import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:formz/formz.dart';
import 'package:go_router/go_router.dart';
import '../../../../core/theme/design_tokens.dart';
import '../../../../core/di/injection.dart';
import '../../../../shared/widgets/app_button.dart';
import '../../../../shared/widgets/banner/app_banner.dart';
import '../../../../shared/widgets/fixed_length_code_input.dart';
import '../../../../shared/widgets/link_button.dart';
import '../../../../shared/widgets/toast/toast.dart';
import '../../../../shared/widgets/toast/toast_type.dart';
import '../../presentation/cubits/register_cubit.dart';
import '../../data/auth_repository.dart';
import '../widgets/auth_page_scaffold.dart';

class RegisterScreen extends StatelessWidget {
  const RegisterScreen({super.key});

  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      create: (context) => RegisterCubit(sl<AuthRepository>()),
      child: const RegisterView(),
    );
  }
}

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

  @override
  State<RegisterView> createState() => _RegisterViewState();
}

class _RegisterViewState extends State<RegisterView> {
  static const _inviteCodeLength = 4;
  static const _inviteAllowedChars = <String>{
    'A',
    'B',
    'C',
    'D',
    'E',
    'F',
    'G',
    'H',
    'J',
    'K',
    'M',
    'N',
    'P',
    'Q',
    'R',
    'S',
    'T',
    'U',
    'V',
    'W',
    'X',
    'Y',
    'Z',
    '2',
    '3',
    '4',
    '5',
    '6',
    '7',
    '8',
    '9',
  };

  final _nicknameController = TextEditingController();
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();
  final _inviteCodeController = TextEditingController();
  bool _obscureText = true;

  @override
  void dispose() {
    _nicknameController.dispose();
    _emailController.dispose();
    _passwordController.dispose();
    _inviteCodeController.dispose();
    super.dispose();
  }

  Future<void> _handleNext() async {
    final cubit = context.read<RegisterCubit>();
    final inviteCode = _inviteCodeController.text.trim().toUpperCase();
    final normalizedInviteCode = inviteCode.length == _inviteCodeLength
        ? inviteCode
        : '';

    cubit.usernameChanged(_nicknameController.text);
    cubit.emailChanged(_emailController.text);
    cubit.passwordChanged(_passwordController.text);
    cubit.inviteCodeChanged(normalizedInviteCode);

    if (!cubit.state.isStep1Valid || cubit.state.isSending) {
      String? errorMsg;
      if (!cubit.state.username.isValid) {
        errorMsg = '请输入有效的昵称（3-30个字符）';
      } else if (!cubit.state.email.isValid) {
        errorMsg = '请输入有效的邮箱地址';
      } else if (!cubit.state.password.isValid) {
        errorMsg = '密码至少需要6个字符';
      }
      if (errorMsg != null && mounted) {
        Toast.show(context, errorMsg, type: ToastType.warning);
      }
      return;
    }

    if (inviteCode.isNotEmpty && normalizedInviteCode.isEmpty && mounted) {
      Toast.show(
        context,
        '邀请码需为 4 位，且仅支持 A-H/J-N/P-Z 与 2-9；已按无邀请码继续注册',
        type: ToastType.warning,
      );
    }

    if (mounted) {
      context.push('/register/verification', extra: cubit);
    }

    unawaited(cubit.sendCodeSilently());
  }

  @override
  Widget build(BuildContext context) {
    return AuthPageScaffold(
      mainContent: Column(
        mainAxisSize: MainAxisSize.min,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          _buildAppIcon(),
          const SizedBox(height: 24),
          _buildAppTitle(),
          const SizedBox(height: 24),
          _buildFormContainer(),
        ],
      ),
      footer: _buildFooter(),
    );
  }

  Widget _buildAppIcon() {
    return Container(
      width: 104,
      height: 104,
      decoration: BoxDecoration(
        color: AppColors.appIconRing,
        borderRadius: BorderRadius.circular(52),
        border: Border.all(color: AppColors.appIconBorder, width: 1),
      ),
      child: Center(
        child: ClipRRect(
          borderRadius: BorderRadius.circular(38),
          child: Image.asset(
            'assets/images/logo.png',
            width: 76,
            height: 76,
            fit: BoxFit.cover,
          ),
        ),
      ),
    );
  }

  Widget _buildAppTitle() {
    return const Text(
      'linksy',
      style: TextStyle(
        fontFamily: 'Playfair Display',
        fontSize: 34,
        fontWeight: FontWeight.w700,
        fontStyle: FontStyle.italic,
        color: AppColors.appTitle,
        letterSpacing: 0.5,
      ),
    );
  }

  Widget _buildFormContainer() {
    return BlocBuilder<RegisterCubit, RegisterState>(
      builder: (context, state) {
        return SizedBox(
          width: 327,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              _buildInput('昵称', '请输入昵称', _nicknameController),
              const SizedBox(height: 12),
              _buildInput('邮箱', '请输入邮箱', _emailController),
              const SizedBox(height: 12),
              _buildPasswordInput(),
              const SizedBox(height: 12),
              _buildInviteCodeInput(),
              const SizedBox(height: 12),
              _buildStepIndicator(),
              if (state.errorMessage != null)
                Padding(
                  padding: const EdgeInsets.only(top: 8),
                  child: AppBanner(
                    message: state.errorMessage!,
                    type: ToastType.error,
                  ),
                ),
              const SizedBox(height: 12),
              AppButton(
                text: '下一步',
                onPressed:
                    state.status == FormzSubmissionStatus.inProgress ||
                        state.isSending
                    ? null
                    : _handleNext,
              ),
            ],
          ),
        );
      },
    );
  }

  Widget _buildInviteCodeInput() {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        const Text(
          '邀请码（选填）',
          style: TextStyle(
            fontSize: 13,
            fontWeight: FontWeight.w500,
            color: AppColors.slate600,
          ),
        ),
        const SizedBox(height: 6),
        FixedLengthCodeInput(
          controller: _inviteCodeController,
          length: _inviteCodeLength,
          semanticLabel: '邀请码输入框',
          uppercase: true,
          allowedCharacters: _inviteAllowedChars,
          onChanged: (value) {
            context.read<RegisterCubit>().inviteCodeChanged(value);
          },
        ),
        const SizedBox(height: 6),
        const Text(
          '4 位邀请码，支持 A-H/J-N/P-Z 与 2-9',
          style: TextStyle(
            fontSize: 12,
            fontWeight: FontWeight.w400,
            color: AppColors.slate500,
          ),
        ),
      ],
    );
  }

  Widget _buildInput(
    String label,
    String hint,
    TextEditingController controller,
  ) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(
          label,
          style: const TextStyle(
            fontSize: 13,
            fontWeight: FontWeight.w500,
            color: AppColors.slate600,
          ),
        ),
        const SizedBox(height: 6),
        TextField(
          controller: controller,
          decoration: InputDecoration(hintText: hint),
        ),
      ],
    );
  }

  Widget _buildPasswordInput() {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        const Text(
          '密码',
          style: TextStyle(
            fontSize: 13,
            fontWeight: FontWeight.w500,
            color: AppColors.slate600,
          ),
        ),
        const SizedBox(height: 6),
        TextField(
          controller: _passwordController,
          obscureText: _obscureText,
          decoration: InputDecoration(
            hintText: '请输入至少 6 位密码',
            suffixIcon: IconButton(
              icon: Icon(
                _obscureText ? Icons.visibility_off : Icons.visibility,
                size: 20,
                color: AppColors.slate400,
              ),
              onPressed: () {
                setState(() {
                  _obscureText = !_obscureText;
                });
              },
            ),
          ),
        ),
      ],
    );
  }

  Widget _buildStepIndicator() {
    return Row(
      children: [
        Expanded(
          child: Container(
            height: 4,
            decoration: BoxDecoration(
              color: AppColors.primary,
              borderRadius: BorderRadius.circular(99),
            ),
          ),
        ),
        const SizedBox(width: 6),
        Expanded(
          child: Container(
            height: 4,
            decoration: BoxDecoration(
              color: const Color(0xFFDCE3EC),
              borderRadius: BorderRadius.circular(99),
            ),
          ),
        ),
      ],
    );
  }

  Widget _buildFooter() {
    return LinkButton(text: '已有账号？去登录', onTap: () => context.pop());
  }
}