timemaster-kiosk/lib/screens/login_screen.dart

import 'dart:async';
import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:nfc_manager/nfc_manager.dart';
import 'package:nfc_manager/nfc_manager_android.dart';
import '../app_version.dart';
import '../models/kiosk_session.dart';
import '../services/api_client.dart';
import '../services/kiosk_service.dart';
import 'enrollment_screen.dart';
import 'stamp_screen.dart';

enum _LoginMode { pin, nfc, list }

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

  @override
  State<LoginScreen> createState() => _LoginScreenState();
}

class _LoginScreenState extends State<LoginScreen> {
  final _service = KioskService();
  final _personnelCtrl = TextEditingController();
  final _pinCtrl = TextEditingController();
  final _nfcPinCtrl = TextEditingController();

  _LoginMode _mode = _LoginMode.pin;
  bool _loading = false;
  bool _nfcScanning = false;
  String? _error;
  String? _scannedUid;
  List<KioskEmployee>? _employees;

  @override
  void dispose() {
    if (_nfcScanning) NfcManager.instance.stopSession();
    super.dispose();
  }

  String _dioMessage(DioException e) {
    final detail = e.response?.data is Map ? e.response?.data['detail'] : null;
    if (detail is String) return detail;
    return 'Verbindung fehlgeschlagen.';
  }

  void _goToStamp(KioskSession session) {
    Navigator.of(context).pushReplacement(
      MaterialPageRoute(builder: (_) => StampScreen(session: session)),
    );
  }

  Future<void> _submitPin() async {
    setState(() {
      _loading = true;
      _error = null;
    });
    try {
      final session = await _service.loginPin(_personnelCtrl.text.trim(), _pinCtrl.text.trim());
      if (!mounted) return;
      _goToStamp(session);
    } on DioException catch (e) {
      setState(() => _error = _dioMessage(e));
    } catch (_) {
      // Unerwartete Antwortform (z.B. fehlendes Pflichtfeld in fromJson) darf
      // nicht stillschweigend verschluckt werden – sonst wirkt der Kiosk nur
      // "eingefroren" (Spinner stoppt, nichts passiert, kein Hinweis).
      if (mounted) setState(() => _error = 'Unerwartete Antwort vom Server.');
    } finally {
      if (mounted) setState(() => _loading = false);
    }
  }

  Future<void> _startNfcScan() async {
    final availability = await NfcManager.instance.checkAvailability();
    if (availability != NfcAvailability.enabled) {
      setState(() => _error = 'NFC ist nicht verfügbar oder deaktiviert (Status: ${availability.name}).');
      return;
    }
    setState(() {
      _nfcScanning = true;
      _scannedUid = null;
      _error = null;
    });
    try {
      await NfcManager.instance.startSession(
        pollingOptions: {NfcPollingOption.iso14443, NfcPollingOption.iso15693, NfcPollingOption.iso18092},
        onDiscovered: (NfcTag tag) async {
          // try/finally: stopSession() muss auch bei einer Exception in
          // _extractUid laufen, sonst bleibt die native NFC-Session offen
          // und jeder weitere Scan-Versuch schlägt dauerhaft fehl (nur durch
          // App-Neustart behebbar).
          String? uid;
          String? err;
          try {
            uid = _extractUid(tag);
          } catch (_) {
            err = 'Karte konnte nicht gelesen werden.';
          } finally {
            await NfcManager.instance.stopSession().catchError((_) {});
          }
          if (!mounted) return;
          setState(() {
            _nfcScanning = false;
            _scannedUid = uid;
            _error = uid == null ? (err ?? 'Karte konnte nicht gelesen werden.') : null;
          });
        },
      );
    } catch (e) {
      if (mounted) {
        setState(() {
          _nfcScanning = false;
          _error = 'NFC-Scan fehlgeschlagen: $e';
        });
      }
    }
  }

  /// Android-spezifisch (siehe nfc_manager 4.x: NfcTagAndroid.from(tag).id).
  /// Nur Android relevant – Kiosk-Tablets, kein iOS-Support geplant.
  String? _extractUid(NfcTag tag) {
    final androidTag = NfcTagAndroid.from(tag);
    if (androidTag == null) return null;
    return androidTag.id.map((b) => b.toRadixString(16).padLeft(2, '0')).join().toUpperCase();
  }

  Future<void> _submitNfc() async {
    if (_scannedUid == null) return;
    setState(() {
      _loading = true;
      _error = null;
    });
    try {
      final session = await _service.loginNfc(_scannedUid!, _nfcPinCtrl.text.trim());
      if (!mounted) return;
      _goToStamp(session);
    } on DioException catch (e) {
      setState(() => _error = _dioMessage(e));
    } catch (_) {
      if (mounted) setState(() => _error = 'Unerwartete Antwort vom Server.');
    } finally {
      if (mounted) setState(() => _loading = false);
    }
  }

  Future<void> _loadEmployees() async {
    setState(() {
      _loading = true;
      _error = null;
    });
    try {
      final list = await _service.listEmployees();
      if (!mounted) return;
      setState(() => _employees = list);
    } on DioException catch (e) {
      setState(() => _error = _dioMessage(e));
    } catch (_) {
      if (mounted) setState(() => _error = 'Unerwartete Antwort vom Server.');
    } finally {
      if (mounted) setState(() => _loading = false);
    }
  }

  Future<void> _submitListLogin(String userId) async {
    setState(() {
      _loading = true;
      _error = null;
    });
    try {
      final session = await _service.loginList(userId);
      if (!mounted) return;
      _goToStamp(session);
    } on DioException catch (e) {
      setState(() => _error = _dioMessage(e));
    } catch (_) {
      if (mounted) setState(() => _error = 'Unerwartete Antwort vom Server.');
    } finally {
      if (mounted) setState(() => _loading = false);
    }
  }

  void _resetEnrollment() {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text('Gerät zurücksetzen?'),
        content: const Text('Bearer-Token wird gelöscht, Ersteinrichtung muss erneut erfolgen.'),
        actions: [
          TextButton(onPressed: () => Navigator.pop(ctx), child: const Text('Abbrechen')),
          TextButton(
            onPressed: () async {
              await NfcManager.instance.stopSession().catchError((_) {});
              await ApiClient.instance.resetEnrollment();
              if (ctx.mounted) Navigator.pop(ctx);
              if (mounted) {
                Navigator.of(context).pushReplacement(
                  MaterialPageRoute(builder: (_) => const EnrollmentScreen()),
                );
              }
            },
            child: const Text('Zurücksetzen'),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('TimeMaster Kiosk · v$kAppVersion'),
        actions: [
          IconButton(icon: const Icon(Icons.settings), onPressed: _resetEnrollment),
        ],
      ),
      body: Center(
        child: ConstrainedBox(
          constraints: const BoxConstraints(maxWidth: 480),
          child: Padding(
            padding: const EdgeInsets.all(24),
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                SegmentedButton<_LoginMode>(
                  segments: const [
                    ButtonSegment(value: _LoginMode.pin, label: Text('PIN'), icon: Icon(Icons.pin)),
                    ButtonSegment(value: _LoginMode.nfc, label: Text('NFC'), icon: Icon(Icons.nfc)),
                    ButtonSegment(value: _LoginMode.list, label: Text('Liste'), icon: Icon(Icons.people)),
                  ],
                  selected: {_mode},
                  onSelectionChanged: (s) {
                    // Modus-Wechsel mitten im NFC-Scan: laufende native
                    // Session beenden, sonst bleibt sie verwaist offen und
                    // der nächste Scan-Versuch (auch für andere Mitarbeiter)
                    // schlägt dauerhaft fehl.
                    if (_nfcScanning) {
                      NfcManager.instance.stopSession().catchError((_) {});
                    }
                    setState(() {
                      _mode = s.first;
                      _error = null;
                      _scannedUid = null;
                      _nfcScanning = false;
                    });
                    if (_mode == _LoginMode.list && _employees == null) _loadEmployees();
                  },
                ),
                const SizedBox(height: 24),
                if (_mode == _LoginMode.pin) ..._pinForm(),
                if (_mode == _LoginMode.nfc) ..._nfcForm(),
                if (_mode == _LoginMode.list) ..._listForm(),
                if (_error != null) ...[
                  const SizedBox(height: 16),
                  Text(_error!, style: const TextStyle(color: Colors.red), textAlign: TextAlign.center),
                ],
              ],
            ),
          ),
        ),
      ),
    );
  }

  List<Widget> _pinForm() {
    return [
      TextField(
        controller: _personnelCtrl,
        decoration: const InputDecoration(labelText: 'Personalnummer'),
        keyboardType: TextInputType.number,
      ),
      const SizedBox(height: 12),
      TextField(
        controller: _pinCtrl,
        decoration: const InputDecoration(labelText: 'PIN'),
        obscureText: true,
        keyboardType: TextInputType.number,
        onSubmitted: (_) => _submitPin(),
      ),
      const SizedBox(height: 24),
      SizedBox(
        width: double.infinity,
        height: 56,
        child: FilledButton(
          onPressed: _loading ? null : _submitPin,
          child: _loading ? const CircularProgressIndicator() : const Text('Anmelden'),
        ),
      ),
    ];
  }

  List<Widget> _nfcForm() {
    if (_scannedUid == null) {
      return [
        Icon(_nfcScanning ? Icons.nfc : Icons.contactless, size: 80, color: Colors.indigo),
        const SizedBox(height: 16),
        Text(_nfcScanning ? 'Karte an Gerät halten…' : 'Karte scannen'),
        const SizedBox(height: 24),
        SizedBox(
          width: double.infinity,
          height: 56,
          child: FilledButton.icon(
            onPressed: _nfcScanning ? null : _startNfcScan,
            icon: const Icon(Icons.nfc),
            label: const Text('Scan starten'),
          ),
        ),
      ];
    }
    return [
      const Icon(Icons.check_circle, size: 64, color: Colors.green),
      const SizedBox(height: 8),
      const Text('Karte erkannt – PIN erforderlich (Pflicht-Zweitfaktor)'),
      const SizedBox(height: 16),
      TextField(
        controller: _nfcPinCtrl,
        decoration: const InputDecoration(labelText: 'PIN'),
        obscureText: true,
        keyboardType: TextInputType.number,
        onSubmitted: (_) => _submitNfc(),
      ),
      const SizedBox(height: 24),
      SizedBox(
        width: double.infinity,
        height: 56,
        child: FilledButton(
          onPressed: _loading ? null : _submitNfc,
          child: _loading ? const CircularProgressIndicator() : const Text('Anmelden'),
        ),
      ),
    ];
  }

  List<Widget> _listForm() {
    if (_loading && _employees == null) {
      return [const CircularProgressIndicator()];
    }
    final employees = _employees ?? [];
    return [
      SizedBox(
        height: 400,
        child: ListView.builder(
          shrinkWrap: true,
          itemCount: employees.length,
          itemBuilder: (context, i) {
            final e = employees[i];
            return Card(
              child: ListTile(
                title: Text(e.displayName),
                trailing: const Icon(Icons.chevron_right),
                onTap: _loading ? null : () => _submitListLogin(e.id),
              ),
            );
          },
        ),
      ),
    ];
  }
}