package org.bouncycastle.asn1.x509;

import java.util.Enumeration;

import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Object;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.DERTaggedObject;

public class NameConstraints
    extends ASN1Object
{
    private GeneralSubtree[] permitted, excluded;

    public static NameConstraints getInstance(Object obj)
    {
        if (obj instanceof NameConstraints)
        {
            return (NameConstraints)obj;
        }
        if (obj != null)
        {
            return new NameConstraints(ASN1Sequence.getInstance(obj));
        }

        return null;
    }

    private NameConstraints(ASN1Sequence seq)
    {
        Enumeration e = seq.getObjects();
        while (e.hasMoreElements())
        {
            ASN1TaggedObject o = ASN1TaggedObject.getInstance(e.nextElement());
            switch (o.getTagNo())
            {
            case 0:
                permitted = createArray(ASN1Sequence.getInstance(o, false));
                break;
            case 1:
                excluded = createArray(ASN1Sequence.getInstance(o, false));
                break;
            default:
                throw new IllegalArgumentException("Unknown tag encountered: " + o.getTagNo());
            }
        }
    }

    /**
     * Constructor from a given details.
     * 
     * <p>
     * permitted and excluded are arrays of GeneralSubtree objects.
     * 
     * @param permitted
     *            Permitted subtrees
     * @param excluded
     *            Excludes subtrees
     */
    public NameConstraints(
        GeneralSubtree[] permitted,
        GeneralSubtree[] excluded)
    {
        this.permitted = cloneSubtree(permitted);
        this.excluded = cloneSubtree(excluded);
    }

    private GeneralSubtree[] createArray(ASN1Sequence subtree)
    {
        // GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree (RFC 5280 sec. 4.2.1.10)
        if (subtree.size() < 1)
        {
            throw new IllegalArgumentException("sequence may not be empty");
        }

        GeneralSubtree[] ar = new GeneralSubtree[subtree.size()];

        for (int i = 0; i != ar.length; i++)
        {
            ar[i] = GeneralSubtree.getInstance(subtree.getObjectAt(i));
        }

        return ar;
    }

    public GeneralSubtree[] getPermittedSubtrees()
    {
        return cloneSubtree(permitted);
    }

    public GeneralSubtree[] getExcludedSubtrees()
    {
        return cloneSubtree(excluded);
    }

    /*
     * NameConstraints ::= SEQUENCE { permittedSubtrees [0] GeneralSubtrees
     * OPTIONAL, excludedSubtrees [1] GeneralSubtrees OPTIONAL }
     */
    public ASN1Primitive toASN1Primitive()
    {
        ASN1EncodableVector v = new ASN1EncodableVector(2);

        if (permitted != null)
        {
            v.add(new DERTaggedObject(false, 0, new DERSequence(permitted)));
        }

        if (excluded != null)
        {
            v.add(new DERTaggedObject(false, 1, new DERSequence(excluded)));
        }

        return new DERSequence(v);
    }

    private static GeneralSubtree[] cloneSubtree(GeneralSubtree[] subtrees)
    {
        if (subtrees != null)
        {
            GeneralSubtree[] rv = new GeneralSubtree[subtrees.length];

            System.arraycopy(subtrees, 0, rv, 0, rv.length);

            return rv;
        }

        return null;
    }
}
