HexEncode.cs

using System.Numerics;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
using Waher.Script.Objects;
using Waher.Security;
 
namespace Waher.Script.Cryptography.Functions.Encoding
{
    public class HexEncode : FunctionMultiVariate
    {
        public HexEncode(ScriptNode Data, int Start, int Length, Expression Expression)
            : base(new ScriptNode[] { Data }, argumentTypes1Normal, Start, Length, Expression)
        {
        }
 
        public HexEncode(ScriptNode Integer, ScriptNode NrBytes, int Start, int Length, Expression Expression)
            : base(new ScriptNode[] { Integer, NrBytes }, argumentTypes2Scalar, Start, Length, Expression)
        {
        }
 
        public override string FunctionName => nameof(HexEncode);
 
        public override string[] DefaultArgumentNames => new string[] { "Data" };
 
        public override IElement Evaluate(IElement[] Arguments, Variables Variables)
        {
            int c = Arguments.Length;
 
            if (c == 1)
            {
                if (!(Arguments[0].AssociatedObjectValue is byte[] Bin))
                    throw new ScriptRuntimeException("Binary data expected.", this);
 
                return new StringValue(Hashes.BinaryToString(Bin));
            }
            else
            {
                object Obj = Arguments[0].AssociatedObjectValue;
                int NrBytes = (int)Expression.ToDouble(Arguments[1].AssociatedObjectValue);
                if (NrBytes <= 0)
                    throw new ScriptRuntimeException("Number of bytes must be positive.", this);
 
                string s;
 
                if (Obj is double d)
                {
                    if (d >= int.MinValue && d <= int.MaxValue)
                        s = ((int)d).ToString("x");
                    else if (d >= long.MinValue && d <= long.MaxValue)
                        s = ((long)d).ToString("x");
                    else
                        s = ((BigInteger)d).ToString("x");
                }
                else if (Obj is BigInteger i)
                    s = i.ToString("x");
                else
                    throw new ScriptRuntimeException("Expected integer as first argument.", this);
 
                int MaxLen = NrBytes << 1;
                c = s.Length;
 
                if (c > MaxLen)
                    throw new ScriptRuntimeException("Integer too long to fit.", this);
                else if (c < MaxLen)
                {
                    if (s[0] >= '8')
                        s = new string('f', MaxLen - c) + s;
                    else
                        s = new string('0', MaxLen - c) + s;
                }
 
                return new StringValue(s);
            }
        }
    }
}