import 'package:flutter/material.dart';
import '../models/problem.dart';

class ProblemCard extends StatelessWidget {
  final Problem problem;
  final bool isSelected;
  final bool isInCart;
  final VoidCallback onTap;
  final ValueChanged<String> onAddToCart;
  final ValueChanged<String>? onRemoveFromCart;

  const ProblemCard({
    super.key,
    required this.problem,
    this.isSelected = false,
    this.isInCart = false,
    required this.onTap,
    required this.onAddToCart,
    this.onRemoveFromCart,
  });

  @override
  Widget build(BuildContext context) {
    final preview = problem.bodyPreview.isNotEmpty
        ? problem.bodyPreview
        : '${problem.questionType} · ${problem.difficultyLabel}(${problem.difficulty})';

    return Card(
      margin: const EdgeInsets.symmetric(horizontal: 8, vertical: 2),
      color: isSelected ? Theme.of(context).colorScheme.primaryContainer : null,
      child: ListTile(
        dense: true,
        leading: _typeIcon(),
        title: Text(
          preview,
          maxLines: 3,
          overflow: TextOverflow.ellipsis,
          style: const TextStyle(fontSize: 13, height: 1.4),
        ),
        subtitle: Row(
          children: [
            _difficultyChip(context),
            const SizedBox(width: 4),
            if (!problem.isAnnotated)
              const Icon(Icons.warning_amber, size: 14, color: Colors.orange),
          ],
        ),
        trailing: isInCart
            ? IconButton(
                icon: const Icon(Icons.remove_shopping_cart, size: 18, color: Colors.red),
                onPressed: () => onRemoveFromCart?.call(problem.id),
                tooltip: '从试题篮移除',
              )
            : IconButton(
                icon: const Icon(Icons.add_shopping_cart, size: 18),
                onPressed: () => onAddToCart(problem.id),
                tooltip: '加入试题篮',
              ),
        onTap: onTap,
      ),
    );
  }

  Widget _difficultyChip(BuildContext context) {
    Color color;
    switch (problem.difficultyLabel) {
      case '易': color = Colors.green; break;
      case '中': color = Colors.orange; break;
      default: color = Colors.red;
    }
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 1),
      decoration: BoxDecoration(
        color: color.withValues(alpha: 0.15),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Text(
        problem.difficultyLabel,
        style: TextStyle(fontSize: 11, color: color, fontWeight: FontWeight.w500),
      ),
    );
  }

  Widget _typeIcon() {
    IconData icon;
    Color color;
    switch (problem.questionType) {
      case '单选题': icon = Icons.radio_button_checked; color = Colors.blue; break;
      case '多选题': icon = Icons.check_box; color = Colors.purple; break;
      case '填空题': icon = Icons.edit_note; color = Colors.orange; break;
      case '解答题': icon = Icons.assignment; color = Colors.green; break;
      default: icon = Icons.question_mark; color = Colors.grey;
    }
    return Icon(icon, color: color, size: 20);
  }
}