package org.bouncycastle.asn1.cms;

import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DEREncodable;
import org.bouncycastle.asn1.DERInteger;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;

public class KeyTransRecipientInfo
    implements DEREncodable
{
	private DERInteger          version;
	private RecipientIdentifier rid;
	private AlgorithmIdentifier keyEncryptionAlgorithm;
	private ASN1OctetString     encryptedKey;

	public KeyTransRecipientInfo(
        RecipientIdentifier rid,
        AlgorithmIdentifier keyEncryptionAlgorithm,
        ASN1OctetString     encryptedKey)
    {
		if (rid.getDERObject() instanceof ASN1TaggedObject)
        {
            this.version = new DERInteger(2);
		}
		else
        {
            this.version = new DERInteger(0);
		}

        this.rid = rid;
        this.keyEncryptionAlgorithm = keyEncryptionAlgorithm;
        this.encryptedKey = encryptedKey;
	}
	
	public KeyTransRecipientInfo(
        ASN1Sequence seq)
    {
		this.version = (DERInteger)seq.getObjectAt(0);
		this.rid = RecipientIdentifier.getInstance(seq.getObjectAt(1));
		this.keyEncryptionAlgorithm = AlgorithmIdentifier.getInstance(seq.getObjectAt(2));
		this.encryptedKey = (ASN1OctetString)seq.getObjectAt(3);
	}

    /**
     * return a KeyTransRecipientInfo object from the given object.
     *
     * @param obj the object we want converted.
     * @exception IllegalArgumentException if the object cannot be converted.
     */
	public static KeyTransRecipientInfo getInstance(
        Object obj)
    {
		if (obj == null || obj instanceof KeyTransRecipientInfo)
        {
			return (KeyTransRecipientInfo)obj;
		}
		
		if(obj instanceof ASN1Sequence)
        {
			return new KeyTransRecipientInfo((ASN1Sequence)obj);
		}
		
		throw new IllegalArgumentException(
        "Illegal object in KeyTransRecipientInfo: " + obj.getClass().getName());
	} 

	public DERInteger getVersion()
    {
		return version;
	}

	public RecipientIdentifier getRecipientIdentifier()
    {
		return rid;
	}

	public AlgorithmIdentifier getKeyEncryptionAlgorithm()
    {
		return keyEncryptionAlgorithm;
	}

	public ASN1OctetString getEncryptedKey()
    {
		return encryptedKey;
	}

    /** 
     * <pre>
     * KeyTransRecipientInfo ::= SEQUENCE {
     * 	version CMSVersion,  -- always set to 0 or 2
     * 	rid RecipientIdentifier,
     * 	keyEncryptionAlgorithm KeyEncryptionAlgorithmIdentifier,
     * 	encryptedKey EncryptedKey 
     * }
     * </pre>
     */
	public DERObject getDERObject()
    {
        ASN1EncodableVector  v = new ASN1EncodableVector();

		v.add(version);
		v.add(rid);
		v.add(keyEncryptionAlgorithm);
		v.add(encryptedKey);

		return new DERSequence(v);
	}
}
