package org.bouncycastle.asn1.x509;

import java.math.BigInteger;

import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERInteger;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.DERTaggedObject;

Class for containing a restriction object subtrees in NameConstraints. See
RFC 3280.
      
      GeneralSubtree ::= SEQUENCE 
      {
        base                    GeneralName,
        minimum         [0]     BaseDistance DEFAULT 0,
        maximum         [1]     BaseDistance OPTIONAL 
      }

See Also:
NameConstraints/**
 * Class for containing a restriction object subtrees in NameConstraints. See
 * RFC 3280.
 * 
 * <pre>
 *       
 *       GeneralSubtree ::= SEQUENCE 
 *       {
 *         base                    GeneralName,
 *         minimum         [0]     BaseDistance DEFAULT 0,
 *         maximum         [1]     BaseDistance OPTIONAL 
 *       }
 * </pre>
 * 
 * @see org.bouncycastle.asn1.x509.NameConstraints
 * 
 */
public class GeneralSubtree 
    extends ASN1Encodable 
{
    private static final BigInteger ZERO = BigInteger.valueOf(0);

    private GeneralName base;

    private DERInteger minimum;

    private DERInteger maximum;

    public GeneralSubtree(
        ASN1Sequence seq) 
    {
        base = GeneralName.getInstance(seq.getObjectAt(0));

        switch (seq.size()) 
        {
        case 1:
            break;
        case 2:
            ASN1TaggedObject o = ASN1TaggedObject.getInstance(seq.getObjectAt(1));
            switch (o.getTagNo()) 
            {
            case 0:
                minimum = DERInteger.getInstance(o, false);
                break;
            case 1:
                maximum = DERInteger.getInstance(o, false);
                break;
            default:
                throw new IllegalArgumentException("Bad tag number: "
                        + o.getTagNo());
            }
            break;
        case 3:
        {
            {
                ASN1TaggedObject oMin = ASN1TaggedObject.getInstance(seq.getObjectAt(1));
                if (oMin.getTagNo() != 0)
                {
                    throw new IllegalArgumentException("Bad tag number for 'minimum': " + oMin.getTagNo());
                }
                minimum = DERInteger.getInstance(oMin, false);
            }

            {
                ASN1TaggedObject oMax = ASN1TaggedObject.getInstance(seq.getObjectAt(2));
                if (oMax.getTagNo() != 1)
                {
                    throw new IllegalArgumentException("Bad tag number for 'maximum': " + oMax.getTagNo());
                }
                maximum = DERInteger.getInstance(oMax, false);
            }

            break;
        }
        default:
            throw new IllegalArgumentException("Bad sequence size: "
                    + seq.size());
        }
    }

    
Constructor from a given details.
According RFC 3280, the minimum and maximum fields are not used with any
name forms, thus minimum MUST be zero, and maximum MUST be absent.

If minimum is null, zero is assumed, if
maximum is null, maximum is absent.
Params:
base – 
           A restriction.
minimum – 
           Minimum
maximum – 
           Maximum/**
     * Constructor from a given details.
     * 
     * According RFC 3280, the minimum and maximum fields are not used with any
     * name forms, thus minimum MUST be zero, and maximum MUST be absent.
     * <p>
     * If minimum is <code>null</code>, zero is assumed, if
     * maximum is <code>null</code>, maximum is absent.
     * 
     * @param base
     *            A restriction.
     * @param minimum
     *            Minimum
     * 
     * @param maximum
     *            Maximum
     */
    public GeneralSubtree(
        GeneralName base,
        BigInteger minimum,
        BigInteger maximum)
    {
        this.base = base;
        if (maximum != null)
        {
            this.maximum = new DERInteger(maximum);
        }
        if (minimum == null)
        {
            this.minimum = null;
        }
        else
        {
            this.minimum = new DERInteger(minimum);
        }
    }

    public GeneralSubtree(GeneralName base)
    {
        this(base, null, null);
    }

    public static GeneralSubtree getInstance(
        ASN1TaggedObject o,
        boolean explicit)
    {
        return new GeneralSubtree(ASN1Sequence.getInstance(o, explicit));
    }

    public static GeneralSubtree getInstance(
        Object obj)
    {
        if (obj == null)
        {
            return null;
        }

        if (obj instanceof GeneralSubtree)
        {
            return (GeneralSubtree) obj;
        }

        return new GeneralSubtree(ASN1Sequence.getInstance(obj));
    }

    public GeneralName getBase()
    {
        return base;
    }

    public BigInteger getMinimum()
    {
        if (minimum == null)
        {
            return ZERO;
        }

        return minimum.getValue();
    }

    public BigInteger getMaximum()
    {
        if (maximum == null)
        {
            return null;
        }

        return maximum.getValue();
    }

    
Produce an object suitable for an ASN1OutputStream.
Returns:
      GeneralSubtree ::= SEQUENCE 
      {
        base                    GeneralName,
        minimum         [0]     BaseDistance DEFAULT 0,
        maximum         [1]     BaseDistance OPTIONAL 
      }

Returns:
a DERObject/**
     * Produce an object suitable for an ASN1OutputStream.
     * 
     * Returns:
     * 
     * <pre>
     *       GeneralSubtree ::= SEQUENCE 
     *       {
     *         base                    GeneralName,
     *         minimum         [0]     BaseDistance DEFAULT 0,
     *         maximum         [1]     BaseDistance OPTIONAL 
     *       }
     * </pre>
     * 
     * @return a DERObject
     */
    public DERObject toASN1Object()
    {
        ASN1EncodableVector v = new ASN1EncodableVector();

        v.add(base);

        if (minimum != null && !minimum.getValue().equals(ZERO))
        {
            v.add(new DERTaggedObject(false, 0, minimum));
        }

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

        return new DERSequence(v);
    }
}