using Sarand.Net.Standard.Base.Utils;
using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Text;

namespace Sarand.Net.Standard.Base.Helpers
{
	//=======================================================================
	public static class SacsRandomHelper
	{
		//-------------------------------------------------------------------
		// Properties.
		public static RandomNumberGenerator RandomNumberGenerator { get; } = RandomNumberGenerator.Create();
		private static Random random;
		public static Random Random { get { if (random == null) random = new Random(GetInt32(Int32.MaxValue)); return random; } }

		public static void Fill(byte[] byteArray)
		{
			RandomNumberGenerator.Fill(byteArray);
			//RandomNumberGenerator.GetBytes(byteArray);
		}

		//-------------------------------------------------------------------
		/// <summary>
		/// Generates a random integer between 0 (inclusive) and a specified exclusive upper
		/// bound using a cryptographically strong random number generator.
		/// </summary>
		/// <param name="toExclusive">The exclusive upper bound of the random range.</param>
		/// <returns>A random integer between 0 (inclusive) and toExclusive (exclusive).</returns>
		/// <exception cref="ArgumentOutOfRangeException">The toExclusive parameter is less than or equal to 0.</exception>
		public static int GetInt32(int toExclusive)
		{
			return RandomNumberGenerator.GetInt32(toExclusive);
			//return Random.Next(toExclusive);
		}

		//-------------------------------------------------------------------
		/// <summary>
		/// Generates a random integer between a specified inclusive lower bound and a specified
		/// exclusive upper bound using a cryptographically strong random number generator.
		/// </summary>
		/// <param name="fromInclusive">The inclusive lower bound of the random range.</param>
		/// <param name="toExclusive">The exclusive upper bound of the random range.</param>
		/// <returns>A random integer between fromInclusive (inclusive) and toExclusive (exclusive).</returns>
		/// <exception cref="ArgumentOutOfRangeException">The toExclusive parameter is less than or equal to the fromInclusive parameter.</exception>
		public static int GetInt32(int fromInclusive, int toExclusive)
		{
			return RandomNumberGenerator.GetInt32(fromInclusive, toExclusive);
			//return Random.Next(fromInclusive, toExclusive);
		}

		//-------------------------------------------------------------------
		public static String getRandomLengthNumber(ushort maxLength=4)
		{
			String value = "";
			int len = GetInt32(1, maxLength + 1);
			for (int i = 0; i < len; i++)
				value += GetInt32(0,10);
			if (StringUtil.IsEmpty(value))
				throw new NotSupportedException("getRandomLengthNumber Generated blank value");
			if (value.Length > maxLength)
				throw new NotSupportedException("getRandomLengthNumber Generated excess length value");
			return value;
		}

		//-------------------------------------------------------------------
	}
	//=======================================================================
}