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

/// NavBar 配置，由各页面在 build 中设置，AppShell 统一渲染
class NavBarConfig {
  final String title;
  final bool showBack;
  final bool showRight;
  final Widget? rightWidget;
  final VoidCallback? onBack;
  final IconData? leadingIcon;
  final bool hasFilter;
  final int filterVersion;

  const NavBarConfig({
    required this.title,
    this.showBack = false,
    this.showRight = false,
    this.rightWidget,
    this.onBack,
    this.leadingIcon,
    this.hasFilter = false,
    this.filterVersion = 0,
  });

  /// 根页面默认配置（无返回按钮）
  static const home = NavBarConfig(title: 'TBOSS 工作台', showBack: false);
  static const messages = NavBarConfig(title: '消息', showBack: false);
  static const profile = NavBarConfig(title: '我的', showBack: false);

  /// 带返回按钮的页面快捷构造
  factory NavBarConfig.withBack(String title, {VoidCallback? onBack}) {
    return NavBarConfig(title: title, showBack: true, onBack: onBack);
  }

  /// 带返回按钮 + 右侧按钮的页面快捷构造
  factory NavBarConfig.withRight(
    String title, {
    required Widget rightWidget,
    VoidCallback? onBack,
  }) {
    return NavBarConfig(
      title: title,
      showBack: true,
      showRight: true,
      rightWidget: rightWidget,
      onBack: onBack,
    );
  }

  @override
  bool operator ==(Object other) =>
      other is NavBarConfig &&
      other.title == title &&
      other.showBack == showBack &&
      other.showRight == showRight &&
      other.hasFilter == hasFilter &&
      other.filterVersion == filterVersion;
  // 故意不比较 onBack / rightWidget / leadingIcon，避免每次 build 新闭包触发无限重建

  @override
  int get hashCode =>
      Object.hash(title, showBack, showRight, hasFilter, filterVersion);
}

/// NavBar 配置变更器，内部做相等判断避免无限重建
///
/// 通过 [Future.microtask] 将状态更新推迟到事件循环下一个 tick，
/// 避免子页面在 build 中更新 provider 时与 AppShell watch 冲突。
class NavBarConfigNotifier extends StateNotifier<NavBarConfig> {
  NavBarConfigNotifier() : super(NavBarConfig.home);

  void update(NavBarConfig config) {
    if (state != config) {
      Future.microtask(() {
        if (mounted) state = config;
      });
    }
  }
}

/// NavBar 配置的 Provider —— 各页面在 build 中更新，AppShell 统一消费
final navBarConfigProvider =
    StateNotifierProvider<NavBarConfigNotifier, NavBarConfig>(
      (ref) => NavBarConfigNotifier(),
    );

/// 仅在当前路由可见时更新导航栏标题，避免被覆盖的页面因 GoRouter
/// rebuild 级联效应竞争标题（如 showDatePicker 导致的路由栈全量重建）。
///
/// [context] 为当前页面 build 的 context，
/// [config] 为要设置的 NavBarConfig。
void setNavBarTitle(BuildContext context, WidgetRef ref, NavBarConfig config) {
  final route = ModalRoute.of(context);
  // null = 首次 build 路由尚未完全插入，仍需更新
  // isCurrent = 当前可见路由
  // false = 已被覆盖的旧页面，跳过
  if (route == null || route.isCurrent) {
    ref.read(navBarConfigProvider.notifier).update(config);
  }
}