nj/app/lib/features/auth/views/role_selection_page.dart

// 角色选择页面 — 注册后选择身份角色
//
// 暖记四种角色：
// - 🎓 老师 — 创建班级、布置主题、点评日记
// - ✏️ 学生 — 加入班级、写日记、查看点评
// - 👨‍👩‍👧 家长 — 查看孩子日记、管理数据
// - 📖 独立用户 — 个人日记、不加入班级

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:go_router/go_router.dart';

import '../../../core/constants/design_tokens.dart';
import '../../../core/theme/app_radius.dart';
import '../../../data/models/user.dart';
import '../bloc/auth_bloc.dart';

/// 角色卡片数据
class _RoleCard {
  final UserRoleType type;
  final String title;
  final String subtitle;
  final IconData icon;
  final Color color;

  const _RoleCard({
    required this.type,
    required this.title,
    required this.subtitle,
    required this.icon,
    required this.color,
  });
}

/// 角色选择页面
class RoleSelectionPage extends StatelessWidget {
  const RoleSelectionPage({super.key});

  static const _roles = [
    _RoleCard(
      type: UserRoleType.student,
      title: '我是学生',
      subtitle: '加入班级，记录每一天',
      icon: Icons.school_rounded,
      color: Color(0xFF81B29A), // 鼠尾草绿
    ),
    _RoleCard(
      type: UserRoleType.teacher,
      title: '我是老师',
      subtitle: '创建班级，陪伴学生成长',
      icon: Icons.auto_stories_rounded,
      color: Color(0xFFE07A5F), // 珊瑚色
    ),
    _RoleCard(
      type: UserRoleType.parent,
      title: '我是家长',
      subtitle: '关注孩子的成长记录',
      icon: Icons.family_restroom_rounded,
      color: Color(0xFFF2CC8F), // 暖金
    ),
    _RoleCard(
      type: UserRoleType.independent,
      title: '独立使用',
      subtitle: '个人日记，随心记录',
      icon: Icons.menu_book_rounded,
      color: Color(0xFFD4A5A5), // 玫瑰粉
    ),
  ];

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;

    return Scaffold(
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.symmetric(
            horizontal: DesignTokens.spacing24,
            vertical: DesignTokens.spacing32,
          ),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              // 标题
              Text(
                '你好！👋',
                style: Theme.of(context).textTheme.headlineMedium?.copyWith(
                      fontWeight: FontWeight.bold,
                    ),
              ),
              const SizedBox(height: DesignTokens.spacing8),
              Text(
                '告诉我你的身份，我会为你定制体验',
                style: Theme.of(context).textTheme.bodyLarge?.copyWith(
                      color: colorScheme.onSurface.withValues(alpha: 0.7),
                    ),
              ),
              const SizedBox(height: DesignTokens.spacing32),

              // 角色卡片网格
              Expanded(
                child: GridView.count(
                  crossAxisCount: 2,
                  mainAxisSpacing: DesignTokens.spacing16,
                  crossAxisSpacing: DesignTokens.spacing16,
                  childAspectRatio: 0.85,
                  children: _roles.map((role) => _RoleCardWidget(
                        role: role,
                        onTap: () => _selectRole(context, role.type),
                      )).toList(),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  void _selectRole(BuildContext context, UserRoleType role) {
    context.read<AuthBloc>().add(RoleSelected(role));

    final state = context.read<AuthBloc>().state;
    if (state is Authenticated) {
      if (state.needsClassCode) {
        context.go('/class-code');
      } else {
        context.go('/home');
      }
    }
  }
}

/// 角色卡片组件
class _RoleCardWidget extends StatelessWidget {
  final _RoleCard role;
  final VoidCallback onTap;

  const _RoleCardWidget({
    required this.role,
    required this.onTap,
  });

  @override
  Widget build(BuildContext context) {
    return Material(
      color: Colors.transparent,
      child: InkWell(
        onTap: onTap,
        borderRadius: AppRadius.lgBorder,
        child: Ink(
          decoration: BoxDecoration(
            color: role.color.withValues(alpha: 0.12),
            borderRadius: AppRadius.lgBorder,
            border: Border.all(
              color: role.color.withValues(alpha: 0.3),
              width: 2,
            ),
          ),
          child: Padding(
            padding: const EdgeInsets.all(DesignTokens.spacing16),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                // 图标
                Container(
                  width: 56,
                  height: 56,
                  decoration: BoxDecoration(
                    color: role.color.withValues(alpha: 0.2),
                    shape: BoxShape.circle,
                  ),
                  child: Icon(
                    role.icon,
                    size: 28,
                    color: role.color,
                  ),
                ),
                const SizedBox(height: DesignTokens.spacing12),

                // 标题
                Text(
                  role.title,
                  style: Theme.of(context).textTheme.titleMedium?.copyWith(
                        fontWeight: FontWeight.bold,
                        color: role.color,
                      ),
                  textAlign: TextAlign.center,
                ),
                const SizedBox(height: DesignTokens.spacing4),

                // 副标题
                Text(
                  role.subtitle,
                  style: Theme.of(context).textTheme.bodySmall?.copyWith(
                        color: Theme.of(context)
                            .colorScheme
                            .onSurface
                            .withValues(alpha: 0.6),
                      ),
                  textAlign: TextAlign.center,
                  maxLines: 2,
                  overflow: TextOverflow.ellipsis,
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}