import 'dart:async';

import 'package:abawo_bt_app/model/shifter_types.dart';
import 'package:abawo_bt_app/service/shifter_service.dart';
import 'package:abawo_bt_app/widgets/bike_scan_dialog.dart';
import 'package:abawo_bt_app/widgets/gear_ratio_editor_card.dart';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:nb_utils/nb_utils.dart';

import '../controller/bluetooth.dart';
import '../database/database.dart';

class DeviceDetailsPage extends ConsumerStatefulWidget {
  const DeviceDetailsPage({
    required this.deviceAddress,
    super.key,
  });

  final String deviceAddress;

  @override
  ConsumerState<DeviceDetailsPage> createState() => _DeviceDetailsPageState();
}

class _DeviceDetailsPageState extends ConsumerState<DeviceDetailsPage> {
  static const List<double> _keAntRatios = [
    0.35,
    0.40,
    0.47,
    0.54,
    0.61,
    0.69,
    0.82,
    0.95,
    1.13,
    1.29,
    1.50,
    1.71,
    1.89,
    2.12,
    2.40,
    2.77,
    3.27,
  ];

  bool _isReconnecting = false;
  bool _wasConnectedToCurrentDevice = false;
  bool _isExitingPage = false;
  bool _hasRequestedDisconnect = false;
  Timer? _reconnectTimeoutTimer;
  ProviderSubscription<AsyncValue<(ConnectionStatus, String?)>>?
      _connectionStatusSubscription;

  ShifterService? _shifterService;
  StreamSubscription<CentralStatus>? _statusSubscription;
  CentralStatus? _latestStatus;
  final List<_StatusHistoryEntry> _statusHistory = [];

  bool _isGearRatiosLoading = false;
  bool _hasLoadedGearRatios = false;
  String? _gearRatiosError;
  List<double> _gearRatios = const [];
  int _defaultGearIndex = 0;

  @override
  void initState() {
    super.initState();
    _connectionStatusSubscription =
        ref.listenManual<AsyncValue<(ConnectionStatus, String?)>>(
      connectionStatusProvider,
      (_, next) {
        final data = next.valueOrNull;
        if (data == null) {
          return;
        }
        _onConnectionStatusChanged(data);
      },
      fireImmediately: true,
    );
  }

  @override
  void dispose() {
    unawaited(_disconnectOnClose());
    _reconnectTimeoutTimer?.cancel();
    _connectionStatusSubscription?.close();
    _statusSubscription?.cancel();
    _shifterService?.dispose();
    super.dispose();
  }

  Future<void> _disconnectOnClose() async {
    if (_hasRequestedDisconnect) {
      return;
    }

    _hasRequestedDisconnect = true;
    _isExitingPage = true;
    _reconnectTimeoutTimer?.cancel();

    final bluetooth = ref.read(bluetoothProvider).value;
    await bluetooth?.disconnect();
    await _stopStatusStreaming();
  }

  void _onConnectionStatusChanged((ConnectionStatus, String?) data) {
    if (!mounted || _isExitingPage) {
      return;
    }

    final (status, connectedDeviceId) = data;
    final isCurrentDevice = connectedDeviceId == widget.deviceAddress;

    if (isCurrentDevice && status == ConnectionStatus.connected) {
      _wasConnectedToCurrentDevice = true;
      _startStatusStreamingIfNeeded();
      if (_isReconnecting) {
        _reconnectTimeoutTimer?.cancel();
        setState(() {
          _isReconnecting = false;
        });
      }
      return;
    }

    if (_wasConnectedToCurrentDevice &&
        !_isReconnecting &&
        status == ConnectionStatus.disconnected) {
      _startReconnect();
    }

    if (!isCurrentDevice || status == ConnectionStatus.disconnected) {
      _stopStatusStreaming();
    }
  }

  Future<void> _startReconnect() async {
    if (!mounted || _isExitingPage || _isReconnecting) {
      return;
    }

    setState(() {
      _isReconnecting = true;
    });

    final bluetooth = ref.read(bluetoothProvider).value;
    await bluetooth?.connectById(widget.deviceAddress);

    _reconnectTimeoutTimer?.cancel();
    _reconnectTimeoutTimer = Timer(const Duration(seconds: 10), () {
      if (!mounted || !_isReconnecting || _isExitingPage) {
        return;
      }
      _terminateConnectionAndGoHome(
        'Connection lost. Could not reconnect in time.',
      );
    });
  }

  Future<void> _startStatusStreamingIfNeeded() async {
    if (_shifterService != null) {
      if (!_hasLoadedGearRatios && !_isGearRatiosLoading) {
        unawaited(_loadGearRatios());
      }
      return;
    }
    final asyncBluetooth = ref.read(bluetoothProvider);
    final BluetoothController bluetooth;
    if (asyncBluetooth.hasValue) {
      bluetooth = asyncBluetooth.requireValue;
    } else {
      bluetooth = await ref.read(bluetoothProvider.future);
    }
    final service = ShifterService(
      bluetooth: bluetooth,
      buttonDeviceId: widget.deviceAddress,
    );

    final initialStatusResult = await service.readStatus();
    if (mounted && initialStatusResult.isOk()) {
      _recordStatus(initialStatusResult.unwrap());
    }

    _statusSubscription = service.statusStream.listen((status) {
      if (!mounted) {
        return;
      }
      _recordStatus(status);
    });

    service.startStatusNotifications();
    setState(() {
      _shifterService = service;
    });
    unawaited(_loadGearRatios());
  }

  void _recordStatus(CentralStatus status) {
    setState(() {
      _latestStatus = status;
      _statusHistory.insert(
        0,
        _StatusHistoryEntry(
          timestamp: DateTime.now(),
          status: status,
        ),
      );
      if (_statusHistory.length > 100) {
        _statusHistory.removeRange(100, _statusHistory.length);
      }
    });
  }

  Future<void> _stopStatusStreaming() async {
    await _statusSubscription?.cancel();
    _statusSubscription = null;
    await _shifterService?.dispose();
    _shifterService = null;
  }

  Future<void> _loadGearRatios() async {
    final shifter = _shifterService;
    if (shifter == null || _isGearRatiosLoading) {
      return;
    }

    setState(() {
      _isGearRatiosLoading = true;
      _gearRatiosError = null;
    });

    final result = await shifter.readGearRatios();
    if (!mounted) {
      return;
    }

    if (result.isErr()) {
      setState(() {
        _gearRatiosError = 'Failed to read gear ratios: ${result.unwrapErr()}';
        _isGearRatiosLoading = false;
        _hasLoadedGearRatios = false;
      });
      return;
    }

    setState(() {
      final data = result.unwrap();
      _gearRatios = data.ratios;
      _defaultGearIndex = data.defaultGearIndex;
      _isGearRatiosLoading = false;
      _hasLoadedGearRatios = true;
      _gearRatiosError = null;
    });
  }

  Future<String?> _saveGearRatios(
      List<double> ratios, int defaultGearIndex) async {
    final shifter = _shifterService;
    if (shifter == null) {
      return 'Status channel is not ready yet.';
    }

    final result = await shifter.writeGearRatios(
      GearRatiosData(
        ratios: ratios,
        defaultGearIndex: defaultGearIndex,
      ),
    );
    if (result.isErr()) {
      return 'Could not save gear ratios: ${result.unwrapErr()}';
    }

    if (!mounted) {
      return null;
    }

    setState(() {
      _gearRatios = List<double>.from(ratios);
      _defaultGearIndex = ratios.isEmpty
          ? 0
          : defaultGearIndex.clamp(0, ratios.length - 1).toInt();
      _hasLoadedGearRatios = true;
      _gearRatiosError = null;
    });

    return null;
  }

  Future<void> _connectButtonToBike() async {
    final selectedBike = await BikeScanDialog.show(
      context,
      excludedDeviceId: widget.deviceAddress,
    );
    if (selectedBike == null || !mounted) {
      return;
    }

    await _startStatusStreamingIfNeeded();
    final shifter = _shifterService;
    if (shifter == null) {
      if (!mounted) {
        return;
      }
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Status channel is not ready yet.')),
      );
      return;
    }

    final result = await shifter.connectButtonToBike(selectedBike.id);
    if (!mounted) {
      return;
    }

    if (result.isErr()) {
      final err = result.unwrapErr();
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('Connect request failed: $err')),
      );
      toast('Connect request failed.');
      return;
    }

    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text('Sent connect request for ${selectedBike.id}.')),
    );
  }

  Future<void> _terminateConnectionAndGoHome(String toastMessage) async {
    await _disconnectOnClose();

    if (!mounted) {
      return;
    }

    toast(toastMessage);
    context.replace('/');
  }

  Future<void> _cancelReconnect() async {
    await _terminateConnectionAndGoHome('Reconnect cancelled.');
  }

  Future<void> _exitPage() async {
    await _disconnectOnClose();
    if (!mounted) {
      return;
    }
    context.replace('/');
  }

  void _showStatusHistory() {
    showModalBottomSheet<void>(
      context: context,
      isScrollControlled: true,
      showDragHandle: true,
      builder: (context) {
        return SizedBox(
          height: MediaQuery.of(context).size.height * 0.72,
          child: Column(
            children: [
              Padding(
                padding: const EdgeInsets.fromLTRB(16, 8, 16, 8),
                child: Row(
                  children: [
                    const Expanded(
                      child: Text(
                        'Status Console',
                        style: TextStyle(
                          fontSize: 18,
                          fontWeight: FontWeight.w600,
                        ),
                      ),
                    ),
                  ],
                ),
              ),
              const Divider(height: 1),
              Expanded(
                child: _statusHistory.isEmpty
                    ? const Center(child: Text('No status updates yet.'))
                    : ListView.builder(
                        itemCount: _statusHistory.length,
                        itemBuilder: (context, index) {
                          final item = _statusHistory[index];
                          final errorCode = _effectiveErrorCode(item.status);
                          return ListTile(
                            dense: true,
                            visualDensity: VisualDensity.compact,
                            title: Text(
                              item.status.statusLine,
                              style: const TextStyle(fontSize: 13),
                            ),
                            subtitle: Text(
                              _formatTimestamp(item.timestamp),
                              style: const TextStyle(
                                fontFamily: 'monospace',
                                fontSize: 12,
                              ),
                            ),
                            trailing: errorCode == null
                                ? null
                                : IconButton(
                                    tooltip: 'Explain error',
                                    onPressed: () {
                                      _showErrorInfoDialog(errorCode);
                                    },
                                    icon: const Icon(Icons.info_outline),
                                  ),
                            onTap: errorCode == null
                                ? null
                                : () {
                                    _showErrorInfoDialog(errorCode);
                                  },
                          );
                        },
                      ),
              ),
            ],
          ),
        );
      },
    );
  }

  String _formatTimestamp(DateTime time) {
    final h = time.hour.toString().padLeft(2, '0');
    final m = time.minute.toString().padLeft(2, '0');
    final s = time.second.toString().padLeft(2, '0');
    return '$h:$m:$s';
  }

  int? _effectiveErrorCode(CentralStatus status) {
    if (status.trainer.state == TrainerConnectionState.error) {
      return status.trainer.errorCode ?? status.lastFailure;
    }
    return status.lastFailure;
  }

  void _showErrorInfoDialog(int errorCode) {
    final info = shifterErrorInfo(errorCode);
    showDialog<void>(
      context: context,
      builder: (context) {
        return AlertDialog(
          icon: const Icon(Icons.info_outline),
          title: Text('Error ${info.code}: ${info.title}'),
          content: Text(info.details),
          actions: [
            TextButton(
              onPressed: () => Navigator.of(context).pop(),
              child: const Text('Close'),
            ),
          ],
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    final connectionData = ref.watch(connectionStatusProvider).valueOrNull;
    final isCurrentConnected = connectionData != null &&
        connectionData.$1 == ConnectionStatus.connected &&
        connectionData.$2 == widget.deviceAddress;

    return PopScope(
      canPop: false,
      onPopInvokedWithResult: (bool didPop, bool? result) {
        _exitPage();
      },
      child: Scaffold(
        appBar: AppBar(
          title: const Text('Device Details'),
          leading: IconButton(
            icon: const Icon(Icons.arrow_back),
            onPressed: _exitPage,
          ),
        ),
        body: Stack(
          fit: StackFit.expand,
          children: [
            SingleChildScrollView(
              padding: const EdgeInsets.all(16),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  _buildDeviceInfo(context, ref, widget.deviceAddress),
                  const SizedBox(height: 16),
                  _buildConnectionStatus(context, ref, widget.deviceAddress),
                  const SizedBox(height: 16),
                  if (isCurrentConnected) ...[
                    _StatusBanner(
                      status: _latestStatus,
                      onTap: _showStatusHistory,
                      onErrorInfoTap: _latestStatus == null
                          ? null
                          : () {
                              final code = _effectiveErrorCode(_latestStatus!);
                              if (code != null) {
                                _showErrorInfoDialog(code);
                              }
                            },
                    ),
                    const SizedBox(height: 16),
                    GearRatioEditorCard(
                      ratios: _gearRatios,
                      defaultGearIndex: _defaultGearIndex,
                      isLoading: _isGearRatiosLoading,
                      errorText: _gearRatiosError,
                      onRetry: _loadGearRatios,
                      onSave: _saveGearRatios,
                      presets: const [
                        GearRatioPreset(
                          name: 'KeAnt Classic',
                          description:
                              '17-step baseline from KeAnt cross app gearing.',
                          ratios: _keAntRatios,
                        ),
                      ],
                    ),
                    const SizedBox(height: 16),
                    SizedBox(
                      width: double.infinity,
                      child: FilledButton.icon(
                        onPressed: _connectButtonToBike,
                        icon: const Icon(Icons.link),
                        label: const Text('Connect Button to Bike'),
                      ),
                    ),
                  ],
                ],
              ),
            ),
            if (_isReconnecting)
              Positioned.fill(
                child: ColoredBox(
                  color: Colors.black.withValues(alpha: 0.55),
                  child: Center(
                    child: Container(
                      margin: const EdgeInsets.symmetric(horizontal: 24),
                      padding: const EdgeInsets.all(20),
                      decoration: BoxDecoration(
                        color: Theme.of(context).cardColor,
                        borderRadius: BorderRadius.circular(16),
                      ),
                      child: Column(
                        mainAxisSize: MainAxisSize.min,
                        children: [
                          const CircularProgressIndicator(),
                          const SizedBox(height: 16),
                          Text(
                            'Reconnecting...',
                            style: Theme.of(context).textTheme.titleMedium,
                          ),
                          const SizedBox(height: 16),
                          TextButton(
                            onPressed: _cancelReconnect,
                            child: const Text('Cancel'),
                          ),
                        ],
                      ),
                    ),
                  ),
                ),
              ),
          ],
        ),
      ),
    );
  }
}

class _StatusHistoryEntry {
  const _StatusHistoryEntry({
    required this.timestamp,
    required this.status,
  });

  final DateTime timestamp;
  final CentralStatus status;
}

class _StatusBanner extends StatelessWidget {
  const _StatusBanner({
    required this.status,
    required this.onTap,
    this.onErrorInfoTap,
  });

  final CentralStatus? status;
  final VoidCallback onTap;
  final VoidCallback? onErrorInfoTap;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final color = _resolveColor(colorScheme);
    final text = status?.statusLine ?? 'Waiting for status updates...';

    return Material(
      color: color.withValues(alpha: 0.16),
      borderRadius: BorderRadius.circular(12),
      child: InkWell(
        borderRadius: BorderRadius.circular(12),
        onTap: onTap,
        child: Padding(
          padding: const EdgeInsets.all(12),
          child: Row(
            children: [
              Icon(Icons.memory, color: color),
              const SizedBox(width: 10),
              Expanded(
                child: Text(
                  text,
                  maxLines: 2,
                  overflow: TextOverflow.ellipsis,
                ),
              ),
              if (onErrorInfoTap != null &&
                  status != null &&
                  (status!.trainer.state == TrainerConnectionState.error ||
                      status!.lastFailure != null))
                IconButton(
                  tooltip: 'Explain error',
                  onPressed: onErrorInfoTap,
                  icon: Icon(Icons.info_outline, color: color),
                ),
              Icon(Icons.chevron_right, color: color),
            ],
          ),
        ),
      ),
    );
  }

  Color _resolveColor(ColorScheme scheme) {
    final current = status;
    if (current == null) {
      return scheme.primary;
    }
    if (current.trainer.state == TrainerConnectionState.error) {
      return scheme.error;
    }
    if (current.trainer.state == TrainerConnectionState.ftmsReady) {
      return Colors.green;
    }
    if (current.trainer.state == TrainerConnectionState.connecting ||
        current.trainer.state == TrainerConnectionState.pairing ||
        current.trainer.state == TrainerConnectionState.discoveringFtms) {
      return Colors.orange;
    }
    return scheme.primary;
  }
}

Widget _buildDeviceInfo(
  BuildContext context,
  WidgetRef ref,
  String deviceAddress,
) {
  final asyncSavedDevices = ref.watch(nConnectedDevicesProvider);

  return asyncSavedDevices.when(
    data: (devices) {
      ConnectedDevice? currentDeviceData;
      try {
        currentDeviceData = devices.firstWhere(
          (d) => d.deviceAddress == deviceAddress,
        );
      } catch (_) {
        currentDeviceData = null;
      }

      if (currentDeviceData == null) {
        return Center(
          child: Text('Device details not found for $deviceAddress.'),
        );
      }

      return Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            'Name: ${currentDeviceData.deviceName}',
            style: Theme.of(context).textTheme.titleLarge,
          ),
          const SizedBox(height: 8),
          Text(
            'Address: ${currentDeviceData.deviceAddress}',
            style: Theme.of(context).textTheme.bodyMedium,
          ),
          const SizedBox(height: 8),
          Text(
            'Type: ${currentDeviceData.deviceType}',
            style: Theme.of(context).textTheme.bodyMedium,
          ),
        ],
      );
    },
    loading: () => const Center(child: CircularProgressIndicator()),
    error: (error, stackTrace) =>
        Center(child: Text('Error loading device info: $error')),
  );
}

Widget _buildConnectionStatus(
  BuildContext context,
  WidgetRef ref,
  String deviceAddress,
) {
  final asyncConnectionStatus = ref.watch(connectionStatusProvider);

  return asyncConnectionStatus.when(
    data: (data) {
      final (status, connectedDeviceId) = data;
      String statusText;
      final isCurrentDeviceConnected =
          connectedDeviceId != null && connectedDeviceId == deviceAddress;

      if (isCurrentDeviceConnected) {
        switch (status) {
          case ConnectionStatus.connected:
            statusText = 'Status: Connected';
            break;
          case ConnectionStatus.connecting:
            statusText = 'Status: Connecting...';
            break;
          case ConnectionStatus.disconnecting:
            statusText = 'Status: Disconnecting...';
            break;
          case ConnectionStatus.disconnected:
            statusText = 'Status: Disconnected';
            break;
        }
      } else {
        statusText = 'Status: Disconnected';
      }

      return Text(statusText, style: Theme.of(context).textTheme.titleMedium);
    },
    loading: () => const Text(
      'Status: Unknown',
      style: TextStyle(fontStyle: FontStyle.italic),
    ),
    error: (error, stackTrace) => Text(
      'Status: Error ($error)',
      style: const TextStyle(color: Colors.red),
    ),
  );
}