companion/lib/features/connection/server_discovery_screen.dart

import 'dart:async';

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

import '../../data/sources/localiser/onboarding_client.dart';
import '../../data/sources/mdns/mdns_discovery.dart';
import '../../domain/models/server_config.dart';
import '../../providers.dart';

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

  @override
  ConsumerState<ServerDiscoveryScreen> createState() =>
      _ServerDiscoveryScreenState();
}

class _ServerDiscoveryScreenState extends ConsumerState<ServerDiscoveryScreen> {
  final _hostController = TextEditingController();
  final _portController = TextEditingController(text: '4000');
  bool _connecting = false;
  String? _error;

  final _discovery = MdnsDiscovery();
  final _discoveredServers = <ServerConfig>[];
  StreamSubscription<ServerConfig>? _discoverySub;

  @override
  void initState() {
    super.initState();
    _discoverySub = _discovery.discover().listen(
      (server) {
        if (!_discoveredServers.contains(server)) {
          setState(() => _discoveredServers.add(server));
        }
      },
      onError: (_) {},
    );
  }

  @override
  void dispose() {
    _discoverySub?.cancel();
    _hostController.dispose();
    _portController.dispose();
    _discovery.stop();
    super.dispose();
  }

  Future<void> _connect(ServerConfig config) async {
    setState(() {
      _connecting = true;
      _error = null;
    });
    try {
      final checklist =
          await OnboardingClient(config: config).getChecklist();

      ref.read(serverConfigProvider.notifier).state = config;

      if (!mounted) return;
      if (!checklist.hasAdmin) {
        context.go('/onboarding');
      } else {
        context.go('/login');
      }
    } catch (e) {
      setState(() => _error = e.toString());
    } finally {
      if (mounted) setState(() => _connecting = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Connect to Server')),
      body: Padding(
        padding: const EdgeInsets.all(24),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            const Text('Discovered servers'),
            const SizedBox(height: 8),
            if (_discoveredServers.isEmpty)
              const Padding(
                padding: EdgeInsets.symmetric(vertical: 32),
                child: Center(
                  child: Text(
                    'Scanning…',
                    style: TextStyle(color: Colors.grey),
                  ),
                ),
              )
            else
              ConstrainedBox(
                constraints: const BoxConstraints(maxHeight: 200),
                child: ListView.builder(
                  shrinkWrap: true,
                  itemCount: _discoveredServers.length,
                  itemBuilder: (context, i) {
                    final server = _discoveredServers[i];
                    return ListTile(
                      title: Text(server.host),
                      subtitle: Text('Port ${server.port}'),
                      trailing: const Icon(Icons.chevron_right),
                      onTap: _connecting ? null : () => _connect(server),
                    );
                  },
                ),
              ),
            const Divider(),
            const SizedBox(height: 16),
            const Text('Manual entry'),
            const SizedBox(height: 8),
            TextField(
              controller: _hostController,
              decoration: const InputDecoration(
                labelText: 'Host / IP',
                hintText: '192.168.1.100',
                border: OutlineInputBorder(),
              ),
              keyboardType: TextInputType.url,
            ),
            const SizedBox(height: 12),
            TextField(
              controller: _portController,
              decoration: const InputDecoration(
                labelText: 'Port',
                border: OutlineInputBorder(),
              ),
              keyboardType: TextInputType.number,
            ),
            const SizedBox(height: 16),
            if (_error != null)
              Padding(
                padding: const EdgeInsets.only(bottom: 12),
                child: Text(
                  _error!,
                  style: TextStyle(color: Theme.of(context).colorScheme.error),
                ),
              ),
            FilledButton(
              onPressed: _connecting
                  ? null
                  : () => _connect(ServerConfig(
                        host: _hostController.text.trim(),
                        port: int.tryParse(_portController.text) ?? 4000,
                      )),
              child: _connecting
                  ? const SizedBox.square(
                      dimension: 20,
                      child: CircularProgressIndicator(strokeWidth: 2),
                    )
                  : const Text('Connect'),
            ),
          ],
        ),
      ),
    );
  }
}