import 'package:flutter/widgets.dart';
import 'package:patbond_flutter/analytics/analytics_page_name.dart';
import 'package:patbond_flutter/analytics/page_view_tracker.dart';

/// 集中式 page_viewed 路由埋点（03 号评估 §3.2：NavigatorObserver 派生，
/// 页面零侵入；06 号报告 §5.2 验收 1/4）。
///
/// 只统计 [PageRoute]（bottom sheet / dialog 是 PopupRoute，不计曝光）；
/// 路由名不在 [AnalyticsPageName] 枚举内不上报（后端会整条 rejected，
/// 不白白消耗队列）。didPop 补报「回退后重新曝光的前一页」；弹回到
/// 无名根路由（认证状态机的 AnimatedSwitcher 宿主）时经 [resolveRootPage]
/// 解析当前根部页面。
class AnalyticsRouteObserver extends NavigatorObserver {
  AnalyticsRouteObserver({required this.tracker, this.resolveRootPage});

  final PageViewTracker tracker;

  /// 根路由（无 RouteSettings.name）当前展示页的解析器，由 app.dart
  /// 按认证状态与主壳当前 Tab 提供；返回 null 则不补报。
  final AnalyticsPageName? Function()? resolveRootPage;

  void _reportRoute(Route<dynamic>? route) {
    if (route is! PageRoute) return;
    final page = AnalyticsPageName.fromRouteName(route.settings.name);
    if (page != null) tracker.report(page);
  }

  @override
  void didPush(Route<dynamic> route, Route<dynamic>? previousRoute) {
    _reportRoute(route);
  }

  @override
  void didReplace({Route<dynamic>? newRoute, Route<dynamic>? oldRoute}) {
    _reportRoute(newRoute);
  }

  @override
  void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) {
    if (previousRoute is! PageRoute) return;
    final page = AnalyticsPageName.fromRouteName(previousRoute.settings.name);
    if (page != null) {
      tracker.report(page);
    } else if (previousRoute.isFirst) {
      final rootPage = resolveRootPage?.call();
      if (rootPage != null) tracker.report(rootPage);
    }
  }
}