using System;

using Org.BouncyCastle.Asn1.Crmf;

namespace Org.BouncyCastle.Asn1.Cmp
{
	public class CertOrEncCert
		: Asn1Encodable, IAsn1Choice
	{
		private readonly CmpCertificate certificate;
		private readonly EncryptedValue encryptedCert;

		private CertOrEncCert(Asn1TaggedObject tagged)
		{
			if (tagged.TagNo == 0)
			{
				certificate = CmpCertificate.GetInstance(tagged.GetObject());
			}
			else if (tagged.TagNo == 1)
			{
				encryptedCert = EncryptedValue.GetInstance(tagged.GetObject());
			}
			else
			{
				throw new ArgumentException("unknown tag: " + tagged.TagNo, "tagged");
			}
		}
		
		public static CertOrEncCert GetInstance(object obj)
		{
			if (obj is CertOrEncCert)
				return (CertOrEncCert)obj;

			if (obj is Asn1TaggedObject)
				return new CertOrEncCert((Asn1TaggedObject)obj);

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

		public CertOrEncCert(CmpCertificate certificate)
		{
			if (certificate == null)
				throw new ArgumentNullException("certificate");

			this.certificate = certificate;
		}

		public CertOrEncCert(EncryptedValue encryptedCert)
		{
			if (encryptedCert == null)
				throw new ArgumentNullException("encryptedCert");

			this.encryptedCert = encryptedCert;
		}

		public virtual CmpCertificate Certificate
		{
			get { return certificate; }
		}

		public virtual EncryptedValue EncryptedCert
		{
			get { return encryptedCert; }
		}

		/**
		 * <pre>
		 * CertOrEncCert ::= CHOICE {
		 *                      certificate     [0] CMPCertificate,
		 *                      encryptedCert   [1] EncryptedValue
		 *           }
		 * </pre>
		 * @return a basic ASN.1 object representation.
		 */
		public override Asn1Object ToAsn1Object()
		{
			if (certificate != null)
			{
				return new DerTaggedObject(true, 0, certificate);
			}

			return new DerTaggedObject(true, 1, encryptedCert);
		}
	}
}
