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

import '../../../transport/bluetooth/bluetooth_device_info.dart';
import '../../../transport/bluetooth/bluetooth_system_settings.dart';
import '../../../transport/link_transport.dart';
import '../../dmc_colors.dart';
import '../../providers/bluetooth_connection_provider.dart';
import '../../providers/connection_settings_provider.dart';
import '../../providers/database_provider.dart';

/// Einstellungen: Drohnen-Profile (Doku 3.5/7.3, noch nicht hier
/// angebunden - siehe DroneProfileEditor) und Verbindung (Doku
/// Kommunikationsschicht Abschnitt 7).
class SettingsScreen extends StatelessWidget {
  const SettingsScreen({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Settings')),
      // Bewusst nicht symmetrisch: links den echten Geraete-Inset einhalten
      // (z.B. eine Frontkamera-Aussparung im Querformat), rechts bis an den
      // Bildschirmrand - anders als in der Fusszeile (BottomStatsBar) soll
      // hier keine gespiegelte/erzwungene Symmetrie zwischen beiden Seiten
      // entstehen.
      body: ListView(
        padding: EdgeInsets.only(
          left: 16 + MediaQuery.of(context).padding.left,
          top: 16,
          bottom: 16,
        ),
        children: const [_ConnectionSection()],
      ),
    );
  }
}

class _ConnectionSection extends ConsumerWidget {
  const _ConnectionSection();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final linkState = ref.watch(linkStateProvider).value;
    final errorReason = ref.watch(linkErrorReasonProvider);
    final bondedDevices = ref.watch(bondedDevicesProvider);
    final connectionSettings = ref.watch(connectionSettingsProvider).value;
    final log = ref.watch(connectionLogProvider);
    final packetCount = ref.watch(connectionLogProvider.notifier).packetCount;

    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Text('Connection', style: Theme.of(context).textTheme.titleMedium),
                const Spacer(),
                _StatePill(state: linkState),
              ],
            ),
            const SizedBox(height: 12),
            const Text('Type: Bluetooth'),
            const SizedBox(height: 4),
            const Text(
              'Wi-Fi and USB support are coming later.',
              style: TextStyle(fontSize: 12, color: Colors.grey),
            ),
            if (errorReason != null) ...[
              const SizedBox(height: 12),
              _ErrorHint(reason: errorReason),
            ],
            const SizedBox(height: 16),
            Row(
              children: [
                ElevatedButton(
                  onPressed: () => _connect(ref),
                  child: const Text('Connect'),
                ),
                const SizedBox(width: 8),
                OutlinedButton(
                  onPressed: () => ref.read(bluetoothTransportProvider).disconnect(),
                  child: const Text('Disconnect'),
                ),
                const SizedBox(width: 8),
                TextButton(
                  onPressed: BluetoothSystemSettings.openBluetoothSettings,
                  child: const Text('Pair device'),
                ),
              ],
            ),
            const SizedBox(height: 16),
            SwitchListTile(
              contentPadding: EdgeInsets.zero,
              title: const Text('Auto-connect when entering Fly mode'),
              value: connectionSettings?.connectionAutoConnect ?? true,
              onChanged: (value) async {
                await ref
                    .read(appSettingsRepositoryProvider)
                    .setConnectionAutoConnect(value);
                ref.invalidate(connectionSettingsProvider);
              },
            ),
            const SizedBox(height: 8),
            Text('Paired devices', style: Theme.of(context).textTheme.titleSmall),
            const SizedBox(height: 4),
            bondedDevices.when(
              data: (devices) => devices.isEmpty
                  ? const Text(
                      'No paired devices yet. Pair one once via the system '
                      'dialog using "Pair device".',
                      style: TextStyle(fontSize: 12, color: Colors.grey),
                    )
                  : RadioGroup<String>(
                      groupValue: connectionSettings?.connectionDeviceAddress,
                      onChanged: (address) =>
                          _selectDevice(ref, address, devices),
                      child: Column(
                        children: [
                          for (final device in devices)
                            RadioListTile<String>(
                              contentPadding: EdgeInsets.zero,
                              dense: true,
                              value: device.address,
                              title: Text(device.displayName),
                              subtitle: Text(
                                device.address,
                                style: const TextStyle(fontSize: 11),
                              ),
                            ),
                        ],
                      ),
                    ),
              loading: () => const Padding(
                padding: EdgeInsets.symmetric(vertical: 8),
                child: LinearProgressIndicator(),
              ),
              error: (e, _) => Text(
                'Could not read paired devices: $e',
                style: const TextStyle(fontSize: 12, color: Colors.grey),
              ),
            ),
            const SizedBox(height: 16),
            Text(
              'Connection log ($packetCount packets received)',
              style: Theme.of(context).textTheme.titleSmall,
            ),
            const SizedBox(height: 4),
            SizedBox(
              height: 120,
              child: log.isEmpty
                  ? const Text(
                      'No events yet.',
                      style: TextStyle(fontSize: 12, color: Colors.grey),
                    )
                  : ListView.builder(
                      reverse: true,
                      itemCount: log.length,
                      itemBuilder: (context, index) {
                        final entry = log[log.length - 1 - index];
                        return Text(
                          '${_formatTime(entry.timestamp)}  ${entry.message}',
                          style: const TextStyle(fontSize: 12, fontFamily: 'monospace'),
                        );
                      },
                    ),
            ),
          ],
        ),
      ),
    );
  }

  Future<void> _connect(WidgetRef ref) async {
    try {
      await ref.read(bluetoothTransportProvider).connect();
    } on LinkConnectException {
      // Grund/Nachricht sind bereits ueber lastErrorReason/state gemeldet
      // (siehe LinkConnectException-Doku) - die Oberflaeche reagiert darauf
      // ueber linkErrorReasonProvider/_ErrorHint, hier ist nichts weiter zu tun.
    }
  }

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

  Future<void> _selectDevice(
    WidgetRef ref,
    String? address,
    List<BluetoothDeviceInfo> devices,
  ) async {
    if (address == null) return;
    await ref
        .read(appSettingsRepositoryProvider)
        .setConnectionDeviceAddress(address);
    ref.invalidate(connectionSettingsProvider);
    try {
      await ref.read(bluetoothTransportProvider).connect();
    } on LinkConnectException {
      // siehe _connect() oben
    }
  }
}

class _StatePill extends StatelessWidget {
  const _StatePill({required this.state});

  final LinkState? state;

  @override
  Widget build(BuildContext context) {
    final (label, color) = switch (state) {
      LinkState.connected => ('Connected', DmcColors.liveGreen),
      LinkState.connecting => ('Connecting…', DmcColors.pafAmber),
      LinkState.error => ('Error', DmcColors.warnRed),
      LinkState.disconnected || null => ('Disconnected', Colors.grey),
    };
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 4),
      decoration: BoxDecoration(
        color: color.withValues(alpha: 0.15),
        borderRadius: BorderRadius.circular(12),
        border: Border.all(color: color),
      ),
      child: Text(label, style: TextStyle(color: color, fontSize: 12)),
    );
  }
}

class _ErrorHint extends StatelessWidget {
  const _ErrorHint({required this.reason});

  final LinkErrorReason reason;

  @override
  Widget build(BuildContext context) {
    final (text, action) = switch (reason) {
      LinkErrorReason.bluetoothOff => (
          'Bluetooth is off. Please enable it in system settings.',
          _HintAction('Settings', BluetoothSystemSettings.openBluetoothSettings),
        ),
      LinkErrorReason.permissionDenied => (
          'The "Nearby devices" permission is required. Please tap '
              '"Connect" again.',
          null,
        ),
      LinkErrorReason.permissionDeniedPermanently => (
          'The "Nearby devices" permission was permanently denied. Please '
              'grant it manually in the app settings.',
          _HintAction('App settings', BluetoothSystemSettings.openAppSettings),
        ),
      LinkErrorReason.deviceSelectionRequired => (
          'No paired mLRS device found. Please select a device below.',
          null,
        ),
      LinkErrorReason.connectionFailed => (
          'Connection to the device failed.',
          null,
        ),
      LinkErrorReason.unknown => ('Unknown connection error.', null),
    };
    return Container(
      padding: const EdgeInsets.all(8),
      decoration: BoxDecoration(
        color: DmcColors.warnRed.withValues(alpha: 0.1),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Row(
        children: [
          Expanded(child: Text(text, style: const TextStyle(fontSize: 12))),
          if (action != null)
            TextButton(onPressed: action.onTap, child: Text(action.label)),
        ],
      ),
    );
  }
}

class _HintAction {
  const _HintAction(this.label, this.onTap);
  final String label;
  final Future<void> Function() onTap;
}