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/connection_type.dart';
import '../../../transport/flight_controller_link.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';
import '../../providers/telemetry_provider.dart';
import '../../providers/wifi_connection_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 connectionSettings = ref.watch(connectionSettingsProvider).value;
    final selectedType = connectionSettings?.connectionType ?? ConnectionType.wifi;

    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            // Fuer WLAN rendert _WifiPanel das Typ-Dropdown selbst als Teil
            // seiner kompakten ersten Zeile (zusammen mit Connect/Disconnect
            // und den Status-Pillen) - fuer die anderen Verbindungsarten
            // bleibt die bisherige, einfachere Kopfzeile bestehen.
            if (selectedType != ConnectionType.wifi) ...[
              Text('Connection', style: Theme.of(context).textTheme.titleMedium),
              const SizedBox(height: 12),
              DropdownButtonFormField<ConnectionType>(
                initialValue: selectedType,
                decoration: const InputDecoration(
                  labelText: 'Type',
                  isDense: true,
                  border: OutlineInputBorder(),
                ),
                items: _connectionTypeItems,
                onChanged: (type) async {
                  if (type == null) return;
                  await ref.read(appSettingsRepositoryProvider).setConnectionType(type);
                  ref.invalidate(connectionSettingsProvider);
                },
              ),
              const SizedBox(height: 16),
            ],
            switch (selectedType) {
              ConnectionType.wifi => const _WifiPanel(),
              ConnectionType.bluetooth => const _BluetoothPanel(),
              ConnectionType.cellular5g => const _NotAvailablePanel(
                  label: '5G',
                ),
              ConnectionType.usb => const _NotAvailablePanel(label: 'USB'),
            },
          ],
        ),
      ),
    );
  }
}

/// Geteilt zwischen der kompakten WLAN-Zeile ([_WifiPanel]) und der
/// generischen Kopfzeile fuer die anderen Verbindungsarten
/// ([_ConnectionSection]), damit die Beschriftungen an beiden Stellen
/// gleich lauten.
const _connectionTypeItems = [
  DropdownMenuItem(value: ConnectionType.wifi, child: Text('WiFi mLRS UDP')),
  DropdownMenuItem(value: ConnectionType.cellular5g, child: Text('5G (soon)')),
  DropdownMenuItem(value: ConnectionType.bluetooth, child: Text('Bluetooth')),
  DropdownMenuItem(value: ConnectionType.usb, child: Text('USB (soon)')),
];

class _NotAvailablePanel extends StatelessWidget {
  const _NotAvailablePanel({required this.label});

  final String label;

  @override
  Widget build(BuildContext context) {
    return Text(
      '$label support is not available yet.',
      style: const TextStyle(fontSize: 12, color: Colors.grey),
    );
  }
}

/// SSID-Praefix und Port werden bewusst nicht mehr als Textfelder angeboten
/// (Doku: "Preset WiFi mLRS UDP, alles automatisch setzen") - die
/// gespeicherten Defaults ("mLRS-"/14550, siehe AppDatabase) passen fuer die
/// mLRS-WLAN-Bruecke immer, ein manuelles Ueberschreiben war in der Praxis
/// nur eine Fehlerquelle beim Verbindungsaufbau.
class _WifiPanel extends ConsumerWidget {
  const _WifiPanel();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final linkState = ref.watch(wifiLinkStateProvider).value;
    final errorReason = ref.watch(wifiLinkErrorReasonProvider);
    final isReceiving = ref.watch(wifiStreamActivityProvider);
    final connectionSettings = ref.watch(connectionSettingsProvider).value;
    final log = ref.watch(wifiConnectionLogProvider);
    final packetCount = ref.watch(wifiPacketCountProvider);
    final connectedSsid = ref.watch(wifiConnectedSsidProvider).value;

    // MSP-Telemetrie nur beobachten, wenn der Transport bereits verbunden
    // ist - sonst wuerde allein das Oeffnen dieses Screens ueber
    // telemetryProvider einen neuen Verbindungsversuch (samt Systemdialog)
    // auslösen. Ist bereits eine echte Verbindung aktiv (z.B. weil der
    // Fly-Modus sie aufgebaut hat), liefert dies denselben Provider/dieselbe
    // MSP-Client-Instanz wie FlyScreen - keine zweite, konkurrierende
    // Abfrage-Schleife. Der Telemetrie-Strom selbst ist nicht auf einen
    // GPS-Fix gegated (siehe TelemetryFrame-Doku) - die Felder erscheinen
    // hier also auch ohne Fix, sobald ueberhaupt eine MSP-Antwort ankommt.
    final telemetry = linkState == LinkState.connected
        ? ref.watch(telemetryProvider).value
        : null;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          children: [
            SizedBox(
              width: 260,
              child: DropdownButtonFormField<ConnectionType>(
                initialValue: ConnectionType.wifi,
                decoration: const InputDecoration(isDense: true, border: OutlineInputBorder()),
                items: _connectionTypeItems,
                onChanged: (type) async {
                  if (type == null) return;
                  await ref.read(appSettingsRepositoryProvider).setConnectionType(type);
                  ref.invalidate(connectionSettingsProvider);
                },
              ),
            ),
            const SizedBox(width: 8),
            _ConnectToggleButton(
              state: linkState,
              onConnect: () => _connect(ref),
              onDisconnect: () => ref.read(wifiTransportProvider).disconnect(),
            ),
            const Spacer(),
            _StreamActivityPill(isReceiving: isReceiving, packetCount: packetCount),
            const SizedBox(width: 6),
            _StatePill(state: linkState, connectedLabel: connectedSsid ?? 'unknown'),
          ],
        ),
        if (errorReason != null) ...[
          const SizedBox(height: 12),
          _WifiErrorHint(reason: errorReason),
        ],
        const SizedBox(height: 12),
        SwitchListTile(
          contentPadding: EdgeInsets.zero,
          title: const Text('Auto-connect when entering Fly mode'),
          subtitle: const Text(
            'Only once a network has been remembered.',
            style: TextStyle(fontSize: 11),
          ),
          value: connectionSettings?.connectionAutoConnect ?? true,
          onChanged: (value) async {
            await ref
                .read(appSettingsRepositoryProvider)
                .setConnectionAutoConnect(value);
            ref.invalidate(connectionSettingsProvider);
          },
        ),
        const SizedBox(height: 8),
        Text('Telemetry', style: Theme.of(context).textTheme.titleSmall),
        const SizedBox(height: 4),
        _TelemetryFields(telemetry: telemetry),
        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(wifiTransportProvider).connect();
    } on LinkConnectException {
      // Grund/Nachricht sind bereits ueber wifiLinkErrorReasonProvider
      // gemeldet, siehe _WifiErrorHint.
    }
  }

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

/// Empfangene, ueber MSP dekodierte Telemetriefelder (Doku: "vor dem
/// Connection log die empfangenen Telemetriefelder anzeigen") - zum
/// schnellen Pruefen auf echter Hardware, ohne in den Fly-Modus wechseln zu
/// muessen.
class _TelemetryFields extends StatelessWidget {
  const _TelemetryFields({required this.telemetry});

  final TelemetryFrame? telemetry;

  @override
  Widget build(BuildContext context) {
    final t = telemetry;
    if (t == null) {
      return const Text(
        'No telemetry yet.',
        style: TextStyle(fontSize: 12, color: Colors.grey),
      );
    }
    return Wrap(
      spacing: 16,
      runSpacing: 4,
      children: [
        _field('GPS', t.hasFix ? 'Fix (${t.numSat} sats)' : 'No fix (${t.numSat} sats)'),
        _field('Lat', t.lat.toStringAsFixed(6)),
        _field('Lon', t.lon.toStringAsFixed(6)),
        _field('Alt', '${t.altitudeM.toStringAsFixed(1)} m'),
        _field('Speed', '${t.speedMs.toStringAsFixed(1)} m/s'),
        _field('Heading', '${t.headingDeg.toStringAsFixed(0)}°'),
        _field('Armed', t.armed ? 'Yes' : 'No'),
        if (t.activeWaypointIndex != null)
          _field('Active WP', '${t.activeWaypointIndex}'),
      ],
    );
  }

  Widget _field(String label, String value) => Text(
        '$label: $value',
        style: const TextStyle(fontSize: 12, fontFamily: 'monospace'),
      );
}

/// Runder Connect/Disconnect-Umschalter fuer die kompakte erste Zeile des
/// WLAN-Panels (Doku: "kompakter gestalten") - ein Knopf statt zwei, der je
/// nach [state] Beschriftung und Aktion wechselt.
class _ConnectToggleButton extends StatelessWidget {
  const _ConnectToggleButton({
    required this.state,
    required this.onConnect,
    required this.onDisconnect,
  });

  final LinkState? state;
  final VoidCallback onConnect;
  final VoidCallback onDisconnect;

  @override
  Widget build(BuildContext context) {
    final isActive =
        state == LinkState.connected || state == LinkState.connecting;
    final color = isActive ? DmcColors.warnRed : DmcColors.liveGreen;
    return OutlinedButton(
      onPressed: isActive ? onDisconnect : onConnect,
      style: OutlinedButton.styleFrom(
        shape: const StadiumBorder(),
        side: BorderSide(color: color),
        foregroundColor: color,
      ),
      child: Text(isActive ? 'Disconnect' : 'Connect'),
    );
  }
}

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

  final LinkErrorReason reason;

  @override
  Widget build(BuildContext context) {
    final text = switch (reason) {
      LinkErrorReason.networkUnavailable =>
        'No matching WiFi network found, or the system connection dialog '
            'was dismissed. Make sure the mLRS bridge is powered on and not '
            'saved/connected in system WiFi settings, then tap "Connect" '
            'again.',
      LinkErrorReason.networkLost =>
        'The mLRS WiFi network was lost (out of range or bridge powered '
            'off). Tap "Connect" to reconnect.',
      LinkErrorReason.connectionFailed => 'Connection to the bridge failed.',
      _ => 'Connection error: ${reason.name}.',
    };
    return Container(
      padding: const EdgeInsets.all(8),
      decoration: BoxDecoration(
        color: DmcColors.warnRed.withValues(alpha: 0.1),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Text(text, style: const TextStyle(fontSize: 12)),
    );
  }
}

class _BluetoothPanel extends ConsumerWidget {
  const _BluetoothPanel();

  @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 Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          children: [
            Text('Bluetooth', style: Theme.of(context).textTheme.titleSmall),
            const Spacer(),
            _StatePill(state: linkState),
          ],
        ),
        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
    }
  }
}

/// Zeigt neben [_StatePill], ob gerade UDP-Pakete ankommen ("receiving") -
/// unabhaengig vom Verbindungszustand, der Socket kann offen sein, ohne
/// dass die Gegenstelle sendet (siehe wifiStreamActivityProvider).
class _StreamActivityPill extends StatelessWidget {
  const _StreamActivityPill({required this.isReceiving, required this.packetCount});

  final bool isReceiving;

  /// Gesamtzahl empfangener Pakete (Doku: "Receiving-Pille soll empfangene
  /// Pakete anzeigen und automatisch aktualisieren") - reaktiv ueber
  /// wifiPacketCountProvider, aktualisiert sich also mit jedem Paket.
  final int packetCount;

  @override
  Widget build(BuildContext context) {
    final color = isReceiving ? DmcColors.liveGreen : Colors.grey;
    final label = isReceiving ? 'Receiving ($packetCount)' : 'Not receiving';
    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 _StatePill extends StatelessWidget {
  const _StatePill({required this.state, this.connectedLabel});

  final LinkState? state;

  /// WLAN-Netzname, falls bekannt - erscheint im verbundenen Zustand als
  /// "Connected to {name}" statt des generischen "Connected" (Doku: "die
  /// connected pille soll den WiFi-Namen anzeigen").
  final String? connectedLabel;

  @override
  Widget build(BuildContext context) {
    final (label, color) = switch (state) {
      LinkState.connected => (
          connectedLabel != null ? 'Connected to $connectedLabel' : '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,
        ),
      // networkUnavailable/networkLost betreffen nur den WLAN-Transport
      // (siehe _WifiErrorHint) - hier nur der Vollstaendigkeit halber, damit
      // der gemeinsame LinkErrorReason-Enum exhaustiv bleibt.
      LinkErrorReason.networkUnavailable ||
      LinkErrorReason.networkLost ||
      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;
}