tstor/ui/lib/components/sliver_header.dart

import 'package:flutter/material.dart';

class HideableHeaderSliver extends StatelessWidget {
  final Widget? leading;
  final Widget body;
  final double height;
  final List<Widget>? actions;

  const HideableHeaderSliver({
    super.key,
    this.leading,
    required this.body,
    this.actions,
    this.height = 150,
  });

  @override
  Widget build(BuildContext context) {
    return SliverPersistentHeader(
      floating: true,
      pinned: false,
      delegate: _HideableHeaderSliverDelegate(
        leading: leading,
        body: body,
        actions: actions,
        height: height,
      ),
    );
  }
}

class _HideableHeaderSliverDelegate extends SliverPersistentHeaderDelegate {
  final Widget? leading;
  final Widget body;
  final List<Widget>? actions;
  final double height;

  const _HideableHeaderSliverDelegate({
    required this.leading,
    required this.body,
    required this.actions,
    required this.height,
  });

  @override
  double get maxExtent => height;

  @override
  double get minExtent => height;

  @override
  bool shouldRebuild(covariant SliverPersistentHeaderDelegate oldDelegate) => true;

  @override
  Widget build(BuildContext context, double shrinkOffset, bool overlapsContent) {
    final content = <Widget>[
      if (leading != null) leading!,
      Expanded(child: body),
      if (actions != null && actions!.isNotEmpty) ButtonBar(children: actions!),
    ];

    final appBarTheme = AppBarTheme.of(context);
    final colorScheme = Theme.of(context).colorScheme;
    final onTop = (shrinkOffset == 0);

    return Material(
      color:
          onTop ? appBarTheme.backgroundColor ?? colorScheme.surface : colorScheme.surfaceContainer,
      elevation: onTop ? 0 : appBarTheme.elevation ?? 3,
      surfaceTintColor: appBarTheme.surfaceTintColor ?? colorScheme.surfaceTint,
      child: ClipRect(
        child: SizedBox(
          height: maxExtent,
          child: Column(
            children: [
              const Spacer(),
              Row(
                children: content,
              ),
              const Spacer(),
              const Divider(
                height: 1,
                thickness: 1,
              ),
            ],
          ),
        ),
      ),
    );
  }
}