using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using AppleAuth;
using AppleAuth.Enums;
using AppleAuth.Interfaces;
using AppleAuth.Native;
using Kill.Utils;
using UnityEngine;

#if (UNITY_ANDROID || UNITY_IOS) && !UNITY_EDITOR
using Firebase;
using Firebase.Auth;
#endif

namespace Kill.Managers
{
    /// <summary>
    /// Firebase 第三方登录管理器（支持 Google / Apple）
    /// </summary>
    public class FirebaseAuthManager : MonoBehaviour
    {
        public static FirebaseAuthManager Instance { get; private set; }

        // Google 登录配置 - 从 Firebase 控制台获取的 Web 客户端 ID
        private const string WEB_CLIENT_ID = "785438724947-kpjbqi43hbj6eddianbjsgkgkkclkfmd.apps.googleusercontent.com";

#if (UNITY_ANDROID || UNITY_IOS) && !UNITY_EDITOR
        private FirebaseAuth auth;
#endif

        private AppleAuthManager appleAuthManager;

        private void Awake()
        {
            Instance = this;
            InitializeFirebase();
            InitializeAppleAuth();
        }

        private void Update()
        {
            appleAuthManager?.Update();
        }

        /// <summary>
        /// 初始化 Firebase
        /// </summary>
        private void InitializeFirebase()
        {
#if (UNITY_ANDROID || UNITY_IOS) && !UNITY_EDITOR
            FirebaseApp.CheckAndFixDependenciesAsync().ContinueWith(task =>
            {
                var dependencyStatus = task.Result;
                if (dependencyStatus == DependencyStatus.Available)
                {
                    auth = FirebaseAuth.DefaultInstance;
                    Debug.Log("Firebase 初始化成功");
                }
                else
                {
                    Debug.LogError($"Firebase 初始化失败: {dependencyStatus}");
                }
            });
#else
            Debug.Log("Firebase 第三方登录仅在 Android / iOS 平台可用");
#endif
        }

        /// <summary>
        /// 初始化 Apple Sign In
        /// </summary>
        private void InitializeAppleAuth()
        {
            if (AppleAuthManager.IsCurrentPlatformSupported)
            {
                appleAuthManager = new AppleAuthManager(new PayloadDeserializer());
                Debug.Log("Apple Sign In 初始化成功");
            }
            else
            {
                Debug.Log("当前平台不支持 Apple Sign In");
            }
        }

        /// <summary>
        /// 谷歌登录
        /// </summary>
        public void SignInWithGoogle(Action<GoogleLoginResult> onSuccess, Action<string> onError, int timeoutSeconds = 30)
        {
            SignInWithProvider("google.com", new string[] { "email", "profile" }, onSuccess, onError, timeoutSeconds);
        }

        /// <summary>
        /// 苹果登录（使用 apple-signin-unity + Firebase OAuth Credential）
        /// </summary>
        public void SignInWithApple(Action<GoogleLoginResult> onSuccess, Action<string> onError, int timeoutSeconds = 30)
        {
#if UNITY_IOS && !UNITY_EDITOR
            if (appleAuthManager == null)
            {
                onError?.Invoke("Apple Sign In 未初始化");
                return;
            }

            if (!AppleAuthManager.IsCurrentPlatformSupported)
            {
                onError?.Invoke("当前平台不支持苹果登录");
                return;
            }

            var rawNonce = GenerateRandomString(32);
            var nonce = GenerateSHA256NonceFromRawNonce(rawNonce);

            var loginArgs = new AppleAuthLoginArgs(
                LoginOptions.IncludeEmail | LoginOptions.IncludeFullName,
                nonce);

            appleAuthManager.LoginWithAppleId(
                loginArgs,
                credential =>
                {
                    var appleIdCredential = credential as IAppleIDCredential;
                    if (appleIdCredential == null)
                    {
                        MainThread.Enqueue(() => onError?.Invoke("未获取到 Apple ID 凭证"));
                        return;
                    }

                    var identityToken = Encoding.UTF8.GetString(appleIdCredential.IdentityToken);
                    var authorizationCode = Encoding.UTF8.GetString(appleIdCredential.AuthorizationCode);

                    if (string.IsNullOrEmpty(identityToken))
                    {
                        MainThread.Enqueue(() => onError?.Invoke("Apple identity token 为空"));
                        return;
                    }

                    SignInWithAppleCredential(appleIdCredential, identityToken, authorizationCode, rawNonce, onSuccess, onError);
                },
                error =>
                {
                    MainThread.Enqueue(() => onError?.Invoke($"Apple 登录失败: {error.LocalizedDescription}"));
                });
#else
            onError?.Invoke("苹果登录仅在 iOS 平台可用");
#endif
        }

#if UNITY_IOS && !UNITY_EDITOR
        /// <summary>
        /// 使用 Apple 凭证完成 Firebase 登录
        /// </summary>
        private void SignInWithAppleCredential(
            IAppleIDCredential appleIdCredential,
            string identityToken,
            string authorizationCode,
            string rawNonce,
            Action<GoogleLoginResult> onSuccess,
            Action<string> onError)
        {
            if (auth == null)
            {
                onError?.Invoke("Firebase 未初始化");
                return;
            }

            var firebaseCredential = OAuthProvider.GetCredential(
                "apple.com",
                identityToken,
                rawNonce,
                authorizationCode);

            auth.SignInWithCredentialAsync(firebaseCredential).ContinueWith(task =>
            {
                if (task.IsCanceled)
                {
                    MainThread.Enqueue(() => onError?.Invoke("Firebase 登录被取消"));
                    return;
                }

                if (task.IsFaulted)
                {
                    MainThread.Enqueue(() => onError?.Invoke("Firebase 登录失败"));
                    return;
                }

                var user = auth.CurrentUser;
                if (user == null)
                {
                    MainThread.Enqueue(() => onError?.Invoke("获取 Firebase 用户信息失败"));
                    return;
                }

                MainThread.Enqueue(() =>
                {
                    var result = new GoogleLoginResult
                    {
                        FirebaseUserId = user.UserId,
                        Email = user.Email ?? appleIdCredential.Email,
                        DisplayName = user.DisplayName ?? GetAppleDisplayName(appleIdCredential.FullName),
                        PhotoUrl = user.PhotoUrl?.ToString(),
                        IdToken = ""
                    };
                    onSuccess?.Invoke(result);
                });
            });
        }
#endif

        /// <summary>
        /// 通用 OAuth 登录（Google）
        /// </summary>
        private void SignInWithProvider(string providerId, string[] scopes, Action<GoogleLoginResult> onSuccess, Action<string> onError, int timeoutSeconds)
        {
#if UNITY_ANDROID && !UNITY_EDITOR
            if (auth == null)
            {
                onError?.Invoke("Firebase 未初始化");
                return;
            }

            bool isCompleted = false;

            // 启动超时检测
            Task.Run(async () =>
            {
                await Task.Delay(TimeSpan.FromSeconds(timeoutSeconds));
                if (!isCompleted)
                {
                    isCompleted = true;
                    MainThread.Enqueue(() => onError?.Invoke($"{providerId} 登录超时（{timeoutSeconds}秒）"));
                }
            });

            var provider = new FederatedOAuthProviderData(providerId);
            provider.Scopes = scopes;

            var federatedProvider = new FederatedOAuthProvider(provider);

            auth.SignInWithProviderAsync(federatedProvider).ContinueWith(task =>
            {
                if (isCompleted) return; // 已超时，忽略结果
                isCompleted = true;

                if (task.IsFaulted)
                {
                    MainThread.Enqueue(() => onError?.Invoke($"{providerId} 登录失败"));
                    return;
                }

                if (task.IsCanceled)
                {
                    MainThread.Enqueue(() => onError?.Invoke($"{providerId} 登录被取消"));
                    return;
                }

                var user = auth.CurrentUser;
                if (user == null)
                {
                    MainThread.Enqueue(() => onError?.Invoke("获取用户信息失败"));
                    return;
                }

                // 构造登录结果
                MainThread.Enqueue(() =>
                {
                    var result = new GoogleLoginResult
                    {
                        FirebaseUserId = user.UserId,
                        Email = user.Email,
                        DisplayName = user.DisplayName,
                        PhotoUrl = user.PhotoUrl?.ToString(),
                        IdToken = ""
                    };
                    onSuccess?.Invoke(result);
                });
            });
#else
            // 编辑器 / iOS 下谷歌登录不可用
            Task.Delay(1000).ContinueWith(_ =>
            {
                Debug.Log($"编辑器模拟 {providerId} 登录");
                MainThread.Enqueue(() =>
                {
                    onError?.Invoke($"{providerId} 登录在当前平台不可用");
                });
            });
#endif
        }

        /// <summary>
        /// 登出
        /// </summary>
        public void SignOut()
        {
#if (UNITY_ANDROID || UNITY_IOS) && !UNITY_EDITOR
            auth?.SignOut();
            Debug.Log("Firebase 登出成功");
#endif
        }

        #region Nonce 生成

        /// <summary>
        /// 生成随机字符串作为 raw nonce
        /// </summary>
        private static string GenerateRandomString(int length)
        {
            if (length <= 0)
            {
                throw new Exception("Expected nonce to have positive length");
            }

            const string charset = "0123456789ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz-._";
            using (var rng = new RNGCryptoServiceProvider())
            {
                var result = new StringBuilder();
                var randomNumberHolder = new byte[1];

                while (result.Length < length)
                {
                    var randomNumbers = new List<int>(16);
                    for (var i = 0; i < 16; i++)
                    {
                        rng.GetBytes(randomNumberHolder);
                        randomNumbers.Add(randomNumberHolder[0]);
                    }

                    foreach (var randomNumber in randomNumbers)
                    {
                        if (result.Length >= length)
                            break;

                        if (randomNumber < charset.Length)
                        {
                            result.Append(charset[randomNumber]);
                        }
                    }
                }

                return result.ToString();
            }
        }

        /// <summary>
        /// 计算 raw nonce 的 SHA256 值，传给 Apple
        /// </summary>
        private static string GenerateSHA256NonceFromRawNonce(string rawNonce)
        {
            using (var sha = SHA256.Create())
            {
                var hash = sha.ComputeHash(Encoding.UTF8.GetBytes(rawNonce));
                var result = new StringBuilder();
                for (var i = 0; i < hash.Length; i++)
                {
                    result.Append(hash[i].ToString("x2"));
                }
                return result.ToString();
            }
        }

        #endregion

        #region 辅助方法

        /// <summary>
        /// 从 Apple 全名构造显示名称
        /// </summary>
        private static string GetAppleDisplayName(IPersonName fullName)
        {
            if (fullName == null)
                return null;

            var parts = new List<string>();
            if (!string.IsNullOrEmpty(fullName.GivenName))
                parts.Add(fullName.GivenName);
            if (!string.IsNullOrEmpty(fullName.FamilyName))
                parts.Add(fullName.FamilyName);

            return parts.Count > 0 ? string.Join(" ", parts) : null;
        }

        #endregion
    }

    /// <summary>
    /// 第三方登录结果（兼容 Google / Apple）
    /// </summary>
    public class GoogleLoginResult
    {
        public string FirebaseUserId;   // Firebase 用户ID（用于绑定）
        public string Email;            // 邮箱
        public string DisplayName;      // 显示名称
        public string PhotoUrl;         // 头像URL
        public string IdToken;          // ID Token
    }
}