import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:play_install_referrer/play_install_referrer.dart';

/// 安装来源 referrer 服务（用于 ch/crest 渠道参数）
class ReferrerService {
  ReferrerService._();

  static String? _cachedReferrer;
  static final Completer<String?> _completer = Completer<String?>();

  /// 获取 referrer，Android 使用 Google Play Install Referrer，iOS 返回空
  static Future<String?> getReferrer() async {
    if (_cachedReferrer != null) return _cachedReferrer;
    if (_completer.isCompleted) return _completer.future;

    if (defaultTargetPlatform != TargetPlatform.android) {
      _cachedReferrer = '';
      if (!_completer.isCompleted) _completer.complete('');
      return '';
    }

    try {
      final details = await PlayInstallReferrer.installReferrer;
      _cachedReferrer = details.installReferrer ?? '';
    } catch (_) {
      _cachedReferrer = '';
    }
    if (!_completer.isCompleted) _completer.complete(_cachedReferrer);
    return _cachedReferrer;
  }

  /// 初始化并缓存 referrer（建议在 app 启动时调用）
  static Future<void> init() async {
    await getReferrer();
  }
}