package org.bouncycastle.asn1.ocsp;

import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERBitString;
import org.bouncycastle.asn1.DEREncodable;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.DERTaggedObject;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;

public class Signature
    implements DEREncodable
{
	AlgorithmIdentifier	signatureAlgorithm;
	DERBitString		signature;
	ASN1Sequence		certs;

    public Signature(
        AlgorithmIdentifier signatureAlgorithm,
        DERBitString        signature)
    {
        this.signatureAlgorithm = signatureAlgorithm;
        this.signature = signature;
    }

    public Signature(
        AlgorithmIdentifier signatureAlgorithm,
        DERBitString        signature,
        ASN1Sequence        certs)
    {
        this.signatureAlgorithm = signatureAlgorithm;
        this.signature = signature;
        this.certs = certs;
    }

	public Signature(
		ASN1Sequence	seq)
	{
		signatureAlgorithm  = AlgorithmIdentifier.getInstance(seq.getObjectAt(0));
		signature = (DERBitString)seq.getObjectAt(1);

		if (seq.size() == 3)
		{
			certs = ASN1Sequence.getInstance(
								(ASN1TaggedObject)seq.getObjectAt(2), true);
		}
	}

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

    public static Signature getInstance(
        Object  obj)
    {
        if (obj == null || obj instanceof Signature)
        {
            return (Signature)obj;
        }
        else if (obj instanceof ASN1Sequence)
        {
            return new Signature((ASN1Sequence)obj);
        }

        throw new IllegalArgumentException("unknown object in factory");
    }

	public AlgorithmIdentifier getSignatureAlgorithm()
	{
		return signatureAlgorithm;
	}

	public DERBitString getSignature()
	{
		return signature;
	}

	public ASN1Sequence getCerts()
	{
		return certs;
	}

	/**
	 * <pre>
	 * Signature       ::=     SEQUENCE {
	 *     signatureAlgorithm      AlgorithmIdentifier,
	 *     signature               BIT STRING,
	 *     certs               [0] EXPLICIT SEQUENCE OF Certificate OPTIONAL}
	 * </pre>
	 */
	public DERObject getDERObject()
	{
		ASN1EncodableVector	v = new ASN1EncodableVector();

		v.add(signatureAlgorithm);
		v.add(signature);

		if (certs != null)
		{
			v.add(new DERTaggedObject(true, 0, certs));
		}

		return new DERSequence(v);
	}
}
