import 'dart:async';
import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:flutter_bluetooth_serial/flutter_bluetooth_serial.dart';
import 'package:permission_handler/permission_handler.dart';

import 'core/bluetooth/bt_poller.dart';
import 'core/bluetooth/bt_service.dart';
import 'core/protocol/kpro_parser.dart';
import 'core/protocol/s300_parser.dart';
import 'core/protocol/sensor_state.dart';

void main() {
  runApp(const HvbtApp());
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'HV BT Dashboard',
      theme: ThemeData.dark(useMaterial3: true).copyWith(
        colorScheme: ColorScheme.fromSeed(
          seedColor: const Color(0xFFFF4444),
          brightness: Brightness.dark,
        ),
      ),
      home: const BtPickerScreen(),
      debugShowCheckedModeBanner: false,
    );
  }
}

// ─── Bluetooth Device Picker ──────────────────────────────────────────────────

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

  @override
  State<BtPickerScreen> createState() => _BtPickerScreenState();
}

class _BtPickerScreenState extends State<BtPickerScreen> {
  final BtService _btService = BtService();
  List<BluetoothDevice> _devices = [];
  bool _loading = true;
  String? _connectingAddress;
  String? _error;

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

  Future<void> _initBluetooth() async {
    setState(() { _loading = true; _error = null; });

    // 1. Request all required runtime permissions
    final statuses = await [
      Permission.bluetoothConnect,
      Permission.bluetoothScan,
      Permission.locationWhenInUse,
    ].request();

    final denied = statuses.entries
        .where((e) => e.value.isDenied || e.value.isPermanentlyDenied)
        .map((e) => e.key.toString())
        .toList();

    if (denied.isNotEmpty) {
      setState(() {
        _loading = false;
        _error = 'Permissions denied: ${denied.join(", ")}\n\n'
            'Go to Settings → Apps → HV BT Dashboard → Permissions and allow Bluetooth + Location, then tap Refresh.';
      });
      return;
    }

    // 2. Make sure Bluetooth is enabled (shows system dialog to turn it on)
    final btState = await FlutterBluetoothSerial.instance.state;
    if (btState != BluetoothState.STATE_ON) {
      await FlutterBluetoothSerial.instance.requestEnable();
      // Give the radio a moment to come up
      await Future<void>.delayed(const Duration(seconds: 1));
    }

    await _loadDevices();
  }

  Future<void> _loadDevices() async {
    setState(() { _loading = true; _error = null; });
    try {
      final devices = await _btService.getPairedDevices();
      setState(() {
        _devices = devices;
        _loading = false;
      });
    } catch (e) {
      setState(() {
        _error = 'Failed to load devices:\n$e\n\nMake sure Bluetooth is ON and tap Refresh.';
        _loading = false;
      });
    }
  }

  Future<void> _connect(BluetoothDevice device, EcuType ecuType) async {
    setState(() => _connectingAddress = device.address);
    try {
      await _btService.connect(device);
      if (!mounted) return;
      Navigator.of(context).pushReplacement(
        MaterialPageRoute(
          builder: (_) => LiveDataScreen(
            btService: _btService,
            deviceName: device.name ?? device.address,
            ecuType: ecuType,
          ),
        ),
      );
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _connectingAddress = null;
        _error = 'Connection to ${device.name ?? device.address} failed:\n$e\n\nMake sure the device is powered on and paired.';
      });
    }
  }

  void _showProtocolDialog(BluetoothDevice device) {
    showDialog<void>(
      context: context,
      builder: (ctx) => AlertDialog(
        title: Text(device.name ?? device.address),
        content: const Text('Select ECU protocol:'),
        actions: [
          TextButton(
            onPressed: () {
              Navigator.of(ctx).pop();
              _connect(device, EcuType.s300);
            },
            child: const Text('S300'),
          ),
          TextButton(
            onPressed: () {
              Navigator.of(ctx).pop();
              _connect(device, EcuType.kpro);
            },
            child: const Text('KPro'),
          ),
          TextButton(
            onPressed: () => Navigator.of(ctx).pop(),
            child: const Text('Cancel'),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('HV BT — Select Device'),
        actions: [
          IconButton(
            icon: const Icon(Icons.refresh),
            onPressed: _loading ? null : _initBluetooth,
            tooltip: 'Refresh',
          ),
        ],
      ),
      body: Column(
        children: [
          // Error banner
          if (_error != null)
            _ErrorBanner(
              message: _error!,
              onDismiss: () => setState(() => _error = null),
            ),

          Expanded(
            child: _loading
                ? const Center(
                    child: Column(
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        CircularProgressIndicator(),
                        SizedBox(height: 12),
                        Text('Loading paired devices…'),
                      ],
                    ),
                  )
                : _devices.isEmpty
                    ? const Center(
                        child: Padding(
                          padding: EdgeInsets.all(24),
                          child: Column(
                            mainAxisSize: MainAxisSize.min,
                            children: [
                              Icon(Icons.bluetooth_disabled,
                                  size: 64, color: Colors.grey),
                              SizedBox(height: 16),
                              Text(
                                'No paired Bluetooth devices found.',
                                style: TextStyle(fontSize: 16),
                                textAlign: TextAlign.center,
                              ),
                              SizedBox(height: 8),
                              Text(
                                'Go to Android Settings → Bluetooth and pair your ECU module first, then come back and tap Refresh.',
                                style: TextStyle(color: Colors.grey),
                                textAlign: TextAlign.center,
                              ),
                            ],
                          ),
                        ),
                      )
                    : ListView.separated(
                        itemCount: _devices.length,
                        separatorBuilder: (_, __) =>
                            const Divider(height: 1),
                        itemBuilder: (context, index) {
                          final device = _devices[index];
                          final isConnecting =
                              _connectingAddress == device.address;
                          return ListTile(
                            leading: Icon(
                              Icons.bluetooth,
                              color: isConnecting
                                  ? Colors.blue
                                  : Colors.grey,
                            ),
                            title:
                                Text(device.name ?? 'Unknown Device'),
                            subtitle: Text(device.address),
                            trailing: isConnecting
                                ? const SizedBox(
                                    width: 24,
                                    height: 24,
                                    child: CircularProgressIndicator(
                                        strokeWidth: 2),
                                  )
                                : const Icon(
                                    Icons.arrow_forward_ios,
                                    size: 16,
                                    color: Colors.grey,
                                  ),
                            onTap: isConnecting
                                ? null
                                : () => _showProtocolDialog(device),
                          );
                        },
                      ),
          ),
        ],
      ),
    );
  }
}

// ─── Live Data Screen ─────────────────────────────────────────────────────────

class LiveDataScreen extends StatefulWidget {
  final BtService btService;
  final String deviceName;
  final EcuType ecuType;

  const LiveDataScreen({
    super.key,
    required this.btService,
    required this.deviceName,
    required this.ecuType,
  });

  @override
  State<LiveDataScreen> createState() => _LiveDataScreenState();
}

class _LiveDataScreenState extends State<LiveDataScreen> {
  late final BtPoller _poller;
  StreamSubscription<Uint8List>? _frameSub;

  SensorState? _state;
  int _frameCount = 0;
  int _dropped = 0;
  DateTime? _lastFrameTime;

  // Debug log — last 20 events shown on screen
  final List<_LogEntry> _log = [];

  @override
  void initState() {
    super.initState();
    _addLog('Connecting to ${widget.deviceName}…', LogLevel.info);
    _addLog(
        'Protocol: ${widget.ecuType == EcuType.s300 ? "S300" : "KPro"}',
        LogLevel.info);

    _poller = BtPoller(
      widget.btService,
      ecuType: widget.ecuType,
      pollingInterval: const Duration(milliseconds: 100),
    );
    _poller.start();
    _addLog('Poller started — sending requests every 100ms', LogLevel.info);

    _frameSub = _poller.frameStream.listen(
      (Uint8List frame) {
        try {
          final SensorState s = widget.ecuType == EcuType.s300
              ? parseS300(frame)
              : parseKPro(frame);
          final now = DateTime.now();
          if (mounted) {
            setState(() {
              _state = s;
              _frameCount++;
              _dropped = _poller.droppedFrames;
              _lastFrameTime = now;
            });
            // Log first frame and then every 100 frames
            if (_frameCount == 1) {
              _addLog('First frame received! RPM=${s.rpm.toStringAsFixed(0)}',
                  LogLevel.ok);
            } else if (_frameCount % 100 == 0) {
              _addLog(
                  'Frame #$_frameCount  RPM=${s.rpm.toStringAsFixed(0)}  ECT=${s.ect.toStringAsFixed(1)}°C',
                  LogLevel.info);
            }
          }
        } catch (e) {
          _addLog('Parse error: $e', LogLevel.error);
        }
      },
      onError: (Object e) {
        _addLog('BT stream error: $e', LogLevel.error);
      },
      onDone: () {
        _addLog('BT stream closed (device disconnected?)', LogLevel.error);
      },
    );
  }

  void _addLog(String msg, LogLevel level) {
    if (!mounted) return;
    setState(() {
      _log.insert(
          0,
          _LogEntry(
            message: msg,
            level: level,
            time: DateTime.now(),
          ));
      if (_log.length > 20) _log.removeLast();
    });
  }

  @override
  void dispose() {
    _frameSub?.cancel();
    _poller.dispose();
    widget.btService.dispose();
    super.dispose();
  }

  Future<void> _disconnect() async {
    _poller.stop();
    await widget.btService.disconnect();
    if (!mounted) return;
    Navigator.of(context).pushReplacement(
      MaterialPageRoute(builder: (_) => const BtPickerScreen()),
    );
  }

  String get _statusText {
    if (_frameCount == 0) return 'Waiting for data…';
    final ago = _lastFrameTime == null
        ? '?'
        : '${DateTime.now().difference(_lastFrameTime!).inMilliseconds}ms ago';
    return 'LIVE  •  last frame $ago';
  }

  Color get _statusColor {
    if (_frameCount == 0) return Colors.orange;
    final ms = _lastFrameTime == null
        ? 999
        : DateTime.now().difference(_lastFrameTime!).inMilliseconds;
    return ms < 500 ? Colors.green : Colors.orange;
  }

  @override
  Widget build(BuildContext context) {
    final protocol =
        widget.ecuType == EcuType.s300 ? 'S300' : 'KPro';

    return DefaultTabController(
      length: 2,
      child: Scaffold(
        backgroundColor: const Color(0xFF0A0A0A),
        appBar: AppBar(
          backgroundColor: const Color(0xFF1A1A1A),
          title: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(widget.deviceName,
                  style: const TextStyle(fontSize: 15)),
              Row(
                children: [
                  Icon(_frameCount == 0
                      ? Icons.hourglass_empty
                      : Icons.circle,
                      size: 10,
                      color: _statusColor),
                  const SizedBox(width: 4),
                  Text(
                    '$protocol  •  $_statusText  •  dropped: $_dropped',
                    style: const TextStyle(
                        fontSize: 10, color: Colors.grey),
                  ),
                ],
              ),
            ],
          ),
          actions: [
            IconButton(
              icon: const Icon(Icons.bluetooth_disabled,
                  color: Colors.redAccent),
              onPressed: _disconnect,
              tooltip: 'Disconnect',
            ),
          ],
          bottom: const TabBar(
            tabs: [
              Tab(text: 'LIVE DATA'),
              Tab(text: 'DEBUG LOG'),
            ],
          ),
        ),
        body: TabBarView(
          children: [
            // ── Tab 1: Live Sensor Data ──
            _state == null
                ? Center(
                    child: Column(
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        const CircularProgressIndicator(
                            color: Colors.orange),
                        const SizedBox(height: 20),
                        const Text('Waiting for ECU response…',
                            style: TextStyle(fontSize: 16)),
                        const SizedBox(height: 8),
                        Text(
                          'Sending ${protocol} request every 100ms\nMake sure ECU is powered on',
                          style: const TextStyle(
                              color: Colors.grey, fontSize: 13),
                          textAlign: TextAlign.center,
                        ),
                        const SizedBox(height: 24),
                        const Text(
                          'Check DEBUG LOG tab for details',
                          style: TextStyle(
                              color: Colors.orange, fontSize: 13),
                        ),
                      ],
                    ),
                  )
                : _SensorGrid(state: _state!, frameCount: _frameCount),

            // ── Tab 2: Debug Log ──
            _DebugLogView(log: _log),
          ],
        ),
      ),
    );
  }
}

// ─── Sensor Grid ─────────────────────────────────────────────────────────────

class _SensorGrid extends StatelessWidget {
  final SensorState state;
  final int frameCount;

  const _SensorGrid({required this.state, required this.frameCount});

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
      padding: const EdgeInsets.all(12),
      child: Column(
        children: [
          _BigValue(
            label: 'RPM',
            value: state.rpm.toStringAsFixed(0),
            unit: 'rpm',
            color: _rpmColor(state.rpm),
          ),
          const SizedBox(height: 10),
          Wrap(
            spacing: 8,
            runSpacing: 6,
            children: [
              _FlagPill('MIL', state.mil, Colors.amber),
              _FlagPill('VTEC', state.vtec, Colors.blue),
              _FlagPill('KNOCK', state.knock, Colors.red),
              _FlagPill('FUEL CUT', state.fuelCut, Colors.red),
              _FlagPill('REV LIM', state.revLimit, Colors.orange),
              _FlagPill('FAN', state.fanOut, Colors.green),
              _FlagPill('LAUNCH', state.launch, Colors.purple),
            ],
          ),
          const SizedBox(height: 10),
          GridView.count(
            crossAxisCount: 2,
            shrinkWrap: true,
            physics: const NeverScrollableScrollPhysics(),
            mainAxisSpacing: 6,
            crossAxisSpacing: 6,
            childAspectRatio: 2.4,
            children: [
              _SensorTile('VSS', '${state.vss.toStringAsFixed(1)} km/h'),
              _SensorTile('MAP', '${state.map.toStringAsFixed(1)} kPa'),
              _SensorTile('TPS', '${state.tps.toStringAsFixed(1)} %'),
              _SensorTile('ECT', '${state.ect.toStringAsFixed(1)} °C'),
              _SensorTile('IAT', '${state.iat.toStringAsFixed(1)} °C'),
              _SensorTile('BAT', '${state.bat.toStringAsFixed(2)} V'),
              _SensorTile('IGN', '${state.ign.toStringAsFixed(1)} °'),
              _SensorTile('INJ', '${state.inj.toStringAsFixed(2)} ms'),
              _SensorTile('O2', state.o2.toStringAsFixed(0)),
              _SensorTile('AFR', state.afr.toStringAsFixed(2)),
              _SensorTile('ETH', '${state.eth.toStringAsFixed(0)} %'),
              _SensorTile('GEAR', state.gear.toString()),
            ],
          ),
          const SizedBox(height: 8),
          Text(
            'Frames received: $frameCount',
            style: const TextStyle(color: Colors.grey, fontSize: 11),
          ),
        ],
      ),
    );
  }

  Color _rpmColor(double rpm) {
    if (rpm > 7000) return Colors.red;
    if (rpm > 5500) return Colors.orange;
    return const Color(0xFF00E676);
  }
}

// ─── Debug Log View ───────────────────────────────────────────────────────────

class _DebugLogView extends StatelessWidget {
  final List<_LogEntry> log;
  const _DebugLogView({required this.log});

  @override
  Widget build(BuildContext context) {
    if (log.isEmpty) {
      return const Center(
        child: Text('No log entries yet.',
            style: TextStyle(color: Colors.grey)),
      );
    }
    return ListView.builder(
      padding: const EdgeInsets.all(8),
      itemCount: log.length,
      itemBuilder: (context, index) {
        final entry = log[index];
        return Padding(
          padding: const EdgeInsets.symmetric(vertical: 2),
          child: Row(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                _ts(entry.time),
                style: const TextStyle(
                    color: Colors.grey,
                    fontSize: 11,
                    fontFamily: 'monospace'),
              ),
              const SizedBox(width: 8),
              Icon(
                entry.level == LogLevel.error
                    ? Icons.error_outline
                    : entry.level == LogLevel.ok
                        ? Icons.check_circle_outline
                        : Icons.info_outline,
                size: 14,
                color: entry.level == LogLevel.error
                    ? Colors.red
                    : entry.level == LogLevel.ok
                        ? Colors.green
                        : Colors.grey,
              ),
              const SizedBox(width: 6),
              Expanded(
                child: Text(
                  entry.message,
                  style: TextStyle(
                    fontSize: 12,
                    color: entry.level == LogLevel.error
                        ? Colors.redAccent
                        : entry.level == LogLevel.ok
                            ? Colors.greenAccent
                            : Colors.white70,
                  ),
                ),
              ),
            ],
          ),
        );
      },
    );
  }

  String _ts(DateTime t) =>
      '${t.hour.toString().padLeft(2, '0')}:${t.minute.toString().padLeft(2, '0')}:${t.second.toString().padLeft(2, '0')}';
}

enum LogLevel { info, ok, error }

class _LogEntry {
  final String message;
  final LogLevel level;
  final DateTime time;
  const _LogEntry(
      {required this.message, required this.level, required this.time});
}

// ─── Error Banner ─────────────────────────────────────────────────────────────

class _ErrorBanner extends StatelessWidget {
  final String message;
  final VoidCallback onDismiss;

  const _ErrorBanner({required this.message, required this.onDismiss});

  @override
  Widget build(BuildContext context) {
    return Container(
      width: double.infinity,
      color: const Color(0xFF4A0000),
      padding: const EdgeInsets.fromLTRB(16, 12, 8, 12),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          const Icon(Icons.error_outline,
              color: Colors.redAccent, size: 20),
          const SizedBox(width: 10),
          Expanded(
            child: Text(
              message,
              style: const TextStyle(
                  color: Colors.redAccent, fontSize: 13),
            ),
          ),
          IconButton(
            icon: const Icon(Icons.close,
                color: Colors.redAccent, size: 20),
            onPressed: onDismiss,
            padding: EdgeInsets.zero,
            constraints: const BoxConstraints(),
          ),
        ],
      ),
    );
  }
}

// ─── UI helpers ──────────────────────────────────────────────────────────────

class _BigValue extends StatelessWidget {
  final String label;
  final String value;
  final String unit;
  final Color color;

  const _BigValue(
      {required this.label,
      required this.value,
      required this.unit,
      required this.color});

  @override
  Widget build(BuildContext context) {
    return Container(
      width: double.infinity,
      padding: const EdgeInsets.symmetric(vertical: 18, horizontal: 24),
      decoration: BoxDecoration(
        color: const Color(0xFF1A1A1A),
        borderRadius: BorderRadius.circular(12),
        border: Border.all(color: color.withAlpha(120), width: 1.5),
      ),
      child: Column(
        children: [
          Text(label,
              style: TextStyle(
                  color: color,
                  fontSize: 12,
                  letterSpacing: 2,
                  fontWeight: FontWeight.w600)),
          const SizedBox(height: 2),
          Text(value,
              style: TextStyle(
                  color: color,
                  fontSize: 48,
                  fontWeight: FontWeight.bold,
                  letterSpacing: -2)),
          Text(unit,
              style: TextStyle(
                  color: color.withAlpha(160), fontSize: 12)),
        ],
      ),
    );
  }
}

class _SensorTile extends StatelessWidget {
  final String label;
  final String value;
  const _SensorTile(this.label, this.value);

  @override
  Widget build(BuildContext context) {
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
      decoration: BoxDecoration(
        color: const Color(0xFF1A1A1A),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: [
          Text(label,
              style: const TextStyle(
                  color: Colors.grey,
                  fontSize: 11,
                  letterSpacing: 1)),
          Text(value,
              style: const TextStyle(
                  color: Colors.white,
                  fontSize: 14,
                  fontWeight: FontWeight.w600)),
        ],
      ),
    );
  }
}

class _FlagPill extends StatelessWidget {
  final String label;
  final bool active;
  final Color color;
  const _FlagPill(this.label, this.active, this.color);

  @override
  Widget build(BuildContext context) {
    return AnimatedContainer(
      duration: const Duration(milliseconds: 120),
      padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 5),
      decoration: BoxDecoration(
        color: active ? color.withAlpha(40) : const Color(0xFF1A1A1A),
        borderRadius: BorderRadius.circular(20),
        border: Border.all(
          color: active ? color : Colors.grey.withAlpha(60),
          width: 1.5,
        ),
      ),
      child: Text(
        label,
        style: TextStyle(
          color: active ? color : Colors.grey,
          fontSize: 11,
          fontWeight: active ? FontWeight.bold : FontWeight.normal,
          letterSpacing: 1,
        ),
      ),
    );
  }
}