ReelShort/lib/pages/player/widgets/player_double_tap_hearts.dart

// Author: fruit.com.cn

import 'dart:async';

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

import '../../../core/theme/app_colors.dart';

const int _heartDurationMs = 1500;
const double _heartPopPortion = 0.18;
const double _heartStartScale = 0.7;
const double _heartHoldPortion = 0.55;

const List<_HeartParticle> _hearts = [
  _HeartParticle(
    delay: 0,
    travel: 108,
    drift: 0,
    size: 48,
    color: AppColors.doubleTapHeartRed,
  ),
  _HeartParticle(
    delay: 50,
    travel: 96,
    drift: -28,
    size: 36,
    color: AppColors.doubleTapHeartPink,
  ),
  _HeartParticle(
    delay: 90,
    travel: 118,
    drift: 26,
    size: 40,
    color: AppColors.doubleTapHeartRed,
  ),
];

/// 双击点赞时，在点击位置飘出一小簇心。
class PlayerDoubleTapHeartBurst extends StatefulWidget {
  const PlayerDoubleTapHeartBurst({
    super.key,
    required this.burstId,
    required this.onCompleted,
    this.origin = Offset.zero,
    this.now,
  });

  final int burstId;
  final VoidCallback onCompleted;
  final Offset origin;
  final DateTime Function()? now;

  @override
  State<PlayerDoubleTapHeartBurst> createState() =>
      _PlayerDoubleTapHeartBurstState();
}

class _PlayerDoubleTapHeartBurstState extends State<PlayerDoubleTapHeartBurst> {
  Timer? _timer;
  late final DateTime _startAt;
  late final int _totalMs;
  final Stopwatch _lifetime = Stopwatch();
  int _elapsedMs = 0;
  int _tickCount = 0;
  bool _completed = false;

  @override
  void initState() {
    super.initState();
    _lifetime.start();
    _startAt = _now();
    _totalMs = _hearts
        .map((heart) => heart.delay + _heartDurationMs)
        .reduce((left, right) => left > right ? left : right);
    if (kDebugMode) {
      debugPrint(
        '[player] phase=heart-burst-start '
        'id=${widget.burstId} count=${_hearts.length} '
        'configuredMs=$_totalMs at=${widget.origin.dx.toStringAsFixed(1)},'
        '${widget.origin.dy.toStringAsFixed(1)}',
      );
    }
    _timer = Timer.periodic(
      const Duration(milliseconds: 16),
      (_) => _handleTick(),
    );
  }

  DateTime _now() => widget.now?.call() ?? DateTime.now();

  void _handleTick() {
    if (!mounted || _completed) return;
    final rawElapsedMs = _now().difference(_startAt).inMilliseconds;
    final elapsedMs = rawElapsedMs < 0
        ? 0
        : rawElapsedMs > _totalMs
        ? _totalMs
        : rawElapsedMs;
    _elapsedMs = elapsedMs;
    _tickCount++;
    if (kDebugMode && _tickCount % 10 == 0) {
      debugPrint(
        '[player] phase=heart-tick id=${widget.burstId} '
        'elapsedMs=$_elapsedMs',
      );
    }
    if (_elapsedMs >= _totalMs) {
      _complete();
      return;
    }
    setState(() {});
  }

  void _complete() {
    if (_completed) return;
    _completed = true;
    _timer?.cancel();
    if (kDebugMode) {
      debugPrint(
        '[player] phase=heart-burst-complete '
        'id=${widget.burstId} '
        'configuredMs=$_totalMs',
      );
    }
    widget.onCompleted();
  }

  @override
  void dispose() {
    if (kDebugMode) {
      final elapsedMs = _completed ? _totalMs : _elapsedMs;
      debugPrint(
        '[player] phase=heart-burst-dispose '
        'id=${widget.burstId} elapsedMs=$elapsedMs '
        'completed=${_completed ? 1 : 0}',
      );
      if (!_completed) {
        debugPrintStack(
          maxFrames: 30,
          label:
              '[player] heart-burst-premature-dispose '
              'id=${widget.burstId} mount=root-overlay',
        );
      }
    }
    _lifetime.stop();
    _timer?.cancel();
    _timer = null;
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return IgnorePointer(
      child: Stack(
        fit: StackFit.expand,
        clipBehavior: Clip.none,
        children: [
          for (var index = 0; index < _hearts.length; index++)
            _heart(_hearts[index], _elapsedMs.toDouble(), index),
        ],
      ),
    );
  }

  Widget _heart(_HeartParticle heart, double elapsed, int index) {
    final rawProgress = (elapsed - heart.delay) / _heartDurationMs;
    if (rawProgress < 0) return const SizedBox.shrink();
    final progress = rawProgress.clamp(0.0, 1.0);
    final move = Curves.easeOutCubic.transform(progress);
    final scale = progress < _heartPopPortion
        ? _heartStartScale +
              (1 - _heartStartScale) * (progress / _heartPopPortion)
        : 1.0;
    final opacity = progress < _heartHoldPortion
        ? 1.0
        : 1 - ((progress - _heartHoldPortion) / (1 - _heartHoldPortion));
    return Positioned(
      left: widget.origin.dx + heart.drift * move - heart.size / 2,
      top: widget.origin.dy - heart.size / 2 - heart.travel * move,
      child: Opacity(
        opacity: opacity.clamp(0.0, 1.0),
        child: Transform.scale(
          scale: scale,
          child: Icon(
            key: Key('double-tap-heart-$index'),
            Icons.favorite_rounded,
            color: heart.color,
            size: heart.size,
          ),
        ),
      ),
    );
  }
}

class _HeartParticle {
  const _HeartParticle({
    required this.delay,
    required this.travel,
    required this.drift,
    required this.size,
    required this.color,
  });

  final int delay;
  final double travel;
  final double drift;
  final double size;
  final Color color;
}