using System;

using Org.BouncyCastle.Asn1.Pkcs;

namespace Org.BouncyCastle.Asn1.X509
{
    /**
     * an X509Certificate structure.
     * <pre>
     *  Certificate ::= Sequence {
     *      tbsCertificate          TbsCertificate,
     *      signatureAlgorithm      AlgorithmIdentifier,
     *      signature               BIT STRING
     *  }
     * </pre>
     */
    public class X509CertificateStructure
        : Asn1Encodable
    {
        private readonly TbsCertificateStructure	tbsCert;
        private readonly AlgorithmIdentifier		sigAlgID;
        private readonly DerBitString				sig;

		public static X509CertificateStructure GetInstance(
            Asn1TaggedObject	obj,
            bool				explicitly)
        {
            return GetInstance(Asn1Sequence.GetInstance(obj, explicitly));
        }

		public static X509CertificateStructure GetInstance(
            object obj)
        {
            if (obj is X509CertificateStructure)
                return (X509CertificateStructure)obj;

			if (obj != null)
				return new X509CertificateStructure(Asn1Sequence.GetInstance(obj));

			return null;
        }

		public X509CertificateStructure(
			TbsCertificateStructure	tbsCert,
			AlgorithmIdentifier		sigAlgID,
			DerBitString			sig)
		{
			if (tbsCert == null)
				throw new ArgumentNullException("tbsCert");
			if (sigAlgID == null)
				throw new ArgumentNullException("sigAlgID");
			if (sig == null)
				throw new ArgumentNullException("sig");

			this.tbsCert = tbsCert;
			this.sigAlgID = sigAlgID;
			this.sig = sig;
		}

		private X509CertificateStructure(
            Asn1Sequence seq)
        {
			if (seq.Count != 3)
				throw new ArgumentException("sequence wrong size for a certificate", "seq");

			//
            // correct x509 certficate
            //
			tbsCert = TbsCertificateStructure.GetInstance(seq[0]);
			sigAlgID = AlgorithmIdentifier.GetInstance(seq[1]);
			sig = DerBitString.GetInstance(seq[2]);
        }

		public TbsCertificateStructure TbsCertificate
        {
			get { return tbsCert; }
        }

		public int Version
        {
            get { return tbsCert.Version; }
        }

		public DerInteger SerialNumber
        {
            get { return tbsCert.SerialNumber; }
        }

		public X509Name Issuer
        {
            get { return tbsCert.Issuer; }
        }

		public Time StartDate
        {
            get { return tbsCert.StartDate; }
        }

		public Time EndDate
        {
            get { return tbsCert.EndDate; }
        }

		public X509Name Subject
        {
            get { return tbsCert.Subject; }
        }

		public SubjectPublicKeyInfo SubjectPublicKeyInfo
        {
            get { return tbsCert.SubjectPublicKeyInfo; }
        }

		public AlgorithmIdentifier SignatureAlgorithm
        {
            get { return sigAlgID; }
        }

		public DerBitString Signature
        {
            get { return sig; }
        }

		public override Asn1Object ToAsn1Object()
        {
			return new DerSequence(tbsCert, sigAlgID, sig);
        }
	}
}
