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

class OtpScreen extends StatefulWidget {
  final String phone;
  const OtpScreen({super.key, required this.phone});

  @override
  State<OtpScreen> createState() => _OtpScreenState();
}

class _OtpScreenState extends State<OtpScreen> {
  final List<TextEditingController> _controllers =
      List.generate(6, (_) => TextEditingController());
  final List<FocusNode> _focusNodes = List.generate(6, (_) => FocusNode());

  @override
  void dispose() {
    for (final c in _controllers) {
      c.dispose();
    }
    for (final f in _focusNodes) {
      f.dispose();
    }
    super.dispose();
  }

  String get _otp => _controllers.map((c) => c.text).join();

  void _onChanged(int index, String value) {
    if (value.length == 1 && index < 5) {
      _focusNodes[index + 1].requestFocus();
    }
    if (_otp.length == 6) {
      _submit();
    }
  }

  void _onKeyDown(int index, KeyEvent event) {
    if (event is KeyDownEvent &&
        event.logicalKey == LogicalKeyboardKey.backspace &&
        _controllers[index].text.isEmpty &&
        index > 0) {
      _controllers[index - 1].clear();
      _focusNodes[index - 1].requestFocus();
    }
  }

  void _submit() {
    final otp = _otp;
    if (otp.length != 6) return;
    final state = context.read<AuthBloc>().state;
    final verificationId = state is AuthOtpSent ? state.verificationId : '';
    context.read<AuthBloc>().add(OtpVerified(verificationId, otp));
  }

  @override
  Widget build(BuildContext context) {
    return BlocListener<AuthBloc, AuthState>(
      listener: (context, state) {
        if (state is AuthError) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text(state.message)),
          );
          // Clear fields on error
          for (final c in _controllers) {
            c.clear();
          }
          _focusNodes[0].requestFocus();
        }
      },
      child: Scaffold(
        appBar: AppBar(title: const Text('Masukkan OTP')),
        body: Padding(
          padding: const EdgeInsets.all(24),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              Text(
                'Kode OTP telah dikirim ke ${widget.phone}',
                textAlign: TextAlign.center,
              ),
              const SizedBox(height: 32),
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: List.generate(6, (index) {
                  return SizedBox(
                    width: 48,
                    child: KeyboardListener(
                      focusNode: FocusNode(),
                      onKeyEvent: (event) => _onKeyDown(index, event),
                      child: TextField(
                        controller: _controllers[index],
                        focusNode: _focusNodes[index],
                        textAlign: TextAlign.center,
                        keyboardType: TextInputType.number,
                        maxLength: 1,
                        style: const TextStyle(
                          fontSize: 24,
                          fontWeight: FontWeight.bold,
                        ),
                        decoration: const InputDecoration(
                          counterText: '',
                          border: OutlineInputBorder(),
                          contentPadding: EdgeInsets.symmetric(vertical: 14),
                        ),
                        inputFormatters: [
                          FilteringTextInputFormatter.digitsOnly,
                        ],
                        onChanged: (value) => _onChanged(index, value),
                      ),
                    ),
                  );
                }),
              ),
              const SizedBox(height: 32),
              BlocBuilder<AuthBloc, AuthState>(
                builder: (context, state) => ElevatedButton(
                  onPressed: state is AuthLoading ? null : _submit,
                  child: state is AuthLoading
                      ? const CircularProgressIndicator()
                      : const Text('Verifikasi'),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}