using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;

namespace STUN.Utils
{
	public static class BitUtils
	{
		public static IEnumerable<byte> ToBe(this int num)
		{
			var res = BitConverter.GetBytes(num);
			return BitConverter.IsLittleEndian ? res.Reverse() : res;
		}

		public static IEnumerable<byte> ToBe(this ushort num)
		{
			var res = BitConverter.GetBytes(num);
			return BitConverter.IsLittleEndian ? res.Reverse() : res;
		}

		public static ushort FromBe(byte b1, byte b2)
		{
			return BitConverter.ToUInt16(BitConverter.IsLittleEndian ? new[] { b2, b1 } : new[] { b1, b2 }, 0);
		}

		public static ushort FromBe(IEnumerable<byte> b)
		{
			return BitConverter.ToUInt16(BitConverter.IsLittleEndian ? b.Reverse().ToArray() : b.ToArray(), 0);
		}

		public static int FromBeToInt(IEnumerable<byte> b)
		{
			return BitConverter.ToInt32(BitConverter.IsLittleEndian ? b.Reverse().ToArray() : b.ToArray(), 0);
		}

		public static IEnumerable<byte> GetRandomBytes(int n)
		{
			var temp = new byte[n];
			using var rng = new RNGCryptoServiceProvider();
			rng.GetBytes(temp);
			return temp;
		}

		public static bool IsEqual(this IEnumerable<byte>? a, IEnumerable<byte>? b)
		{
			return a != null && b != null && a.SequenceEqual(b);
		}
	}
}