swing_account/lib/widgets/statistics/category_chart.dart

import 'package:flutter/material.dart';
import '../../models/record.dart';
import '../../data/categories.dart';
import 'dart:math' as math;

class CategoryChart extends StatefulWidget {
  final List<Record> records;

  const CategoryChart({
    Key? key,
    required this.records,
  }) : super(key: key);

  @override
  State<CategoryChart> createState() => _CategoryChartState();
}

class _CategoryChartState extends State<CategoryChart> {
  bool _showExpense = true;  // true显示支出，false显示收入

  @override
  Widget build(BuildContext context) {
    final categoryData = _getCategoryData();
    if (categoryData.isEmpty) return const SizedBox();

    final isYearView = widget.records.any((r) => 
      r.createTime.month != widget.records.first.createTime.month);

    return Container(
      padding: const EdgeInsets.all(20),
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(12),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withOpacity(0.05),
            blurRadius: 8,
            offset: const Offset(0, 2),
          ),
        ],
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(
            children: [
              Text(
                '${isYearView ? "年度" : ""}分类统计',
                style: const TextStyle(
                  fontSize: 16,
                  fontWeight: FontWeight.bold,
                ),
              ),
              const Spacer(),
              ToggleButtons(
                isSelected: [_showExpense, !_showExpense],
                onPressed: (index) {
                  setState(() {
                    _showExpense = index == 0;
                  });
                },
                borderRadius: BorderRadius.circular(8),
                selectedColor: Theme.of(context).primaryColor,
                constraints: const BoxConstraints(
                  minWidth: 60,
                  minHeight: 32,
                ),
                children: const [
                  Text('支出'),
                  Text('收入'),
                ],
              ),
            ],
          ),
          const SizedBox(height: 20),
          SizedBox(
            height: 200,
            child: Row(
              children: [
                Expanded(
                  flex: 3,
                  child: CustomPaint(
                    size: const Size(200, 200),
                    painter: PieChartPainter(
                      categories: categoryData,
                      total: categoryData.fold(
                        0.0,
                        (sum, item) => sum + item.amount,
                      ),
                    ),
                  ),
                ),
                Expanded(
                  flex: 2,
                  child: _buildLegend(categoryData),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

  List<CategoryData> _getCategoryData() {
    final Map<String, double> categoryAmounts = {};
    final targetType = _showExpense ? RecordType.expense : RecordType.income;
    
    // 统计各分类金额
    for (final record in widget.records) {
      if (record.type == targetType) {
        categoryAmounts[record.categoryId] = 
            (categoryAmounts[record.categoryId] ?? 0) + record.amount;
      }
    }
    
    // 转换为列表并排序
    final categories = CategoryConfig.getCategoriesByType(targetType);
    return categoryAmounts.entries.map((entry) {
      final category = categories.firstWhere(
        (c) => c.id == entry.key,
        orElse: () => Category(
          id: 'unknown',
          name: '未知',
          iconKey: 'other',
          type: targetType,
          sortOrder: 999,
        ),
      );
      return CategoryData(
        category: category,
        amount: entry.value,
      );
    }).toList()
      ..sort((a, b) => b.amount.compareTo(a.amount));
  }

  Widget _buildLegend(List<CategoryData> data) {
    return ListView.builder(
      shrinkWrap: true,
      itemCount: data.length,
      itemBuilder: (context, index) {
        final item = data[index];
        final total = data.fold(0.0, (sum, item) => sum + item.amount);
        final percentage = (item.amount / total * 100).toStringAsFixed(1);
        
        return Padding(
          padding: const EdgeInsets.symmetric(vertical: 4),
          child: Row(
            children: [
              Container(
                width: 12,
                height: 12,
                decoration: BoxDecoration(
                  color: Colors.primaries[index % Colors.primaries.length],
                  shape: BoxShape.circle,
                ),
              ),
              const SizedBox(width: 8),
              Expanded(
                child: Text(
                  item.category.name,
                  style: const TextStyle(fontSize: 12),
                ),
              ),
              Text(
                '$percentage%',
                style: const TextStyle(fontSize: 12),
              ),
            ],
          ),
        );
      },
    );
  }
}

class CategoryData {
  final Category category;
  final double amount;

  CategoryData({
    required this.category,
    required this.amount,
  });
}

class PieChartPainter extends CustomPainter {
  final List<CategoryData> categories;
  final double total;

  PieChartPainter({
    required this.categories,
    required this.total,
  });

  @override
  void paint(Canvas canvas, Size size) {
    final center = Offset(size.width / 2, size.height / 2);
    final radius = math.min(size.width, size.height) / 2;
    
    var startAngle = -math.pi / 2;
    
    for (var i = 0; i < categories.length; i++) {
      final sweepAngle = 2 * math.pi * categories[i].amount / total;
      
      final paint = Paint()
        ..color = Colors.primaries[i % Colors.primaries.length]
        ..style = PaintingStyle.fill;
      
      canvas.drawArc(
        Rect.fromCircle(center: center, radius: radius),
        startAngle,
        sweepAngle,
        true,
        paint,
      );
      
      startAngle += sweepAngle;
    }
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => true;
}