using System;
using System.Globalization;

public class DateUtil
{
    private static DateTime startStandardTime;
    private static DateTime pauseStandardTime = new DateTime(1970, 1, 1);
    private static DateTime localStandardTime;

    //如果12月31号与下一年的1月1好在同一个星期则算下一年的第一周
    public static int GetWeekIndex(DateTime dTime)
    {
        try
        {
            //确定此时间在一年中的位置
            var dayOfYear = dTime.DayOfYear;
            //当年第一天
            var tempDate = new DateTime(dTime.Year, 1, 1);
            //确定当年第一天
            var tempDayOfWeek = (int)tempDate.DayOfWeek;
            tempDayOfWeek = tempDayOfWeek == 0 ? 7 : tempDayOfWeek;
            //确定星期几
            var index = (int)dTime.DayOfWeek;
            index = index == 0 ? 7 : index;
            //当前周的范围
            DateTime retStartDay = dTime.AddDays(-(index - 1));
            DateTime retEndDay = dTime.AddDays(7 - index);
            //确定当前是第几周
            var weekIndex = (int)Math.Ceiling(((double)dayOfYear + tempDayOfWeek - 1) / 7);
            if (retStartDay.Year < retEndDay.Year)
            {
                weekIndex = 1;
            }

            return weekIndex;
        }
        catch (Exception ex)
        {
            throw new Exception(ex.Message);
        }
    }


    public static int GetWeekIndex(string strDate)
    {
        try
        {
            //需要判断的时间
            DateTime dTime = Convert.ToDateTime(strDate);
            return GetWeekIndex(dTime);
        }
        catch (Exception ex)
        {
            throw new Exception(ex.Message);
        }

    }

    /// <summary>
    /// 用年份和第几周来获得一周开始和结束的时间,这里用星期一做开始。
    /// </summary>
    public static void GetWeek(int year, int weekNum, out DateTime weekStart, out DateTime weekeEnd)
    {
        var dateTime = new DateTime(year, 1, 1);
        dateTime = dateTime.AddDays(7 * weekNum);
        weekStart = dateTime.AddDays(-(int)dateTime.DayOfWeek + (int)DayOfWeek.Monday);
        weekeEnd = dateTime.AddDays((int)DayOfWeek.Saturday - (int)dateTime.DayOfWeek + 1);
    }

    /// <summary> 求某年有多少周
    /// </summary>
    public static int GetYearWeekCount(int year)
    {
        var dateTime = DateTime.Parse(year + "-01-01");
        var firstDayOfWeek = Convert.ToInt32(dateTime.DayOfWeek);//得到该年的第一天是周几 
        if (firstDayOfWeek == 1)
        {
            var countDay = dateTime.AddYears(1).AddDays(-1).DayOfYear;
            var countWeek = countDay / 7 + 1;
            return countWeek;
        }
        else
        {
            var countDay = dateTime.AddYears(1).AddDays(-1).DayOfYear;
            var countWeek = countDay / 7 + 2;
            return countWeek;
        }
    }

    /// <summary>
    /// 求当前日期是一年的中第几周
    /// </summary>
    public static int WeekOfYear(DateTime todayTime)
    {
        var firstdayofweek = Convert.ToInt32(Convert.ToDateTime(todayTime.Year.ToString(CultureInfo.InvariantCulture) + "- " + "1-1 ").DayOfWeek);
        var days = todayTime.DayOfYear;
        var daysOutOneWeek = days - (7 - firstdayofweek);
        if (daysOutOneWeek <= 0)
        {
            return 1;
        }
        var weeks = daysOutOneWeek / 7;
        if (daysOutOneWeek % 7 != 0)
            weeks++;
        return weeks + 1;
    }

    /// <summary>
    /// 当前月有多少天
    /// </summary>
    public static int HowMonthDay(int year, int month)
    {
        int next_month;
        int next_year;
        if (month < 12)
        {
            next_month = month + 1;
            next_year = year;
        }
        else
        {
            next_month = 1;
            next_year = year + 1;
        }
        DateTime dt1 = Convert.ToDateTime(year + "-" + month + "-1");
        DateTime dt2 = Convert.ToDateTime(next_year + "-" + next_month + "-1");
        TimeSpan diff = dt2 - dt1;
        return diff.Days;
    }

    //get day in week by hashcode
    private static Array dayOfWeekArr = Enum.GetValues(typeof(DayOfWeek));
    public static DayOfWeek GetDayOfWeekByHashCode(int code)
    {
        return (DayOfWeek)dayOfWeekArr.GetValue(code);
    }

    /// <summary>
    /// 时间戳转为C#格式时间
    /// </summary>
    /// <param name="timeStamp">Unix时间戳格式</param>
    /// <returns>C#格式时间</returns>
    public static DateTime GetTime(string timeStamp)
    {
        DateTime dtStart = TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970, 1, 1));
        long lTime = long.Parse(timeStamp + "0000000");
        TimeSpan toNow = new TimeSpan(lTime);
        return dtStart.Add(toNow);
    }

    public static DateTime GetTimeFromSeconds(string timeStamp)
    {
        DateTime dtStart = TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970, 1, 1));
        long lTime = long.Parse(timeStamp + "0000");
        TimeSpan toNow = new TimeSpan(lTime);
        return dtStart.Add(toNow);
    }

    public static DateTime GetTimeFromMiliseconds(string timeStamp)
    {
        DateTime dtStart = TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970, 1, 1));
        long lTime = long.Parse(timeStamp);
        TimeSpan toNow = new TimeSpan(lTime);
        return dtStart.Add(toNow);
    }

    /// <summary>
    /// DateTime时间格式转换为Unix时间戳格式
    /// </summary>
    /// <param name="time"> DateTime时间格式</param>
    /// <returns>Unix时间戳格式</returns>
    public static int ConvertDateTimeInt(System.DateTime time)
    {
        System.DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime(new System.DateTime(1970, 1, 1));
        return (int)(time - startTime).TotalSeconds;
    }

    /// <summary>
    /// 从标准服务器获取当前正确时间，如果获取失败，则获取本地时间，并存在startStandardTime
    /// </summary>
    /// <param name="timeZone">时区</param>
    /// <returns>DateTime时间格式</returns>
    public static DateTime GetStandardTime(int timeZone = 8)
    {
        DateTime dt;

        //返回国际标准时间
        //只使用的时间服务器的IP地址，未使用域名
        try
        {
            string[,] timeServer = new string[14, 2];
            int[] searchOrder = new int[] { 3, 2, 4, 8, 9, 6, 11, 5, 10, 0, 1, 7, 12 };
            timeServer[0, 0] = "time-a.nist.gov";
            timeServer[0, 1] = "129.6.15.28";
            timeServer[1, 0] = "time-b.nist.gov";
            timeServer[1, 1] = "129.6.15.29";
            timeServer[2, 0] = "time-a.timefreq.bldrdoc.gov";
            timeServer[2, 1] = "132.163.4.101";
            timeServer[3, 0] = "time-b.timefreq.bldrdoc.gov";
            timeServer[3, 1] = "132.163.4.102";
            timeServer[4, 0] = "time-c.timefreq.bldrdoc.gov";
            timeServer[4, 1] = "132.163.4.103";
            timeServer[5, 0] = "utcnist.colorado.edu";
            timeServer[5, 1] = "128.138.140.44";
            timeServer[6, 0] = "time.nist.gov";
            timeServer[6, 1] = "192.43.244.18";
            timeServer[7, 0] = "time-nw.nist.gov";
            timeServer[7, 1] = "131.107.1.10";
            timeServer[8, 0] = "nist1.symmetricom.com";
            timeServer[8, 1] = "69.25.96.13";
            timeServer[9, 0] = "nist1-dc.glassey.com";
            timeServer[9, 1] = "216.200.93.8";
            timeServer[10, 0] = "nist1-ny.glassey.com";
            timeServer[10, 1] = "208.184.49.9";
            timeServer[11, 0] = "nist1-sj.glassey.com";
            timeServer[11, 1] = "207.126.98.204";
            timeServer[12, 0] = "nist1.aol-ca.truetime.com";
            timeServer[12, 1] = "207.200.81.113";
            timeServer[13, 0] = "nist1.aol-va.truetime.com";
            timeServer[13, 1] = "64.236.96.53";
            int portNum = 13;
            string hostName;
            byte[] bytes = new byte[1024];
            int bytesRead = 0;
            System.Net.Sockets.TcpClient client = new System.Net.Sockets.TcpClient();
            for (int i = 0; i < 13; i++)
            {
                hostName = timeServer[searchOrder[i], 1];
                try
                {
                    client.Connect(hostName, portNum);
                    System.Net.Sockets.NetworkStream ns = client.GetStream();
                    bytesRead = ns.Read(bytes, 0, bytes.Length);
                    client.Close();
                    break;
                }
                catch (System.Exception)
                {
                }
            }
            char[] sp = new char[1];
            sp[0] = ' ';
            dt = new DateTime();
            string str1;
            str1 = System.Text.Encoding.ASCII.GetString(bytes, 0, bytesRead);

            string[] s;
            s = str1.Split(sp);
            dt = DateTime.Parse(s[1] + " " + s[2]);//得到标准时间
            dt = dt.AddHours(timeZone);
        }
        catch (Exception)
        {
            dt = DateTime.Parse("1970-1-1");
        }

        if ((dt.ToString() != "1970-1-1 0:00:00"))
            startStandardTime = dt;
        else
        {
            Debuger.LogError("Can not get server time, use local instead!");
            startStandardTime = DateTime.Now;
        }

        localStandardTime = DateTime.Now;
        //Debuger.LogWarning("[Server Standard Time]" + standardTime);
        return dt;
    }

    /// <summary>
    /// 按照当前时间重新设置起始时间
    /// </summary>
    /// <param name="interval">设置可重置的时间差，单位为秒</param>
    public static void ResetStandardTime(int interval)
    {
        if(GetCurrentTimeByStandardTime() - ConvertDateTimeInt(pauseStandardTime) > interval && pauseStandardTime != new DateTime(1970, 1, 1))
        {
            startStandardTime = GetCurrenTimeByStandardTimeUseDateTime();
            pauseStandardTime = new DateTime(1970, 1, 1);
        }
    }

    /// <summary>
    /// 设置暂停时的时间
    /// </summary>
    public static void SetPauseStandardTime()
    {
        pauseStandardTime = GetCurrenTimeByStandardTimeUseDateTime();
    }

    /// <summary>
    /// 从打开游戏到当前所经历的秒数
    /// </summary>
    /// <returns>单位为秒</returns>
    public static int GetRealTimeSinceStart()
    {
        return ConvertDateTimeInt(DateTime.Now) - ConvertDateTimeInt(localStandardTime);
    }

    /// <summary>
    /// 获取当前标准时间的时间戳
    /// </summary>
    /// <returns>返回时间戳</returns>
    public static int GetCurrentTimeByStandardTime()
    {
        return GetRealTimeSinceStart() + ConvertDateTimeInt(startStandardTime);
    }

    /// <summary>
    /// 获取当前标准时间
    /// </summary>
    /// <returns>返回DateTime时间格式</returns>
    public static DateTime GetCurrenTimeByStandardTimeUseDateTime()
    {
        return GetTime(GetCurrentTimeByStandardTime().ToString());
    }

    /// <summary>
    /// 设置当前标准时间
    /// </summary>
    /// <param name="dateTime"></param>
    public static void SetStandardTime(DateTime dateTime)
    {
        startStandardTime = dateTime;
        localStandardTime = DateTime.Now;
    }

    /// <summary>
    /// 获取当前标准时间
    /// </summary>
    public static DateTime GetStandardTimeExist()
    {
        return startStandardTime; 
        //if (startStandardTime != null) 
        //    return startStandardTime;
        //else
        //    return DateTime.Now;
    }

    public static int GetStandardTimeExistByTimeStamp()
    {
        return ConvertDateTimeInt(GetStandardTimeExist());
    }
}