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/di/injection.dart';
import '../../../../core/theme/design_tokens.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 '../../data/auth_repository.dart';
import '../../presentation/cubits/register_cubit.dart';
import '../widgets/auth_field.dart';
import '../widgets/auth_page_scaffold.dart';
import '../widgets/password_field.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();

  @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: Padding(
        padding: const EdgeInsets.symmetric(horizontal: AppSpacing.sm),
        child: Center(
          child: ConstrainedBox(
            constraints: const BoxConstraints(maxWidth: 388),
            child: Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.center,
              children: [
                const AuthHeroHeader(showBrand: true),
                SizedBox(height: AppSpacing.xxl),
                BlocBuilder<RegisterCubit, RegisterState>(
                  builder: (context, state) {
                    return AuthSurfaceCard(
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.stretch,
                        children: [
                          const Text(
                            '创建账号',
                            style: TextStyle(
                              fontSize: 20,
                              fontWeight: FontWeight.w700,
                              color: AppColors.slate900,
                            ),
                          ),
                          SizedBox(height: AppSpacing.lg),
                          AuthSection(
                            title: '基础信息',
                            child: Column(
                              crossAxisAlignment: CrossAxisAlignment.stretch,
                              children: [
                                AuthField(
                                  label: '昵称',
                                  hint: '请输入昵称（3-30字符）',
                                  controller: _nicknameController,
                                ),
                                SizedBox(height: AppSpacing.lg),
                                AuthField(
                                  label: '邮箱',
                                  hint: 'name@example.com',
                                  controller: _emailController,
                                  keyboardType: TextInputType.emailAddress,
                                ),
                                SizedBox(height: AppSpacing.lg),
                                PasswordField(
                                  controller: _passwordController,
                                  label: '密码',
                                  hint: '请输入至少 6 位密码',
                                ),
                              ],
                            ),
                          ),
                          SizedBox(height: AppSpacing.md),
                          AuthSection(
                            title: '邀请码（选填）',
                            child: Column(
                              crossAxisAlignment: CrossAxisAlignment.stretch,
                              children: [
                                FixedLengthCodeInput(
                                  controller: _inviteCodeController,
                                  length: _inviteCodeLength,
                                  semanticLabel: '邀请码输入框',
                                  uppercase: true,
                                  allowedCharacters: _inviteAllowedChars,
                                  onChanged: (value) {
                                    context
                                        .read<RegisterCubit>()
                                        .inviteCodeChanged(value);
                                  },
                                ),
                                SizedBox(height: AppSpacing.md),
                                AppBanner(
                                  title: '邀请码',
                                  message: '4 位，支持 A-H/J-N/P-Z 与 2-9。',
                                  type: ToastType.info,
                                ),
                              ],
                            ),
                          ),
                          if (state.errorMessage != null) ...[
                            SizedBox(height: AppSpacing.lg),
                            AppBanner(
                              title: '注册失败',
                              message: state.errorMessage!,
                              type: ToastType.error,
                            ),
                          ],
                          SizedBox(height: AppSpacing.lg),
                          Row(
                            crossAxisAlignment: CrossAxisAlignment.center,
                            children: [
                              Expanded(
                                child: Container(
                                  height: 6,
                                  decoration: BoxDecoration(
                                    color: AppColors.authPrimaryButton,
                                    borderRadius: BorderRadius.circular(
                                      AppRadius.full,
                                    ),
                                  ),
                                ),
                              ),
                              SizedBox(width: AppSpacing.sm),
                              Expanded(
                                child: Container(
                                  height: 6,
                                  decoration: BoxDecoration(
                                    color: AppColors.authSectionBorder,
                                    borderRadius: BorderRadius.circular(
                                      AppRadius.full,
                                    ),
                                  ),
                                ),
                              ),
                            ],
                          ),
                          SizedBox(height: AppSpacing.sm),
                          const Text(
                            '第 1 步：完善基础信息',
                            textAlign: TextAlign.center,
                            style: TextStyle(
                              fontSize: 12,
                              fontWeight: FontWeight.w600,
                              color: AppColors.authLinkMuted,
                            ),
                          ),
                          SizedBox(height: AppSpacing.lg),
                          AppButton(
                            text: '下一步',
                            onPressed:
                                state.status ==
                                        FormzSubmissionStatus.inProgress ||
                                    state.isSending
                                ? null
                                : _handleNext,
                            isLoading: state.isSending,
                          ),
                        ],
                      ),
                    );
                  },
                ),
              ],
            ),
          ),
        ),
      ),
      footer: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          const Text(
            '已有账号？',
            style: TextStyle(fontSize: 14, color: AppColors.authLinkMuted),
          ),
          LinkButton(text: '去登录', onTap: () => context.pop()),
        ],
      ),
    );
  }
}