import 'package:flutter/material.dart';
import '../api_service.dart';
import '../settings.dart';
import 'auth_shell.dart';
import 'home_screen.dart';

class LoginScreen extends StatefulWidget {
  final ApiService api;
  final Settings settings;
  const LoginScreen({super.key, required this.api, required this.settings});

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

class _LoginScreenState extends State<LoginScreen> {
  final _email = TextEditingController();
  final _pin = TextEditingController();
  bool _busy = false;
  String? _error;
  /// Zoho-style: the email first, then the PIN on its own step.
  bool _askPin = false;
  bool _keep = true;

  static final _emailPattern = RegExp(r'^[^@\s]+@[^@\s]+\.[^@\s]+$');

  void _next() {
    final email = _email.text.trim();
    if (!_emailPattern.hasMatch(email)) {
      setState(() => _error = 'Enter a valid work email address');
      return;
    }
    setState(() { _askPin = true; _error = null; });
  }

  void _change() => setState(() { _askPin = false; _pin.clear(); _error = null; });

  Future<void> _login() async {
    if (_pin.text.isEmpty) {
      setState(() => _error = 'Enter your PIN');
      return;
    }
    setState(() { _busy = true; _error = null; });
    try {
      await widget.api.login(_email.text.trim(), _pin.text);
      await KeepSignedIn.save(_keep);
      if (!mounted) return;
      Navigator.pushReplacement(context,
          MaterialPageRoute(builder: (_) => HomeScreen(api: widget.api, settings: widget.settings)));
    } on ApiException catch (e) {
      setState(() => _error = e.message);
    } finally {
      if (mounted) setState(() => _busy = false);
    }
  }

  void _forgotEmail() {
    ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
      content: Text('Use the work email HR added you with. Not sure which one? Ask your HR or manager.'),
      behavior: SnackBarBehavior.floating,
    ));
  }

  void _forgotPin() {
    ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
      content: Text('Your PIN is set by HR. Ask your HR or manager to reset it.'),
      behavior: SnackBarBehavior.floating,
    ));
  }

  @override
  Widget build(BuildContext context) {
    if (_askPin) {
      return AuthShell(
        appName: 'Scalar Presence',
        product: 'Presence',
        tagline: 'Check in, apply for leave and see your payslips.',
        title: 'Enter PIN',
        children: [
          AuthIdentity(value: _email.text.trim(), onBack: _busy ? () {} : _change),
          const SizedBox(height: 16),
          if (_error != null) AuthError(_error!),
          AuthField(
            key: const ValueKey('pin'),
            controller: _pin,
            hint: 'PIN',
            icon: Icons.lock_outline,
            secret: true,
            autofocus: true,
            error: _error != null,
            keyboardType: TextInputType.number,
            action: TextInputAction.done,
            onSubmitted: (_) => _login(),
          ),
          const SizedBox(height: 12),
          AuthLink('Forgot PIN?', onPressed: _forgotPin),
          AuthKeepSignedIn(value: _keep, onChanged: (v) => setState(() => _keep = v)),
          const SizedBox(height: 20),
          AuthButton(label: 'Sign in', busy: _busy, onPressed: _login),
        ],
      );
    }
    return AuthShell(
      appName: 'Scalar Presence',
      product: 'Presence',
      tagline: 'Check in, apply for leave and see your payslips.',
      children: [
        if (_error != null) AuthError(_error!),
        AuthField(
          key: const ValueKey('email'),
          controller: _email,
          hint: 'Work email',
          icon: Icons.mail_outline,
          error: _error != null,
          keyboardType: TextInputType.emailAddress,
          action: TextInputAction.next,
          onSubmitted: (_) => _next(),
        ),
        const SizedBox(height: 12),
        AuthLink('Forgot email?', onPressed: _forgotEmail),
        const SizedBox(height: 28),
        AuthButton(label: 'Next', busy: false, onPressed: _next),
      ],
    );
  }
}