.bump();
        break;
    }
  }

  void _clearTelemetry() {
    _model.satellites = null;
    _model.isFlying = null;
    _model.flightMode = null;
    _model.altitude = null;
    _model.latitude = null;
    _model.longitude = null;
    _model.batteryPercent = null;
  }

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

  // ── API server upload ──────────────────────────────────────────────────────

  Future<void> _toggleUpload() async {
    if (_model.upload == UploadStatus.disabled) {
      await _uploader.enable(_serverHost.text);
    } else {
      await _uploader.disable();
    }
  }

  /// Builds events describing the app's CURRENT state, sent to the server right
  /// after (re)connecting so it always reflects reality.
  List<Map<String, dynamic>> _buildStateSnapshot() {
    final List<Map<String, dynamic>> events = <Map<String, dynamic>>[
      <String, dynamic>{'type': 'registration', 'state': _registrationWire()},
      <String, dynamic>{'type': 'connection', 'connected': _model.connected, 'model': _model.model ?? ''},
    ];
    if (_model.batteryPercent != null) {
      events.add(<String, dynamic>{'type': 'battery', 'percent': _model.batteryPercent});
    }
    final Map<String, dynamic> tel = <String, dynamic>{'type': 'telemetry'};
    if (_model.satellites != null) tel['satelliteCount'] = _model.satellites;
    if (_model.isFlying != null) tel['isFlying'] = _model.isFlying;
    if (_model.flightMode != null) tel['flightMode'] = _model.flightMode;
    if (_model.altitude != null) tel['altitude'] = _model.altitude;
    if (_model.latitude != null) tel['latitude'] = _model.latitude;
    if (_model.longitude != null) tel['longitude'] = _model.longitude;
    if (_model.phoneLatitude != null) tel['phoneLatitude'] = _model.phoneLatitude;
    if (_model.phoneLongitude != null) tel['phoneLongitude'] = _model.phoneLongitude;
    if (tel.length > 1) events.add(tel);
    return events;
  }

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

  /// Handles commands pushed down from the server.
  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');
  }

  @override
  void dispose() {
    _sub?.cancel();
    _authSub?.cancel();
    _phoneLocSub?.cancel();
    _uploadSub?.cancel();
    _uploader.dispose();
    _serverHost.dispose();
    _model.dispose();
    super.dispose();
  }

  /// Opens the login page as a modal popup (from the user panel). Returns to the
  /// caller once dismissed; the auth listener refreshes the UI on success.
  Future<void> _openLogin() async {
    await Navigator.of(context).push(MaterialPageRoute<void>(
      fullscreenDialog: true,
      builder: (BuildContext ctx) => LoginPage(onSignedIn: () => Navigator.of(ctx).pop()),
    ));
  }

  // ── Navigation ───────────────────────────────────────────────────────────

  void _goFly() {
    Navigator.of(context).push(MaterialPageRoute<void>(
      builder: (_) => FlightControlPage(model: _model),
    ));
  }

  void _openAlbum() {
    Navigator.of(context).push(MaterialPageRoute<void>(builder: (_) => const AlbumPage()));
  }

  void _onTile(String tile) => _snack('$tile — coming soon');

  // ── UI ───────────────────────────────────────────────────────────────────

  @override
  Widget build(BuildContext context) {
    return GoFlyPage(
      model: _model,
      onGoFly: _goFly,
      onOpenAlbum: _openAlbum,
      onSettings: _openSettings,
      onTile: _onTile,
    );
  }

  /// Aircraft/connection controls that don't appear on the design's launch
  /// screen live here: MSDK registration, product connection, and telemetry
  /// streaming to the API Server, plus account sign-out.
  void _openSettings() {
    final PVScheme s = PVScheme.of(context);
    showModalBottomSheet<void>(
      context: context,
      backgroundColor: s.surface,
      isScrollControlled: true,
      shape: const RoundedRectangleBorder(
        borderRadius: BorderRadius.vertical(top: Radius.circular(20)),
      ),
      builder: (BuildContext context) {
        return AnimatedBuilder(
          animation: _model,
          builder: (BuildContext context, _) {
            final (Color, String) reg = switch (_model.registration) {
              RegistrationState.idle => (s.textTertiary, 'Not registered'),
              RegistrationState.registering => (s.warning, 'Registering…'),
              RegistrationState.success => (s.success, 'Registered'),
              RegistrationState.failed => (s.danger, 'Registration failed'),
            };
            final (Color, String) up = switch (_model.upload) {
              UploadStatus.disabled => (s.textTertiary, 'Off'),
              UploadStatus.connecting => (s.warning, 'Connecting…'),
              UploadStatus.connected => (s.success, 'Streaming'),
              UploadStatus.error => (s.danger, 'Retrying…'),
            };
            final bool streaming = _model.upload != UploadStatus.disabled;

            return Padding(
              padding: EdgeInsets.fromLTRB(20, 12, 20, 20 + MediaQuery.of(context).viewInsets.bottom),
              child: Column(
                mainAxisSize: MainAxisSize.min,
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: <Widget>[
                  Center(
                    child: Container(
                      width: 40,
                      height: 4,
                      decoration: BoxDecoration(color: s.borderStrong, borderRadius: BorderRadius.circular(999)),
                    ),
                  ),
                  const SizedBox(height: 16),
                  // Account — signed-in identity + sign-out, or a sign-in entry
                  // that opens the login page (biometric / face live there).
                  Row(
                    children: <Widget>[
                      Expanded(
                        child: Text(
                          auth.isAuthed
                              ? (auth.userEmail.isEmpty ? 'Signed in' : auth.userEmail)
                              : 'Not signed in',
                          style: TextStyle(fontFamily: PV.fontSans, fontSize: 14, fontWeight: FontWeight.w600, color: s.textPrimary),
                        ),
                      ),
                      if (auth.isAuthed)
                        TextButton.icon(
                          onPressed: () {
                            Navigator.of(context).pop();
                            auth.signOut();
                          },
                          icon: Icon(Icons.logout, size: 16, color: s.textSecondary),
                          label: Text('Sign out', style: TextStyle(color: s.textSecondary)),
                        )
                      else
                        FilledButton.icon(
                          onPressed: () {
                            Navigator.of(context).pop();
                            _openLogin();
                          },
                          icon: const Icon(Icons.login, size: 16),
                          label: const Text('Sign in'),
                        ),
                    ],
                  ),
                  // Registration, aircraft and telemetry controls require a
                  // session — they only appear once the user has signed in.
                  if (auth.isAuthed) ...<Widget>[
                    Divider(color: s.border, height: 24),

                    _settingRow(s, 'Registration', reg.$1, reg.$2, trailing: 'MSDK · ${_model.sdkVersion}'),
                    if (_model.registrationError != null) ...<Widget>[
                      const SizedBox(height: 6),
                      Text(_model.registrationError!, style: TextStyle(fontFamily: PV.fontSans, fontSize: 13, color: s.danger)),
                    ],
                    const SizedBox(height: 10),
                    FilledButton(
                      onPressed: _model.registration == RegistrationState.registering ? null : _register,
                      child: const Text('Register app'),
                    ),
                    const SizedBox(height: 20),

                    _settingRow(s, 'Aircraft', _model.connected ? s.success : s.textTertiary,
                        _model.connected ? 'Connected' : 'No product',
                        trailing: _model.model ?? '—'),
                    const SizedBox(height: 10),
                    OutlinedButton.icon(
                      onPressed: _model.registered ? _connect : null,
                      icon: const Icon(Icons.usb, size: 18),
                      label: const Text('Connect to product'),
                    ),
                    const SizedBox(height: 20),

                    _settingRow(s, 'Telemetry stream', up.$1, up.$2),
                    const SizedBox(height: 10),
                    TextField(
                      controller: _serverHost,
                      enabled: !streaming,
                      style: PV.body,
                      decoration: const InputDecoration(labelText: 'API Server host', hintText: '10.2.1.101:8080'),
                    ),
                    const SizedBox(height: 10),
                    FilledButton.icon(
                      style: FilledButton.styleFrom(backgroundColor: streaming ? s.danger : s.accent),
                      onPressed: _model.upload == UploadStatus.connecting ? null : _toggleUpload,
                      icon: Icon(streaming ? Icons.stop : Icons.play_arrow, size: 18),
                      label: Text(streaming ? 'Stop streaming' : 'Start streaming'),
                    ),
                  ] else ...<Widget>[
                    const SizedBox(height: 14),
                    Text(
                      'Sign in to manage registration, aircraft connection and telemetry streaming.',
                      style: TextStyle(fontFamily: PV.fontSans, fontSize: 13, color: s.textSecondary),
                    ),
                  ],
                ],
              ),
            );
          },
        );
      },
    );
  }

  Widget _settingRow(PVScheme s, String title, Color dot, String status, {String? trailing}) {
    return Row(
      children: <Widget>[
        Container(width: 8, height: 8, decoration: BoxDecoration(color: dot, shape: BoxShape.circle)),
        const SizedBox(width: 10),
        Text(title, style: TextStyle(fontFamily: PV.fontSans, fontSize: 15, fontWeight: FontWeight.w600, color: s.textPrimary)),
        const SizedBox(width: 8),
        Text(status, style: TextStyle(fontFamily: PV.fontSans, fontSize: 13, color: s.textSecondary)),
        const Spacer(),
        if (trailing != null)
          Text(trailing, style: TextStyle(fontFamily: PV.fontMono, fontSize: 12, color: s.textTertiary)),
      ],
    );
  }
}