/// 轻量分段选择器（UI06 对齐 app-preview .tabs）。
///
/// 形态：#EDF1F6 轨道、padding 4、整体圆角 9；选中实底、未选次文字色。
/// 两种选中风格：
/// - [SegmentTabsStyle.solid]：主蓝实底白字（上传中心筛选等状态筛选）；
/// - [SegmentTabsStyle.light]：#DBEAFF 底 + #145BB9 字（Details/Access 类
///   内容页签——与状态筛选区分，见 app-preview .tabs.light）。
///
/// 替换默认 [SegmentedButton]（M3 黑边胶囊形态与示例不符）。
library;

import 'package:flutter/material.dart';

import '../tokens.dart';

enum SegmentTabsStyle { solid, light }

class SegmentTabs<T> extends StatelessWidget {
  const SegmentTabs({
    required this.value,
    required this.onChanged,
    required this.segments,
    this.style = SegmentTabsStyle.solid,
    super.key,
  });

  /// 当前值；null = 无高亮（次级筛选接管时的中间态）。
  final T? value;
  final ValueChanged<T> onChanged;

  /// 选项：值 + 本地化标签。
  final List<(T, String)> segments;

  final SegmentTabsStyle style;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final light = style == SegmentTabsStyle.light;
    return Container(
      padding: const EdgeInsets.all(4),
      decoration: BoxDecoration(
        color: kColorSegTrack,
        borderRadius: BorderRadius.circular(9),
      ),
      child: Row(
        children: [
          for (final (v, label) in segments)
            Expanded(
              child: _TabButton(
                label: label,
                selected: v == value,
                light: light,
                primary: theme.colorScheme.primary,
                onTap: () => onChanged(v),
              ),
            ),
        ],
      ),
    );
  }
}

class _TabButton extends StatelessWidget {
  const _TabButton({
    required this.label,
    required this.selected,
    required this.light,
    required this.primary,
    required this.onTap,
  });

  final String label;
  final bool selected;
  final bool light;
  final Color primary;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final Color bg;
    final Color fg;
    if (selected) {
      bg = light ? kColorSegLightActive : primary;
      fg = light ? kColorSegLightActiveText : Colors.white;
    } else {
      bg = Colors.transparent;
      fg = kColorTextSecondary;
    }
    return Semantics(
      button: true,
      selected: selected,
      child: InkWell(
        onTap: onTap,
        borderRadius: BorderRadius.circular(7),
        child: Container(
          alignment: Alignment.center,
          height: 36,
          padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 5),
          decoration: BoxDecoration(
            color: bg,
            borderRadius: BorderRadius.circular(7),
          ),
          child: Text(
            label,
            maxLines: 1,
            overflow: TextOverflow.ellipsis,
            style: TextStyle(
              fontSize: 12,
              fontWeight: selected ? FontWeight.w600 : FontWeight.w500,
              color: fg,
            ),
          ),
        ),
      ),
    );
  }
}