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

import '../core/api_client.dart';
import '../core/app_theme.dart';
import '../servicios/delivery_repository.dart';
import '../servicios/push_notification_service.dart';

enum _LoginStep { tenant, credentials }

class LoginScreen extends StatefulWidget {
  const LoginScreen({required this.repository, super.key});

  final DeliveryRepository repository;

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

class _LoginScreenState extends State<LoginScreen> {
  final _ruc = TextEditingController();
  final _email = TextEditingController();
  final _password = TextEditingController();
  _LoginStep _step = _LoginStep.tenant;
  Map<String, dynamic>? _tenant;
  String? _error;
  bool _busy = false;
  bool _obscurePassword = true;

  @override
  void initState() {
    super.initState();
    _loadSavedTenant();
  }

  Future<void> _loadSavedTenant() async {
    final prefs = await SharedPreferences.getInstance();
    final host = prefs.getString('delivery_tenant_host');
    final baseUrl = prefs.getString('delivery_api_base_url');
    if (!mounted ||
        host == null ||
        host.isEmpty ||
        baseUrl == null ||
        baseUrl.isEmpty) {
      return;
    }
    setState(() {
      _tenant = {
        'host': host,
        'base_url': baseUrl,
        'ruc': prefs.getString('delivery_tenant_ruc') ?? '',
        'company_name': prefs.getString('delivery_company_name') ?? host,
      };
      _step = _LoginStep.credentials;
    });
  }

  @override
  void dispose() {
    _ruc.dispose();
    _email.dispose();
    _password.dispose();
    super.dispose();
  }

  Future<void> _submit() async {
    FocusScope.of(context).unfocus();
    setState(() => _error = null);

    if (_step == _LoginStep.tenant) {
      final ruc = _ruc.text.trim();
      if (!RegExp(r'^\d{11}$').hasMatch(ruc)) {
        setState(() => _error = 'Ingresa un RUC válido de 11 dígitos.');
        return;
      }
    } else if (_email.text.trim().isEmpty || _password.text.isEmpty) {
      setState(() => _error = 'Ingresa tu correo y contraseña.');
      return;
    }

    setState(() => _busy = true);
    try {
      if (_step == _LoginStep.tenant) {
        final tenant = await widget.repository.resolveTenant(_ruc.text.trim());
        await widget.repository.saveTenant(tenant);
        if (!mounted) return;
        setState(() {
          _tenant = tenant;
          _step = _LoginStep.credentials;
        });
        return;
      }

      final data = await widget.repository.login(
        _email.text.trim(),
        _password.text,
      );
      final user = (data['user'] as Map?)?.cast<String, dynamic>();
      if (user?['delivery_driver'] != true) {
        throw const ApiException(
          403,
          'Este usuario no está habilitado como repartidor.',
        );
      }
      final prefs = await SharedPreferences.getInstance();
      await prefs.setString('delivery_api_token', '${data['token']}');
      final establishment = (data['establishment'] as Map?)
          ?.cast<String, dynamic>();
      if (establishment != null) {
        await prefs.setString(
          'delivery_establishment_name',
          '${establishment['description'] ?? ''}',
        );
      }
      final push = PushNotificationService();
      await push.requestPermission();
      await push.registerWithBackend(widget.repository);
      if (!mounted) return;
      Navigator.of(context).pushNamedAndRemoveUntil('/orders', (_) => false);
    } on ApiException catch (error) {
      if (mounted) setState(() => _error = error.message);
    } catch (_) {
      if (mounted) {
        setState(() => _error = 'No se pudo conectar. Verifica tu conexión.');
      }
    } finally {
      if (mounted) setState(() => _busy = false);
    }
  }

  void _backToTenant() {
    setState(() {
      _step = _LoginStep.tenant;
      _tenant = null;
      _error = null;
    });
  }

  Future<void> _confirmExit() async {
    final exit = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Salir de SmartPlus Reparto'),
        content: const Text('¿Deseas cerrar la aplicación?'),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context, false),
            child: const Text('Cancelar'),
          ),
          FilledButton(
            onPressed: () => Navigator.pop(context, true),
            child: const Text('Salir'),
          ),
        ],
      ),
    );
    if (exit == true && mounted) SystemNavigator.pop();
  }

  @override
  Widget build(BuildContext context) => PopScope(
    canPop: false,
    onPopInvokedWithResult: (didPop, result) {
      if (didPop) return;
      if (_step == _LoginStep.credentials) {
        _confirmExit();
      } else {
        _confirmExit();
      }
    },
    child: Scaffold(
      appBar: AppBar(title: const Text('SmartPlus Reparto')),
      body: SafeArea(
        child: Center(
          child: SingleChildScrollView(
            padding: const EdgeInsets.all(24),
            child: ConstrainedBox(
              constraints: const BoxConstraints(maxWidth: 430),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  const Icon(
                    Icons.local_shipping_outlined,
                    size: 64,
                    color: AppTheme.primary,
                  ),
                  const SizedBox(height: 16),
                  Text(
                    _step == _LoginStep.tenant
                        ? 'Identifica tu empresa'
                        : 'Ingresa a tu cuenta',
                    style: Theme.of(context).textTheme.headlineSmall?.copyWith(
                      fontWeight: FontWeight.w700,
                      color: AppTheme.ink,
                    ),
                    textAlign: TextAlign.center,
                  ),
                  const SizedBox(height: 8),
                  Text(
                    _step == _LoginStep.tenant
                        ? 'Primero validaremos el RUC para conectarte al sistema correcto.'
                        : 'Empresa: ${_tenant?['company_name'] ?? ''}',
                    textAlign: TextAlign.center,
                    style: const TextStyle(color: AppTheme.muted),
                  ),
                  const SizedBox(height: 20),
                  LinearProgressIndicator(
                    value: _step == _LoginStep.tenant ? .5 : 1,
                  ),
                  const SizedBox(height: 24),
                  if (_error != null) ...[
                    Text(
                      _error!,
                      style: TextStyle(
                        color: Theme.of(context).colorScheme.error,
                      ),
                    ),
                    const SizedBox(height: 12),
                  ],
                  if (_step == _LoginStep.tenant)
                    _tenantForm()
                  else
                    _credentialsForm(),
                  const SizedBox(height: 20),
                  FilledButton(
                    onPressed: _busy ? null : _submit,
                    child: _busy
                        ? const SizedBox(
                            height: 22,
                            width: 22,
                            child: CircularProgressIndicator(strokeWidth: 2),
                          )
                        : Text(
                            _step == _LoginStep.tenant
                                ? 'Continuar'
                                : 'Ingresar',
                          ),
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    ),
  );

  Widget _tenantForm() => TextField(
    controller: _ruc,
    keyboardType: TextInputType.number,
    inputFormatters: [
      FilteringTextInputFormatter.digitsOnly,
      LengthLimitingTextInputFormatter(11),
    ],
    decoration: const InputDecoration(
      labelText: 'RUC',
      hintText: 'Ingresa el RUC de la empresa',
    ),
  );

  Widget _credentialsForm() => Column(
    crossAxisAlignment: CrossAxisAlignment.stretch,
    children: [
      TextField(
        controller: _email,
        keyboardType: TextInputType.emailAddress,
        autofillHints: const [AutofillHints.username],
        decoration: const InputDecoration(labelText: 'Correo electrónico'),
      ),
      const SizedBox(height: 14),
      TextField(
        controller: _password,
        obscureText: _obscurePassword,
        autofillHints: const [AutofillHints.password],
        decoration: InputDecoration(
          labelText: 'Contraseña',
          suffixIcon: IconButton(
            tooltip: _obscurePassword
                ? 'Mostrar contraseña'
                : 'Ocultar contraseña',
            onPressed: () =>
                setState(() => _obscurePassword = !_obscurePassword),
            icon: Icon(
              _obscurePassword
                  ? Icons.visibility_outlined
                  : Icons.visibility_off_outlined,
            ),
          ),
        ),
      ),
      const SizedBox(height: 8),
      Align(
        alignment: Alignment.centerLeft,
        child: TextButton.icon(
          onPressed: _busy ? null : _backToTenant,
          icon: const Icon(Icons.arrow_back, size: 18),
          label: const Text('Cambiar RUC'),
        ),
      ),
    ],
  );
}