package org.bouncycastle.asn1.x509;

import java.util.Enumeration;

import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERGeneralizedTime;
import org.bouncycastle.asn1.DERInteger;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DERTaggedObject;
import org.bouncycastle.asn1.DERUTCTime;

PKIX RFC-2459 - TBSCertList object.
TBSCertList  ::=  SEQUENCE  {
     version                 Version OPTIONAL,
                                  -- if present, shall be v2
     signature               AlgorithmIdentifier,
     issuer                  Name,
     thisUpdate              Time,
     nextUpdate              Time OPTIONAL,
     revokedCertificates     SEQUENCE OF SEQUENCE  {
          userCertificate         CertificateSerialNumber,
          revocationDate          Time,
          crlEntryExtensions      Extensions OPTIONAL
                                        -- if present, shall be v2
                               }  OPTIONAL,
     crlExtensions           [0]  EXPLICIT Extensions OPTIONAL
                                        -- if present, shall be v2
                               }

/**
 * PKIX RFC-2459 - TBSCertList object.
 * <pre>
 * TBSCertList  ::=  SEQUENCE  {
 *      version                 Version OPTIONAL,
 *                                   -- if present, shall be v2
 *      signature               AlgorithmIdentifier,
 *      issuer                  Name,
 *      thisUpdate              Time,
 *      nextUpdate              Time OPTIONAL,
 *      revokedCertificates     SEQUENCE OF SEQUENCE  {
 *           userCertificate         CertificateSerialNumber,
 *           revocationDate          Time,
 *           crlEntryExtensions      Extensions OPTIONAL
 *                                         -- if present, shall be v2
 *                                }  OPTIONAL,
 *      crlExtensions           [0]  EXPLICIT Extensions OPTIONAL
 *                                         -- if present, shall be v2
 *                                }
 * </pre>
 */
public class TBSCertList
    extends ASN1Encodable
{
    public static class CRLEntry
        extends ASN1Encodable
    {
        ASN1Sequence  seq;

        DERInteger          userCertificate;
        Time                revocationDate;
        X509Extensions      crlEntryExtensions;

        public CRLEntry(
            ASN1Sequence  seq)
        {
            if (seq.size() < 2 || seq.size() > 3)
            {
                throw new IllegalArgumentException("Bad sequence size: " + seq.size());
            }
            
            this.seq = seq;

            userCertificate = DERInteger.getInstance(seq.getObjectAt(0));
            revocationDate = Time.getInstance(seq.getObjectAt(1));
        }

        public DERInteger getUserCertificate()
        {
            return userCertificate;
        }

        public Time getRevocationDate()
        {
            return revocationDate;
        }

        public X509Extensions getExtensions()
        {
            if (crlEntryExtensions == null && seq.size() == 3)
            {
                crlEntryExtensions = X509Extensions.getInstance(seq.getObjectAt(2));
            }
            
            return crlEntryExtensions;
        }

        public DERObject toASN1Object()
        {
            return seq;
        }
    }

    private class RevokedCertificatesEnumeration
        implements Enumeration
    {
        private final Enumeration en;

        RevokedCertificatesEnumeration(Enumeration en)
        {
            this.en = en;
        }

        public boolean hasMoreElements()
        {
            return en.hasMoreElements();
        }

        public Object nextElement()
        {
            return new CRLEntry(ASN1Sequence.getInstance(en.nextElement()));
        }
    }

    private class EmptyEnumeration
        implements Enumeration
    {
        public boolean hasMoreElements()
        {
            return false;
        }

        public Object nextElement()
        {
            return null;   // TODO: check exception handling
        }
    }

    ASN1Sequence     seq;

    DERInteger              version;
    AlgorithmIdentifier     signature;
    X509Name                issuer;
    Time                    thisUpdate;
    Time                    nextUpdate;
    ASN1Sequence            revokedCertificates;
    X509Extensions          crlExtensions;

    public static TBSCertList getInstance(
        ASN1TaggedObject obj,
        boolean          explicit)
    {
        return getInstance(ASN1Sequence.getInstance(obj, explicit));
    }

    public static TBSCertList getInstance(
        Object  obj)
    {
        if (obj instanceof TBSCertList)
        {
            return (TBSCertList)obj;
        }
        else if (obj instanceof ASN1Sequence)
        {
            return new TBSCertList((ASN1Sequence)obj);
        }

        throw new IllegalArgumentException("unknown object in factory: " + obj.getClass().getName());
    }

    public TBSCertList(
        ASN1Sequence  seq)
    {
        if (seq.size() < 3 || seq.size() > 7)
        {
            throw new IllegalArgumentException("Bad sequence size: " + seq.size());
        }

        int seqPos = 0;

        this.seq = seq;

        if (seq.getObjectAt(seqPos) instanceof DERInteger)
        {
            version = DERInteger.getInstance(seq.getObjectAt(seqPos++));
        }
        else
        {
            version = new DERInteger(0);
        }

        signature = AlgorithmIdentifier.getInstance(seq.getObjectAt(seqPos++));
        issuer = X509Name.getInstance(seq.getObjectAt(seqPos++));
        thisUpdate = Time.getInstance(seq.getObjectAt(seqPos++));

        if (seqPos < seq.size()
            && (seq.getObjectAt(seqPos) instanceof DERUTCTime
               || seq.getObjectAt(seqPos) instanceof DERGeneralizedTime
               || seq.getObjectAt(seqPos) instanceof Time))
        {
            nextUpdate = Time.getInstance(seq.getObjectAt(seqPos++));
        }

        if (seqPos < seq.size()
            && !(seq.getObjectAt(seqPos) instanceof DERTaggedObject))
        {
            revokedCertificates = ASN1Sequence.getInstance(seq.getObjectAt(seqPos++));
        }

        if (seqPos < seq.size()
            && seq.getObjectAt(seqPos) instanceof DERTaggedObject)
        {
            crlExtensions = X509Extensions.getInstance(seq.getObjectAt(seqPos));
        }
    }

    public int getVersion()
    {
        return version.getValue().intValue() + 1;
    }

    public DERInteger getVersionNumber()
    {
        return version;
    }

    public AlgorithmIdentifier getSignature()
    {
        return signature;
    }

    public X509Name getIssuer()
    {
        return issuer;
    }

    public Time getThisUpdate()
    {
        return thisUpdate;
    }

    public Time getNextUpdate()
    {
        return nextUpdate;
    }

    public CRLEntry[] getRevokedCertificates()
    {
        if (revokedCertificates == null)
        {
            return new CRLEntry[0];
        }

        CRLEntry[] entries = new CRLEntry[revokedCertificates.size()];

        for (int i = 0; i < entries.length; i++)
        {
            entries[i] = new CRLEntry(ASN1Sequence.getInstance(revokedCertificates.getObjectAt(i)));
        }
        
        return entries;
    }

    public Enumeration getRevokedCertificateEnumeration()
    {
        if (revokedCertificates == null)
        {
            return new EmptyEnumeration();
        }

        return new RevokedCertificatesEnumeration(revokedCertificates.getObjects());
    }

    public X509Extensions getExtensions()
    {
        return crlExtensions;
    }

    public DERObject toASN1Object()
    {
        return seq;
    }
}