using System;

using Org.BouncyCastle.Asn1.X509;

namespace Org.BouncyCastle.Asn1.Cmp
{
    public class CmpCertificate
        : Asn1Encodable, IAsn1Choice
    {
        private readonly X509CertificateStructure x509v3PKCert;
        private readonly AttributeCertificate x509v2AttrCert;

        /**
         * Note: the addition of attribute certificates is a BC extension.
         */
        public CmpCertificate(AttributeCertificate x509v2AttrCert)
        {
            this.x509v2AttrCert = x509v2AttrCert;
        }

        public CmpCertificate(X509CertificateStructure x509v3PKCert)
        {
            if (x509v3PKCert.Version != 3)
                throw new ArgumentException("only version 3 certificates allowed", "x509v3PKCert");

            this.x509v3PKCert = x509v3PKCert;
        }

        public static CmpCertificate GetInstance(object obj)
        {
            if (obj is CmpCertificate)
                return (CmpCertificate)obj;

            if (obj is Asn1Sequence)
                return new CmpCertificate(X509CertificateStructure.GetInstance(obj));

            if (obj is Asn1TaggedObject)
                return new CmpCertificate(AttributeCertificate.GetInstance(((Asn1TaggedObject)obj).GetObject()));

            throw new ArgumentException("Invalid object: " + obj.GetType().Name, "obj");
        }

        public virtual bool IsX509v3PKCert
        {
            get { return x509v3PKCert != null; }
        }

        public virtual X509CertificateStructure X509v3PKCert
        {
            get { return x509v3PKCert; }
        }

        public virtual AttributeCertificate X509v2AttrCert
        {
            get { return x509v2AttrCert; }
        }

        /**
         * <pre>
         * CMPCertificate ::= CHOICE {
         *            x509v3PKCert        Certificate
         *            x509v2AttrCert      [1] AttributeCertificate
         *  }
         * </pre>
         * Note: the addition of attribute certificates is a BC extension.
         *
         * @return a basic ASN.1 object representation.
         */
        public override Asn1Object ToAsn1Object()
        {
            if (x509v2AttrCert != null)
            {
                // explicit following CMP conventions
                return new DerTaggedObject(true, 1, x509v2AttrCert);
            }

            return x509v3PKCert.ToAsn1Object();
        }
    }
}
