import 'package:flutter/material.dart';

/// 支持动画过渡和渐变色的进度条
// 使用示例
// AnimatedGradientProgressBar(
//   targetValue: 0.75,
//   gradient: LinearGradient(colors: [Colors.orange, Colors.red]),
//   height: 10,
//   borderRadius: 5,
// )
class AnimatedGradientProgressBar extends StatefulWidget {
  // 目标进度值（0~1）
  final double targetValue;

  // 动画时长
  final Duration duration;

  // 渐变色
  final Gradient gradient;

  // 进度条高度
  final double height;

  // 圆角半径
  final double borderRadius;

  const AnimatedGradientProgressBar({
    super.key,
    required this.targetValue,
    required this.duration,
    required this.gradient,
    this.height = 10.0,
    this.borderRadius = 7.0,
  });

  @override
  AnimatedGradientProgressBarState createState() =>
      AnimatedGradientProgressBarState();
}

class AnimatedGradientProgressBarState
    extends State<AnimatedGradientProgressBar>
    with TickerProviderStateMixin {
  late AnimationController _controller;
  late Animation<double> _animation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(duration: widget.duration, vsync: this);
    _animation = CurvedAnimation(parent: _controller, curve: Curves.easeInOut);
    _startAnimation();
  }

  @override
  void didUpdateWidget(AnimatedGradientProgressBar oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.targetValue != widget.targetValue) {
      _resetAnimation();
      _startAnimation();
    }
  }

  @override
  void dispose() {
    // 移除监听
    _animation.removeListener(() {});
    _controller.dispose();
    super.dispose();
  }

  void _startAnimation() {
    print('进度条 => 初始动画值: ${_animation.value}'); // 0.0

    // 先移除旧监听
    _animation.removeListener(() {});

    // 创建新的 Tween 动画
    _animation = Tween<double>(
      begin: 0,
      end: widget.targetValue,
    ).animate(_animation);

    // 添加监听器并启动动画
    _animation.addListener(() => setState(() {}));
    _controller.forward();

    Future.delayed(widget.duration, () {
      print('进度条 => 最终动画值: ${_animation.value}');
    });
  }

  void _resetAnimation() => _controller.reset();

  @override
  Widget build(BuildContext context) {
    return Stack(
      // 允许子组件溢出自己本身的大小，默认是裁切的
      clipBehavior: Clip.none,
      children: [
        // 百分比文本
        Positioned(
          right: 0,
          // 文字位于进度条上方
          bottom: widget.height + 4,
          child: AnimatedBuilder(
            animation: _animation,
            builder: (context, _) {
              return Text(
                '${(_animation.value * 100).toStringAsFixed(0)}%',
                style: const TextStyle(fontSize: 12, color: Colors.black54),
              );
            },
          ),
        ),
        // 进度条
        ClipRRect(
          borderRadius: BorderRadius.circular(widget.borderRadius),
          child: Container(
            width: double.infinity,
            height: widget.height,
            decoration: BoxDecoration(
              color: Colors.grey[200],
              borderRadius: BorderRadius.circular(widget.borderRadius),
            ),
            child: Stack(
              children: [
                AnimatedBuilder(
                  animation: _animation,
                  builder: (context, _) {
                    return FractionallySizedBox(
                      widthFactor: _animation.value,
                      alignment: Alignment.centerLeft,
                      child: Container(
                        decoration: BoxDecoration(
                          gradient: widget.gradient,
                          borderRadius: BorderRadius.circular(
                            widget.borderRadius,
                          ),
                        ),
                      ),
                    );
                  },
                ),
              ],
            ),
          ),
        ),
      ],
    );
  }
}