using System;
using UnityEngine;
using System.Collections;

/// <summary>
/// 北京时间管理器 - 获取一次后持续自增
/// </summary>
public class BeijingTimeManager : MonoSingleton<BeijingTimeManager>
{
    [Header("时间状态")]
    [SerializeField] private bool _isTimeSynced = false;      // 是否已同步
    [SerializeField] private DateTime _currentBeijingTime;    // 当前北京时间
    [SerializeField] private float _timeSinceLastSync;        // 距离上次同步的秒数

    // 公开属性供其他脚本访问
    public DateTime CurrentBeijingTime
    {
        get
        {
            if (_isTimeSynced)
            {
                // 基准时间 + 流逝的时间
                return _currentBeijingTime.AddSeconds(_timeSinceLastSync);
            }
            else
            {
                Debug.LogWarning("时间尚未同步，返回本地时间");
                return DateTime.Now.AddHours(8); // 降级为本地时间+8小时
            }
        }
    }

    public bool IsTimeSynced => _isTimeSynced;

    // 事件：当时间成功同步时触发
    public event Action<DateTime> OnTimeSynced;
    private void Start()
    {
        SyncBeijingTime();
    }
    private void Update()
    {
        if (_isTimeSynced)
        {
            // 持续累计时间
            _timeSinceLastSync += Time.deltaTime;

            // 可选：每隔一段时间（如5分钟）自动校准
            if (_timeSinceLastSync > 300f) // 5分钟
            {
                StartCoroutine(AutoCalibrateTime());
            }
        }
    }

    /// <summary>
    /// 手动触发时间同步
    /// </summary>
    public void SyncBeijingTime()
    {
        StartCoroutine(FetchBeijingTime());
    }

    /// <summary>
    /// 获取北京时间（协程）
    /// </summary>
    private IEnumerator FetchBeijingTime()
    {
        string[] timeServers = new string[]
        {
            "http://www.beijing-time.org/time.asp",
            "https://www.baidu.com",
            "https://www.taobao.com",
            
        };

        DateTime beijingTime = DateTime.MinValue;
        bool success = false;

        foreach (string url in timeServers)
        {
            using (UnityEngine.Networking.UnityWebRequest request =
                   UnityEngine.Networking.UnityWebRequest.Get(url))
            {
                yield return request.SendWebRequest();

                if (request.result == UnityEngine.Networking.UnityWebRequest.Result.Success)
                {
                    string dateHeader = request.GetResponseHeader("Date");
                    if (!string.IsNullOrEmpty(dateHeader))
                    {
                        try
                        {
                            // 解析GMT时间
                            DateTime gmtTime = DateTime.ParseExact(dateHeader,
                                "ddd, dd MMM yyyy HH:mm:ss 'GMT'",
                                System.Globalization.CultureInfo.InvariantCulture,
                                System.Globalization.DateTimeStyles.AssumeUniversal);

                            beijingTime = gmtTime.AddHours(8);

                            // 更新基准时间和计时器
                            _currentBeijingTime = beijingTime;
                            _timeSinceLastSync = 0f;
                            _isTimeSynced = true;

                            Debug.Log($"时间同步成功！北京时间：{beijingTime:yyyy-MM-dd HH:mm:ss}");

                            // 触发事件
                            OnTimeSynced?.Invoke(beijingTime);

                            success = true;
                            break;
                        }
                        catch (Exception e)
                        {
                            Debug.LogWarning($"解析失败：{e.Message}");
                            continue;
                        }
                    }
                }
            }
        }

        if (!success)
        {
            Debug.LogError("所有时间服务器都失败了，使用本地时间作为备用");
            _currentBeijingTime = DateTime.Now.AddHours(8);
            _timeSinceLastSync = 0f;
            _isTimeSynced = false; // 标记为未同步
        }
    }

    /// <summary>
    /// 自动校准（后台静默同步）
    /// </summary>
    private IEnumerator AutoCalibrateTime()
    {
        Debug.Log("开始自动校准时间...");

        // 保存当前累计时间，用于计算校准时的差距
        float oldElapsed = _timeSinceLastSync;

        yield return StartCoroutine(FetchBeijingTime());

        // 校准后可以计算误差
        Debug.Log($"时间校准完成，误差：{_timeSinceLastSync - oldElapsed:F2}秒");
    }
}