import 'dart:developer';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

import '../../api/errors/auth_exception.dart';
import '../../api/errors/error_mapper.dart';
import '../../api/marianumcloud/talk/room/get_room.dart';
import '../../api/marianumcloud/talk/room/get_room_params.dart';
import '../../model/account_data.dart';
import '../../state/app/modules/account/bloc/account_bloc.dart';
import '../../state/app/modules/account/bloc/account_state.dart';
import '../../theming/light_app_theme.dart';

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

  @override
  State<Login> createState() => _LoginState();
}

class _LoginState extends State<Login> {
  static const _marianumRed = LightAppTheme.marianumRed;

  final _formKey = GlobalKey<FormState>();
  final _usernameController = TextEditingController();
  final _passwordController = TextEditingController();
  final _passwordFocus = FocusNode();

  bool _loading = false;
  String? _errorMessage;
  String? _errorDetails;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    precacheImage(const AssetImage('assets/logo/icon.png'), context);
  }

  @override
  void dispose() {
    _usernameController.dispose();
    _passwordController.dispose();
    _passwordFocus.dispose();
    super.dispose();
  }

  String? _required(String? value) => (value ?? '').trim().isEmpty ? 'Eingabe erforderlich' : null;

  Future<void> _submit() async {
    if (_loading) return;
    if (!(_formKey.currentState?.validate() ?? false)) return;

    setState(() {
      _loading = true;
      _errorMessage = null;
      _errorDetails = null;
    });

    final username = _usernameController.text.trim().toLowerCase();
    final password = _passwordController.text;

    try {
      await AccountData().removeData();
      await AccountData().setData(username, password);
      await GetRoom(GetRoomParams(includeStatus: false)).run();
      if (!mounted) return;
      context.read<AccountBloc>().setStatus(AccountStatus.loggedIn);
    } catch (e) {
      log(e.toString());
      await AccountData().removeData();
      if (!mounted) return;
      // 401 from the probe means the credentials were wrong; everything else
      // (no network, server down, TLS errors, …) gets the generic mapped
      // message so the user knows it isn't their typo.
      final isWrongCredentials = e is AuthException && e.statusCode == 401;
      setState(() {
        _errorMessage = isWrongCredentials
            ? 'Benutzername oder Passwort falsch.'
            : errorToUserMessage(e);
        _errorDetails = errorToTechnicalDetails(e);
      });
    } finally {
      if (mounted) setState(() => _loading = false);
    }
  }

  void _showErrorDetails() {
    final details = _errorDetails;
    if (details == null) return;
    showDialog<void>(
      context: context,
      builder: (dialogContext) {
        final theme = Theme.of(dialogContext);
        return AlertDialog(
          icon: Icon(Icons.error_outline, color: theme.colorScheme.error),
          title: const Text('Fehlerdetails'),
          content: SingleChildScrollView(
            child: SelectableText(
              details,
              style: theme.textTheme.bodySmall,
            ),
          ),
          actions: [
            TextButton.icon(
              onPressed: () async {
                await Clipboard.setData(ClipboardData(text: details));
                if (!dialogContext.mounted) return;
                ScaffoldMessenger.of(dialogContext).showSnackBar(
                  const SnackBar(
                    content: Text('In Zwischenablage kopiert'),
                    duration: Duration(seconds: 2),
                  ),
                );
              },
              icon: const Icon(Icons.copy_outlined, size: 18),
              label: const Text('Kopieren'),
            ),
            TextButton(
              onPressed: () => Navigator.of(dialogContext).pop(),
              child: const Text('Schließen'),
            ),
          ],
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Scaffold(
      backgroundColor: _marianumRed,
      body: SafeArea(
          child: LayoutBuilder(
            builder: (context, constraints) => SingleChildScrollView(
              padding: const EdgeInsets.symmetric(horizontal: 24),
              child: ConstrainedBox(
                constraints: BoxConstraints(minHeight: constraints.maxHeight),
                child: IntrinsicHeight(
                  child: Column(
                    children: [
                      const SizedBox(height: 40),
                      Image.asset(
                        'assets/logo/icon.png',
                        height: 110,
                        fit: BoxFit.contain,
                        gaplessPlayback: true,
                      ),
                      const SizedBox(height: 20),
                      const Text(
                        'Marianum Fulda',
                        textAlign: TextAlign.center,
                        style: TextStyle(
                          color: Colors.white,
                          fontSize: 26,
                          fontWeight: FontWeight.w600,
                          letterSpacing: 0.3,
                        ),
                      ),
                      const SizedBox(height: 6),
                      Text(
                        'Stundenplan, Talk & Dateien an einem Ort.',
                        textAlign: TextAlign.center,
                        style: TextStyle(
                          color: Colors.white.withValues(alpha: 0.85),
                          fontSize: 14,
                          height: 1.3,
                        ),
                      ),
                      const SizedBox(height: 28),
                      ConstrainedBox(
                        constraints: const BoxConstraints(maxWidth: 420),
                        child: Card(
                          elevation: 8,
                          shadowColor: Colors.black.withValues(alpha: 0.35),
                          shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(20),
                          ),
                          color: theme.colorScheme.surface,
                          child: Padding(
                            padding: const EdgeInsets.fromLTRB(24, 24, 24, 20),
                            child: Form(
                              key: _formKey,
                              child: Column(
                                crossAxisAlignment: CrossAxisAlignment.stretch,
                                children: [
                                  Text(
                                    'Anmelden',
                                    style: theme.textTheme.titleLarge?.copyWith(
                                      fontWeight: FontWeight.w600,
                                    ),
                                  ),
                                  const SizedBox(height: 6),
                                  Text(
                                    'Melde dich mit deinen Marianum-Zugangsdaten an.',
                                    style: theme.textTheme.bodySmall?.copyWith(
                                      color: theme.colorScheme.onSurfaceVariant,
                                    ),
                                  ),
                                  const SizedBox(height: 20),
                                  TextFormField(
                                    controller: _usernameController,
                                    enabled: !_loading,
                                    validator: _required,
                                    autocorrect: false,
                                    textInputAction: TextInputAction.next,
                                    onFieldSubmitted: (_) => _passwordFocus.requestFocus(),
                                    decoration: InputDecoration(
                                      labelText: 'Nutzername',
                                      prefixIcon: const Icon(Icons.person_outline),
                                      filled: true,
                                      fillColor: theme.colorScheme.surfaceContainerHighest.withValues(alpha: 0.4),
                                      border: OutlineInputBorder(
                                        borderRadius: BorderRadius.circular(12),
                                        borderSide: BorderSide.none,
                                      ),
                                      enabledBorder: OutlineInputBorder(
                                        borderRadius: BorderRadius.circular(12),
                                        borderSide: BorderSide.none,
                                      ),
                                      focusedBorder: OutlineInputBorder(
                                        borderRadius: BorderRadius.circular(12),
                                        borderSide: BorderSide(color: theme.colorScheme.primary, width: 1.5),
                                      ),
                                    ),
                                  ),
                                  const SizedBox(height: 12),
                                  TextFormField(
                                    controller: _passwordController,
                                    focusNode: _passwordFocus,
                                    enabled: !_loading,
                                    validator: _required,
                                    obscureText: true,
                                    obscuringCharacter: '•',
                                    autocorrect: false,
                                    enableSuggestions: false,
                                    keyboardType: TextInputType.visiblePassword,
                                    textInputAction: TextInputAction.done,
                                    onFieldSubmitted: (_) => _submit(),
                                    decoration: InputDecoration(
                                      labelText: 'Passwort',
                                      prefixIcon: const Icon(Icons.lock_outline),
                                      filled: true,
                                      fillColor: theme.colorScheme.surfaceContainerHighest.withValues(alpha: 0.4),
                                      border: OutlineInputBorder(
                                        borderRadius: BorderRadius.circular(12),
                                        borderSide: BorderSide.none,
                                      ),
                                      enabledBorder: OutlineInputBorder(
                                        borderRadius: BorderRadius.circular(12),
                                        borderSide: BorderSide.none,
                                      ),
                                      focusedBorder: OutlineInputBorder(
                                        borderRadius: BorderRadius.circular(12),
                                        borderSide: BorderSide(color: theme.colorScheme.primary, width: 1.5),
                                      ),
                                    ),
                                  ),
                                  AnimatedSize(
                                    duration: const Duration(milliseconds: 180),
                                    curve: Curves.easeOut,
                                    child: _errorMessage == null
                                        ? const SizedBox(height: 0, width: double.infinity)
                                        : Padding(
                                            padding: const EdgeInsets.only(top: 14),
                                            child: Material(
                                              color: theme.colorScheme.errorContainer.withValues(alpha: 0.6),
                                              borderRadius: BorderRadius.circular(12),
                                              child: InkWell(
                                                onTap: _errorDetails != null ? _showErrorDetails : null,
                                                borderRadius: BorderRadius.circular(12),
                                                child: Padding(
                                                  padding: const EdgeInsets.symmetric(
                                                      horizontal: 12, vertical: 10),
                                                  child: Row(
                                                    children: [
                                                      Icon(Icons.error_outline,
                                                          size: 20,
                                                          color: theme.colorScheme.onErrorContainer),
                                                      const SizedBox(width: 10),
                                                      Expanded(
                                                        child: Text(
                                                          _errorMessage!,
                                                          style: TextStyle(
                                                            color: theme.colorScheme.onErrorContainer,
                                                            fontSize: 13,
                                                            height: 1.3,
                                                          ),
                                                        ),
                                                      ),
                                                      if (_errorDetails != null) ...[
                                                        const SizedBox(width: 8),
                                                        Icon(Icons.chevron_right,
                                                            size: 20,
                                                            color: theme.colorScheme.onErrorContainer
                                                                .withValues(alpha: 0.7)),
                                                      ],
                                                    ],
                                                  ),
                                                ),
                                              ),
                                            ),
                                          ),
                                  ),
                                  const SizedBox(height: 20),
                                  SizedBox(
                                    height: 50,
                                    child: FilledButton(
                                      onPressed: _loading ? null : _submit,
                                      style: FilledButton.styleFrom(
                                        shape: RoundedRectangleBorder(
                                          borderRadius: BorderRadius.circular(12),
                                        ),
                                        textStyle: const TextStyle(
                                          fontSize: 15,
                                          fontWeight: FontWeight.w600,
                                        ),
                                      ),
                                      child: _loading
                                          ? const SizedBox(
                                              height: 22,
                                              width: 22,
                                              child: CircularProgressIndicator(
                                                strokeWidth: 2.5,
                                                color: Colors.white,
                                              ),
                                            )
                                          : const Text('Anmelden'),
                                    ),
                                  ),
                                ],
                              ),
                            ),
                          ),
                        ),
                      ),
                      const SizedBox(height: 18),
                      Padding(
                        padding: const EdgeInsets.symmetric(horizontal: 8),
                        child: Text(
                          'Inoffizieller Nextcloud & Webuntis Client. Wird nicht vom Marianum betrieben. Keine Gewähr für Vollständigkeit, Richtigkeit und Aktualität.',
                          textAlign: TextAlign.center,
                          style: TextStyle(
                            color: Colors.white.withValues(alpha: 0.75),
                            fontSize: 11,
                            height: 1.4,
                          ),
                        ),
                      ),
                      const Spacer(),
                      Padding(
                        padding: const EdgeInsets.only(top: 16, bottom: 8),
                        child: Text(
                          'Marianum Fulda. Die persönliche Schule.',
                          textAlign: TextAlign.center,
                          style: TextStyle(
                            color: Colors.white.withValues(alpha: 0.7),
                            fontSize: 12,
                            fontStyle: FontStyle.italic,
                          ),
                        ),
                      ),
                    ],
                  ),
                ),
              ),
            ),
          ),
      ),
    );
  }
}