import 'dart:async';

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

import '../guardian_login_controller.dart';
import 'login_error_banner.dart';
import 'login_form_parts.dart';

/// Passwordless guardian login: e-mail step, then the mailed six-digit code.
/// A tapped mail link completes the second step without typing (handled by
/// the login screen).
class GuardianLoginCard extends StatefulWidget {
  final GuardianLoginController controller;
  final VoidCallback onSuccess;

  const GuardianLoginCard({
    required this.controller,
    required this.onSuccess,
    super.key,
  });

  @override
  State<GuardianLoginCard> createState() => _GuardianLoginCardState();
}

class _GuardianLoginCardState extends State<GuardianLoginCard> {
  final _emailFormKey = GlobalKey<FormState>();
  final _codeFormKey = GlobalKey<FormState>();
  final _emailController = TextEditingController();
  final _codeController = TextEditingController();
  Timer? _resendTicker;

  GuardianLoginController get _controller => widget.controller;

  @override
  void initState() {
    super.initState();
    _controller.addListener(_onControllerChange);
    _syncResendTicker();
  }

  @override
  void dispose() {
    _controller.removeListener(_onControllerChange);
    _resendTicker?.cancel();
    _emailController.dispose();
    _codeController.dispose();
    super.dispose();
  }

  void _onControllerChange() {
    if (!mounted) return;
    _syncResendTicker();
    setState(() {});
  }

  // Rebuilds once per second while the resend cooldown runs so the countdown
  // stays current.
  void _syncResendTicker() {
    final waiting =
        _controller.step == GuardianLoginStep.enterCode &&
        !_controller.canResend();
    if (waiting && _resendTicker == null) {
      _resendTicker = Timer.periodic(const Duration(seconds: 1), (_) {
        if (!mounted) return;
        setState(() {});
        if (_controller.canResend()) {
          _resendTicker?.cancel();
          _resendTicker = null;
        }
      });
    } else if (!waiting) {
      _resendTicker?.cancel();
      _resendTicker = null;
    }
  }

  String? _validateEmail(String? value) {
    final email = (value ?? '').trim();
    if (email.isEmpty) return 'Eingabe erforderlich';
    if (!RegExp(r'^[^@\s]+@[^@\s]+\.[^@\s]+$').hasMatch(email)) {
      return 'Bitte eine gültige E-Mail-Adresse eingeben';
    }
    return null;
  }

  String? _validateCode(String? value) {
    final length = _controller.pending!.codeLength;
    final code = GuardianLoginController.normalizeCode(value ?? '');
    return code.length == length
        ? null
        : 'Bitte den $length-stelligen Code eingeben';
  }

  Future<void> _requestCode() async {
    if (_controller.loading) return;
    if (!(_emailFormKey.currentState?.validate() ?? false)) return;
    final signedIn = await _controller.requestCode(_emailController.text);
    if (signedIn && mounted) widget.onSuccess();
  }

  Future<void> _submitCode() async {
    if (_controller.loading) return;
    if (!(_codeFormKey.currentState?.validate() ?? false)) return;
    final signedIn = await _controller.submitCode(_codeController.text);
    if (signedIn && mounted) widget.onSuccess();
  }

  @override
  Widget build(BuildContext context) => switch (_controller.step) {
    GuardianLoginStep.enterEmail => _buildEmailStep(context),
    GuardianLoginStep.enterCode => _buildCodeStep(context),
  };

  Widget _buildEmailStep(BuildContext context) {
    final theme = Theme.of(context);
    return Form(
      key: _emailFormKey,
      child: LoginCardFrame(
        title: 'Anmeldung für Eltern',
        hint:
            'Gib die E-Mail-Adresse ein, die bei der Schule hinterlegt ist. '
            'Du erhältst einen Anmeldecode per E-Mail.',
        children: [
          TextFormField(
            key: const Key('guardian-email-field'),
            controller: _emailController,
            enabled: !_controller.loading,
            validator: _validateEmail,
            autocorrect: false,
            keyboardType: TextInputType.emailAddress,
            autofillHints: const [AutofillHints.email],
            textInputAction: TextInputAction.done,
            onFieldSubmitted: (_) => _requestCode(),
            decoration: loginInputDecoration(
              theme,
              'E-Mail-Adresse',
              Icons.alternate_email,
            ),
          ),
          LoginErrorBanner(
            message: _controller.errorMessage,
            details: _controller.errorDetails,
          ),
          const SizedBox(height: 20),
          LoginSubmitButton(
            key: const Key('guardian-request-button'),
            label: 'Code anfordern',
            loading: _controller.loading,
            onPressed: _requestCode,
          ),
        ],
      ),
    );
  }

  Widget _buildCodeStep(BuildContext context) {
    final theme = Theme.of(context);
    final pending = _controller.pending!;
    final remaining = pending.resendAvailableAt.difference(DateTime.now());
    return Form(
      key: _codeFormKey,
      child: LoginCardFrame(
        title: 'Code eingeben',
        hint:
            'Wir haben eine E-Mail an ${pending.email} gesendet. Gib den Code '
            'ein oder tippe auf den Link in der E-Mail.',
        children: [
          TextFormField(
            key: const Key('guardian-code-field'),
            controller: _codeController,
            enabled: !_controller.loading,
            validator: _validateCode,
            autofocus: true,
            keyboardType: TextInputType.number,
            autofillHints: const [AutofillHints.oneTimeCode],
            inputFormatters: [
              FilteringTextInputFormatter.digitsOnly,
              LengthLimitingTextInputFormatter(pending.codeLength),
            ],
            textInputAction: TextInputAction.done,
            onFieldSubmitted: (_) => _submitCode(),
            decoration: loginInputDecoration(
              theme,
              'Anmeldecode',
              Icons.pin_outlined,
            ),
          ),
          LoginErrorBanner(
            message: _controller.errorMessage,
            details: _controller.errorDetails,
          ),
          const SizedBox(height: 20),
          LoginSubmitButton(
            key: const Key('guardian-verify-button'),
            label: 'Anmelden',
            loading: _controller.loading,
            onPressed: _submitCode,
          ),
          const SizedBox(height: 8),
          Row(
            children: [
              TextButton(
                onPressed: _controller.loading ? null : _controller.changeEmail,
                child: const Text('E-Mail ändern'),
              ),
              const Spacer(),
              TextButton(
                onPressed: _controller.loading || !_controller.canResend()
                    ? null
                    : _controller.resend,
                child: Text(
                  _controller.canResend()
                      ? 'Erneut senden'
                      : 'Erneut senden (${remaining.inSeconds + 1} s)',
                ),
              ),
            ],
          ),
        ],
      ),
    );
  }
}