import 'package:flutter/material.dart';

/// 用户积分等全局状态
class UserState {
  UserState._();

  static final ValueNotifier<int?> credits = ValueNotifier<int?>(null);

  static void setCredits(int? value) {
    credits.value = value;
  }

  static String formatCredits(int? value) {
    if (value == null) return '--';
    return value.toString().replaceAllMapped(
          RegExp(r'(\d{1,3})(?=(\d{3})+(?!\d))'),
          (m) => '${m[1]},',
        );
  }
}

/// 提供积分数据的 InheritedWidget
class UserCreditsData extends InheritedWidget {
  const UserCreditsData({
    super.key,
    required this.credits,
    required super.child,
  });

  final int? credits;

  static UserCreditsData? of(BuildContext context) {
    return context.dependOnInheritedWidgetOfExactType<UserCreditsData>();
  }

  String get creditsDisplay => UserState.formatCredits(credits);

  @override
  bool updateShouldNotify(UserCreditsData oldWidget) {
    return oldWidget.credits != credits;
  }
}

/// 监听 UserState.credits 并向下提供 UserCreditsData
class UserCreditsScope extends StatefulWidget {
  const UserCreditsScope({super.key, required this.child});

  final Widget child;

  @override
  State<UserCreditsScope> createState() => _UserCreditsScopeState();
}

class _UserCreditsScopeState extends State<UserCreditsScope> {
  @override
  void initState() {
    super.initState();
    UserState.credits.addListener(_onCreditsChanged);
  }

  @override
  void dispose() {
    UserState.credits.removeListener(_onCreditsChanged);
    super.dispose();
  }

  void _onCreditsChanged() {
    setState(() {});
  }

  @override
  Widget build(BuildContext context) {
    return UserCreditsData(
      credits: UserState.credits.value,
      child: widget.child,
    );
  }
}