using GostCryptography.Properties;
using System;
using System.Text;

namespace GostCryptography.Asn1.Ber
{
    [Serializable]
    public class Asn1Real : Asn1Type
    {
        private const int MinusInfinity = 0x41;
        private const int PlusInfinity = 0x40;
        private const int RealBase2 = 0;
        private const int RealBase8 = 0x10;
        private const int RealBase16 = 0x20;
        private const int RealBaseMask = 0x30;
        private const int RealBinary = 0x80;
        private const int RealExplen1 = 0;
        private const int RealExplen2 = 1;
        private const int RealExplen3 = 2;
        private const int RealExplenLong = 3;
        private const int RealExplenMask = 3;
        private const int RealFactorMask = 12;
        private const int RealIso6093Mask = 0x3f;

        public static readonly Asn1Tag Tag = new Asn1Tag(0, 0, RealTypeCode);

        [NonSerialized]
        public double Value;

        public Asn1Real()
        {
            Value = 0.0;
        }

        public Asn1Real(double value)
        {
            Value = value;
        }

        public override void Decode(Asn1BerDecodeBuffer buffer, bool explicitTagging, int implicitLength)
        {
            var length = explicitTagging ? MatchTag(buffer, Tag) : implicitLength;

            if (length == 0)
            {
                Value = 0.0;
            }
            else
            {
                var num2 = buffer.ReadByte();

                if (length == 1)
                {
                    switch (num2)
                    {
                        case PlusInfinity:
                            Value = double.PositiveInfinity;
                            return;

                        case MinusInfinity:
                            Value = double.NegativeInfinity;
                            return;
                    }

                    throw ExceptionUtility.CryptographicException(Resources.Asn1InvalidFormatOfConstructedValue, buffer.ByteCount);
                }

                length--;

                if ((num2 & RealBinary) == 0)
                {
                    var num8 = length;
                    var num9 = 0;

                    var builder = new StringBuilder { Length = num8 };

                    while (num8 > 0)
                    {
                        var num7 = buffer.Read();

                        if (num7 == -1)
                        {
                            throw ExceptionUtility.CryptographicException(Resources.Asn1EndOfBufferException, buffer.ByteCount);
                        }

                        builder[num9++] = (char)num7;
                        num8--;
                    }

                    var num10 = num2 & RealIso6093Mask;
                    var num11 = 0;

                    for (var i = 0; i < builder.Length; i++)
                    {
                        var ch = builder[i];

                        if ((num10 >= 2) && (ch == ','))
                        {
                            builder[i] = '.';
                            num11++;
                        }
                        else if (((num10 >= 1) && (((ch >= '0') && (ch <= '9')) || ((ch == '+') || (ch == '-')))) || (((num10 >= 2) && (ch == '.')) || ((num10 == 3) && ((ch == 'E') || (ch == 'e')))))
                        {
                            num11++;
                        }
                        else if ((num11 != 0) || (ch != ' '))
                        {
                            throw ExceptionUtility.CryptographicException(Resources.Asn1InvalidFormatOfConstructedValue, buffer.ByteCount);
                        }
                    }
                    try
                    {
                        Value = double.Parse(builder.ToString());
                    }
                    catch (FormatException)
                    {
                        throw ExceptionUtility.CryptographicException(Resources.Asn1InvalidFormatOfConstructedValue, buffer.ByteCount);
                    }
                }
                else
                {
                    int num6;
                    int num3;

                    switch ((num2 & RealExplenMask))
                    {
                        case RealExplen1:
                            num3 = 1;
                            break;

                        case RealExplen2:
                            num3 = 2;
                            break;

                        case RealExplen3:
                            num3 = 3;
                            break;

                        default:
                            num3 = buffer.ReadByte();
                            length--;
                            break;
                    }

                    var num4 = (int)Asn1RunTime.DecodeIntValue(buffer, num3, true);
                    length -= num3;

                    var num5 = Asn1RunTime.DecodeIntValue(buffer, length, false) * (1L << ((num2 & RealFactorMask) >> 2));

                    switch ((num2 & RealBaseMask))
                    {
                        case RealBase2:
                            num6 = 2;
                            break;

                        case RealBase8:
                            num6 = 8;
                            break;

                        case RealBase16:
                            num6 = 16;
                            break;

                        default:
                            throw ExceptionUtility.CryptographicException(Resources.Asn1InvalidFormatOfConstructedValue, buffer.ByteCount);
                    }

                    Value = num5 * Math.Pow(num6, num4);

                    if ((num2 & PlusInfinity) != 0)
                    {
                        Value = -Value;
                    }
                }

                buffer.TypeCode = RealTypeCode;
            }
        }

        public override int Encode(Asn1BerEncodeBuffer buffer, bool explicitTagging)
        {
            var len = 0;

            if (double.IsNegativeInfinity(Value))
            {
                len = buffer.EncodeIntValue(MinusInfinity);
            }
            else if (double.IsPositiveInfinity(Value))
            {
                len = buffer.EncodeIntValue(PlusInfinity);
            }

            else if (Value != 0.0)
            {
                var num2 = BitConverter.DoubleToInt64Bits(Value);
                var num3 = ((num2 >> RealIso6093Mask) == 0L) ? 1 : -1;
                var num4 = ((int)((num2 >> 0x34) & 0x7ffL)) - 0x433;
                var w = (num4 == 0) ? ((num2 & 0xfffffffffffffL) << 1) : ((num2 & 0xfffffffffffffL) | 0x10000000000000L);

                if (w != 0L)
                {
                    var bits = TrailingZerosCnt(w);
                    w = Asn1Util.UrShift(w, bits);
                    num4 += bits;
                }

                len += buffer.EncodeIntValue(w);

                var num7 = buffer.EncodeIntValue(num4);
                len += num7;

                var num8 = RealBinary;

                if (num3 == -1)
                {
                    num8 |= PlusInfinity;
                }

                switch (num7)
                {
                    case RealExplen2:
                        break;

                    case RealExplen3:
                        num8 |= 1;
                        break;

                    case RealExplenLong:
                        num8 |= 2;
                        break;

                    default:
                        num8 |= 3;
                        len += buffer.EncodeIntValue(num7);
                        break;
                }

                buffer.Copy((byte)num8);
                len++;
            }

            if (explicitTagging)
            {
                len += buffer.EncodeTagAndLength(Tag, len);
            }

            return len;
        }

        public override void Encode(Asn1BerOutputStream outs, bool explicitTagging)
        {
            if (explicitTagging)
            {
                outs.EncodeTag(Tag);
            }

            if (Value == 0.0)
            {
                outs.EncodeLength(0);
            }
            else if (Value == double.NegativeInfinity)
            {
                outs.EncodeIntValue(MinusInfinity, true);
            }
            else if (Value == double.PositiveInfinity)
            {
                outs.EncodeIntValue(PlusInfinity, true);
            }
            else
            {
                var len = 1;
                var num2 = BitConverter.DoubleToInt64Bits(Value);
                var num3 = ((num2 >> RealIso6093Mask) == 0L) ? 1 : -1;
                var num4 = ((int)((num2 >> 0x34) & 0x7ffL)) - 0x433;
                var w = (num4 == 0) ? ((num2 & 0xfffffffffffffL) << 1) : ((num2 & 0xfffffffffffffL) | 0x10000000000000L);

                if (w != 0L)
                {
                    var bits = TrailingZerosCnt(w);
                    w = Asn1Util.UrShift(w, bits);
                    num4 += bits;
                    len += Asn1Util.GetUlongBytesCount(w);
                }
                else
                {
                    len++;
                }

                var num7 = RealBinary;

                if (num3 == -1)
                {
                    num7 |= PlusInfinity;
                }

                var bytesCount = Asn1Util.GetBytesCount(num4);
                len += bytesCount;

                switch (bytesCount)
                {
                    case RealExplen2:
                        break;

                    case RealExplen3:
                        num7 |= 1;
                        break;

                    case RealExplenLong:
                        num7 |= 2;
                        break;

                    default:
                        num7 |= 3;
                        len++;
                        break;
                }

                outs.EncodeLength(len);
                outs.WriteByte((byte)num7);

                if ((num7 & 3) == 3)
                {
                    outs.EncodeIntValue(bytesCount, false);
                }

                outs.EncodeIntValue(num4, false);
                outs.EncodeIntValue(w, false);
            }
        }

        public virtual bool Equals(double value)
        {
            return (Value == value);
        }

        public override bool Equals(object value)
        {
            var real = value as Asn1Real;

            if (real == null)
            {
                return false;
            }

            return (Value == real.Value);
        }

        public override int GetHashCode()
        {
            return Value.GetHashCode();
        }

        public override string ToString()
        {
            return Value.ToString();
        }

        private static int TrailingZerosCnt(long w)
        {
            var num = Asn1RunTime.IntTrailingZerosCnt((int)w);

            if (num >= RealBase16)
            {
                return (Asn1RunTime.IntTrailingZerosCnt((int)Asn1Util.UrShift(w, RealBase16)) + RealBase16);
            }

            return num;
        }
    }
}