import 'dart:math';
import 'package:flutter/material.dart';
import 'package:fl_chart/fl_chart.dart';

void main() {
  runApp(const MaterialApp(
    home: Scaffold(
      backgroundColor: Colors.white,
      body: Center(child: MySolidPieChart()),
    ),
  ));
}

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

  @override
  State<MySolidPieChart> createState() => _MySolidPieChartState();
}

class _MySolidPieChartState extends State<MySolidPieChart> {
  int? touchedIndex;
  final double baseRadius = 60.0;

  final List<_PieData> data = [
    _PieData(label: "运行", value: 45, color: Colors.teal),
    _PieData(label: "移动", value: 14, color: Colors.blue),
    _PieData(label: "停留", value: 25, color: Colors.green),
    _PieData(label: "其他", value: 16, color: Colors.orange),
  ];

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: 320,
      height: 320,
      child: Stack(
        children: [
          PieChart(
            PieChartData(
              sectionsSpace: 0,
              centerSpaceRadius: 0,
              // ✅ 实心饼图
              startDegreeOffset: -90,
              pieTouchData: PieTouchData(
                touchCallback: (event, response) {
                  setState(() {
                    final index = response?.touchedSection?.touchedSectionIndex;
                    touchedIndex = (index != null && index >= 0) ? index : null;
                  });
                },
              ),
              sections: List.generate(data.length, (i) {
                final item = data[i];
                final isTouched = i == touchedIndex;
                return PieChartSectionData(
                  color: item.color,
                  value: item.value.toDouble(),
                  title: '${item.value}%',
                  radius: isTouched ? baseRadius + 10 : baseRadius,
                  titleStyle: const TextStyle(
                    fontSize: 14,
                    fontWeight: FontWeight.bold,
                    color: Colors.white,
                  ),
                  titlePositionPercentageOffset: 0.6,
                );
              }),
            ),
          ),
          IgnorePointer(
            child: CustomPaint(
              size: const Size(320, 320),
              painter: PieLineLabelPainter(
                center: const Offset(160, 160),
                baseRadius: baseRadius + 10,
                startAngleOffset: -90,
                data: data,
                touchedIndex: touchedIndex,
              ),
            ),
          ),
        ],
      ),
    );
  }
}

class PieLineLabelPainter extends CustomPainter {
  final Offset center;
  final double baseRadius;
  final double startAngleOffset;
  final List<_PieData> data;
  final int? touchedIndex;

  PieLineLabelPainter({
    required this.center,
    required this.baseRadius,
    required this.startAngleOffset,
    required this.data,
    required this.touchedIndex,
  });

  @override
  void paint(Canvas canvas, Size size) {
    if (touchedIndex == null ||
        touchedIndex! < 0 ||
        touchedIndex! >= data.length) return;

    final paint = Paint()
      ..color = data[touchedIndex!].color
      ..strokeWidth = 1.5;

    final total = data.fold(0, (sum, e) => sum + e.value);
    double angle = startAngleOffset * pi / 180;

    for (int i = 0; i < data.length; i++) {
      final sweepAngle = (data[i].value / total) * 2 * pi;

      if (i == touchedIndex) {
        final midAngle = angle + sweepAngle / 2;

        final startR = baseRadius + 2;
        final bendR = startR + 25;

        final start = Offset(
          center.dx + cos(midAngle) * startR,
          center.dy + sin(midAngle) * startR,
        );

        final bend = Offset(
          center.dx + cos(midAngle) * bendR,
          center.dy + sin(midAngle) * bendR,
        );

        final isRight = cos(midAngle) >= 0;
        final end = Offset(
          bend.dx + (isRight ? 30 : -30),
          bend.dy,
        );

        canvas.drawCircle(start, 3, paint);
        canvas.drawLine(start, bend, paint);
        canvas.drawLine(bend, end, paint);

        final textPainter = TextPainter(
          text: TextSpan(
            text: '${data[i].label} 11h30min',
            style: TextStyle(color: data[i].color, fontSize: 12),
          ),
          textDirection: TextDirection.ltr,
        )..layout();

        textPainter.paint(
          canvas,
          Offset(
            isRight ? end.dx + 4 : end.dx - textPainter.width - 4,
            end.dy - 6,
          ),
        );
      }

      angle += sweepAngle;
    }
  }

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

class _PieData {
  final String label;
  final int value;
  final Color color;

  _PieData({required this.label, required this.value, required this.color});
}