// Author: fruit.com.cn

part of 'home_feed_overlay.dart';

const double _thumbSize = 6;
const double _thumbActiveSize = 14;
const double _trackActiveHeight = 6;
const double _lineCenterFromBottom = 8;

/// 整集条底部的进度线：20px 手势区内可点按/拖动 seek。
class _FeedProgressBar extends StatefulWidget {
  const _FeedProgressBar({
    required this.controller,
    required this.height,
    required this.hitHeight,
    this.onScrubStart,
    this.onSeek,
  });

  final ValueListenable<VideoPlayerValue>? controller;
  final double height;
  final double hitHeight;
  final VoidCallback? onScrubStart;
  final ValueChanged<Duration>? onSeek;

  @override
  State<_FeedProgressBar> createState() => _FeedProgressBarState();
}

class _FeedProgressBarState extends State<_FeedProgressBar> {
  double? _preview;

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(
      builder: (context, constraints) {
        final width = constraints.maxWidth;
        final source = widget.controller;
        final track = source == null
            ? _track(0, width)
            : ValueListenableBuilder<VideoPlayerValue>(
                valueListenable: source,
                builder: (context, value, _) {
                  final total = value.duration.inMilliseconds;
                  final played = total <= 0
                      ? 0.0
                      : (value.position.inMilliseconds / total)
                            .clamp(0.0, 1.0)
                            .toDouble();
                  return _track(_preview ?? played, width);
                },
              );
        return GestureDetector(
          key: const Key('home-feed-progress'),
          behavior: HitTestBehavior.opaque,
          onHorizontalDragStart: (details) {
            widget.onScrubStart?.call();
            _update(details.localPosition.dx / width);
          },
          onHorizontalDragUpdate: (details) =>
              _update(details.localPosition.dx / width),
          onHorizontalDragEnd: (_) => _commit(_preview),
          onHorizontalDragCancel: () => setState(() => _preview = null),
          child: track,
        );
      },
    );
  }

  void _update(double fraction) {
    setState(() => _preview = fraction.clamp(0.0, 1.0).toDouble());
  }

  void _commit(double? fraction) {
    if (fraction == null) return;
    final total = widget.controller?.value.duration.inMilliseconds ?? 0;
    if (total > 0) {
      widget.onSeek?.call(
        Duration(milliseconds: (total * fraction.clamp(0.0, 1.0)).round()),
      );
    }
    setState(() => _preview = null);
  }

  Widget _track(double fraction, double width) {
    final dragging = _preview != null;
    final trackHeight = dragging ? _trackActiveHeight : widget.height;
    final size = dragging ? _thumbActiveSize : _thumbSize;
    final left = (width * fraction - size / 2)
        .clamp(0.0, width - size)
        .toDouble();
    final lineBottom = _lineCenterFromBottom - trackHeight / 2;
    final thumbBottom = _lineCenterFromBottom - size / 2;
    return SizedBox(
      height: widget.hitHeight,
      child: Stack(
        clipBehavior: Clip.none,
        children: [
          Positioned(
            left: 0,
            right: 0,
            bottom: lineBottom,
            child: Container(
              key: const Key('home-feed-progress-track'),
              height: trackHeight,
              color: Colors.white24,
            ),
          ),
          Positioned(
            left: 0,
            bottom: lineBottom,
            child: Container(
              width: width * fraction,
              height: trackHeight,
              color: AppColors.blue,
            ),
          ),
          Positioned(
            left: left,
            bottom: thumbBottom,
            child: Container(
              key: const Key('home-feed-progress-thumb'),
              width: size,
              height: size,
              decoration: const BoxDecoration(
                color: Colors.white,
                shape: BoxShape.circle,
              ),
            ),
          ),
        ],
      ),
    );
  }
}