import 'dart:async';

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

import 'rust/api.dart' as nd;
import 'theme.dart';

/// "Allow remote control" — the Android HOST role.
///
/// Turns this device into a NetDesk host (like RustDesk): once the user grants
/// screen capture and enables the accessibility service, a remote viewer can see
/// and control it. Talks to the native side over the `space.netdesk/host`
/// MethodChannel (see MainActivity.kt / HostService.kt).
///
/// Preview: screen capture + the controls are live; the remote-connection wiring
/// (register by Partner ID, send the encrypted H.264 to a viewer) lands next.
class HostScreen extends StatefulWidget {
  const HostScreen({super.key});

  @override
  State<HostScreen> createState() => _HostScreenState();
}

class _HostScreenState extends State<HostScreen> with WidgetsBindingObserver {
  static const _host = MethodChannel('space.netdesk/host');
  static const _frameChannel = EventChannel('space.netdesk/frames');
  static const _wsUrl = 'wss://netdesk.space/ws';

  bool _running = false;
  bool _accessibility = false;
  bool _hideIcon = false;
  bool _unattended = false;
  int _frames = 0;
  bool _busy = false;

  // Rust host session.
  BigInt? _handle;
  String _id = '';
  String _password = '';
  bool _viewerConnected = false;
  StreamSubscription<dynamic>? _frameSub;
  StreamSubscription<nd.NdHostEvent>? _eventSub;

  // Viewer-mouse -> touch gesture interpretation (coords are in capture space;
  // MainActivity scales to the real display before injecting).
  int _btns = 0;
  double _downX = 0, _downY = 0, _lastX = 0, _lastY = 0;
  int _downMs = 0;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    _refresh();
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    _frameSub?.cancel();
    _eventSub?.cancel();
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    if (state == AppLifecycleState.resumed) _refresh();
  }

  Future<T?> _call<T>(String method, [Map<String, dynamic>? args]) async {
    try {
      return await _host.invokeMethod<T>(method, args);
    } catch (_) {
      return null;
    }
  }

  Future<void> _refresh() async {
    final running = await _call<bool>('isHostRunning') ?? false;
    final acc = await _call<bool>('hasAccessibility') ?? false;
    final hide = await _call<bool>('isIconHidden') ?? false;
    final un = await _call<bool>('isUnattended') ?? false;
    final frames = await _call<int>('lastFrameCount') ?? 0;
    if (mounted) {
      setState(() {
        _running = running;
        _accessibility = acc;
        _hideIcon = hide;
        _unattended = un;
        _frames = frames;
      });
    }
  }

  Future<void> _toggleHost() async {
    setState(() => _busy = true);
    if (_running) {
      await _stopHostFull();
    } else {
      await _startHostFull();
    }
    if (mounted) setState(() => _busy = false);
  }

  /// Load the persisted host id + unattended password, generating them once.
  Future<void> _loadCreds() async {
    var id = await _call<String>('getHostId') ?? '';
    var pw = await _call<String>('getHostPassword') ?? '';
    if (id.isEmpty || pw.isEmpty) {
      id = nd.hostGenId();
      pw = nd.hostGenPassword();
      await _call('setHostCreds', {'id': id, 'password': pw});
    }
    if (mounted) {
      setState(() {
        _id = id;
        _password = pw;
      });
    }
  }

  Future<void> _startHostFull() async {
    await _loadCreds();
    // 1) screen-capture consent -> HostService starts encoding.
    final ok = await _call<bool>('startHost') ?? false;
    if (!ok) {
      await _refresh();
      return;
    }
    // 2) wait for the encoder to report a capture size.
    int w = 0, h = 0;
    for (var i = 0; i < 30; i++) {
      await Future.delayed(const Duration(milliseconds: 200));
      final s = await _call<Map<dynamic, dynamic>>('hostScreenSize');
      if (s != null && (s['w'] as int? ?? 0) > 0) {
        w = s['w'] as int;
        h = s['h'] as int;
        break;
      }
    }
    if (w == 0) {
      await _refresh();
      return;
    }
    // 3) register the Rust host + wire frames out and input in.
    final handle = await nd.hostStart(
      wsUrl: _wsUrl,
      hostId: _id,
      name: 'Android',
      password: _password,
      width: w,
      height: h,
    );
    _handle = handle;
    _frameSub = _frameChannel.receiveBroadcastStream().listen(_onFrame);
    _eventSub = nd.hostEvents(handle: handle).listen(_onHostEvent);
    await _refresh();
  }

  Future<void> _stopHostFull() async {
    await _frameSub?.cancel();
    _frameSub = null;
    await _eventSub?.cancel();
    _eventSub = null;
    final h = _handle;
    _handle = null;
    if (h != null) nd.hostStop(handle: h);
    await _call('stopHost');
    if (mounted) setState(() => _viewerConnected = false);
    await Future.delayed(const Duration(milliseconds: 300));
    await _refresh();
  }

  void _onFrame(dynamic payload) {
    final h = _handle;
    if (h == null || payload is! Uint8List || payload.isEmpty) return;
    final keyframe = payload[0] == 1;
    final data = Uint8List.sublistView(payload, 1);
    nd.hostPushFrame(handle: h, data: data, keyframe: keyframe);
  }

  void _onHostEvent(nd.NdHostEvent ev) {
    switch (ev) {
      case nd.NdHostEvent_Mouse(:final x, :final y, :final buttons, :final wheel):
        _onMouse(x, y, buttons, wheel);
      case nd.NdHostEvent_Key(:final code, :final down):
        _call('injectKey', {'code': code, 'down': down});
      case nd.NdHostEvent_KeyframeRequested():
        _call('requestKeyframe');
      case nd.NdHostEvent_ViewerConnected():
        if (mounted) setState(() => _viewerConnected = true);
      case nd.NdHostEvent_ViewerLeft():
        if (mounted) setState(() => _viewerConnected = false);
      default:
        break;
    }
  }

  /// Translate the viewer's absolute pointer into Android gestures: a quick
  /// press+release = tap, a moved drag = swipe, wheel = scroll.
  void _onMouse(int x, int y, int buttons, double wheel) {
    if (wheel != 0) {
      final dy = (wheel.clamp(-3.0, 3.0) * 140).round();
      _call('injectSwipe', {
        'x1': x.toDouble(), 'y1': y.toDouble(),
        'x2': x.toDouble(), 'y2': (y + dy).toDouble(), 'dur': 120,
      });
      return;
    }
    final leftNow = (buttons & 1) != 0;
    final leftWas = (_btns & 1) != 0;
    _btns = buttons;
    if (leftNow && !leftWas) {
      _downX = x.toDouble();
      _downY = y.toDouble();
      _lastX = _downX;
      _lastY = _downY;
      _downMs = DateTime.now().millisecondsSinceEpoch;
    } else if (leftNow && leftWas) {
      _lastX = x.toDouble();
      _lastY = y.toDouble();
    } else if (!leftNow && leftWas) {
      _lastX = x.toDouble();
      _lastY = y.toDouble();
      final dist = (_lastX - _downX).abs() + (_lastY - _downY).abs();
      if (dist < 12) {
        _call('injectTap', {'x': _downX, 'y': _downY});
      } else {
        final dur = (DateTime.now().millisecondsSinceEpoch - _downMs)
            .clamp(40, 800);
        _call('injectSwipe', {
          'x1': _downX, 'y1': _downY, 'x2': _lastX, 'y2': _lastY, 'dur': dur,
        });
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: NetDeskColors.background,
      appBar: AppBar(
        backgroundColor: NetDeskColors.background,
        elevation: 0,
        title: const Text('Allow remote control'),
      ),
      body: SafeArea(
        child: RefreshIndicator(
          color: NetDeskColors.accent,
          onRefresh: _refresh,
          child: ListView(
            padding: const EdgeInsets.all(16),
            children: [
              _statusCard(),
              if (_running && _id.isNotEmpty) ...[
                const SizedBox(height: 14),
                _credsCard(),
              ],
              const SizedBox(height: 14),
              _startStopButton(),
              const SizedBox(height: 18),
              _tile(
                icon: Icons.touch_app_outlined,
                title: 'Remote input (accessibility)',
                subtitle: _accessibility
                    ? 'Enabled — a viewer can tap and swipe this device.'
                    : 'Required so a viewer can tap and swipe. Tap to enable.',
                trailing: _accessibility
                    ? const Icon(Icons.check_circle, color: NetDeskColors.accent)
                    : const Icon(Icons.chevron_right,
                        color: NetDeskColors.textMuted),
                onTap: _accessibility
                    ? null
                    : () async {
                        await _call('openAccessibilitySettings');
                      },
              ),
              _switchTile(
                icon: Icons.schedule,
                title: 'Unattended access',
                subtitle: 'Start the host automatically after the device reboots.',
                value: _unattended,
                onChanged: (v) async {
                  await _call('setUnattended', {'on': v});
                  await _refresh();
                },
              ),
              _switchTile(
                icon: Icons.visibility_off_outlined,
                title: 'Hide app icon',
                subtitle:
                    'Remove NetDesk from the app drawer (it keeps running). '
                    'Reopen it from your browser at netdesk.space.',
                value: _hideIcon,
                onChanged: (v) async {
                  await _call('setHideIcon', {'hide': v});
                  await _refresh();
                },
              ),
              const SizedBox(height: 16),
              const Padding(
                padding: EdgeInsets.symmetric(horizontal: 4),
                child: Text(
                  'Enter the ID and password above in any NetDesk viewer '
                  '(Windows, web or another phone) to see and control this '
                  'device. Keep the screen-capture notification on. '
                  'Developed by Akronlogic.',
                  style: TextStyle(
                      color: NetDeskColors.textMuted, fontSize: 12, height: 1.4),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _statusCard() {
    final on = _running;
    return Container(
      padding: const EdgeInsets.all(18),
      decoration: BoxDecoration(
        color: NetDeskColors.surface,
        borderRadius: BorderRadius.circular(NetDeskRadius.lg),
        border: Border.all(color: NetDeskColors.border),
      ),
      child: Row(
        children: [
          Container(
            width: 44,
            height: 44,
            decoration: BoxDecoration(
              color: on ? NetDeskColors.accentGlow : NetDeskColors.surfaceAlt,
              borderRadius: BorderRadius.circular(12),
            ),
            child: Icon(
              on ? Icons.cast_connected : Icons.cast,
              color: on ? NetDeskColors.accent : NetDeskColors.textSecondary,
            ),
          ),
          const SizedBox(width: 14),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  on ? 'Host is active' : 'Host is off',
                  style: const TextStyle(
                    color: NetDeskColors.textPrimary,
                    fontSize: 17,
                    fontWeight: FontWeight.w700,
                  ),
                ),
                const SizedBox(height: 2),
                Text(
                  on
                      ? 'Capturing the screen · $_frames frames encoded'
                      : 'This device cannot be controlled yet',
                  style: const TextStyle(
                      color: NetDeskColors.textSecondary, fontSize: 13),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

  Widget _credsCard() {
    return Container(
      padding: const EdgeInsets.all(18),
      decoration: BoxDecoration(
        color: NetDeskColors.surface,
        borderRadius: BorderRadius.circular(NetDeskRadius.lg),
        border: Border.all(
          color: _viewerConnected ? NetDeskColors.accent : NetDeskColors.border,
        ),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(
            children: [
              Icon(
                _viewerConnected ? Icons.lock_person : Icons.vpn_key_outlined,
                size: 18,
                color: _viewerConnected
                    ? NetDeskColors.accent
                    : NetDeskColors.textSecondary,
              ),
              const SizedBox(width: 8),
              Text(
                _viewerConnected ? 'A viewer is connected' : 'Ready for a viewer',
                style: TextStyle(
                  color: _viewerConnected
                      ? NetDeskColors.accent
                      : NetDeskColors.textSecondary,
                  fontSize: 13,
                  fontWeight: FontWeight.w600,
                ),
              ),
            ],
          ),
          const SizedBox(height: 14),
          _credRow('Your ID', _id),
          const SizedBox(height: 10),
          _credRow('Password', _password),
        ],
      ),
    );
  }

  Widget _credRow(String label, String value) {
    return Row(
      children: [
        SizedBox(
          width: 86,
          child: Text(label,
              style: const TextStyle(
                  color: NetDeskColors.textMuted, fontSize: 13)),
        ),
        Expanded(
          child: SelectableText(
            value,
            style: const TextStyle(
              color: NetDeskColors.textPrimary,
              fontSize: 19,
              fontWeight: FontWeight.w700,
              letterSpacing: 1.5,
            ),
          ),
        ),
        IconButton(
          icon: const Icon(Icons.copy_rounded,
              size: 18, color: NetDeskColors.textSecondary),
          onPressed: () {
            Clipboard.setData(ClipboardData(text: value));
            ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(
                content: Text('$label copied'),
                duration: const Duration(seconds: 1),
              ),
            );
          },
        ),
      ],
    );
  }

  Widget _startStopButton() {
    return SizedBox(
      height: 52,
      child: ElevatedButton(
        onPressed: _busy ? null : _toggleHost,
        style: ElevatedButton.styleFrom(
          backgroundColor:
              _running ? NetDeskColors.danger : NetDeskColors.accent,
          foregroundColor: _running ? Colors.white : const Color(0xFF04210F),
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(NetDeskRadius.md),
          ),
        ),
        child: _busy
            ? const SizedBox(
                width: 22,
                height: 22,
                child: CircularProgressIndicator(strokeWidth: 2.4),
              )
            : Text(
                _running ? 'Stop hosting' : 'Start hosting this device',
                style: const TextStyle(
                    fontSize: 16, fontWeight: FontWeight.w700),
              ),
      ),
    );
  }

  Widget _tile({
    required IconData icon,
    required String title,
    required String subtitle,
    Widget? trailing,
    VoidCallback? onTap,
  }) {
    return Container(
      margin: const EdgeInsets.only(bottom: 10),
      decoration: BoxDecoration(
        color: NetDeskColors.surface,
        borderRadius: BorderRadius.circular(NetDeskRadius.md),
        border: Border.all(color: NetDeskColors.border),
      ),
      child: ListTile(
        onTap: onTap,
        leading: Icon(icon, color: NetDeskColors.textSecondary),
        title: Text(title,
            style: const TextStyle(
                color: NetDeskColors.textPrimary,
                fontWeight: FontWeight.w600)),
        subtitle: Text(subtitle,
            style: const TextStyle(
                color: NetDeskColors.textMuted, fontSize: 12.5)),
        trailing: trailing,
      ),
    );
  }

  Widget _switchTile({
    required IconData icon,
    required String title,
    required String subtitle,
    required bool value,
    required ValueChanged<bool> onChanged,
  }) {
    return Container(
      margin: const EdgeInsets.only(bottom: 10),
      decoration: BoxDecoration(
        color: NetDeskColors.surface,
        borderRadius: BorderRadius.circular(NetDeskRadius.md),
        border: Border.all(color: NetDeskColors.border),
      ),
      child: SwitchListTile(
        value: value,
        onChanged: onChanged,
        activeThumbColor: NetDeskColors.accent,
        secondary: Icon(icon, color: NetDeskColors.textSecondary),
        title: Text(title,
            style: const TextStyle(
                color: NetDeskColors.textPrimary,
                fontWeight: FontWeight.w600)),
        subtitle: Text(subtitle,
            style: const TextStyle(
                color: NetDeskColors.textMuted, fontSize: 12.5)),
      ),
    );
  }
}