package org.spongycastle.asn1.x509;

import java.util.Enumeration;

import org.spongycastle.asn1.ASN1Object;
import org.spongycastle.asn1.ASN1Primitive;
import org.spongycastle.asn1.ASN1Sequence;
import org.spongycastle.asn1.DERSequence;

/**
 * Targets structure used in target information extension for attribute
 * certificates from RFC 3281.
 * 
 * <pre>
 *            Targets ::= SEQUENCE OF Target
 *           
 *            Target  ::= CHOICE {
 *              targetName          [0] GeneralName,
 *              targetGroup         [1] GeneralName,
 *              targetCert          [2] TargetCert
 *            }
 *           
 *            TargetCert  ::= SEQUENCE {
 *              targetCertificate    IssuerSerial,
 *              targetName           GeneralName OPTIONAL,
 *              certDigestInfo       ObjectDigestInfo OPTIONAL
 *            }
 * </pre>
 * 
 * @see org.spongycastle.asn1.x509.Target
 * @see org.spongycastle.asn1.x509.TargetInformation
 */
public class Targets
    extends ASN1Object
{
    private ASN1Sequence targets;

    /**
     * Creates an instance of a Targets from the given object.
     * <p>
     * <code>obj</code> can be a Targets or a {@link ASN1Sequence}
     * 
     * @param obj The object.
     * @return A Targets instance.
     * @throws IllegalArgumentException if the given object cannot be
     *             interpreted as Target.
     */
    public static Targets getInstance(Object obj)
    {
        if (obj instanceof Targets)
        {
            return (Targets)obj;
        }
        else if (obj != null)
        {
            return new Targets(ASN1Sequence.getInstance(obj));
        }

        return null;
    }

    /**
     * Constructor from ASN1Sequence.
     * 
     * @param targets The ASN.1 SEQUENCE.
     * @throws IllegalArgumentException if the contents of the sequence are
     *             invalid.
     */
    private Targets(ASN1Sequence targets)
    {
        this.targets = targets;
    }

    /**
     * Constructor from given targets.
     * <p>
     * The vector is copied.
     * 
     * @param targets A <code>Vector</code> of {@link Target}s.
     * @see Target
     * @throws IllegalArgumentException if the vector contains not only Targets.
     */
    public Targets(Target[] targets)
    {
        this.targets = new DERSequence(targets);
    }

    /**
     * Returns the targets in a <code>Vector</code>.
     * <p>
     * The vector is cloned before it is returned.
     * 
     * @return Returns the targets.
     */
    public Target[] getTargets()
    {
        Target[] targs = new Target[targets.size()];
        int count = 0;
        for (Enumeration e = targets.getObjects(); e.hasMoreElements();)
        {
            targs[count++] = Target.getInstance(e.nextElement());
        }
        return targs;
    }

    /**
     * Produce an object suitable for an ASN1OutputStream.
     * 
     * Returns:
     * 
     * <pre>
     *            Targets ::= SEQUENCE OF Target
     * </pre>
     * 
     * @return a ASN1Primitive
     */
    public ASN1Primitive toASN1Primitive()
    {
        return targets;
    }
}