using System;

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

namespace Org.BouncyCastle.Asn1.Cms
{
    public class SignerInfo
        : Asn1Encodable
    {
        private DerInteger              version;
        private SignerIdentifier        sid;
        private AlgorithmIdentifier     digAlgorithm;
        private Asn1Set                 authenticatedAttributes;
        private AlgorithmIdentifier     digEncryptionAlgorithm;
        private Asn1OctetString         encryptedDigest;
        private Asn1Set                 unauthenticatedAttributes;

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

            if (obj is Asn1Sequence)
                return new SignerInfo((Asn1Sequence) obj);

            throw new ArgumentException("Unknown object in factory: " + Platform.GetTypeName(obj), "obj");
        }

        public SignerInfo(
            SignerIdentifier        sid,
            AlgorithmIdentifier     digAlgorithm,
            Asn1Set                 authenticatedAttributes,
            AlgorithmIdentifier     digEncryptionAlgorithm,
            Asn1OctetString         encryptedDigest,
            Asn1Set                 unauthenticatedAttributes)
        {
            this.version = new DerInteger(sid.IsTagged ? 3 : 1);
            this.sid = sid;
            this.digAlgorithm = digAlgorithm;
            this.authenticatedAttributes = authenticatedAttributes;
            this.digEncryptionAlgorithm = digEncryptionAlgorithm;
            this.encryptedDigest = encryptedDigest;
            this.unauthenticatedAttributes = unauthenticatedAttributes;
        }

        public SignerInfo(
            SignerIdentifier        sid,
            AlgorithmIdentifier     digAlgorithm,
            Attributes              authenticatedAttributes,
            AlgorithmIdentifier     digEncryptionAlgorithm,
            Asn1OctetString         encryptedDigest,
            Attributes              unauthenticatedAttributes)
        {
            this.version = new DerInteger(sid.IsTagged ? 3 : 1);
            this.sid = sid;
            this.digAlgorithm = digAlgorithm;
            this.authenticatedAttributes = Asn1Set.GetInstance(authenticatedAttributes);
            this.digEncryptionAlgorithm = digEncryptionAlgorithm;
            this.encryptedDigest = encryptedDigest;
            this.unauthenticatedAttributes = Asn1Set.GetInstance(unauthenticatedAttributes);
        }

        private SignerInfo(Asn1Sequence seq)
        {
            var e = seq.GetEnumerator();

            e.MoveNext();
            version = (DerInteger)e.Current;

            e.MoveNext();
            sid = SignerIdentifier.GetInstance(e.Current.ToAsn1Object());

            e.MoveNext();
            digAlgorithm = AlgorithmIdentifier.GetInstance(e.Current.ToAsn1Object());

            e.MoveNext();
            var obj = e.Current.ToAsn1Object();

            if (obj is Asn1TaggedObject tagged)
            {
                authenticatedAttributes = Asn1Set.GetInstance(tagged, false);

                e.MoveNext();
                digEncryptionAlgorithm = AlgorithmIdentifier.GetInstance(e.Current.ToAsn1Object());
            }
            else
            {
                authenticatedAttributes = null;
                digEncryptionAlgorithm = AlgorithmIdentifier.GetInstance(obj);
            }

            e.MoveNext();
            encryptedDigest = Asn1OctetString.GetInstance(e.Current.ToAsn1Object());

            if (e.MoveNext())
            {
                unauthenticatedAttributes = Asn1Set.GetInstance((Asn1TaggedObject)e.Current.ToAsn1Object(), false);
            }
            else
            {
                unauthenticatedAttributes = null;
            }
        }

        public DerInteger Version
        {
            get { return version; }
        }

        public SignerIdentifier SignerID
        {
            get { return sid; }
        }

        public Asn1Set AuthenticatedAttributes
        {
            get { return authenticatedAttributes; }
        }

        public AlgorithmIdentifier DigestAlgorithm
        {
            get { return digAlgorithm; }
        }

        public Asn1OctetString EncryptedDigest
        {
            get { return encryptedDigest; }
        }

        public AlgorithmIdentifier DigestEncryptionAlgorithm
        {
            get { return digEncryptionAlgorithm; }
        }

        public Asn1Set UnauthenticatedAttributes
        {
            get { return unauthenticatedAttributes; }
        }

        /**
         * Produce an object suitable for an Asn1OutputStream.
         * <pre>
         *  SignerInfo ::= Sequence {
         *      version Version,
         *      SignerIdentifier sid,
         *      digestAlgorithm DigestAlgorithmIdentifier,
         *      authenticatedAttributes [0] IMPLICIT Attributes OPTIONAL,
         *      digestEncryptionAlgorithm DigestEncryptionAlgorithmIdentifier,
         *      encryptedDigest EncryptedDigest,
         *      unauthenticatedAttributes [1] IMPLICIT Attributes OPTIONAL
         *  }
         *
         *  EncryptedDigest ::= OCTET STRING
         *
         *  DigestAlgorithmIdentifier ::= AlgorithmIdentifier
         *
         *  DigestEncryptionAlgorithmIdentifier ::= AlgorithmIdentifier
         * </pre>
         */
        public override Asn1Object ToAsn1Object()
        {
            Asn1EncodableVector v = new Asn1EncodableVector(version, sid, digAlgorithm);
            v.AddOptionalTagged(false, 0, authenticatedAttributes);
            v.Add(digEncryptionAlgorithm, encryptedDigest);
            v.AddOptionalTagged(false, 1, unauthenticatedAttributes);
            return new DerSequence(v);
        }
    }
}