// notifications_page.dart — 通知(真实数据:GET /v1/notices,已读态服务端持久化)
//
// 三态:loading(居中进度圈)/ data 为空(t.notifEmpty 空态)/ error(t.lang.loadFailedRetry)。
// 类型 pill 走 news/feature/important/reward/version/promo 六值映射(未知 type 原样显示
// type 字符串)。点击行展开/收起正文(body 为空则不可展开)。version 类型行尾「去更新」
// 接现有 updateProvider.forceCheck() 流程(与 settings_page.dart 的手动检查同一套逻辑)。
// 首帧后(有未读时)调一次 markAllRead();回前台(resumed)刷新一次列表。
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../l10n/app_text.dart';
import '../pangolin_theme.dart';
import '../services/notices_api.dart';
import '../state/notices_provider.dart';
import '../state/update_provider.dart';
import '../widgets/pangolin_icons.dart';
import '../widgets/pangolin_toast.dart';
import '../widgets/status_pill.dart';
import '../widgets/sub_scaffold.dart';

/// type → (图标, 状态色, 文案) 映射;六个后端合法值 news/feature/important/reward/
/// version/promo。未知 type 原样显示(label=type 字面量,兜底 bell/neutral)。
({IconData icon, PangolinStatus status, String label}) _typeMeta(String type, AppText t) {
  switch (type) {
    case 'news':
      return (icon: PangolinIcons.bell, status: PangolinStatus.neutral, label: t.notifTypeNews);
    case 'feature':
      return (icon: PangolinIcons.zap, status: PangolinStatus.connected, label: t.notifTypeFeature);
    case 'important':
      return (icon: PangolinIcons.alertTriangle, status: PangolinStatus.error, label: t.notifTypeImportant);
    case 'reward':
      return (icon: PangolinIcons.gift, status: PangolinStatus.connected, label: t.notifTypeReward);
    case 'version':
      return (icon: PangolinIcons.refreshCw, status: PangolinStatus.neutral, label: t.notifTypeVersion);
    case 'promo':
      return (icon: PangolinIcons.crown, status: PangolinStatus.pro, label: t.notifTypePromo);
    default:
      return (icon: PangolinIcons.bell, status: PangolinStatus.neutral, label: type);
  }
}

class NotificationsScreen extends ConsumerStatefulWidget {
  const NotificationsScreen({super.key, required this.t, this.onBack, this.embedded = false});
  final AppText t;
  final VoidCallback? onBack;
  final bool embedded;

  @override
  ConsumerState<NotificationsScreen> createState() => _NotificationsScreenState();
}

class _NotificationsScreenState extends ConsumerState<NotificationsScreen> with WidgetsBindingObserver {
  final Set<int> _expanded = {};
  ProviderSubscription<AsyncValue<NoticesData?>>? _noticesSub;
  bool _marked = false;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);

    void tryMarkAllRead() {
      if (_marked) return;
      final data = ref.read(noticesProvider).valueOrNull;
      if (data != null && data.unreadCount > 0) {
        _marked = true;
        ref.read(noticesProvider.notifier).markAllRead();
      }
    }

    // 首帧后标全部已读(仅当当前已有数据且存在未读,避免每次进页空转一次网络请求)。
    // provider 首拉有延迟(build() 惰性等 2s),首帧时数据可能仍在 loading;因此额外
    // listenManual 监听后续到达的数据补触发一次,保证「进页即清读」不受首拉时序影响。
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!mounted) return;
      tryMarkAllRead();
    });
    _noticesSub = ref.listenManual(noticesProvider, (prev, next) => tryMarkAllRead());
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    _noticesSub?.close();
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    // 回前台刷新(全局无 lifecycle 监听点,落在页内;详见 Task 10 报告)。
    if (state == AppLifecycleState.resumed && mounted) {
      ref.read(noticesProvider.notifier).refresh();
    }
  }

  /// version 类型通知行「去更新」:接 settings_page.dart 同一套 updateProvider.forceCheck()
  /// 流程(最小接法,不新开更新入口)。
  Future<void> _goUpdate() async {
    final t = widget.t;
    final info = await ref.read(updateProvider.notifier).forceCheck();
    if (!mounted) return;
    if (info == null) {
      showPangolinToast(context, t.updateCheckFailed);
      return;
    }
    if (!info.hasUpdate) {
      showPangolinToast(context, t.updateUpToDate);
      return;
    }
    ref.read(dismissedUpdateVersionProvider.notifier).state = null;
    showPangolinToast(context, t.updateAvailableTitle(info.latestVersion));
  }

  @override
  Widget build(BuildContext context) {
    final c = context.pangolin;
    final t = widget.t;
    final async = ref.watch(noticesProvider);

    Widget empty() => Padding(
          padding: const EdgeInsets.only(top: 60),
          child: Column(children: [
            Container(
              width: 56,
              height: 56,
              decoration: BoxDecoration(color: c.bgSubtle, shape: BoxShape.circle),
              child: Icon(PangolinIcons.bell, size: 26, color: c.fg3),
            ),
            const SizedBox(height: 14),
            Text(t.notifEmpty, style: PangolinText.sm.copyWith(color: c.fg3)),
          ]),
        );

    Widget loading() => const Padding(
          padding: EdgeInsets.only(top: 80),
          child: Center(child: CircularProgressIndicator()),
        );

    Widget errorView() => Padding(
          padding: const EdgeInsets.only(top: 60),
          child: Center(
            child: Text(t.lang.loadFailedRetry, style: PangolinText.sm.copyWith(color: c.fg3)),
          ),
        );

    Widget row(NoticeItem n, bool divider) {
      final meta = _typeMeta(n.type, t);
      final body = t.lang == AppLang.zh ? n.bodyZh : n.bodyEn;
      final hasBody = body.trim().isNotEmpty;
      final expanded = _expanded.contains(n.id);
      final subLabel =
          n.publishedAt != null ? t.lang.relativeTime(DateTime.now().difference(n.publishedAt!)) : null;

      return InkWell(
        onTap: hasBody
            ? () => setState(() {
                  if (expanded) {
                    _expanded.remove(n.id);
                  } else {
                    _expanded.add(n.id);
                  }
                })
            : null,
        child: Container(
          decoration: BoxDecoration(border: divider ? Border(bottom: BorderSide(color: c.border)) : null),
          padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 13),
          child: Row(crossAxisAlignment: CrossAxisAlignment.start, children: [
            Stack(clipBehavior: Clip.none, children: [
              Container(
                width: 38,
                height: 38,
                decoration: BoxDecoration(color: c.accentSubtle, borderRadius: BorderRadius.circular(PangolinRadius.md)),
                child: Icon(meta.icon, size: 18, color: c.accent),
              ),
              if (n.unread)
                Positioned(
                  top: -2,
                  right: -2,
                  child: Container(
                    key: ValueKey('notif-unread-${n.id}'),
                    width: 8,
                    height: 8,
                    decoration: BoxDecoration(color: c.danger, shape: BoxShape.circle),
                  ),
                ),
            ]),
            const SizedBox(width: 12),
            Expanded(
              child: Column(crossAxisAlignment: CrossAxisAlignment.start, mainAxisSize: MainAxisSize.min, children: [
                Row(children: [
                  Expanded(
                    child: Text(n.title(t.lang),
                        overflow: TextOverflow.ellipsis,
                        style: PangolinText.sm.copyWith(
                            color: c.fg1, fontWeight: n.unread ? FontWeight.w700 : FontWeight.w500, fontSize: 14.5)),
                  ),
                  const SizedBox(width: 8),
                  StatusPill(label: meta.label, status: meta.status),
                ]),
                if (subLabel != null) ...[
                  const SizedBox(height: 4),
                  Text(subLabel, style: PangolinText.caption.copyWith(color: c.fg3, fontWeight: FontWeight.w400)),
                ],
                if (expanded && hasBody) ...[
                  const SizedBox(height: 8),
                  Text(body, style: PangolinText.sm.copyWith(color: c.fg2, fontSize: 13.5)),
                ],
                if (n.type == 'version') ...[
                  const SizedBox(height: 8),
                  Align(
                    alignment: Alignment.centerLeft,
                    child: OutlinedButton(
                      onPressed: _goUpdate,
                      style: OutlinedButton.styleFrom(
                        padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 6),
                        minimumSize: Size.zero,
                        tapTargetSize: MaterialTapTargetSize.shrinkWrap,
                        side: BorderSide(color: c.border),
                      ),
                      child: Text(t.lang.updateNow,
                          style: PangolinText.caption.copyWith(color: c.accent, fontWeight: FontWeight.w600)),
                    ),
                  ),
                ],
              ]),
            ),
          ]),
        ),
      );
    }

    Widget content(NoticesData? data) {
      final items = data?.items ?? const <NoticeItem>[];
      return ListView(
        padding: const EdgeInsets.fromLTRB(20, 8, 20, 24),
        children: [
          if (items.isEmpty)
            empty()
          else
            Container(
              decoration: BoxDecoration(
                color: c.surface,
                borderRadius: BorderRadius.circular(PangolinRadius.lg),
                border: Border.all(color: c.border),
                boxShadow: PangolinShadow.sm,
              ),
              clipBehavior: Clip.antiAlias,
              child: Column(children: [
                for (var i = 0; i < items.length; i++) row(items[i], i < items.length - 1),
              ]),
            ),
        ],
      );
    }

    final body = async.when(
      loading: () => loading(),
      error: (err, st) => errorView(),
      data: (data) => content(data),
    );

    return SubScaffold(
      title: t.notifTitle,
      onBack: widget.onBack,
      embedded: widget.embedded,
      wrapPageBody: true,
      child: body,
    );
  }
}