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

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Padding(
        padding: EdgeInsets.all(16),
        child: AnimatedEngineMeter(targetValue: 0.3),
      ),
    );
  }
}

class AnimatedEngineMeter extends StatelessWidget {
  const AnimatedEngineMeter({required this.targetValue});
  
  final double targetValue;

  @override
  Widget build(BuildContext context) {
    return TweenAnimationBuilder<double>(
      tween: Tween(begin: 0.0, end: targetValue),
      duration: const Duration(seconds: 2),
      builder: (context, value, child) {
        return Tachometer(rpmValue: value);
      },
    );
  }
}

class Tachometer extends StatelessWidget {
  const Tachometer({required this.rpmValue});

  final double rpmValue; // 0.0から1.0までの値。例：0.5は50%のRPMを示す

  @override
  Widget build(BuildContext context) {
    return CustomPaint(
      painter: TachometerPainter(rpmValue),
      size: const Size(300, 200), // こちらのサイズは適宜調整してください
    );
  }
}

class TachometerPainter extends CustomPainter {
  const TachometerPainter(this.rpmValue);
  
  final double rpmValue;

  @override
  void paint(Canvas canvas, Size size) {
    final center = Offset(size.width / 2, size.height);
    final radius = size.width / 2 - 20;

    // 半円背景の描画
    final bgPaint = Paint()..color = Colors.black;
    canvas.drawArc(
      Rect.fromCircle(center: center, radius: radius),
      pi,
      pi,
      false,
      bgPaint,
    );

    // 数値メモリとラベルの描画
    final memPaint = Paint()
      ..color = Colors.white
      ..strokeWidth = 2.0;
    final textPainter = TextPainter(
      textDirection: TextDirection.ltr,
    );

    const totalMarks = 9; 
    const startAngle = 1.1 * pi; // 開始角度を調整
    const endAngle = 1.9 * pi; // 終了角度を調整

    for (int i = 0; i <= totalMarks; i++) {
      // メモリの線を描画
      var angle = startAngle + (endAngle - startAngle) * (i / totalMarks);
      final start = Offset(
        center.dx + (radius - 10) * cos(angle),
        center.dy + (radius - 10) * sin(angle),
      );
      final end = Offset(
        center.dx + radius * cos(angle),
        center.dy + radius * sin(angle),
      );
      canvas.drawLine(start, end, memPaint);

      // メモリの数値ラベルの描画
      textPainter.text = TextSpan(
        text: '${i * 20}',
        style: const TextStyle(color: Colors.white, fontSize: 12.0),
      );
      textPainter.layout();
      textPainter.paint(
        canvas,
        Offset(
          center.dx + (radius - 30) * cos(angle) - textPainter.width / 2,
          center.dy + (radius - 30) * sin(angle) - textPainter.height / 2,
        ),
      );
    }

    // 針の描画
    final angle = startAngle + (endAngle - startAngle) * rpmValue;
    final needleEnd = Offset(
      center.dx + (radius - 20) * cos(angle),
      center.dy + (radius - 20) * sin(angle),
    );

    final needlePaint = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 5.0;

    canvas.drawLine(center, needleEnd, needlePaint);
  }

  @override
  bool shouldRepaint(TachometerPainter oldDelegate) {
    print("oldDelegate.rpmValue ${oldDelegate.rpmValue}");
    return oldDelegate.rpmValue != rpmValue;
  }
}