package org.bouncycastle.x509;

import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DERInteger;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.asn1.x509.GeneralName;
import org.bouncycastle.asn1.x509.GeneralNames;
import org.bouncycastle.asn1.x509.Holder;
import org.bouncycastle.asn1.x509.IssuerSerial;
import org.bouncycastle.asn1.x509.ObjectDigestInfo;
import org.bouncycastle.jce.PrincipalUtil;
import org.bouncycastle.jce.X509Principal;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.Selector;

import javax.security.auth.x500.X500Principal;
import java.io.IOException;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.Principal;
import java.security.cert.CertSelector;
import java.security.cert.Certificate;
import java.security.cert.CertificateEncodingException;
import java.security.cert.CertificateParsingException;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.List;

/**
 * The Holder object.
 * 
 * <pre>
 *          Holder ::= SEQUENCE {
 *                baseCertificateID   [0] IssuerSerial OPTIONAL,
 *                         -- the issuer and serial number of
 *                         -- the holder's Public Key Certificate
 *                entityName          [1] GeneralNames OPTIONAL,
 *                         -- the name of the claimant or role
 *                objectDigestInfo    [2] ObjectDigestInfo OPTIONAL
 *                         -- used to directly authenticate the holder,
 *                         -- for example, an executable
 *          }
 * </pre>
 * 
 */
public class AttributeCertificateHolder
    implements CertSelector, Selector
{
    final Holder holder;

    AttributeCertificateHolder(ASN1Sequence seq)
    {
        holder = Holder.getInstance(seq);
    }

    public AttributeCertificateHolder(X509Principal issuerName,
        BigInteger serialNumber)
    {
        holder = new org.bouncycastle.asn1.x509.Holder(new IssuerSerial(
            new GeneralNames(new DERSequence(new GeneralName(issuerName))),
            new DERInteger(serialNumber)));
    }

    public AttributeCertificateHolder(X500Principal issuerName,
        BigInteger serialNumber)
    {
        this(X509Util.convertPrincipal(issuerName), serialNumber);
    }

    public AttributeCertificateHolder(X509Certificate cert)
        throws CertificateParsingException
    {
        X509Principal name;

        try
        {
            name = PrincipalUtil.getIssuerX509Principal(cert);
        }
        catch (Exception e)
        {
            throw new CertificateParsingException(e.getMessage());
        }

        holder = new Holder(new IssuerSerial(generateGeneralNames(name),
            new DERInteger(cert.getSerialNumber())));
    }

    public AttributeCertificateHolder(X509Principal principal)
    {
        holder = new Holder(generateGeneralNames(principal));
    }

    public AttributeCertificateHolder(X500Principal principal)
    {
        this(X509Util.convertPrincipal(principal));
    }

    /**
     * Constructs a holder for v2 attribute certificates with a hash value for
     * some type of object.
     * <p>
     * <code>digestedObjectType</code> can be one of the following:
     * <ul>
     * <li>0 - publicKey - A hash of the public key of the holder must be
     * passed.
     * <li>1 - publicKeyCert - A hash of the public key certificate of the
     * holder must be passed.
     * <li>2 - otherObjectDigest - A hash of some other object type must be
     * passed. <code>otherObjectTypeID</code> must not be empty.
     * </ul>
     * <p>
     * This cannot be used if a v1 attribute certificate is used.
     * 
     * @param digestedObjectType The digest object type.
     * @param digestAlgorithm The algorithm identifier for the hash.
     * @param otherObjectTypeID The object type ID if
     *            <code>digestedObjectType</code> is
     *            <code>otherObjectDigest</code>.
     * @param objectDigest The hash value.
     */
    public AttributeCertificateHolder(int digestedObjectType,
        String digestAlgorithm, String otherObjectTypeID, byte[] objectDigest)
    {
        holder = new Holder(new ObjectDigestInfo(digestedObjectType,
            otherObjectTypeID, new AlgorithmIdentifier(digestAlgorithm), Arrays
                .clone(objectDigest)));
    }

    /**
     * Returns the digest object type if an object digest info is used.
     * <p>
     * <ul>
     * <li>0 - publicKey - A hash of the public key of the holder must be
     * passed.
     * <li>1 - publicKeyCert - A hash of the public key certificate of the
     * holder must be passed.
     * <li>2 - otherObjectDigest - A hash of some other object type must be
     * passed. <code>otherObjectTypeID</code> must not be empty.
     * </ul>
     * 
     * @return The digest object type or -1 if no object digest info is set.
     */
    public int getDigestedObjectType()
    {
        if (holder.getObjectDigestInfo() != null)
        {
            return holder.getObjectDigestInfo().getDigestedObjectType()
                .getValue().intValue();
        }
        return -1;
    }

    /**
     * Returns the other object type ID if an object digest info is used.
     * 
     * @return The other object type ID or <code>null</code> if no object
     *         digest info is set.
     */
    public String getDigestAlgorithm()
    {
        if (holder.getObjectDigestInfo() != null)
        {
            holder.getObjectDigestInfo().getDigestAlgorithm().getObjectId()
                .getId();
        }
        return null;
    }

    /**
     * Returns the hash if an object digest info is used.
     * 
     * @return The hash or <code>null</code> if no object digest info is set.
     */
    public byte[] getObjectDigest()
    {
        if (holder.getObjectDigestInfo() != null)
        {
            holder.getObjectDigestInfo().getObjectDigest().getBytes();
        }
        return null;
    }

    /**
     * Returns the digest algorithm ID if an object digest info is used.
     * 
     * @return The digest algorithm ID or <code>null</code> if no object
     *         digest info is set.
     */
    public String getOtherObjectTypeID()
    {
        if (holder.getObjectDigestInfo() != null)
        {
            holder.getObjectDigestInfo().getOtherObjectTypeID().getId();
        }
        return null;
    }

    private GeneralNames generateGeneralNames(X509Principal principal)
    {
        return new GeneralNames(new DERSequence(new GeneralName(principal)));
    }

    private boolean matchesDN(X509Principal subject, GeneralNames targets)
    {
        GeneralName[] names = targets.getNames();

        for (int i = 0; i != names.length; i++)
        {
            GeneralName gn = names[i];

            if (gn.getTagNo() == GeneralName.directoryName)
            {
                try
                {
                    if (new X509Principal(((ASN1Encodable)gn.getName())
                        .getEncoded()).equals(subject))
                    {
                        return true;
                    }
                }
                catch (IOException e)
                {
                }
            }
        }

        return false;
    }

    private Object[] getNames(GeneralName[] names)
    {
        List l = new ArrayList(names.length);

        for (int i = 0; i != names.length; i++)
        {
            if (names[i].getTagNo() == GeneralName.directoryName)
            {
                try
                {
                    l.add(new X500Principal(
                        ((ASN1Encodable)names[i].getName()).getEncoded()));
                }
                catch (IOException e)
                {
                    throw new RuntimeException("badly formed Name object");
                }
            }
        }

        return l.toArray(new Object[l.size()]);
    }

    private Principal[] getPrincipals(GeneralNames names)
    {
        Object[] p = this.getNames(names.getNames());
        List l = new ArrayList();

        for (int i = 0; i != p.length; i++)
        {
            if (p[i] instanceof Principal)
            {
                l.add(p[i]);
            }
        }

        return (Principal[])l.toArray(new Principal[l.size()]);
    }

    /**
     * Return any principal objects inside the attribute certificate holder
     * entity names field.
     * 
     * @return an array of Principal objects (usually X500Principal), null if no
     *         entity names field is set.
     */
    public Principal[] getEntityNames()
    {
        if (holder.getEntityName() != null)
        {
            return getPrincipals(holder.getEntityName());
        }

        return null;
    }

    /**
     * Return the principals associated with the issuer attached to this holder
     * 
     * @return an array of principals, null if no BaseCertificateID is set.
     */
    public Principal[] getIssuer()
    {
        if (holder.getBaseCertificateID() != null)
        {
            return getPrincipals(holder.getBaseCertificateID().getIssuer());
        }

        return null;
    }

    /**
     * Return the serial number associated with the issuer attached to this
     * holder.
     * 
     * @return the certificate serial number, null if no BaseCertificateID is
     *         set.
     */
    public BigInteger getSerialNumber()
    {
        if (holder.getBaseCertificateID() != null)
        {
            return holder.getBaseCertificateID().getSerial().getValue();
        }

        return null;
    }

    public Object clone()
    {
        return new AttributeCertificateHolder((ASN1Sequence)holder
            .toASN1Object());
    }

    public boolean match(Certificate cert)
    {
        if (!(cert instanceof X509Certificate))
        {
            return false;
        }

        X509Certificate x509Cert = (X509Certificate)cert;

        try
        {
            if (holder.getBaseCertificateID() != null)
            {
                return holder.getBaseCertificateID().getSerial().getValue().equals(x509Cert.getSerialNumber())
                    && matchesDN(PrincipalUtil.getIssuerX509Principal(x509Cert), holder.getBaseCertificateID().getIssuer());
            }

            if (holder.getEntityName() != null)
            {
                if (matchesDN(PrincipalUtil.getSubjectX509Principal(x509Cert),
                    holder.getEntityName()))
                {
                    return true;
                }
            }
            if (holder.getObjectDigestInfo() != null)
            {
                MessageDigest md = null;
                try
                {
                    md = MessageDigest.getInstance(getDigestAlgorithm(), "BC");

                }
                catch (Exception e)
                {
                    return false;
                }
                switch (getDigestedObjectType())
                {
                case ObjectDigestInfo.publicKey:
                    // TODO: DSA Dss-parms
                    md.update(cert.getPublicKey().getEncoded());
                    break;
                case ObjectDigestInfo.publicKeyCert:
                    md.update(cert.getEncoded());
                    break;
                }
                if (!Arrays.areEqual(md.digest(), getObjectDigest()))
                {
                    return false;
                }
            }
        }
        catch (CertificateEncodingException e)
        {
            return false;
        }

        return false;
    }

    public boolean equals(Object obj)
    {
        if (obj == this)
        {
            return true;
        }

        if (!(obj instanceof AttributeCertificateHolder))
        {
            return false;
        }

        AttributeCertificateHolder other = (AttributeCertificateHolder)obj;

        return this.holder.equals(other.holder);
    }

    public int hashCode()
    {
        return this.holder.hashCode();
    }

    public boolean match(Object obj)
    {
        if (!(obj instanceof X509Certificate))
        {
            return false;
        }

        return match((Certificate)obj);
    }
}