using System;

namespace CommonTool
{
	public class UtilRandom
	{
		static Random _random;

		public static int GetRandomSeed()
		{
			byte[] bytes = new byte[4];
			System.Security.Cryptography.RNGCryptoServiceProvider rng = new System.Security.Cryptography.RNGCryptoServiceProvider();
			rng.GetBytes(bytes);
			return BitConverter.ToInt32(bytes, 0);
		}


		public static int GetIntRandom()
		{
			if (_random == null)
				_random = new Random(0x989680);

			return _random.Next(0x989680, 0x5f5e0ff);
		}

		public static string GetRandom()
		{
			if (_random == null)
				_random = new Random(0x989680);
			int liInt = _random.Next(0x989680, 0x5f5e0ff);
			return ("R" + liInt.ToString());
		}

		public static string GetRandom1()
		{
			if (_random == null)
				_random = new Random(0x989680);
			int liInt = _random.Next(0x989680, 0x5f5e0ff);
			return ("+" + liInt + " GS");
		}

		/// <summary>
		/// 从字符串里随机得到，规定个数的字符串.
		/// </summary>
		/// <param name="codeCount"></param>
		/// <param name="allChar"></param>
		/// <returns></returns>
		public static string GetRandomCode(int codeCount, string allChar = "1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,i,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z")
		{
			//string allChar = "1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,i,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z"; 
			string[] allCharArray = allChar.Split(',');
			string randomCode = "";
			int temp = -1;
			Random rand = new Random();
			for (int i = 0; i < codeCount; i++)
			{
				if (temp != -1)
					rand = new Random(temp * i * ((int) DateTime.Now.Ticks));

				int t = rand.Next(allCharArray.Length - 1);

				while (temp == t)
				{
					t = rand.Next(allCharArray.Length - 1);
				}

				temp = t;
				randomCode += allCharArray[t];
			}
			return randomCode;
		}

		public static string GetNextDataTableName()
		{
			return ("T" + GetRandom());
		}


		public static string GetGuid()
		{
			return Guid.NewGuid().ToString("N");
		}
		/// <summary>
		/// 
		/// </summary>
		/// <returns></returns>
		public static string Uuid()
		{
			byte[] buffer = Guid.NewGuid().ToByteArray();
			long longGuid = BitConverter.ToInt64(buffer, 0);

			string value = Math.Abs(longGuid).ToString();

			byte[] buf = new byte[value.Length];
			int p = 0;
			for (int i = 0; i < value.Length;)
			{
				byte ph = Convert.ToByte(value[i]);

				int fix = 1;
				if ((i + 1) < value.Length)
				{
					byte pl = Convert.ToByte(value[i + 1]);
					buf[p] = (byte)((ph << 4) + pl);
					fix = 2;
				}
				else
				{
					buf[p] = ph;
				}

				if ((i + 3) < value.Length)
				{
					if (Convert.ToInt16(value.Substring(i, 3)) < 256)
					{
						buf[p] = Convert.ToByte(value.Substring(i, 3));
						fix = 3;
					}
				}
				p++;
				i = i + fix;
			}
			byte[] buf2 = new byte[p];
			for (int i = 0; i < p; i++)
			{
				buf2[i] = buf[i];
			}
			string cRtn = Convert.ToBase64String(buf2);
			cRtn = cRtn.ToLower();
			cRtn = cRtn.Replace("/", "");
			cRtn = cRtn.Replace("+", "");
			cRtn = cRtn.Replace("=", "");
			return cRtn.Length == 12 ? cRtn : Uuid();
		}

		/// <summary> 
		/// 根据GUID获取16位的唯一字符串 
		/// </summary> 
		/// <returns></returns> 
		public static string GuidTo16String()
		{
			long i = 1;
			foreach (byte b in Guid.NewGuid().ToByteArray())
				i *= (b + 1);
			return $"{i - DateTime.Now.Ticks:x}";
		}
		/// <summary> 
		/// 根据GUID获取19位的唯一数字序列 
		/// </summary> 
		/// <returns></returns> 
		public static long GuidToLongId()
		{
			byte[] buffer = Guid.NewGuid().ToByteArray();
			return BitConverter.ToInt64(buffer, 0);
		}
		/// <summary>
		/// 生成随机数的种子
		/// </summary>
		/// <returns></returns>
		private static int GetNewSeed()
		{
			byte[] rndBytes = new byte[4];
			System.Security.Cryptography.RNGCryptoServiceProvider rng = new System.Security.Cryptography.RNGCryptoServiceProvider();
			rng.GetBytes(rndBytes);
			return BitConverter.ToInt32(rndBytes, 0);
		}

		/// <summary>
		/// 生成len位随机数
		/// </summary>
		/// <param name="len"></param>
		/// <returns></returns>
		public static string GetRandomString(int len)
		{
			string s = "123456789abcdefghijklmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ";
			string reValue = string.Empty;
			Random rnd = new Random(GetNewSeed());
			while (reValue.Length < len)
			{
				string s1 = s[rnd.Next(0, s.Length)].ToString();
				if (reValue.IndexOf(s1, StringComparison.Ordinal) == -1) reValue += s1;
			}
			return reValue;
		}
		/// <summary>
		/// 获得有序的GUID
		/// </summary>
		/// <returns></returns>
		public static Guid GenerateGuid()
		{
			byte[] guidArray = Guid.NewGuid().ToByteArray();

			var baseDate = new DateTime(1900, 1, 1);
			DateTime now = DateTime.Now;
			var days = new TimeSpan(now.Ticks - baseDate.Ticks);
			TimeSpan msecs = now.TimeOfDay;

			byte[] daysArray = BitConverter.GetBytes(days.Days);
			byte[] msecsArray = BitConverter.GetBytes((long)(msecs.TotalMilliseconds / 3.333333));

			Array.Reverse(daysArray);
			Array.Reverse(msecsArray);

			Array.Copy(daysArray, daysArray.Length - 2, guidArray, guidArray.Length - 6, 2);
			Array.Copy(msecsArray, msecsArray.Length - 4, guidArray, guidArray.Length - 4, 4);

			return new Guid(guidArray);
		}


		
	}
}