import 'dart:convert';
import 'dart:io';
import 'dart:math';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/foundation.dart';
import 'package:sign_in_with_apple/sign_in_with_apple.dart';
import 'package:crypto/crypto.dart';
import 'package:get/get.dart';

class Apple {
  String? token = '';
  String name = '';
  String email = '';
  String pictureurl = '';
  String id = '';

  /// 生成随机nonce字符串
  String generateNonce([int length = 32]) {
    const charset =
        '0123456789ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz-._';
    final random = Random.secure();
    return List.generate(length, (_) => charset[random.nextInt(charset.length)])
        .join();
  }

  /// 返回输入字符串的sha256哈希值（十六进制表示）
  String sha256ofString(String input) {
    final bytes = utf8.encode(input);
    final digest = sha256.convert(bytes);
    return digest.toString();
  }

  /// Apple登录主方法
  Future<bool> signInWithApple() async {
    try {
      // 检查Apple登录可用性
      if (!await SignInWithApple.isAvailable()) {
        if (kDebugMode) {
          print('Apple登录不可用');
        }
        return false;
      }

      UserCredential userCredential = await loginApple();
      token = await userCredential.user?.getIdToken();

      if (kDebugMode) {
        print('Apple登录响应数据token: $token');
      }

      return token != null && token!.isNotEmpty;
    } catch (e) {
      if (kDebugMode) {
        print('Apple登录异常：$e');
      }
      return false;
    }
  }

  /// 执行Apple登录流程
  Future<UserCredential> loginApple() async {
    // 生成nonce用于安全验证
    final rawNonce = generateNonce();
    final nonce = sha256ofString(rawNonce);

    try {
      // 请求Apple登录凭证
      final appleCredential = await SignInWithApple.getAppleIDCredential(
        scopes: [
          AppleIDAuthorizationScopes.email,
          AppleIDAuthorizationScopes.fullName,
        ],
        nonce: nonce,
      );

      // 提取用户信息
      _extractUserInfo(appleCredential);

      // 创建Firebase OAuth凭证
      final oauthCredential = OAuthProvider("apple.com").credential(
        idToken: appleCredential.identityToken,
        rawNonce: rawNonce,
      );

      if (kDebugMode) {
        print('Apple OAuth凭证创建成功');
        print('用户信息: name=$name, email=$email, id=$id');
      }

      // 使用Firebase Auth进行登录
      return await FirebaseAuth.instance.signInWithCredential(oauthCredential);
    } catch (e) {
      if (kDebugMode) {
        print('Apple登录流程异常：$e');
      }
      throw Exception('Apple登录失败: $e');
    }
  }

  /// 提取Apple返回的用户信息
  void _extractUserInfo(AuthorizationCredentialAppleID credential) {
    // 用户ID
    id = credential.userIdentifier ?? '';

    // 邮箱（可能为空，如果用户选择隐藏邮箱）
    email = credential.email ?? '';

    // 用户姓名（仅首次登录时提供）
    if (credential.givenName != null || credential.familyName != null) {
      final givenName = credential.givenName ?? '';
      final familyName = credential.familyName ?? '';
      name = '$givenName $familyName'.trim();
    }

    // Apple不提供头像，使用默认值
    pictureurl = '';

    if (kDebugMode) {
      print('提取的用户信息:');
      print('ID: $id');
      print('Email: $email');
      print('Name: $name');
      print('Picture URL: $pictureurl');
    }
  }

  /// 退出Apple登录
  Future<void> signOutApple() async {
    try {
      await FirebaseAuth.instance.signOut();
      // 清空用户信息
      token = '';
      name = '';
      email = '';
      pictureurl = '';
      id = '';

      if (kDebugMode) {
        print('Apple登录退出成功');
      }
    } catch (e) {
      if (kDebugMode) {
        print('Apple登录退出异常：$e');
      }
    }
  }

  /// 检查Apple登录环境
  static Future<void> checkAppleSignInEnvironment() async {
    if (kDebugMode) {
      print('=== Apple登录环境检查 ===');
      print('平台: ${GetPlatform.isIOS ? "iOS" : "非iOS"}');
      print('Apple登录可用性: ${await SignInWithApple.isAvailable()}');
      print('Firebase Auth实例: ${FirebaseAuth.instance.currentUser?.uid ?? "未登录"}');
      print('========================');
    }
  }
}