using System;

using Org.BouncyCastle.Asn1.X509;

namespace Org.BouncyCastle.Asn1.Cmp
{
    /**
     * <pre>
     * Challenge ::= SEQUENCE {
     *          owf                 AlgorithmIdentifier  OPTIONAL,
     *
     *          -- MUST be present in the first Challenge; MAY be omitted in
     *          -- any subsequent Challenge in POPODecKeyChallContent (if
     *          -- omitted, then the owf used in the immediately preceding
     *          -- Challenge is to be used).
     *
     *          witness             OCTET STRING,
     *          -- the result of applying the one-way function (owf) to a
     *          -- randomly-generated INTEGER, A.  [Note that a different
     *          -- INTEGER MUST be used for each Challenge.]
     *          challenge           OCTET STRING
     *          -- the encryption (under the public key for which the cert.
     *          -- request is being made) of Rand, where Rand is specified as
     *          --   Rand ::= SEQUENCE {
     *          --      int      INTEGER,
     *          --       - the randomly-generated INTEGER A (above)
     *          --      sender   GeneralName
     *          --       - the sender's name (as included in PKIHeader)
     *          --   }
     *      }
     *      </pre>
     */
    public class Challenge
		: Asn1Encodable
	{
        public static Challenge GetInstance(object obj)
        {
            if (obj == null)
                return null;
            if (obj is Challenge challenge)
                return challenge;
            return new Challenge(Asn1Sequence.GetInstance(obj));
        }

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

        private readonly AlgorithmIdentifier m_owf;
		private readonly Asn1OctetString m_witness;
		private readonly Asn1OctetString m_challenge;

		private Challenge(Asn1Sequence seq)
		{
			int index = 0;

			if (seq.Count == 3)
			{
				m_owf = AlgorithmIdentifier.GetInstance(seq[index++]);
			}

			m_witness = Asn1OctetString.GetInstance(seq[index++]);
			m_challenge = Asn1OctetString.GetInstance(seq[index]);
		}

        public Challenge(byte[] witness, byte[] challenge)
            : this(null, witness, challenge)
        {
        }

        public Challenge(AlgorithmIdentifier owf, byte[] witness, byte[] challenge)
        {
            m_owf = owf;
            m_witness = new DerOctetString(witness);
            m_challenge = new DerOctetString(challenge);
        }

        public virtual AlgorithmIdentifier Owf => m_owf;

		public virtual Asn1OctetString Witness => m_witness;

		public virtual Asn1OctetString ChallengeValue => m_challenge;

        /**
		 * <pre>
		 * Challenge ::= SEQUENCE {
		 *                 owf                 AlgorithmIdentifier  OPTIONAL,
		 *
		 *                 -- MUST be present in the first Challenge; MAY be omitted in
		 *                 -- any subsequent Challenge in POPODecKeyChallContent (if
		 *                 -- omitted, then the owf used in the immediately preceding
		 *                 -- Challenge is to be used).
		 *
		 *                 witness             OCTET STRING,
		 *                 -- the result of applying the one-way function (owf) to a
		 *                 -- randomly-generated INTEGER, A.  [Note that a different
		 *                 -- INTEGER MUST be used for each Challenge.]
		 *                 challenge           OCTET STRING
		 *                 -- the encryption (under the public key for which the cert.
		 *                 -- request is being made) of Rand, where Rand is specified as
		 *                 --   Rand ::= SEQUENCE {
		 *                 --      int      INTEGER,
		 *                 --       - the randomly-generated INTEGER A (above)
		 *                 --      sender   GeneralName
		 *                 --       - the sender's name (as included in PKIHeader)
		 *                 --   }
		 *      }
		 * </pre>
		 * @return a basic ASN.1 object representation.
		 */
        public override Asn1Object ToAsn1Object()
		{
			Asn1EncodableVector v = new Asn1EncodableVector();
			v.AddOptional(m_owf);
			v.Add(m_witness, m_challenge);
			return new DerSequence(v);
		}

        /**
         * Rand is the inner type
         */
        public class Rand
            : Asn1Encodable
        {
            public static Rand GetInstance(object obj)
            {
                if (obj == null)
                    return null;
                if (obj is Rand rand)
                    return rand;
                return new Rand(Asn1Sequence.GetInstance(obj));
            }

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

            private readonly DerInteger m_intVal;
            private readonly GeneralName m_sender;

            public Rand(DerInteger intVal, GeneralName sender)
            {
                m_intVal = intVal;
                m_sender = sender;
            }

            public Rand(Asn1Sequence seq)
            {
                if (seq.Count != 2)
                    throw new ArgumentException("expected sequence size of 2", nameof(seq));

                m_intVal = DerInteger.GetInstance(seq[0]);
                m_sender = GeneralName.GetInstance(seq[1]);
            }

            public virtual DerInteger IntVal => m_intVal;

			public virtual GeneralName Sender => m_sender;

			public override Asn1Object ToAsn1Object()
			{
                return new DerSequence(m_intVal, m_sender);
            }
        }
	}
}