// routing_screen.dart — 分流规则子屏(代理模式段选 + 内置规则 + 我的规则增删排序 + 添加弹层 + 冲突提示)
//
// 视觉对照 design/prototype/screens/ui-mobile.html(data-sub="routing")/ui-desktop.html
// (data-view="routing")。状态层 routing_provider.dart(Task 6):routingProfileProvider
// 的 setMode/setBuiltin/addRule/removeRule/reorder。
//
// 冲突提示两类(prototype 里只是静态示例,这里落成真computed 逻辑):
// ①「已被上面规则覆盖」——同 type+value 的自定义规则被更靠前的规则遮蔽(纯本地计算,
//    首命中生效语义决定)。
// ②「系统强制走隧道,此规则不生效」——命中系统锁定目标,两类启发式并存:
//    - ip_cidr 落在私网/回环地址段(RFC1918 + 127.0.0.0/8)——恒被内置「局域网 / 私网
//      直连」(builtin.lanDirect,强制不可关)接管。
//    - 域名类规则(domain/domain_suffix/domain_keyword)命中 RoutingProfile.
//      systemLockedDomains(FT-A 起 GET /v1/me/routing 下发的私有服务域名清单,
//      PANGOLIN_PRIVATE_SPLIT_DOMAINS)——服务端渲染时恒强制走隧道,与用户规则动作冲突。
import 'dart:io' show InternetAddress, InternetAddressType;

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

import '../l10n/app_text.dart';
import '../models/routing_profile.dart';
import '../pangolin_theme.dart';
import '../services/auth_api.dart' show AuthApiException;
import '../state/app_providers.dart';
import '../state/routing_provider.dart';
import 'pangolin_button.dart';
import 'pangolin_field.dart';
import 'pangolin_icons.dart';
import 'seg_switch.dart';
import 'sub_scaffold.dart';

/// 分流模式段选的选项顺序,与 [RoutingProfile.mode] 后端取值一一对应
/// (UI 第二档「智能分流」= 后端 `rule`)。
const _kModeValues = ['global', 'rule', 'direct'];

class RoutingScreen extends ConsumerWidget {
  const RoutingScreen({super.key, this.onBack, this.embedded = false});

  final VoidCallback? onBack;
  final bool embedded;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final c = context.pangolin;
    final t = ref.watch(appTextProvider);
    final profileAsync = ref.watch(routingProfileProvider);

    return SubScaffold(
      title: t.routingRulesTitle,
      onBack: onBack,
      embedded: embedded,
      child: profileAsync.when(
        loading: () => const Center(child: Padding(padding: EdgeInsets.all(40), child: CircularProgressIndicator())),
        error: (_, __) => Center(
          child: Padding(
            padding: const EdgeInsets.all(40),
            child: Text(t.lang.loadFailedRetry, style: PangolinText.body.copyWith(color: c.fg3)),
          ),
        ),
        data: (profile) => _RoutingBody(t: t, profile: profile),
      ),
    );
  }
}

/// 变更类操作统一守卫:await + 失败弹 SnackBar(不再静默回滚 / 抛未捕获异步异常)。
/// _persist 失败已回滚 state 并 rethrow,这里兜住并把原因告知用户;AuthApiException
/// 带服务端双语文案(含 routing_invalid 校验错误),其余异常回退通用「保存失败」。
Future<void> _guardSave(BuildContext context, AppText t, Future<void> Function() op) async {
  try {
    await op();
  } on AuthApiException catch (e) {
    if (!context.mounted) return;
    _showRoutingError(context, t.lang == AppLang.zh ? e.messageZh : e.messageEn);
  } catch (_) {
    if (!context.mounted) return;
    _showRoutingError(context, t.routingSaveFailed);
  }
}

void _showRoutingError(BuildContext context, String msg) {
  ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(msg)));
}

class _RoutingBody extends ConsumerWidget {
  const _RoutingBody({required this.t, required this.profile});
  final AppText t;
  final RoutingProfile profile;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final c = context.pangolin;
    final notifier = ref.read(routingProfileProvider.notifier);
    final smart = profile.mode == 'rule';
    final modeIdx = _kModeValues.indexOf(profile.mode);
    final selectedIdx = modeIdx < 0 ? 1 : modeIdx;

    return ListView(
      padding: const EdgeInsets.fromLTRB(20, 4, 20, 24),
      children: [
        // ── 代理模式段选 ──
        _secLabel(c, t.routingProxyMode),
        SegSwitch(
          options: [
            (icon: PangolinIcons.globe, label: t.routingModeGlobal),
            (icon: PangolinIcons.zap, label: t.routingModeSmart),
            (icon: PangolinIcons.arrowRight, label: t.routingModeDirect),
          ],
          selectedIndex: selectedIdx,
          onChanged: (i) => _guardSave(context, t, () => notifier.setMode(_kModeValues[i])),
        ),
        const SizedBox(height: 8),
        Text(t.routingModeNote, style: PangolinText.caption.copyWith(color: c.fg3, height: 1.5)),
        const SizedBox(height: 20),

        // ── 内置规则 ──
        _secLabel(c, t.routingBuiltin),
        _cardFlush(c, [
          _builtinToggleRow(
            context, c,
            icon: PangolinIcons.globe,
            title: t.routingCnDirect,
            sub: 'GeoIP / GeoSite CN',
            value: profile.builtin.chinaDirect,
            onChanged: (v) => _guardSave(context, t, () => notifier.setBuiltin(profile.builtin.copyWith(chinaDirect: v))),
            last: false,
          ),
          _forcedRow(c, icon: PangolinIcons.home, title: t.routingLanDirect, sub: t.routingLanForced, pill: t.routingForcedPill),
        ]),
        const SizedBox(height: 20),

        // ── 我的规则(仅智能分流模式生效,其余模式灰化 + 忽略提示已由上方 modeNote 说明) ──
        Opacity(
          opacity: smart ? 1 : 0.5,
          child: IgnorePointer(
            ignoring: !smart,
            child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
              _secLabel(c, t.routingMyRulesOrdered),
              if (profile.rules.isEmpty)
                _cardFlush(c, [
                  Padding(
                    padding: const EdgeInsets.symmetric(horizontal: 18, vertical: 20),
                    child: Center(child: Text(t.routingNoRules, style: PangolinText.sm.copyWith(color: c.fg3))),
                  ),
                ])
              else
                Container(
                  decoration: BoxDecoration(
                    color: c.surface,
                    border: Border.all(color: c.border),
                    borderRadius: BorderRadius.circular(PangolinRadius.lg),
                    boxShadow: PangolinShadow.sm,
                  ),
                  clipBehavior: Clip.antiAlias,
                  child: ReorderableListView(
                    shrinkWrap: true,
                    physics: const NeverScrollableScrollPhysics(),
                    buildDefaultDragHandles: false,
                    onReorder: (oldIndex, newIndex) => _guardSave(context, t, () => notifier.reorder(oldIndex, newIndex)),
                    children: [
                      for (var i = 0; i < profile.rules.length; i++)
                        _ruleRow(
                            context, c, t, i, profile.rules[i],
                            _conflictFor(profile.rules, i, profile.systemLockedDomains),
                            i < profile.rules.length - 1,
                            onDelete: () => _guardSave(context, t, () => notifier.removeRule(i))),
                    ],
                  ),
                ),
              const SizedBox(height: 12),
              PangolinButton(
                label: t.routingAddRule,
                icon: PangolinIcons.plus,
                variant: PangolinButtonVariant.secondary,
                expand: true,
                onPressed: smart ? () => _openAddDialog(context, ref, t) : null,
              ),
            ]),
          ),
        ),
        const SizedBox(height: 20),

        // ── FINAL 兜底 ──
        _secLabel(c, t.routingFinalShort),
        _cardFlush(c, [
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 18, vertical: 14),
            child: Row(children: [
              Expanded(
                child: Text(t.routingFinalFallback,
                    style: PangolinText.body.copyWith(color: c.fg1, fontSize: 14, fontWeight: FontWeight.w500)),
              ),
              _actionPill(c, t, profile.finalAction),
            ]),
          ),
        ]),
        const SizedBox(height: 20),

        // ── 重置默认(桌面/移动共用同一按钮;二次确认防误触) ──
        PangolinButton(
          label: t.routingReset,
          icon: PangolinIcons.refreshCw,
          variant: PangolinButtonVariant.ghost,
          expand: true,
          onPressed: () => _confirmReset(context, ref, c, t),
        ),
      ],
    );
  }

  Future<void> _confirmReset(BuildContext context, WidgetRef ref, PangolinScheme c, AppText t) async {
    final ok = await showDialog<bool>(
      context: context,
      builder: (ctx) => AlertDialog(
        backgroundColor: c.surface,
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(PangolinRadius.xl)),
        title: Row(children: [
          Container(
            width: 34, height: 34,
            decoration: BoxDecoration(color: c.dangerSubtle, shape: BoxShape.circle),
            child: Icon(PangolinIcons.refreshCw, size: 18, color: c.danger),
          ),
          const SizedBox(width: 12),
          Expanded(
            child: Text(t.routingResetConfirmTitle,
                overflow: TextOverflow.ellipsis,
                style: PangolinText.body.copyWith(color: c.fg1, fontWeight: FontWeight.w700)),
          ),
        ]),
        content: Text(t.routingResetConfirmBody, style: PangolinText.sm.copyWith(color: c.fg2, height: 1.5)),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx, false),
            child: Text(t.devCancel, style: PangolinText.sm.copyWith(color: c.fg2, fontWeight: FontWeight.w600)),
          ),
          TextButton(
            onPressed: () => Navigator.pop(ctx, true),
            child: Text(t.routingResetConfirmAction, style: PangolinText.sm.copyWith(color: c.danger, fontWeight: FontWeight.w700)),
          ),
        ],
      ),
    );
    if (ok != true) return;
    if (!context.mounted) return;
    await _guardSave(context, t, () => ref.read(routingProfileProvider.notifier).resetToDefault());
  }

  Future<void> _openAddDialog(BuildContext context, WidgetRef ref, AppText t) async {
    final rule = await showDialog<RoutingRule>(context: context, builder: (_) => _AddRuleDialog(t: t));
    if (rule == null) return;
    if (!context.mounted) return;
    await _guardSave(context, t, () => ref.read(routingProfileProvider.notifier).addRule(rule));
  }

  Widget _builtinToggleRow(
    BuildContext context,
    PangolinScheme c, {
    required IconData icon,
    required String title,
    required String sub,
    required bool value,
    required ValueChanged<bool> onChanged,
    required bool last,
  }) {
    return Container(
      decoration: BoxDecoration(border: last ? null : Border(bottom: BorderSide(color: c.border))),
      padding: const EdgeInsets.symmetric(horizontal: 18, vertical: 14),
      child: Row(children: [
        _iconBox(c, icon),
        const SizedBox(width: 12),
        Expanded(
          child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
            Text(title, style: PangolinText.body.copyWith(color: c.fg1, fontSize: 14, fontWeight: FontWeight.w500)),
            Text(sub, style: PangolinText.caption.copyWith(color: c.fg3)),
          ]),
        ),
        Switch(value: value, activeThumbColor: c.accent, onChanged: onChanged),
      ]),
    );
  }

  Widget _forcedRow(PangolinScheme c, {required IconData icon, required String title, required String sub, required String pill}) {
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 18, vertical: 14),
      child: Row(children: [
        _iconBox(c, icon),
        const SizedBox(width: 12),
        Expanded(
          child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
            Text(title, style: PangolinText.body.copyWith(color: c.fg1, fontSize: 14, fontWeight: FontWeight.w500)),
            Text(sub, style: PangolinText.caption.copyWith(color: c.fg3)),
          ]),
        ),
        Container(
          padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 5),
          decoration: BoxDecoration(color: c.bgSubtle, borderRadius: BorderRadius.circular(PangolinRadius.full)),
          child: Text(pill, style: PangolinText.caption.copyWith(color: c.fg2, fontWeight: FontWeight.w700, fontSize: 11)),
        ),
      ]),
    );
  }

  Widget _iconBox(PangolinScheme c, IconData icon) => Container(
        width: 34,
        height: 34,
        decoration: BoxDecoration(color: c.accentSubtle, borderRadius: BorderRadius.circular(PangolinRadius.md)),
        child: Icon(icon, size: 17, color: c.accent),
      );

  Widget _ruleRow(
    BuildContext context,
    PangolinScheme c,
    AppText t,
    int i,
    RoutingRule rule,
    _RuleConflict conflict,
    bool divider, {
    required VoidCallback onDelete,
  }) {
    final dim = conflict != _RuleConflict.none;
    final subText = switch (conflict) {
      _RuleConflict.shadowed => t.routingRuleShadowed,
      _RuleConflict.systemLocked => t.routingForcedRow,
      _RuleConflict.none => _routingTypeLabel(t, rule.type),
    };
    return Container(
      key: ValueKey('rt_rule_$i'),
      decoration: BoxDecoration(border: divider ? Border(bottom: BorderSide(color: c.border)) : null),
      padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 13),
      child: Opacity(
        opacity: dim ? 0.55 : 1,
        child: Row(children: [
          ReorderableDragStartListener(
            index: i,
            child: Padding(
              padding: const EdgeInsets.only(right: 10),
              child: Text('≡', style: PangolinText.body.copyWith(color: c.fg3, fontWeight: FontWeight.w700)),
            ),
          ),
          Expanded(
            child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
              Text(rule.value, style: PangolinText.mono.copyWith(color: c.fg1, fontSize: 14)),
              const SizedBox(height: 2),
              Text(subText, style: PangolinText.caption.copyWith(color: dim ? c.warning : c.fg3)),
            ]),
          ),
          const SizedBox(width: 8),
          _actionPill(c, t, rule.action),
          IconButton(
            onPressed: onDelete,
            icon: Icon(PangolinIcons.trash2, size: 17, color: c.fg3),
            padding: const EdgeInsets.only(left: 6),
            constraints: const BoxConstraints(),
          ),
        ]),
      ),
    );
  }
}

/// 规则行冲突类型:先判系统锁定(与规则顺序无关),再判是否被更靠前的同规则遮蔽。
enum _RuleConflict { none, shadowed, systemLocked }

_RuleConflict _conflictFor(List<RoutingRule> rules, int i, List<String> systemLockedDomains) {
  final r = rules[i];
  if (_looksSystemLocked(r, systemLockedDomains)) return _RuleConflict.systemLocked;
  for (var j = 0; j < i; j++) {
    final o = rules[j];
    if (o.type == r.type && o.value.trim().toLowerCase() == r.value.trim().toLowerCase()) {
      return _RuleConflict.shadowed;
    }
  }
  return _RuleConflict.none;
}

/// 私网/回环地址段启发式(RFC1918 + 127.0.0.0/8),见文件头注释。
final _privateIpPrefix = RegExp(r'^(10\.|192\.168\.|127\.|172\.(1[6-9]|2\d|3[01])\.)');

/// 系统锁定判定:ip_cidr 私网/回环启发式,或域名类规则命中 [systemLockedDomains]。
bool _looksSystemLocked(RoutingRule r, List<String> systemLockedDomains) {
  if (r.type == 'ip_cidr') return _privateIpPrefix.hasMatch(r.value);
  if (systemLockedDomains.isEmpty) return false;
  final value = r.value.trim().toLowerCase();
  if (value.isEmpty) return false;
  switch (r.type) {
    case 'domain':
      return systemLockedDomains.any((d) => d.toLowerCase() == value);
    case 'domain_suffix':
      return systemLockedDomains.any((d) {
        final dl = d.toLowerCase();
        return dl == value || dl.endsWith('.$value');
      });
    case 'domain_keyword':
      return systemLockedDomains.any((d) => d.toLowerCase().contains(value));
    default:
      return false;
  }
}

String _routingTypeLabel(AppText t, String type) => switch (type) {
      'domain' => t.routingTypeDomain,
      'domain_suffix' => t.routingTypeDomainSuffix,
      'domain_keyword' => t.routingTypeDomainKeyword,
      'ip_cidr' => t.routingTypeIpCidr,
      'geoip' => t.routingTypeGeoip,
      'geosite' => t.routingTypeGeosite,
      _ => type,
    };

Widget _actionPill(PangolinScheme c, AppText t, String action) {
  late Color bg, fg;
  late String label;
  switch (action) {
    case 'direct':
      bg = c.successSubtle;
      fg = c.success;
      label = t.routingActDirect;
    case 'reject':
      bg = c.dangerSubtle;
      fg = c.danger;
      label = t.routingActReject;
    case 'proxy':
    default:
      bg = c.warningSubtle;
      fg = c.warning;
      label = t.routingActProxy;
  }
  return Container(
    padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 5),
    decoration: BoxDecoration(color: bg, borderRadius: BorderRadius.circular(PangolinRadius.full)),
    child: Text(label, style: PangolinText.caption.copyWith(color: fg, fontWeight: FontWeight.w700, fontSize: 11)),
  );
}

Widget _secLabel(PangolinScheme c, String text) => Padding(
      padding: const EdgeInsets.fromLTRB(4, 0, 4, 10),
      child: Text(text, style: PangolinText.sm.copyWith(color: c.fg2, fontWeight: FontWeight.w700, fontSize: 13)),
    );

Widget _cardFlush(PangolinScheme c, List<Widget> children) => Container(
      decoration: BoxDecoration(
        color: c.surface,
        border: Border.all(color: c.border),
        borderRadius: BorderRadius.circular(PangolinRadius.lg),
        boxShadow: PangolinShadow.sm,
      ),
      clipBehavior: Clip.antiAlias,
      child: Column(children: children),
    );

/// 「添加规则」弹层:类型 chip 选择 + 目标输入(mono)+ 动作段选。
/// 仿 account_screens.dart:_renameDialog 的 AlertDialog 表单范式。
class _AddRuleDialog extends StatefulWidget {
  const _AddRuleDialog({required this.t});
  final AppText t;

  @override
  State<_AddRuleDialog> createState() => _AddRuleDialogState();
}

class _AddRuleDialogState extends State<_AddRuleDialog> {
  String _type = kRuleTypes.first;
  String _action = kRuleActions.first;
  final _value = TextEditingController();

  @override
  void dispose() {
    _value.dispose();
    super.dispose();
  }

  /// 字段级预校验:只拦明显格式错(空由按钮禁用兜底),避免"乐观显示→服务端 400→静默消失"。
  /// 语义级(保留段/catch-all direct)仍由服务端权威判定,经 SnackBar 呈现。返回 null=通过。
  String? _valueError(AppText t) {
    final v = _value.text.trim();
    if (v.isEmpty) return null;
    switch (_type) {
      case 'ip_cidr':
        if (!_isValidCidr(v)) return t.routingRuleValueInvalid;
      case 'geoip':
      case 'geosite':
        if (v.toLowerCase() != 'cn') return t.routingRuleValueInvalid; // geo 白名单仅 cn
    }
    return null;
  }

  bool _isValidCidr(String s) {
    final parts = s.split('/');
    if (parts.length != 2) return false;
    final prefix = int.tryParse(parts[1]);
    if (prefix == null) return false;
    final addr = InternetAddress.tryParse(parts[0]);
    if (addr == null) return false;
    final max = addr.type == InternetAddressType.IPv6 ? 128 : 32;
    return prefix >= 0 && prefix <= max;
  }

  @override
  Widget build(BuildContext context) {
    final c = context.pangolin;
    final t = widget.t;
    final valueError = _valueError(t);
    final canSave = _value.text.trim().isNotEmpty && valueError == null;

    return AlertDialog(
      backgroundColor: c.surface,
      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(PangolinRadius.xl)),
      title: Text(t.routingAddRule, style: PangolinText.body.copyWith(color: c.fg1, fontWeight: FontWeight.w700)),
      content: SizedBox(
        width: 340,
        child: Column(mainAxisSize: MainAxisSize.min, crossAxisAlignment: CrossAxisAlignment.start, children: [
          Wrap(
            spacing: 8,
            runSpacing: 8,
            children: [for (final ty in kRuleTypes) _typeChip(c, t, ty)],
          ),
          const SizedBox(height: 14),
          PangolinFieldBox(
            fill: c.bg,
            child: TextField(
              controller: _value,
              autofocus: true,
              style: PangolinText.mono.copyWith(color: c.fg1, fontSize: 14),
              decoration: bareInputDecoration(
                contentPadding: const EdgeInsets.symmetric(vertical: 13),
                hintText: t.routingRuleValueHint,
                hintStyle: PangolinText.sm.copyWith(color: c.fg3),
              ),
              onChanged: (_) => setState(() {}),
            ),
          ),
          if (valueError != null)
            Padding(
              padding: const EdgeInsets.only(top: 6, left: 4),
              child: Text(valueError, style: PangolinText.caption.copyWith(color: c.danger)),
            ),
          const SizedBox(height: 14),
          SegSwitch(
            options: [
              (icon: PangolinIcons.checkCircle, label: t.routingActDirect),
              (icon: PangolinIcons.zap, label: t.routingActProxy),
              (icon: PangolinIcons.x, label: t.routingActReject),
            ],
            selectedIndex: kRuleActions.indexOf(_action),
            onChanged: (i) => setState(() => _action = kRuleActions[i]),
          ),
        ]),
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.pop(context),
          child: Text(t.devCancel, style: PangolinText.sm.copyWith(color: c.fg2, fontWeight: FontWeight.w600)),
        ),
        TextButton(
          onPressed: canSave
              ? () => Navigator.pop(context, RoutingRule(type: _type, value: _value.text.trim(), action: _action))
              : null,
          child: Text(t.devSave, style: PangolinText.sm.copyWith(color: c.accent, fontWeight: FontWeight.w700)),
        ),
      ],
    );
  }

  Widget _typeChip(PangolinScheme c, AppText t, String type) {
    final active = type == _type;
    return GestureDetector(
      onTap: () => setState(() => _type = type),
      child: Container(
        padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 7),
        decoration: BoxDecoration(
          color: active ? c.accentSubtle : c.bgSubtle,
          border: Border.all(color: active ? c.accentBorder : c.border),
          borderRadius: BorderRadius.circular(PangolinRadius.full),
        ),
        child: Text(_routingTypeLabel(t, type),
            style: PangolinText.caption.copyWith(color: active ? c.accent : c.fg2, fontWeight: FontWeight.w600)),
      ),
    );
  }
}