// lib/widgets/bouncing_loader.dart
import 'package:flutter/material.dart';

/// Three-dot bouncing loader using Curves.bounceOut.
/// Drop-in replacement for CircularProgressIndicator on full-screen loads.
class BouncingLoader extends StatefulWidget {
  final Color? color;
  final double dotSize;
  final double spacing;

  const BouncingLoader({
    Key? key,
    this.color,
    this.dotSize = 8.0,
    this.spacing = 6.0,
  }) : super(key: key);

  @override
  State<BouncingLoader> createState() => _BouncingLoaderState();
}

class _BouncingLoaderState extends State<BouncingLoader> with TickerProviderStateMixin {
  late final List<AnimationController> _controllers;
  late final List<Animation<double>> _animations;

  static const _duration = Duration(milliseconds: 600);
  static const _staggerDelay = Duration(milliseconds: 200);

  @override
  void initState() {
    super.initState();
    _controllers = List.generate(
      3,
      (i) => AnimationController(vsync: this, duration: _duration),
    );
    _animations = _controllers.map((c) {
      return Tween<double>(begin: 0.0, end: -12.0).animate(
        CurvedAnimation(parent: c, curve: Curves.bounceOut),
      );
    }).toList();

    _startWithStagger();
  }

  void _startWithStagger() async {
    for (int i = 0; i < _controllers.length; i++) {
      await Future.delayed(i == 0 ? Duration.zero : _staggerDelay);
      if (!mounted) return;
      _startLoop(i);
    }
  }

  void _startLoop(int index) {
    if (!mounted) return;
    _controllers[index].forward(from: 0).whenComplete(() {
      if (mounted) {
        Future.delayed(
          Duration(milliseconds: _staggerDelay.inMilliseconds * (_controllers.length - 1)),
          () { if (mounted) _startLoop(index); },
        );
      }
    });
  }

  @override
  void dispose() {
    for (final c in _controllers) {
      c.dispose();
    }
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final dotColor = widget.color ?? Theme.of(context).colorScheme.primary;
    return Row(
      mainAxisSize: MainAxisSize.min,
      children: List.generate(3, (i) {
        return Padding(
          padding: EdgeInsets.symmetric(horizontal: widget.spacing / 2),
          child: AnimatedBuilder(
            animation: _animations[i],
            builder: (_, __) => Transform.translate(
              offset: Offset(0, _animations[i].value),
              child: Container(
                width: widget.dotSize,
                height: widget.dotSize,
                decoration: BoxDecoration(
                  color: dotColor,
                  shape: BoxShape.circle,
                ),
              ),
            ),
          ),
        );
      }),
    );
  }
}