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 is OobCertHash oobCertHash)
				return oobCertHash;

			if (obj != null)
				return new OobCertHash(Asn1Sequence.GetInstance(obj));

			return null;
        }

        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.TagNo == 0)
				{
					m_hashAlg = AlgorithmIdentifier.GetInstance(tObj, true);
				}
				else
				{
					m_certId = CertId.GetInstance(tObj, true);
				}
			}
		}

		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();
            v.AddOptionalTagged(true, 0, m_hashAlg);
            v.AddOptionalTagged(true, 1, m_certId);
			v.Add(m_hashVal);
			return new DerSequence(v);
		}
	}
}