// seg_switch.dart — 分段开关(镜像 design/prototype atoms .segswitch)。
// 一排等宽选项,每项 leading 图标 + 文字;选中态 surface 底 + 柔和阴影 + fg1,
// 未选 fg2;容器 bg-subtle + border + full 圆角。渠道/币种/主题等二选一场景通用。
import 'package:flutter/material.dart';
import '../pangolin_theme.dart';

/// 单个分段项:图标 + 文案。
typedef SegOption = ({IconData icon, String label});

class SegSwitch extends StatelessWidget {
  const SegSwitch({
    super.key,
    required this.options,
    required this.selectedIndex,
    required this.onChanged,
  });

  final List<SegOption> options;
  final int selectedIndex;
  final ValueChanged<int> onChanged;

  @override
  Widget build(BuildContext context) {
    final c = context.pangolin;
    return Container(
      // .segswitch:bg-subtle + border + full 圆角 + space-1 内边距/间隙
      padding: const EdgeInsets.all(4),
      decoration: BoxDecoration(
        color: c.bgSubtle,
        border: Border.all(color: c.border),
        borderRadius: BorderRadius.circular(PangolinRadius.full),
      ),
      child: Row(
        children: [
          for (var i = 0; i < options.length; i++) ...[
            if (i > 0) const SizedBox(width: 4),
            Expanded(child: _opt(c, i, options[i])),
          ],
        ],
      ),
    );
  }

  Widget _opt(PangolinScheme c, int i, SegOption o) {
    final active = i == selectedIndex;
    return GestureDetector(
      behavior: HitTestBehavior.opaque,
      onTap: active ? null : () => onChanged(i),
      child: AnimatedContainer(
        duration: const Duration(milliseconds: 140),
        curve: Curves.easeOut,
        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
        decoration: BoxDecoration(
          // .segswitch-opt.is-active:surface 底 + shadow-sm;未选透明
          color: active ? c.surface : Colors.transparent,
          borderRadius: BorderRadius.circular(PangolinRadius.full),
          boxShadow: active ? PangolinShadow.sm : null,
        ),
        child: Row(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Icon(o.icon, size: 16, color: active ? c.fg1 : c.fg2),
            const SizedBox(width: 8),
            Flexible(
              child: Text(
                o.label,
                maxLines: 1,
                overflow: TextOverflow.ellipsis,
                style: PangolinText.sm.copyWith(
                  color: active ? c.fg1 : c.fg2,
                  fontWeight: FontWeight.w600,
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}