using System;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;

namespace GFGGame
{
    public sealed class AccountManager
    {
        private const string SAVE_KEY = "RecentAccountsData";
        private const int MAX_ACCOUNT_COUNT = 20;
        private List<AccountData> _cachedAccounts = new List<AccountData>();

        // 单例实例
        private static readonly Lazy<AccountManager> _instance = new Lazy<AccountManager>(() => new AccountManager());
        public static AccountManager Instance => _instance.Value;

        // 私有构造函数，防止外部实例化
        private AccountManager()
        {
            LoadAccounts();
        }

        /// <summary>
        /// 登录成功时调用此方法
        /// </summary>
        /// <param name="username">用户名</param>
        /// <param name="plainPassword">明文密码</param>
        public void SaveAccount(string username, string plainPassword)
        {
            // 1. 加密密码
            string encryptedPwd = null;
            if (plainPassword != null)
            {
                encryptedPwd = AesEncryption.Encrypt(plainPassword);
            }

            // 2. 检查列表中是否已有该账号
            AccountData existingAccount = _cachedAccounts.FirstOrDefault(a => a.username == username);
            if (existingAccount != null)
            {
                // 如果存在，更新密码和时间戳，并移到列表最前面（表示最新）
                existingAccount.encryptedPassword = encryptedPwd;
                existingAccount.timestamp = DateTime.UtcNow.ToString("yyyyMMddHHmmss");
                _cachedAccounts.Remove(existingAccount);
                _cachedAccounts.Insert(0, existingAccount);
            }
            else
            {
                // 如果不存在，创建新账号数据并添加到最前面
                AccountData newAccount = new AccountData(username, encryptedPwd);
                _cachedAccounts.Insert(0, newAccount);
            }

            // 3. 如果超出最大数量，移除最旧的一个（列表最后一个）
            if (_cachedAccounts.Count > MAX_ACCOUNT_COUNT)
            {
                _cachedAccounts.RemoveAt(_cachedAccounts.Count - 1);
            }

            // 4. 立即保存
            SaveAccounts();
        }

        /// <summary>
        /// 获取存储的所有账号信息（密码已解密）
        /// </summary>
        public List<AccountPasswordModel> GetAccounts()
        {
            List<AccountPasswordModel> result = new List<AccountPasswordModel>();
            foreach (var acc in _cachedAccounts)
            {
                string decryptedPwd = null;
                if (acc.encryptedPassword != null)
                {
                    decryptedPwd = AesEncryption.Decrypt(acc.encryptedPassword);
                }

                AccountPasswordModel accountPasswordModel = new AccountPasswordModel()
                {
                    Account = acc.username,
                    Password = decryptedPwd
                };
                result.Add(accountPasswordModel);
            }

            return result;
        }

        /// <summary>
        /// 删除指定的账号缓存
        /// </summary>
        /// <param name="username">要删除的用户名</param>
        /// <returns>是否成功删除</returns>
        public bool DeleteAccount(string username)
        {
            // 查找要删除的账号
            AccountData accountToDelete = _cachedAccounts.FirstOrDefault(a => a.username == username);

            if (accountToDelete != null)
            {
                // 从缓存列表中移除
                _cachedAccounts.Remove(accountToDelete);

                // 立即保存
                SaveAccounts();

                Debug.Log($"已成功删除账号: {username}");
                return true;
            }
            else
            {
                Debug.LogWarning($"未找到账号: {username}，删除失败");
                return false;
            }
        }

        /// <summary>
        /// 批量删除多个账号缓存
        /// </summary>
        /// <param name="usernames">要删除的用户名列表</param>
        /// <returns>成功删除的数量</returns>
        public int DeleteAccounts(List<string> usernames)
        {
            int deletedCount = 0;

            foreach (string username in usernames)
            {
                if (DeleteAccount(username))
                {
                    deletedCount++;
                }
            }

            Debug.Log($"成功删除了 {deletedCount} 个账号");
            return deletedCount;
        }

        /// <summary>
        /// 清除所有账号记录
        /// </summary>
        public void ClearAllAccounts()
        {
            _cachedAccounts.Clear();
            PlayerPrefs.DeleteKey(SAVE_KEY);
            PlayerPrefs.Save();
            Debug.Log("已清除所有账号记录");
        }

        /// <summary>
        /// 检查指定账号是否存在
        /// </summary>
        public bool HasAccount(string username)
        {
            return _cachedAccounts.Any(a => a.username == username);
        }

        /// <summary>
        /// 获取缓存的账号数量
        /// </summary>
        public int GetAccountCount()
        {
            return _cachedAccounts.Count;
        }

        // 内部方法：从PlayerPrefs加载账号列表
        private void LoadAccounts()
        {
            _cachedAccounts.Clear();
            string encryptedJson = PlayerPrefs.GetString(SAVE_KEY, null);

            if (!string.IsNullOrEmpty(encryptedJson))
            {
                string decryptedJson = AesEncryption.Decrypt(encryptedJson);
                if (!string.IsNullOrEmpty(decryptedJson))
                {
                    try
                    {
                        // 反序列化JSON字符串到对象
                        AccountDataList loadedData = JsonUtility.FromJson<AccountDataList>(decryptedJson);
                        if (loadedData != null && loadedData.accounts != null)
                        {
                            // 按时间戳降序排序，最新的在最前面
                            _cachedAccounts = loadedData.accounts
                                .OrderByDescending(a => a.timestamp)
                                .ToList();
                        }
                    }
                    catch (Exception e)
                    {
                        Debug.LogError("Failed to parse account data: " + e.Message);
                    }
                }
            }
        }

        // 内部方法：保存账号列表到PlayerPrefs
        private void SaveAccounts()
        {
            // 包装列表
            AccountDataList dataToSave = new AccountDataList();
            dataToSave.accounts = _cachedAccounts;

            // 序列化为JSON
            string json = JsonUtility.ToJson(dataToSave);
            // 加密JSON字符串
            string encryptedJson = AesEncryption.Encrypt(json);
            // 保存到PlayerPrefs
            PlayerPrefs.SetString(SAVE_KEY, encryptedJson);
            PlayerPrefs.Save(); // 确保立即写入磁盘
        }
    }

    public class AccountPasswordModel
    {
        public string Account { get; set; }
        public string Password { get; set; }
    }
}