import 'dart:async';

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

import 'core/providers/bt_provider.dart';
import 'core/providers/sensor_provider.dart';
import 'core/providers/settings_provider.dart';
import 'core/providers/theme_provider.dart';
import 'core/bluetooth/bt_poller.dart';
import 'core/protocol/sensor_state.dart';

void main() {
  runApp(const ProviderScope(child: HvbtApp()));
}

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

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final themeVariant = ref.watch(themeProvider);
    final accent = themeVariant.accentColor;

    return MaterialApp(
      title: 'HV BT Dashboard',
      debugShowCheckedModeBanner: false,
      theme: ThemeData.dark(useMaterial3: true).copyWith(
        colorScheme: ColorScheme.fromSeed(
          seedColor: accent,
          brightness: Brightness.dark,
        ),
      ),
      home: const BtPickerScreen(),
    );
  }
}

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

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

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

class _BtPickerScreenState extends ConsumerState<BtPickerScreen> {
  String? _error;
  bool _initDone = false;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) => _initBluetooth());
  }

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

    // 1. 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(() {
        _error = 'Permissions denied: ${denied.join(", ")}\n\n'
            'Go to Settings → Apps → HV BT Dashboard → Permissions '
            'and allow Bluetooth + Location, then tap Refresh.';
        _initDone = true;
      });
      return;
    }

    // 2. Auto-enable Bluetooth
    final btState = await FlutterBluetoothSerial.instance.state;
    if (btState != BluetoothState.STATE_ON) {
      await FlutterBluetoothSerial.instance.requestEnable();
      await Future<void>.delayed(const Duration(seconds: 1));
    }

    setState(() => _initDone = true);
    ref.invalidate(pairedDevicesProvider);
  }

  Future<void> _connect(BluetoothDevice device, EcuType ecuType) async {
    // Set protocol before connecting so the poller uses it
    ref.read(settingsProvider.notifier).setEcuType(ecuType);
    await ref.read(btProvider.notifier).connect(device);

    if (!mounted) return;
    final btState = ref.read(btProvider);
    if (btState.status == BtStatus.connected) {
      Navigator.of(context).pushReplacement(
        MaterialPageRoute(builder: (_) => const LiveDataScreen()),
      );
    }
  }

  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.pop(ctx); _connect(device, EcuType.s300); },
            child: const Text('S300'),
          ),
          TextButton(
            onPressed: () { Navigator.pop(ctx); _connect(device, EcuType.kpro); },
            child: const Text('KPro'),
          ),
          TextButton(
            onPressed: () => Navigator.pop(ctx),
            child: const Text('Cancel'),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final btState = ref.watch(btProvider);
    final devicesAsync = ref.watch(pairedDevicesProvider);

    return Scaffold(
      appBar: AppBar(
        title: const Text('HV BT — Select Device'),
        actions: [
          IconButton(
            icon: const Icon(Icons.refresh),
            onPressed: btState.isConnecting
                ? null
                : () { setState(() => _error = null); _initBluetooth(); },
            tooltip: 'Refresh',
          ),
        ],
      ),
      body: Column(
        children: [
          // BT connection error banner
          if (btState.status == BtStatus.error)
            _ErrorBanner(
              message: 'Connection failed: ${btState.error}',
              onDismiss: () =>
                  ref.read(btProvider.notifier).disconnect(),
            ),

          // Permission / init error banner
          if (_error != null)
            _ErrorBanner(
              message: _error!,
              onDismiss: () => setState(() => _error = null),
            ),

          Expanded(
            child: !_initDone
                ? const Center(
                    child: Column(
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        CircularProgressIndicator(),
                        SizedBox(height: 12),
                        Text('Requesting permissions…'),
                      ],
                    ),
                  )
                : devicesAsync.when(
                    loading: () => const Center(
                      child: Column(
                        mainAxisSize: MainAxisSize.min,
                        children: [
                          CircularProgressIndicator(),
                          SizedBox(height: 12),
                          Text('Loading paired devices…'),
                        ],
                      ),
                    ),
                    error: (e, _) => Center(
                      child: _ErrorBanner(
                        message: 'Failed to load devices:\n$e',
                        onDismiss: () => ref.refresh(pairedDevicesProvider),
                      ),
                    ),
                    data: (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 BT devices found.',
                                      style: TextStyle(fontSize: 16)),
                                  SizedBox(height: 8),
                                  Text(
                                    'Pair your ECU module in Android Settings → Bluetooth, then tap Refresh.',
                                    style: TextStyle(color: Colors.grey),
                                    textAlign: TextAlign.center,
                                  ),
                                ],
                              ),
                            ),
                          )
                        : ListView.separated(
                            itemCount: devices.length,
                            separatorBuilder: (_, __) =>
                                const Divider(height: 1),
                            itemBuilder: (context, i) {
                              final device = devices[i];
                              final isConnecting = btState.isConnecting &&
                                  btState.deviceName == (device.name ?? device.address);
                              return ListTile(
                                leading: Icon(Icons.bluetooth,
                                    color: isConnecting
                                        ? Colors.blue
                                        : Colors.grey),
                                title: Text(device.name ?? 'Unknown'),
                                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: btState.isConnecting
                                    ? null
                                    : () => _showProtocolDialog(device),
                              );
                            },
                          ),
                  ),
          ),
        ],
      ),
    );
  }
}

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

class LiveDataScreen extends ConsumerWidget {
  const LiveDataScreen({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final btState = ref.watch(btProvider);
    final sensorAsync = ref.watch(sensorStateProvider);
    final settings = ref.watch(settingsProvider);
    final protocol = settings.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(btState.deviceName ?? 'ECU',
                  style: const TextStyle(fontSize: 15)),
              Row(
                children: [
                  Icon(
                    btState.isConnected ? Icons.circle : Icons.hourglass_empty,
                    size: 9,
                    color: btState.isConnected ? Colors.green : Colors.orange,
                  ),
                  const SizedBox(width: 4),
                  Text(
                    '$protocol  •  frames: ${btState.frameCount}  •  dropped: ${btState.droppedFrames}',
                    style: const TextStyle(fontSize: 10, color: Colors.grey),
                  ),
                ],
              ),
            ],
          ),
          actions: [
            IconButton(
              icon: const Icon(Icons.bluetooth_disabled, color: Colors.redAccent),
              tooltip: 'Disconnect',
              onPressed: () async {
                await ref.read(btProvider.notifier).disconnect();
                if (context.mounted) {
                  Navigator.of(context).pushReplacement(
                    MaterialPageRoute(builder: (_) => const BtPickerScreen()),
                  );
                }
              },
            ),
          ],
          bottom: const TabBar(
            tabs: [Tab(text: 'LIVE DATA'), Tab(text: 'DEBUG LOG')],
          ),
        ),
        body: TabBarView(
          children: [
            // ── Tab 1: Live sensor data ──
            sensorAsync.when(
              loading: () => const _WaitingForData(),
              error: (e, _) => _ErrorCenter(message: e.toString()),
              data: (state) => _SensorGrid(
                state: state,
                frameCount: btState.frameCount,
              ),
            ),

            // ── Tab 2: Error/status log ──
            _DebugTab(btState: btState, sensorAsync: sensorAsync),
          ],
        ),
      ),
    );
  }
}

// ─── Waiting / Error states ───────────────────────────────────────────────────

class _WaitingForData extends StatelessWidget {
  const _WaitingForData();

  @override
  Widget build(BuildContext context) {
    return const Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          CircularProgressIndicator(color: Colors.orange),
          SizedBox(height: 20),
          Text('Waiting for ECU response…', style: TextStyle(fontSize: 16)),
          SizedBox(height: 8),
          Text(
            'Sending request every 100ms\nMake sure ECU is powered on',
            style: TextStyle(color: Colors.grey, fontSize: 13),
            textAlign: TextAlign.center,
          ),
          SizedBox(height: 24),
          Text('Check DEBUG LOG tab for details',
              style: TextStyle(color: Colors.orange, fontSize: 13)),
        ],
      ),
    );
  }
}

class _ErrorCenter extends StatelessWidget {
  final String message;
  const _ErrorCenter({required this.message});

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(24),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Icon(Icons.error_outline, size: 48, color: Colors.red),
            const SizedBox(height: 12),
            Text(message,
                style: const TextStyle(color: Colors.redAccent),
                textAlign: TextAlign.center),
          ],
        ),
      ),
    );
  }
}

// ─── Debug Tab ────────────────────────────────────────────────────────────────

class _DebugTab extends StatelessWidget {
  final BtState btState;
  final AsyncValue<SensorState> sensorAsync;

  const _DebugTab({required this.btState, required this.sensorAsync});

  @override
  Widget build(BuildContext context) {
    final lines = <_DebugLine>[];

    lines.add(_DebugLine(
      icon: btState.isConnected ? Icons.check_circle_outline : Icons.info_outline,
      color: btState.isConnected ? Colors.green : Colors.orange,
      text: 'BT: ${btState.status.name.toUpperCase()}  '
          '${btState.deviceName != null ? "→ ${btState.deviceName}" : ""}',
    ));

    if (btState.error != null) {
      lines.add(_DebugLine(
          icon: Icons.error_outline,
          color: Colors.red,
          text: 'Error: ${btState.error}'));
    }

    lines.add(_DebugLine(
      icon: Icons.analytics_outlined,
      color: Colors.grey,
      text:
          'Frames: ${btState.frameCount}  Dropped: ${btState.droppedFrames}  '
          'Rate: ${btState.frameCount > 0 ? "~10 Hz" : "0 Hz"}',
    ));

    sensorAsync.whenOrNull(
      error: (e, _) => lines.add(_DebugLine(
          icon: Icons.error_outline, color: Colors.red, text: 'Parse error: $e')),
      data: (s) => lines.add(_DebugLine(
          icon: Icons.check_circle_outline,
          color: Colors.green,
          text: 'Last frame: RPM=${s.rpm.toStringAsFixed(0)} '
              'ECT=${s.ect.toStringAsFixed(1)}°C '
              'BAT=${s.bat.toStringAsFixed(2)}V')),
    );

    return ListView(
      padding: const EdgeInsets.all(12),
      children: lines
          .map((l) => Padding(
                padding: const EdgeInsets.symmetric(vertical: 5),
                child: Row(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Icon(l.icon, size: 15, color: l.color),
                    const SizedBox(width: 8),
                    Expanded(
                      child: Text(l.text,
                          style: TextStyle(
                              color: l.color.withAlpha(220), fontSize: 12)),
                    ),
                  ],
                ),
              ))
          .toList(),
    );
  }
}

class _DebugLine {
  final IconData icon;
  final Color color;
  final String text;
  const _DebugLine({required this.icon, required this.color, required this.text});
}

// ─── 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: [
              _Tile('VSS', '${state.vss.toStringAsFixed(1)} km/h'),
              _Tile('MAP', '${state.map.toStringAsFixed(1)} kPa'),
              _Tile('TPS', '${state.tps.toStringAsFixed(1)} %'),
              _Tile('ECT', '${state.ect.toStringAsFixed(1)} °C'),
              _Tile('IAT', '${state.iat.toStringAsFixed(1)} °C'),
              _Tile('BAT', '${state.bat.toStringAsFixed(2)} V'),
              _Tile('IGN', '${state.ign.toStringAsFixed(1)} °'),
              _Tile('INJ', '${state.inj.toStringAsFixed(2)} ms'),
              _Tile('O2', state.o2.toStringAsFixed(0)),
              _Tile('AFR', state.afr.toStringAsFixed(2)),
              _Tile('ETH', '${state.eth.toStringAsFixed(0)} %'),
              _Tile('GEAR', state.gear.toString()),
            ],
          ),
          const SizedBox(height: 8),
          Text('Frames: $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);
  }
}

// ─── Shared UI widgets ────────────────────────────────────────────────────────

class _BigValue extends StatelessWidget {
  final String label, value, 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 _Tile extends StatelessWidget {
  final String label, value;
  const _Tile(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),
      ),
    );
  }
}

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, 10, 8, 10),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          const Icon(Icons.error_outline, color: Colors.redAccent, size: 18),
          const SizedBox(width: 8),
          Expanded(
              child: Text(message,
                  style: const TextStyle(
                      color: Colors.redAccent, fontSize: 12))),
          IconButton(
            icon: const Icon(Icons.close, color: Colors.redAccent, size: 18),
            onPressed: onDismiss,
            padding: EdgeInsets.zero,
            constraints: const BoxConstraints(),
          ),
        ],
      ),
    );
  }
}