import 'package:flutter/material.dart';

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

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

  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: 3,
      child: Scaffold(
        appBar: AppBar(
          title: const Text('KC-App'),
          bottom: const TabBar(
            tabs: [
              Tab(text: 'Konfi / Gast'),
              Tab(text: 'Team-Login'),
              Tab(text: 'Einladung'),
            ],
          ),
        ),
        body: SafeArea(
          child: Center(
            child: ConstrainedBox(
              constraints: const BoxConstraints(maxWidth: 420),
              child: Padding(
                padding: const EdgeInsets.all(24),
                child: TabBarView(
                  children: const [
                    _GuestForm(),
                    _TeamForm(),
                    _InviteForm(),
                  ],
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}

/// Shared submit-button + error handling for the three little forms.
class _FormShell extends StatefulWidget {
  const _FormShell({required this.title, required this.fields, required this.onSubmit});
  final String title;
  final List<Widget> fields;
  final Future<void> Function() onSubmit;

  @override
  State<_FormShell> createState() => _FormShellState();
}

class _FormShellState extends State<_FormShell> {
  bool _busy = false;
  String? _error;

  Future<void> _run() async {
    setState(() {
      _busy = true;
      _error = null;
    });
    try {
      await widget.onSubmit();
    } on ApiException catch (e) {
      setState(() => _error = e.message);
    } catch (e) {
      setState(() => _error = e.toString());
    } finally {
      if (mounted) setState(() => _busy = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    return ListView(
      shrinkWrap: true,
      children: [
        if (widget.title.isNotEmpty) ...[
          Text(widget.title, style: Theme.of(context).textTheme.titleLarge),
          const SizedBox(height: 16),
        ],
        ...widget.fields,
        const SizedBox(height: 20),
        if (_error != null) ...[
          Text(_error!, style: TextStyle(color: Theme.of(context).colorScheme.error)),
          const SizedBox(height: 12),
        ],
        FilledButton(
          onPressed: _busy ? null : _run,
          child: _busy
              ? const SizedBox(
                  height: 18, width: 18, child: CircularProgressIndicator(strokeWidth: 2))
              : const Text('Weiter'),
        ),
      ],
    );
  }
}

TextField _field(TextEditingController c, String label, {bool obscure = false}) => TextField(
      controller: c,
      obscureText: obscure,
      decoration: InputDecoration(labelText: label, border: const OutlineInputBorder()),
    );

class _GuestForm extends StatefulWidget {
  const _GuestForm();
  @override
  State<_GuestForm> createState() => _GuestFormState();
}

class _GuestFormState extends State<_GuestForm> {
  final _code = TextEditingController();
  final _first = TextEditingController();
  final _last = TextEditingController();

  @override
  Widget build(BuildContext context) {
    final state = AppScope.of(context);
    return _FormShell(
      title: 'Mit Einladungscode beitreten',
      fields: [
        _field(_code, 'Einladungscode'),
        const SizedBox(height: 12),
        _field(_first, 'Vorname'),
        const SizedBox(height: 12),
        _field(_last, 'Nachname'),
      ],
      onSubmit: () => state.guestLogin(_code.text.trim(), _first.text.trim(), _last.text.trim()),
    );
  }
}

class _TeamForm extends StatefulWidget {
  const _TeamForm();
  @override
  State<_TeamForm> createState() => _TeamFormState();
}

class _TeamFormState extends State<_TeamForm> {
  final _email = TextEditingController();
  final _password = TextEditingController();

  @override
  Widget build(BuildContext context) {
    final state = AppScope.of(context);
    return ListView(
      shrinkWrap: true,
      children: [
        Text('Leitungsteam / Verantwortliche',
            style: Theme.of(context).textTheme.titleLarge),
        const SizedBox(height: 12),
        if (state.authError != null) ...[
          Text(state.authError!,
              style: TextStyle(color: Theme.of(context).colorScheme.error)),
          const SizedBox(height: 12),
        ],
        FilledButton.icon(
          onPressed: () => state.beginOidcLogin(),
          icon: const Icon(Icons.login),
          label: const Text('Mit Konfi-Castle-ID anmelden'),
        ),
        const SizedBox(height: 8),
        const Text(
          'Öffnet die Konfi-Castle-ID (Authentik). Leitungsteam-Rechte kommen '
          'aus deiner Authentik-Gruppe.',
          style: TextStyle(fontSize: 12),
        ),
        const Divider(height: 40),
        Text('Lokaler Teamer:in-Login',
            style: Theme.of(context).textTheme.titleMedium),
        const SizedBox(height: 12),
        _TeamPasswordForm(email: _email, password: _password),
      ],
    );
  }
}

class _TeamPasswordForm extends StatelessWidget {
  const _TeamPasswordForm({required this.email, required this.password});
  final TextEditingController email;
  final TextEditingController password;

  @override
  Widget build(BuildContext context) {
    final state = AppScope.of(context);
    return _FormShell(
      title: '',
      fields: [
        _field(email, 'E-Mail'),
        const SizedBox(height: 12),
        _field(password, 'Passwort', obscure: true),
      ],
      onSubmit: () => state.teamLogin(email.text.trim(), password.text),
    );
  }
}

class _InviteForm extends StatefulWidget {
  const _InviteForm();
  @override
  State<_InviteForm> createState() => _InviteFormState();
}

class _InviteFormState extends State<_InviteForm> {
  final _token = TextEditingController();
  final _first = TextEditingController();
  final _last = TextEditingController();
  final _email = TextEditingController();
  final _password = TextEditingController();

  @override
  Widget build(BuildContext context) {
    final state = AppScope.of(context);
    return _FormShell(
      title: 'Teamer:in-Einladung einlösen',
      fields: [
        _field(_token, 'Einladungscode / Token'),
        const SizedBox(height: 12),
        _field(_first, 'Vorname'),
        const SizedBox(height: 12),
        _field(_last, 'Nachname'),
        const SizedBox(height: 12),
        _field(_email, 'E-Mail (bei Gruppen-Link nötig)'),
        const SizedBox(height: 12),
        _field(_password, 'Passwort wählen (min. 8 Zeichen)', obscure: true),
      ],
      onSubmit: () => state.redeemInvite(
        token: _token.text.trim(),
        first: _first.text.trim(),
        last: _last.text.trim(),
        password: _password.text,
        email: _email.text.trim(),
      ),
    );
  }
}