using System;

using Org.BouncyCastle.Asn1.Crmf;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1.Cmp
{
    /**
     * <pre>
     * OOBCertHash ::= SEQUENCE {
     * hashAlg     [0] AlgorithmIdentifier     OPTIONAL,
     * certId      [1] CertId                  OPTIONAL,
     * hashVal         BIT STRING
     * -- hashVal is calculated over the DER encoding of the
     * -- self-signed certificate with the identifier certID.
     * }
     * </pre>
     */
    public class OobCertHash
		: Asn1Encodable
	{
        public static OobCertHash GetInstance(object obj)
        {
            if (obj == null)
                return null;
            if (obj is OobCertHash oobCertHash)
                return oobCertHash;
            return new OobCertHash(Asn1Sequence.GetInstance(obj));
        }

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

        private readonly AlgorithmIdentifier m_hashAlg;
		private readonly CertId m_certId;
		private readonly DerBitString m_hashVal;

		private OobCertHash(Asn1Sequence seq)
		{
			int index = seq.Count - 1;

			m_hashVal = DerBitString.GetInstance(seq[index--]);

			for (int i = index; i >= 0; i--)
			{
				Asn1TaggedObject tObj = (Asn1TaggedObject)seq[i];

				if (tObj.HasContextTag(0))
				{
					m_hashAlg = AlgorithmIdentifier.GetInstance(tObj, true);
				}
				else if (tObj.HasContextTag(1))
				{
					m_certId = CertId.GetInstance(tObj, true);
				}
				else
				{
                    throw new ArgumentException("unknown tag " + Asn1Utilities.GetTagText(tObj));
                }
            }
		}

		public virtual CertId CertID => m_certId;

        public virtual AlgorithmIdentifier HashAlg => m_hashAlg;

		public virtual DerBitString HashVal => m_hashVal;

		/**
		 * <pre>
		 * OobCertHash ::= SEQUENCE {
		 *                      hashAlg     [0] AlgorithmIdentifier     OPTIONAL,
		 *                      certId      [1] CertId                  OPTIONAL,
		 *                      hashVal         BIT STRING
		 *                      -- hashVal is calculated over the Der encoding of the
		 *                      -- self-signed certificate with the identifier certID.
		 *       }
		 * </pre>
		 * @return a basic ASN.1 object representation.
		 */
		public override Asn1Object ToAsn1Object()
		{
			Asn1EncodableVector v = new Asn1EncodableVector(3);
            v.AddOptionalTagged(true, 0, m_hashAlg);
            v.AddOptionalTagged(true, 1, m_certId);
			v.Add(m_hashVal);
			return new DerSequence(v);
		}
	}
}