using System;

using Org.BouncyCastle.Math;
using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1.CryptoPro
{
    public class Gost3410ParamSetParameters
        : Asn1Encodable
    {
        private readonly int keySize;
        private readonly DerInteger	p, q, a;

		public static Gost3410ParamSetParameters GetInstance(Asn1TaggedObject obj, bool explicitly)
        {
            return GetInstance(Asn1Sequence.GetInstance(obj, explicitly));
        }

		public static Gost3410ParamSetParameters GetInstance(object obj)
        {
            if (obj == null || obj is Gost3410ParamSetParameters)
                return (Gost3410ParamSetParameters) obj;

			if (obj is Asn1Sequence seq)
                return new Gost3410ParamSetParameters(seq);

            throw new ArgumentException("Invalid GOST3410Parameter: " + Platform.GetTypeName(obj));
        }

		public Gost3410ParamSetParameters(int keySize, BigInteger p, BigInteger q, BigInteger a)
        {
            this.keySize = keySize;
            this.p = new DerInteger(p);
            this.q = new DerInteger(q);
            this.a = new DerInteger(a);
        }

		private Gost3410ParamSetParameters(Asn1Sequence seq)
        {
			if (seq.Count != 4)
				throw new ArgumentException("Wrong number of elements in sequence", "seq");

            this.keySize = DerInteger.GetInstance(seq[0]).IntValueExact;
			this.p = DerInteger.GetInstance(seq[1]);
            this.q = DerInteger.GetInstance(seq[2]);
			this.a = DerInteger.GetInstance(seq[3]);
        }

		public int KeySize
		{
			get { return keySize; }
		}

		public BigInteger P
		{
			get { return p.PositiveValue; }
		}

		public BigInteger Q
		{
			get { return q.PositiveValue; }
		}

		public BigInteger A
		{
			get { return a.PositiveValue; }
		}

		public override Asn1Object ToAsn1Object()
        {
			return new DerSequence(new DerInteger(keySize), p, q, a);
        }
    }
}