// Author: fruit.com.cn

import 'dart:async';

import 'package:flutter/material.dart';

import '../../../core/data/services/sprite_thumbnail_axis.dart';
import '../../../core/theme/app_colors.dart';
import 'scrub_preview_card.dart';

/// 当前集雪碧图首帧在视频纹理未就绪时占位；空地址交还纯黑底。
Widget? playerOpeningFrame(
  String? thumbnailsUrl, {
  required SpriteThumbnailAxisSource spriteSource,
  BoxFit fit = BoxFit.cover,
}) {
  final url = thumbnailsUrl?.trim() ?? '';
  if (url.isEmpty) return null;
  return PlayerOpeningFrame(
    thumbnailsUrl: url,
    spriteSource: spriteSource,
    fit: fit,
  );
}

/// 与视频共用全屏父约束和 BoxFit，切换时保持相同可见区域。
class PlayerOpeningFrame extends StatefulWidget {
  const PlayerOpeningFrame({
    super.key,
    required this.thumbnailsUrl,
    required this.spriteSource,
    this.fit = BoxFit.cover,
  });

  /// 当前视频雪碧图 WebVTT 地址。
  final String thumbnailsUrl;

  /// 进度条拖动预览共用的雪碧图时间轴与解码缓存。
  final SpriteThumbnailAxisSource spriteSource;

  /// 必须与同页视频层使用相同适配规则。
  final BoxFit fit;

  @override
  State<PlayerOpeningFrame> createState() => _PlayerOpeningFrameState();
}

class _PlayerOpeningFrameState extends State<PlayerOpeningFrame> {
  @override
  void initState() {
    super.initState();
    widget.spriteSource.addListener(_handleSpriteChanged);
    unawaited(
      widget.spriteSource.prepareAt(widget.thumbnailsUrl, Duration.zero),
    );
  }

  @override
  void didUpdateWidget(covariant PlayerOpeningFrame oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.spriteSource != widget.spriteSource) {
      oldWidget.spriteSource.removeListener(_handleSpriteChanged);
      widget.spriteSource.addListener(_handleSpriteChanged);
    }
    if (oldWidget.thumbnailsUrl != widget.thumbnailsUrl) {
      unawaited(
        widget.spriteSource.prepareAt(widget.thumbnailsUrl, Duration.zero),
      );
    }
  }

  @override
  void dispose() {
    widget.spriteSource.removeListener(_handleSpriteChanged);
    super.dispose();
  }

  void _handleSpriteChanged() {
    if (mounted) setState(() {});
  }

  @override
  Widget build(BuildContext context) => Stack(
    fit: StackFit.expand,
    children: [
      const ColoredBox(color: AppColors.mediaBlack),
      if (widget.spriteSource.cachedFrameAt(widget.thumbnailsUrl, Duration.zero)
          case final frame?)
        SpriteCropPreview(
          key: const Key('player-opening-sprite'),
          image: frame.image,
          sourceRect: frame.sourceRect,
          fit: widget.fit,
        ),
    ],
  );
}