pangolin/client/lib/shell/mobile_shell.dart

// mobile_shell.dart — 移动外壳（底 Tab + 左右滑动），对照 ui_kits/mobile
import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../screens/account_page.dart';
import '../screens/connect_page.dart';
import '../screens/nodes_page.dart';
import '../screens/stats_page.dart';
import '../state/navigation_provider.dart';
import '../widgets/bottom_tab_bar.dart';
import '../widgets/tab_swipe.dart';

class MobileShell extends ConsumerStatefulWidget {
  const MobileShell({super.key});

  @override
  ConsumerState<MobileShell> createState() => _MobileShellState();
}

class _MobileShellState extends ConsumerState<MobileShell> {
  int _dir = 0;
  Timer? _dirReset;

  int _indexOf(NavView v) {
    final i = kPrimaryNav.indexOf(v);
    return i < 0 ? 3 : i; // contact/settings/plans/redeem 归到账户
  }

  void _goTo(NavView v) {
    final cur = _indexOf(ref.read(navViewProvider));
    final next = _indexOf(v);
    if (next == cur) return;
    setState(() => _dir = next > cur ? 1 : -1);
    ref.read(navViewProvider.notifier).state = v;
    _dirReset?.cancel();
    _dirReset = Timer(const Duration(milliseconds: 260), () {
      if (mounted) setState(() => _dir = 0);
    });
  }

  void _swipe(int delta) {
    final cur = _indexOf(ref.read(navViewProvider));
    _goTo(kPrimaryNav[(cur + delta).clamp(0, kPrimaryNav.length - 1)]);
  }

  @override
  void dispose() {
    _dirReset?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final view = ref.watch(navViewProvider);
    final index = _indexOf(view);
    final pages = <Widget>[
      ConnectPage(isWide: false, onOpenNodes: () => _goTo(NavView.servers)),
      NodesPage(isWide: false, onPicked: () => _goTo(NavView.connect)),
      const StatsPage(isWide: false),
      const AccountPage(isWide: false),
    ];

    return SafeArea(
      bottom: false,
      child: Column(children: [
        Expanded(
          child: HorizontalSwipeArea(
            onSwipeLeft: () => _swipe(1),
            onSwipeRight: () => _swipe(-1),
            child: DirectionalTabSwitcher(index: index, direction: _dir, child: pages[index]),
          ),
        ),
        BottomTabBar(current: kPrimaryNav[index], onTap: _goTo),
      ]),
    );
  }
}