KC-APP/client/app/lib/screens/wahl_screen.dart

import 'package:flutter/material.dart';

import '../api.dart';
import '../main.dart';

class WahlScreen extends StatefulWidget {
  const WahlScreen({super.key});

  @override
  State<WahlScreen> createState() => _WahlScreenState();
}

class _WahlScreenState extends State<WahlScreen> {
  Future<GuestOverview>? _future;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    _future ??= AppScope.of(context).api.guestWahlOverview();
  }

  void _reload() {
    setState(() {
      _future = AppScope.of(context).api.guestWahlOverview();
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Workshop-Wahl')),
      body: FutureBuilder<GuestOverview>(
        future: _future,
        builder: (context, snap) {
          if (snap.connectionState != ConnectionState.done) {
            return const Center(child: CircularProgressIndicator());
          }
          if (snap.hasError) {
            return _ErrorView(message: '${snap.error}', onRetry: _reload);
          }
          final data = snap.data!;
          if (data.wahlen.isEmpty) {
            return const Center(child: Text('Aktuell ist keine Wahl geöffnet.'));
          }
          return ListView(
            padding: const EdgeInsets.all(16),
            children: [
              Text(data.kcName, style: Theme.of(context).textTheme.titleMedium),
              const SizedBox(height: 8),
              for (final w in data.wahlen)
                _WahlCard(wahl: w, onSubmitted: _reload),
            ],
          );
        },
      ),
    );
  }
}

class _WahlCard extends StatefulWidget {
  const _WahlCard({required this.wahl, required this.onSubmitted});
  final Wahl wahl;
  final VoidCallback onSubmitted;

  @override
  State<_WahlCard> createState() => _WahlCardState();
}

class _WahlCardState extends State<_WahlCard> {
  late final List<String> _picked = [...?widget.wahl.meinePrioritaeten];
  bool _busy = false;
  String? _error;
  bool _done = false;

  static const _maxPicks = 3;

  void _toggle(String workshopId) {
    setState(() {
      if (_picked.contains(workshopId)) {
        _picked.remove(workshopId);
      } else if (_picked.length < _maxPicks) {
        _picked.add(workshopId);
      }
      _done = false;
    });
  }

  Future<void> _submit() async {
    setState(() {
      _busy = true;
      _error = null;
    });
    try {
      await AppScope.of(context).api.submitPrioritaeten(widget.wahl.id, _picked);
      setState(() => _done = true);
      widget.onSubmitted();
    } on ApiException catch (e) {
      setState(() => _error = e.message);
    } finally {
      if (mounted) setState(() => _busy = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final w = widget.wahl;
    return Card(
      margin: const EdgeInsets.only(bottom: 16),
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(w.name, style: Theme.of(context).textTheme.titleLarge),
            Text('${w.datumsSchluessel} · Teil ${w.teil}',
                style: Theme.of(context).textTheme.bodySmall),
            const SizedBox(height: 4),
            Text(
              'Tippe deine Wünsche in Reihenfolge an (max. $_maxPicks). '
              'Die Zahl zeigt den Rang.',
              style: Theme.of(context).textTheme.bodySmall,
            ),
            const SizedBox(height: 8),
            for (final ws in w.workshops)
              _WorkshopRow(
                workshop: ws,
                rank: _picked.indexOf(ws.id),
                enabled: !_busy,
                onTap: () => _toggle(ws.id),
              ),
            const SizedBox(height: 12),
            if (_error != null) ...[
              Text(_error!, style: TextStyle(color: Theme.of(context).colorScheme.error)),
              const SizedBox(height: 8),
            ],
            Row(
              children: [
                FilledButton(
                  onPressed: (_busy || _picked.isEmpty) ? null : _submit,
                  child: _busy
                      ? const SizedBox(
                          height: 18, width: 18, child: CircularProgressIndicator(strokeWidth: 2))
                      : const Text('Wünsche absenden'),
                ),
                const SizedBox(width: 12),
                if (_done)
                  Row(
                    children: const [
                      Icon(Icons.check_circle, color: Colors.green, size: 20),
                      SizedBox(width: 4),
                      Text('Gespeichert'),
                    ],
                  ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}

class _WorkshopRow extends StatelessWidget {
  const _WorkshopRow({
    required this.workshop,
    required this.rank,
    required this.enabled,
    required this.onTap,
  });
  final Workshop workshop;
  final int rank;
  final bool enabled;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final selected = rank >= 0;
    return ListTile(
      dense: true,
      enabled: enabled,
      onTap: onTap,
      leading: CircleAvatar(
        radius: 14,
        backgroundColor: selected
            ? Theme.of(context).colorScheme.primary
            : Theme.of(context).colorScheme.surfaceContainerHighest,
        child: Text(
          selected ? '${rank + 1}' : '',
          style: TextStyle(
            fontSize: 13,
            color: selected ? Theme.of(context).colorScheme.onPrimary : null,
          ),
        ),
      ),
      title: Text(workshop.name),
      subtitle: Text('Kapazität ${workshop.kapazitaet}'),
      trailing: Icon(selected ? Icons.check_box : Icons.check_box_outline_blank),
    );
  }
}

class _ErrorView extends StatelessWidget {
  const _ErrorView({required this.message, required this.onRetry});
  final String message;
  final VoidCallback onRetry;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(24),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(message, textAlign: TextAlign.center),
            const SizedBox(height: 12),
            OutlinedButton(onPressed: onRetry, child: const Text('Erneut versuchen')),
          ],
        ),
      ),
    );
  }
}