using System;

namespace Org.BouncyCastle.Asn1.X509
{
    public class AttributeCertificate
        : Asn1Encodable
    {
        public static AttributeCertificate GetInstance(object obj)
        {
            if (obj == null)
                return null;
            if (obj is AttributeCertificate attributeCertificate)
                return attributeCertificate;
            return new AttributeCertificate(Asn1Sequence.GetInstance(obj));
        }

        public static AttributeCertificate GetInstance(Asn1TaggedObject taggedObject, bool declaredExplicit)
        {
            return new AttributeCertificate(Asn1Sequence.GetInstance(taggedObject, declaredExplicit));
        }

        private readonly AttributeCertificateInfo acinfo;
        private readonly AlgorithmIdentifier signatureAlgorithm;
        private readonly DerBitString signatureValue;

        public AttributeCertificate(AttributeCertificateInfo acinfo, AlgorithmIdentifier signatureAlgorithm,
            DerBitString signatureValue)
        {
            this.acinfo = acinfo;
            this.signatureAlgorithm = signatureAlgorithm;
            this.signatureValue = signatureValue;
        }

		private AttributeCertificate(Asn1Sequence seq)
        {
			if (seq.Count != 3)
				throw new ArgumentException("Bad sequence size: " + seq.Count);

			this.acinfo = AttributeCertificateInfo.GetInstance(seq[0]);
            this.signatureAlgorithm = AlgorithmIdentifier.GetInstance(seq[1]);
            this.signatureValue = DerBitString.GetInstance(seq[2]);
        }

		public AttributeCertificateInfo ACInfo
		{
			get { return acinfo; }
		}

		public AlgorithmIdentifier SignatureAlgorithm
		{
			get { return signatureAlgorithm; }
		}

		public DerBitString SignatureValue
		{
			get { return signatureValue; }
		}

        public byte[] GetSignatureOctets()
        {
            return signatureValue.GetOctets();
        }

        /**
         * Produce an object suitable for an Asn1OutputStream.
         * <pre>
         *  AttributeCertificate ::= Sequence {
         *       acinfo               AttributeCertificateInfo,
         *       signatureAlgorithm   AlgorithmIdentifier,
         *       signatureValue       BIT STRING
         *  }
         * </pre>
         */
        public override Asn1Object ToAsn1Object()
        {
			return new DerSequence(acinfo, signatureAlgorithm, signatureValue);
        }
    }
}