// Chanora Flutter application entry point — Alpha build.
//
// Wires the Alpha UI: server-address + nickname form, connect button,
// channel tree, disconnect. All names from server-side state are
// preserved verbatim per ADR-008 / DEC-015.

import 'package:flutter/material.dart';

import 'l10n/generated/app_localizations.dart';
import 'src/rust/api.dart' as rust;
import 'src/rust/frb_generated.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await RustLib.init();
  runApp(const ChanoraApp());
}

class ChanoraApp extends StatelessWidget {
  const ChanoraApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      onGenerateTitle: (ctx) => AppL10n.of(ctx).appTitle,
      theme: ThemeData(
        useMaterial3: true,
        colorSchemeSeed: const Color(0xFF3F51B5),
      ),
      // DEC-015 (register v0.9.5): English + Chinese Simplified at MVP.
      localizationsDelegates: AppL10n.localizationsDelegates,
      supportedLocales: AppL10n.supportedLocales,
      home: const _AlphaHome(),
    );
  }
}

/// Three-state UI: idle / connecting / connected. Errors collapse
/// back to idle with the message captured.
class _AlphaHome extends StatefulWidget {
  const _AlphaHome();

  @override
  State<_AlphaHome> createState() => _AlphaHomeState();
}

enum _Phase { idle, connecting, connected }

class _AlphaHomeState extends State<_AlphaHome> {
  final _hostCtl = TextEditingController(text: 'cn.teamspeak.app');
  final _nickCtl = TextEditingController(text: 'ChanoraAlpha');

  _Phase _phase = _Phase.idle;
  rust.BridgeSnapshot? _snapshot;
  String? _error;

  @override
  void dispose() {
    _hostCtl.dispose();
    _nickCtl.dispose();
    super.dispose();
  }

  Future<void> _onConnect() async {
    setState(() {
      _phase = _Phase.connecting;
      _error = null;
      _snapshot = null;
    });
    try {
      final snap = await rust.connect(
        host: _hostCtl.text.trim(),
        nickname: _nickCtl.text.trim(),
      );
      if (!mounted) return;
      setState(() {
        _phase = _Phase.connected;
        _snapshot = snap;
      });
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _phase = _Phase.idle;
        _error = e.toString();
      });
    }
  }

  Future<void> _onRefresh() async {
    try {
      final snap = await rust.snapshot();
      if (!mounted) return;
      setState(() => _snapshot = snap);
    } catch (e) {
      if (!mounted) return;
      setState(() => _error = e.toString());
    }
  }

  Future<void> _onDisconnect() async {
    try {
      await rust.disconnect();
    } catch (_) {
      // Best-effort. Even if disconnect throws we drop back to idle.
    }
    if (!mounted) return;
    setState(() {
      _phase = _Phase.idle;
      _snapshot = null;
      _error = null;
    });
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppL10n.of(context);
    final theme = Theme.of(context);

    String statusText() {
      switch (_phase) {
        case _Phase.idle:
          return _error != null ? l10n.statusError(_error!) : l10n.statusIdle;
        case _Phase.connecting:
          return l10n.statusConnecting;
        case _Phase.connected:
          return l10n.statusConnected(_snapshot?.serverName ?? '');
      }
    }

    return Scaffold(
      appBar: AppBar(
        title: Text(l10n.appTitle),
        actions: [
          if (_phase == _Phase.connected) ...[
            IconButton(
              tooltip: l10n.refreshAction,
              icon: const Icon(Icons.refresh),
              onPressed: _onRefresh,
            ),
            IconButton(
              tooltip: l10n.disconnectAction,
              icon: const Icon(Icons.logout),
              onPressed: _onDisconnect,
            ),
          ],
        ],
      ),
      body: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            // Banner
            Container(
              padding: const EdgeInsets.all(10),
              decoration: BoxDecoration(
                color: theme.colorScheme.tertiaryContainer,
                borderRadius: BorderRadius.circular(8),
              ),
              child: Text(
                l10n.homeNotProductionReadyBanner,
                style: TextStyle(color: theme.colorScheme.onTertiaryContainer),
              ),
            ),
            const SizedBox(height: 12),
            // Status
            Text(statusText(), style: theme.textTheme.titleMedium),
            const SizedBox(height: 12),
            if (_phase == _Phase.idle) ...[
              _ConnectForm(
                hostCtl: _hostCtl,
                nickCtl: _nickCtl,
                onConnect: _onConnect,
              ),
            ] else if (_phase == _Phase.connecting) ...[
              const Center(child: Padding(
                padding: EdgeInsets.all(32),
                child: CircularProgressIndicator(),
              )),
            ] else if (_phase == _Phase.connected && _snapshot != null) ...[
              Expanded(child: _SnapshotView(snapshot: _snapshot!)),
            ],
          ],
        ),
      ),
    );
  }
}

class _ConnectForm extends StatelessWidget {
  const _ConnectForm({
    required this.hostCtl,
    required this.nickCtl,
    required this.onConnect,
  });

  final TextEditingController hostCtl;
  final TextEditingController nickCtl;
  final VoidCallback onConnect;

  @override
  Widget build(BuildContext context) {
    final l10n = AppL10n.of(context);
    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        TextField(
          controller: hostCtl,
          decoration: InputDecoration(
            labelText: l10n.fieldServerHost,
            border: const OutlineInputBorder(),
          ),
        ),
        const SizedBox(height: 8),
        TextField(
          controller: nickCtl,
          decoration: InputDecoration(
            labelText: l10n.fieldNickname,
            border: const OutlineInputBorder(),
          ),
        ),
        const SizedBox(height: 16),
        FilledButton.icon(
          icon: const Icon(Icons.login),
          label: Text(l10n.connectAction),
          onPressed: onConnect,
        ),
      ],
    );
  }
}

class _SnapshotView extends StatelessWidget {
  const _SnapshotView({required this.snapshot});

  final rust.BridgeSnapshot snapshot;

  @override
  Widget build(BuildContext context) {
    final l10n = AppL10n.of(context);
    final theme = Theme.of(context);

    final channels = [...snapshot.channels]
      ..sort((a, b) => a.order.compareTo(b.order));

    // Index clients by channel id for the tree view.
    final byChannel = <BigInt, List<rust.BridgeClient>>{};
    for (final c in snapshot.clients) {
      byChannel.putIfAbsent(c.channel, () => []).add(c);
    }

    return ListView(
      children: [
        Text(
          l10n.countChannelsAndClients(snapshot.channels.length, snapshot.clients.length),
          style: theme.textTheme.bodyMedium,
        ),
        if (snapshot.welcomeMessage.isNotEmpty) ...[
          const SizedBox(height: 8),
          Container(
            padding: const EdgeInsets.all(8),
            decoration: BoxDecoration(
              color: theme.colorScheme.surfaceContainerHighest,
              borderRadius: BorderRadius.circular(6),
            ),
            // Server-provided content; preserved verbatim per ADR-008.
            child: Text(snapshot.welcomeMessage, style: theme.textTheme.bodySmall),
          ),
        ],
        const Divider(height: 24),
        Text(l10n.channelsHeading, style: theme.textTheme.titleMedium),
        const SizedBox(height: 4),
        for (final ch in channels) ...[
          ListTile(
            dense: true,
            leading: const Icon(Icons.tag),
            title: Text(ch.name),
            subtitle: Text('id=${ch.id}  parent=${ch.parent}'),
          ),
          for (final cl in byChannel[ch.id] ?? const <rust.BridgeClient>[])
            Padding(
              padding: const EdgeInsets.only(left: 64),
              child: ListTile(
                dense: true,
                visualDensity: VisualDensity.compact,
                leading: const Icon(Icons.person, size: 18),
                title: Text(cl.name),
              ),
            ),
        ],
      ],
    );
  }
}